CA1115503A - Method and apparatus for moulding hydraulic cement or the like material - Google Patents

Abstract

Abstract of the Disclosure Hydraulic cement or the like is poured into a closed mould under a reduced pressure condition to a level slightly higher than a predetermined level.
Coarse aggregate and steel rodes are prepacked in the mould. After pouring the pressure in the mould is in-creased to atmospheric pressure or a higher pressure to force the hydraulic cement above the predetermined level back into the space below the level thus compacting the poured in hydraulic cement. A cushion device is provided for the pouring device. An overflow tank is connected to the mould to observe the level of the poured cement. The pressure in the overflow tank is also decreased during pouring and increased after pouring. In this way substantially all the excess water and entrained air is removed from the hydraulic cement before it is poured.
By reducing the pressure in the mould pouring of hydraulic cement into the mould is facilitated. The produces so formed are dense and have high mechanical strength.

Description

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This invention relates to methods and apparatus for moulding hydraulic substances.
Many methods and apparatus for manufacturin~ various articles from hydraulic cement and similar materials have been proposed in the past and has been used in many fields. According to these prior art methods a mix-ture of the castable substance is cast into an open mould under atmospheric pressure and after the cast substance has been hardened it is taken out of the mould. To increase the density of the cast substance, oscillation, com-pressive force or centrifugal force is applied to the cast substance or the surface of the cast article is sub~ected to a reduced pressure. Even when any one or combinations of these treatmen~s are used, it is not always pos-sible to obtain products having desired density and mechanical strength.
More particularly, in order to prepare a desired mixture it is necessary to thoroughly admix the raw materials and in order to satisfactory cast the mixture thus prepared it is necessary to add an excess quantity of water to the raw materials. Even when minute care is taken during the mixing opera-tion, it is inavoidable to entrain air bubbles into the mixture. Such ex-cessive water or entrained air results in air volds in the body of the cast article or causes it to shrink. Where curing heat is applied, ~he excess water is vapourized to form large voids. Also the entrained air increases its volume when heated thus forming large voids which are often intercon-nected to form cracks. Although many efforts have been made to remove such excess water or entrained air it has been difficult to completely remove them so that it has been difficult to obtain dense, crack and void free products. For this reason, f~r finishing .

- ' ' the surface of the cast products as described above it i5 necessary to let them stand still for one or two hours for the purpose of stabilizing the composition of the cast mixture. During this interval, the excess water oozes fro~ the cast product and collects on the surface thereof. Unless such oozed water is completely removed, surface finishing or post treat-ment should not be made. For this reason, while the casting process itself of the mixture i5 simple and ready, it takes considerable labour and time to obtain finishèd products of the desired characteristic, which is not suitable for the present day mass production which requires high speed pro-duction at low cost. The post treatment including vibration or centrifugal force generates noise thus causing public hazards. On the contrary, appli-cation of a pressure or reduced pressure can improve the quality of only the surface portion of the cast product and can not improve the quality of deep portions or cores. Of course these post treatments require special equipment, skills and additional labour and costs.
Accordingly the general object of a broad aspect of this inven-tion is to provide an improved method and apparatus for moulding hydraulic cement or the like which can obviate difficulties of the prior art method and apparatus described above.
An object of an aspect of this invention is to provide an im-proved method and apparatus for removing substantially all excess water and entrained air from the hydraulic cement before it is poured. According to the conventional method of moulding whereln the hydraulic cement is poured in the mould under atmospheric pressure although pouring can be made very easily, it is difficult to remove the excess water and en-trained air once the hydraulic cement has been poured into the mould.
According to aspects of this invention, this ob~ect can be accompllshed by reducing the pressure in the mould. Thus, when the hydraulic cement is poured into the mould its excess water and entrained air are removed readily thus assuring void free cast product. When the pressure in the mould is restored to the atmospheric pressure of a higher pressure, the ~
structure of the cast product becomes more dense. Furthermore, as a closed mould is used no surface finishing is necessary.
An ob~ect of another aspect of this invention is to make easy the pouring of the hydraulic cement into the mould. Generally, it is not easy to pour the hydraulic cement or mixture into a closed mould and such method requires a long time. ~owever, according to aspects of this inven-tion since the pressure in the mould is reduced below the atmospheric pres-sure it is possible to rapidly pour the mixture into the mould by utilizing the pressure difference on the inside and outside of the mould. Except in a case wherein coarse aggregate is prepacked in the mould it is not necessary to use any pump or other mea~s for feeding the mixture under pressure, thus greatly simplifying the apparatus. The operator i5 required only to operate valves while watching the level of the moulded mixture. In certain cases l~ead difference and an independent source of pressure are utilized for pouring, under normal moulding operations it is necessary to only reduce the pressure in the mould to a value less than the atmospheric pressure, the the pressure difference on the inside and outside of the mould is ,~ . ' . -" ~ ' sufficient to produce adequate pouring.
An ob~ect of still another aspect of thls inventlon is to plrovide an improved method and apparatus that can produce dense products having high mechanical strength. In aspects of this invention a so-called prepacking process is used wherein coarse aggregate is packed (if necessary together with steel rods) in the mould before pouring. It is already known in the art that where the prepacking process is used, it is possible to adequately arrange the coarse aggregate in the mould and to improve the strength of the moulded products thereby eliminating the limit imposed upon the specific gravity of the coarse aggregate. However, according to this process there is a tendency of forming a large number of air voids caused by the air con-tained in the closed mould. Moreover, the prepacked coarse aggregate ex-hibits a large resistance to the flow of the poured-in-mixture. Even when an open mould is used-such difficulties are unavoidable. The area in which one pourlng port can pour efficiently the mixture or cement mortar is small even when pressure is applied to the mixture during pouring by means of a pouring pump. As a result, it has been necessary to install a plurality of pouring ports at a spacing of one to two meters. For this reason, al-though the prepacking process have been used for more than 30 years it was not used to manufacture precast concrete products. I`he invention in one of its aspects fully utilizes the advantage of the prepacking process.
Thus, since the pressure in the mould is reduced it is possible to remove substantially all the air in small interstices between the grains of the coarse aggregate thus enabling to impregnate the poured mortar even in very small interstices , ~,-. ..

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Accordingly, the bonding strength between the mortar and the coarse aggre-gate is improved greatly thus increasing the mechanical strength of the product. As has been pointed out before it is possible to smoothly and readily pour the mortar not containing the coarse aggregate without any severe limits on the coarse aggregate. In the prior art method, however, the coarse aggregate should have substantially spherical shape and its grain size should lie in a predetermined range. According to aspects of this invention, it is possible to use any one of many types of the coarse aggregate for efficiently utili~ing thin desirable characteristics. Ex-cessive water contained in the mortar is preferentially absorbed by the coarse aggregate thus improving the cast product and making it easier to pour. For this reason, the area that can be efficiently poured by one pouring port is increased several times than that of the conventional method.
An object of a further aspect of this invention is to provide an improved method and apparatus for effectively removing excess water and en-trained air before pouring which are contained in a mixture having a high content of water and hence high degree of fluidity. Where the mortar ls poured into a closed mould, it is necessary to use an excess quantity of water into the mortar for the purpose of permitting it to flow through a pouring pipe without clogging the same. According to aspects of this inven-tion an improved pouring tank is used inc~uding means for removing excess water and entrained air.
An object of a still further aspect of this invcntion is to .
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provide an improved method and apparatus for moulding hydraulic cement or the like capable of uniformly pouring the mortar into a closed mould~
Even when the mortar is poured under a reduced pressure condition, where the mortar is poured into a closed mould having a considerable width, after the mortar has impregnated into areas of small resistance, the air remain-ing in the remaining portions manifests substantial resistance to the flow of the mortar.
An object of yet another aspect of this invention is to provide a method which makes it possible ot carry out the invention in a limited floor area or a structure. The size of the cast concrete products is in-creasing annually and it is necessary to manufacture in factories such huge products having sides of several meters or more. Mass production of such huge plate-shaped cast concrete products in a horizontal plane requires a large floor space. Accordingly, the invention in another aspect also pro-vides an improved method and apparatus for moulding hydraulic cement in a vertical mould, thus making lt possible to manufacture with a mass produc-tion scale in a relatively narrow floor space.
An object of another aspect of this invention is to provide relatively compact apparatus capable of smoothly pourin~ the mortar into a closed mould under a reduced pressure condition. To mould various products under a reduced pressure condition, it is necessary to use a speclally con-structed mould. ~owever!due to increased size of the products, in certain cases it is necessary to use a huge mould having one side e~ceeding several meters. Moreover, as it is necessary to construct the mould to have a mechanical strength sufficient to withstand at least the atmospheric , ' , ,,~ ~

pressure, it is necessary to use a large volume of the material. The in-ventlon in another of its aspects provides a simplified mould that can be used as a chamber for treating the mortar under reduced condition. Thus, the mould is fabricated by plates and removable sealing members and the plates are removably connected to the pouring tank flnd the source of re-duced pressure. After moulding, the mould is disassembled to subject the moulded product to a suitable curing treatment.
An object of another aspect of this invention is to provide an improved apparatus capable of moulding products having irregular surfaces or complicated construction under a reduced pressure. I~ere the product has a large and complicated construction, it is difficult to evenly distri-bute the cast ~ortar over the entire surface of the product. Moreover, such complicated construction requires using complicated sealing members for the closed mould. The invention in another of its aspects contemplates provision of improved method and apparatus capable of assuring smooth pour-ing under a reduced pressure condition for products of complicated con~
struction.
- An object of another aspect of this invention is to provide an improved method and apparatus for satisfactorily moulding tubular products or structures having openings for windows or passages or recesses. I~hen moulding such products having openings or recesses under a reduced pressure, fabrication and handling are difficult due to complicated construction and reduced pressure. According to aspects of this invention such difficulty can be obviated.
An ob~ect of yet another aspect of this invention is to provide an improved method and apparatus for forming foundations .

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; - ' ' for various buildings or the like and constructing roads. When construct-ing such foundations or roads, as it is necessary to use the ground as a portion of the mould, it is diffucult to mould the mortar under a reduced pressure condition. The invention in yet another aspect provides am im-proved method and apparatus for efficiently pourlng mortar in such appli-cations.
An object of still anothar aspect of this invention is to provide a method and apparatus suitable for repair cracks formed in concrete struc-tures and to strongly join concrete structures such as concrete pillars.
By a broad aspect of this invention a method is provided for moulding a hydraulic substance comprising aggregate and a cement and water mixture, utilizing an injection zone, a moulding zone and an overflow æone, said overflow zone being separate from the moulding zone, which comprises filling the moulding zone with aggregate, reducing the pressure in the in-jection zone, in the moulding zone and in the overflow zone to a vacuum, introducing said cement and water mixture into the moulding zone in suffici-ent excess quantity to cause said mixture to overflow from the moulding zone into the overflow zone, returning the overflow zone to at least at-mo`spheric pressure whereby at least a portion of said excess quantity of 20 said mixture in the overflow zone is returned to the moulding zone to elim-inate the voids between the aggregate in the moulding zone created by mov ing the excess water and entrained air under reduced pressure, and replac-ing said voids wibh said cement and water mixture to produce a substantial-ly void-free product, said mixture being maintained in sufficient quantity in said overflow zone to avoid the introduction of air into the moulding zone.
By another aspect of this invention, an apparatus is provided for moulding a hydraylic substance comprising an injection tank, a moulding tank, and an overflow tank, said moulding tank being adapted to contain ~. _ 9 _ .

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an aggregate, means for reducing the pressure in the moulding tank and in the overflow ZRne to a vacuum, means for introducing a cement and water mixture into the injection tank, means ~or transferring said mixture from the injection tank into the moulding tank in sufficient excess quantity to cause said mixture to overflow from the moulding tank into the overflow zone, and means for returning the overflow ~one to at least atmospheric pressure, whereby at least a portion of said excess quantity of said mix-ture in the overflow zone is returned to the--moulding tank to eliminate the voids between the aggregate in the moulding tank created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow zone to avoid the introduction of air into the moulding tank.
By yet another aspect of this invention an apparatus is provided for moulding a hydraulic substance comprising a closed injection tank, a closed moulding tank and a closed overflow tank9 said moulding tank being adapted to contain an aggregate, means for reducing the pressure in said tanks, conduit means connecting said pressure-reducing means to said tanks, an open supply tank operatively connected to the injection tank by conduit means, conduit means providing communication between said injectlon tank and said moulding tank, said conduit means containing a closed pump means which i5 also operatively connected with said pressure-reducing means, and a circulation conduit containing a pressure-regulating means, said circu-lation conduit being connected at one end to the in;ection tank and at the other end to the conduit between the moulding tank and the pump means, wherein a cement and water mixture is transferred from the open supply tank to the closed injection tank and, in turn, to the moulding tank in suffici-ent excess quantity to cause.-said mixture~:to overflow from the mol~lding - 9a -':, ; ~ , : , , . : :.~ ,, . . `' : '`:

tank into the overflow tank, and means are provlded for returning the over-flow tank to at least atmospheric pressure whereby at least 8 portion of said excess quantity of said mixture in the overflow tank is returned to the mouldin~ tank to eliminate the voids between the aggregate in the moulding tank created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mix-ture to produce a substantially void-free product, said mixture being main-tained in.sufficient quantity in said overflow tank to avoid the introduc-tion of air into the moulding tank.
By still another aspect of this invention an apparatus is pro-vided for moulding a hydraulic substance comprising an injection tank, a moulding tank, and an overflow chamber, said moulding tank being provided with double-walled end portions whic divide the moulding tank into a cen-tral moulding tank and two lateral absorption chambers, said central mould-ing tank being adapted to contain an aggregate and said lateral absorption chambers being adapted to contain an abso~ption material, said lateral cham-bers communicating with the central moulding tank9 means for reducing the pressure in the injection tank, the central moulding chamber, and the over-flow chamber, means for evacuating the lateral absorption chambers, means 20. for introducing a cement and water mixture into the injection tank, means for transferring said mixture from the in~ection tank into the central moulding tank in sufficient excess quantity to cause said mixture to over-flow from the central moulding tank to the overflow chamber and means for returning said overflow chamber to at least atmospheric prcssure whereby at least a portion of said excess quantity of said mixture in the overflow chamber is returned to the central moulding tank to eliminate the voids between the aggregate in the central moulding tank created by removing the excess water and entrained air under reduced pressure1 and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said ~i, ' ir . ~, .

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: ~ -overflow chamber to avoid the introduction of air into the central moulding tank.
By a still further aspect of this invention an apparatus is pro-vided for moulding a hydraulic substance comprising a closed injection tank, a mould adapted to contain an aggregate, and a closed overflow tank, said mould being disposed in a vacuum chamber, means for evacllating the injec-tion tank, the vacuum chamber and the overflow tank, means for introducing a cement and water mixture into the injection tank, means for transfe-rring said mixture from the injection tank into the mould disposed in the vacuum chamber in sufficient excess quantity to cause said mixture to overflow from the mould into the overflow tank and means for returnlng the over10w tank to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the mould disposed in said vacuum chamber to eliminate the voids between the aggre-gate in the mould created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free, moulded product, said mixture being maintained in sufficient quantity in said overflow tank to,avoid the introduction of air into the mould.
By a further aspect of this invention an apparatus is provided for repairing a crack in a concrete structure which comprises providing a cover plate on all sides of said crack to seal the crack from the atmosphere, provided an injection tank and an overflow tank in the vicinity of said crack, means for reducing the pressure in said crack and in the injectlon and overflow tanks, means for introducing a cement and wa~er mixture into the injection tank, means for transferring said mixture from the injection tank into the crack in sufficient excess quantity to cause said mixture to overflow from the crack into the overflow tank, means for returning the overflow tank to at least atmospheric pressure whereby at least a portion of :,. g ` ''t '.

said excess quantity of said mixture in the overflow tank i6 returned to the crack to eliminate any voids which may have been produced in the mixture, by removing excess water and entrained air under reduced pressure, and re-placing said voids with said cement and water mixture to produce a sub-stantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the crack.
By a still further aspect of this invention an apparatus is pro-vided for interconnecting different portions of a concrete structure wherein a gap exists between said concrete structure whlch comprises disposing a coarse aggregate in said gap9 providing a porous cover around said aggregate disposed in said gap, applying a thin coating of concrete to said porous cover to seal said gap, disposing an injection tank and an overflow tank in the vicinity of said gap, ~eans for reducing the pressure in said gap and in the injection and overflow tanks, means for intxoducing a cement and water mixture into the injection tank, means for transferring said mixture from the injection tank to the gap in sufficient excess quantity to cause said mixture to overflow from the gap into the overflow tank, returning the overflow tank to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the gap to elirninate the voids between the aggregate in the gap created by re-moving the excess water and entrained air under reduced pressure, and re-placing said voids with said cement and water mixture to produce a sub-stantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the gap.
By anQther aspect of this invention an apparatus is provided for moulding a hydraulic substance comprising an aggregate and a cement and water mixture, utilizing an injection tank, a moulding tank adapted to con-tain an aggregate and an overflow tank, which compr~ses means for reducing the pressure in the injection tank, in the moulding tank, and in the over-~, - 9d -. : .

ù~.3 flow tank to a vacuum~ means for introducing the cement and water mixture into the injection tank, means for transferring said mixture from the in-jection tank into the moulding tank in sufficient excess quantity to cause said mixture to overflow from the moulding tank lnto the overflow tank, and means for returning the overflow tank to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the moulding tank to eliminate voids between the aggregate in the moulding tank created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the moulding tank.
In the accompanying drawings in which:
Fig. 1 is a diagrammatic sectional view of the basic embodiment of the invention;
Fig. 2 is a diagrammatic sectional view of a modified embodiment of this invention;
Fig. 3 is a general view showing the detail of the arrangement of various component parts of another embodiment of this invention;
Fig. 4 is a diagrammatic representation of a first embodiment of the pouring apparatus;
Fi~. 5 to 11 show still another modification of the pouring apparatus;
Fig. 12 is a diagrammatic representation of a modified embodi-ment of this invention wherein a pump is used in the pouring apparatus;
Figs. 13 and 14 are diagrams showing modifications - 9e -~ .

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$ 3 of the embodiment shown in Fig. 12;
Fig. 15 is a slde view, partly in section of the pouring appara-tus utilizing means ifor spreading mortar for the purpose removing excess water and air;
Figs. 1~ through 19 show side views, partly in section, of modi-fied spreading means;
Fig. 20 is a side view, partly in section, showing the manner of packing flow resistance material in an overflow mechanism;
Fig. 21 shows a modification of Fig. 20;
Figs. 22 through 24 show still another modified overflow mechan-ism;
Fig. 25 is a diagram showing an arrangement for detecting an overflow condition by means of a mortar detector;
Figs, 26 through 28 show modified examples of the overflow mechanism;
Figs. 29 and 30 show front and side views, partly in section, of a modified overflow mechanisms for use in combination, with a vertical mould;
Fig. 31 shows a front view, partly in section, another example of the moulding apparatus utilizing a vertical mould;
Fig. 32 shows a front view, partly in section of a modification of the embodiment shown in Fig. 31;
Fig. 33 is a diagram, partly in section of another embodiment of this invention whereln the castable material is poured from under;
Fig. 34 is a diagram~atic representation, partly in section, of yet another modification of this invention - . ~ . . . . . ,. i ~,~L ~

suitable for manufacturing a cast product having a central opening;
Fig. 35 is a upper plan view of the mould shown in Fig. 34 with its upper plate removed;
Fig. 36 i9 a diagrammatic representation, partly in section, of still another embodiment of this invention which is suitable for manufactur-ing a cylindrical cast article;
Fig. 37 is a diagrammatic representation of the casting apparatus suitable for casting articles having a complicated cross-sectional configur-ation;
Fig. 38 is a similar view showing a modification of the embodi-ment shown in Fig. 37;
Fig. 39 shows another embodiment of this invention suitable for constructing a foundation of a structure or road;
Fig. 40 is a diagrammatic representation of a modification of this invention utilized to repair cracks formed in a concrete structure; and Fig. 41 through 44 are diagrams showing applications of the invention for jointing concrete or steel pillars to other concrete pillar or foundation;
Fig. 45 is a another diagrammatic side view of the invention for jointing between concrete pillars suitable for the field works;
Fig. 46 is a cross section at the intermediate of Fig~ 45.

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~ eferring now to the accompanying drawings, the basic embodiments of this invention are illustrated in Figs. 1 and 2. It is to be understood that Figs. 1 and 2 merely illustrate the principle of this invention. In the embodiment shown in Fig. 1, a reduced pressure chamber 11 independent of a mould 1 is used whereas in the embodiment shown in Fig. 2, a reduced pressure condition is created in the mould itself as wiil be described later. Each arrangement has specific advantages, More particularly, the mould 1 shown in Fig. 1 is not required to be provided with any particular sealing means whereas the arrangement shown in Fig. 2 does not require a large reduced pressure chamber-so that the arrangement as a whole can be made small and compact. Accordingly, these arrangements can be selectively used according to the Eleld of application o~ this invention.
In the embodiment shown in Fig. 1, a suitable pressure reducing device 6, e.g. a vacuum pump is connected to the reduced pressure chamber 11 through a valve 8 and a pipe 16. There is also provided a vent opening 12 normally closed by a valve 10 for communicating the lnterior of the cham-ber 11 with the atmosphere. In the modified embodiment shown in Fig. 2, the pipe 16 and the vent openlng 12 are provided to the mould 1. In this modification, the upper end of the mould 1 is closed by a lid 14 and a suitable cast mixture receiving chamber 13 having a suitable volume is in~
terposed between the lid 14 and the vent pipe 12. In each embodiment a vertical casting or pouring tube 4 is provided at the center of the :~
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mould 1J the upper end of tube 4 being connected to a mortar hopper 5 through a valve 7. Thus, when the valve 7 is opened, the castable mixture, e.g. as mortar 9 is poured into the mould. In the embodiment shown in Fig~ 1 a perforated plate 3 is inserted into the mould after coarse aggre-gate 2 has been filled for the purpose of preventing floating and dis-placement of the coarse aggregate when the mortar is poured into the mould 1. Of course, it is not necessary to use such perforated plate where coarse aggregate is not filled beforehand. l~here a reduced pressure cham-ber as shown in Fig. 1 is used, the chamber 11 should have sufficient strength and air tightness necessary to withstand against the reduced pres-sure. Accordingly, the mould 1 is required to have a mechanical strèngth only to prevent flow out of the poured morta~. On the contrary,the mould 1 used in the embodiment shown in ~ig. 2 should have sufficient mechanical strength and air tightness to withstand the reduced pressure. In the embodiment shown in Fig. 2, a sealed tank 15 is inserted in the pipe 16 for the purpose of preventing the mortar cast in the mould from flowing into the evacuating device b. ~here the coarse aggregate 2 is preloaded in the mould l as illustrated, the mixture of course comprises mortar, but where the coarse aggregate is not preloaded, the mlxture contains also the coarse aggregate.
The embodiment shown in Fig. 3 is suitable for inductrial applications. More particularly, beds 22 are provided on the upper and lower sides of the mould l which are closed by upper and bottom plates 23 and 24 respec~ively. The beds are sufficlently larger than the mould to accommodate -. ,, "

the mould. The periphery o~ the mould 1 is formed by a partition member 25 having flat abutting sur~aces 18, e.g. I or C shaped beam, and suitable packing members, not shown, are interposed between the partition member 25 and the mould 1 at the abuttin~ surfaces for providing air tight seals.
An inlet pipe 26 for the mixture is connected between one side of the mould 1 and the partition member 25 and the inlet pipe 26 is removably connected to a closed tank 27 through a connecting pipe 19 including valves Vl and V2 and a coupling 33. A conduit 30 from an open tank 29 is connected to the top of the closed tank 27 through a valve V3. To the tank 27 are also connected a vent pipe 36 including a valve V4, a reduced pressure pipe 47 which is connected to a source of reduced pressure 42 through a valve V17, an air-liquid separating tank 41 and a pipe 45, a pressurizing pipe 20 to a source of pressure 43 via a valve V15.
An indicating or overflow tank 38 positioned above the mould 1 is connected to the opposite end thereof through connecting pipes 28 and 37, valves V5 and V6 and a coupling 34. To the indicating tank 38 are . ;
also connected a vent pipe 39 including a valve V8, a reduced pressure conduit 48 including a valve V18 and connected to the air-liquid separat-ing tank 41, and a pressurizing conduit 21b including a valve Vl~ and connected to the source of pressure 43~ Another reduced pressure pipe 44 provi.ded with an intermediate valve V13 and an air inlet valve V14 is pro-vided between the air-liquid separating tank 41 and the par~ition n~ember 25.
Further, a vent pipe 46 having a valve V16 is also provi.ded for the air-liquid separating ,. ~: . , .
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J L~ , tank 41. Closed liquid tanks 41 and 41a are connected to connecting pipes l9 and 37, respectively, through valves Vg. The source of pressure 43 is connected to the liquid tanks 41 and 40a through pipes 21 and 21a and valves V10 respectively~ Vent pipes 31 including valves Vll and vent pipes 32 including valves V12 are also provided for the liquid tanks 40 and 40a. The packing members interposed between the mould 1, partition member 25 and the top plate 23 and bottom plate 24 of the beds 24 at the abutting surfaces 18 preferably comprise a dual sealing construction in-cluding a mortar sealing member and a tongue shaped air sealing member which are automatically compressed together by the atmospheric pressure when the inside of the mould 1 is evacuated thereby enhancing the sealing function. However, lf the abutting surfaces 18 were precisely finished it would not necessary to use the mortar sealing member.
The closed tank 27 is provided with stirring blades 27a for stirring the mortar admitted into tank 27~ Hemispherical or cylindrical metal wire net 51 or 5~a is provided to cover the opening of the inlet pipe 26 in the mould 1 for preventing the preloaded coarse aggregate 2 from entering into the inlet pipe 26. The closed tank 27, the indicating tank 38, and the air-liquid separating tank 41 are provided with pressure meters Ml, M2 and M3~ respectively, to display the pressure in respective tanks. Where the volume of the mould is large, 10 m3 for example, the inner end of the inlet pipe 26 is caused to extend through the coarse aggregate 2. In this case, the extension of the inlet pipe 26 is left in the cast concrete product, and the end of such extensio~ is of course covered by ,, ~ .

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cylindrical metal wire net 51a to prevent the coarse aggregate from enter-ing thereinto. Each of the closed tank 27 and the indicating tank 38 is provided with upper and lower mortar indicators 17 and 17a~ In the case of tank 27, supply of the mortar to the tank 27 from the tank 29 can be controlled by observing the level of the mortar through these indicators 17 and 17a.
The apparatus shown in Fig. 3 operates as follows. Like the conventional prepacking process, the coarse aggregate 2 iw packad in the mould 1 before casting of the mortal. For the purpose of preventing the coarse aggregate from contacting directly with the upper plate 23 of the lower bed 22 thereby causing coarse the surface of the cast element product, it is advantageous to apply a thin coating of mortar 35 on the bottom sur-face of the mould 1 and ~hen pack the coarse aggregate 2. The coarse aggregate 2 is packed to a level slightly lower than the top edge of the mould 1. Such prepacked coarse aggregate has a larger density than that of ordinary concrete product. Upon completion of the packing of the coarse aggregate 2, the upper bed 22 is mounted to cover the mould 1 and the upper and lower beds and the mould 1 are clamped together by suitable clamping means, not shown, with suitable sealing members interposed at the abutting surfaces 18. Where a tongue shaped sealing members which are held at an inclined position under normal condition are used, when the upper and lower beds 22 are clamped to the mould, the inclined sealing members are also clamped therebetween thus forming air tight seals. Moreover, when the in-side of the mould 1 is evacuated, as the upper and lower beds are urged against . . : ,.

the mould by the atmospherlc pressure, the sealing members are clamped more tightly thereby enhancing the sealing effect.
Then, while maintaining valves Vl and V5, or valves Vl, Vg and V6 or valves V99 V7 and V8 in the closed state, the valve V13 in the re-duced pressure conduit 44 ls opened to reduce the pressure in the parti-tion member 25 and hence the mould 1. The degree of pressure reduction should be high as far as possible for the purpose of removing air in the mould~ especially in the interstices in the coarse aggregate but should not be too()high in order to avoid the necessity of installing an expen-sive evacuation system. Generally, the reduced pressure is of the orderof less than 0.5 Kg/cm , preferably from 0.1 to 0.3 Kg/cm2. Concurrently with, or before or after such evacuation, the pressure in the tanks 27 and 38 is also suitably reduced, a~d a suitably blended mixture of mortar is admitted into the tank 27 from tank 29 by opening valve V3.
To observe the degree of pressure reduction of the mould 1 we have substituted a transparent member for the upper bed 22 to close the mould 1 and a fine powder was sprinkled into the mould 1 and the parti-tion member 25. Then, when the pressure reduction proceeds to a certain degree, a violent flow of the air was noted in the space between the mould 1 and the partition member 25 in-which the reduced pressure con-duit 44 opens directly, but the air in the mould 1 containing the coarse aggregate was substantially stagnant. This means that the pressure in the space between the mould and the partition member was highly reduced whereas that in the mould was not reduced so hlghly.

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Thus, an intermediate chamber of a reduced pressure is formed between the atmosphere and the mould 1 so that even when certain amount of air leaks into thls intermediate chamber, the pressure in the mould 1 will not be affected to any appreciable extent.
After confirming that the pressure in the mould 1 has been re-duced to the desired value, valves Vl and V2 are opened and the valve V17 is closed. Then, the mortar in tank 27 will be poured into the mould 1 under the pressure difference. At this time, when the valve V4 is also opened, the atmospheric pressure will cooperate with the pressure difference to pour the mortar at a higher speed thereby more efficiently pouring the mortar throughout the entire volume of the mould. However, care should be taken t`o avoid occurrence of closing phenomena (to be described later) which were confirmed by a number of field experiments performed by the inventors. For this reason, lt is important to reduce the pressure difference between the external atmospheric pressure and the pressure prevailing in the mould 1 at the time of starting the pouring operation of the mortar. Generally, a-t the commencement of pouring, it is advantageous to slowly pour the mortar contained in the closed tank 7 which is generally positioned more than 1 meter above the mould 1, under the difference in the head. Where the coarse aggregate 2 is packed in the mould 1 and the pressure in the coarse aggregate is reduced as described hereinabove, it is advantageous to decrease the pressure in the mould to a substantial degree. Then, the pressure difference between inside of the mould and the outside atmosphere increases. If the mortar were .,, .~.
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poured under such a large pressure difference, the prepacked coarse aggregate would not only flow, but also resist against the flow of the mortar. Relatively high viscosity of the mortar also decreases its fluidi-ty. Impregnation of the poured mortar into the coarse aggregate starts from the opening of the inlet pipe 26 and the mortar gradually decreases its fluidity due to dehydration and deviation caused by the reduced pres-sure. For this reason, at the time of commencing the pouring operation, closing phenomenon was noted. More particularly, at the commencement of the pouring, the cross-sec~ional area of the flow of the mortar through the coarse aggregate rapidly increases from the end of the inlet pipe 26 and the reduced pressure causes evaporation of water thus decreasing the fluldity of the remalning fine aggregate such as sand. Such fine aggregate of increased viscosity accumulates at the exit end of the inlet pipe. Moreover, such accumulat ed fine aggregate func~lons as a filter to pass only the water component of the succeeding mortar thus creating the closing phenomenon described above. When such phenomenon occured actually, we stopped th~ operation and opened the mould. Upon inspection, we found that in each case there was formed a solidified layer consisting essentially of the fine aggregate or sand at the exit end of the inlet pipe 26. When such solidified layer is once formed it is impossible to further pour the mortal in the mould so that it is necessary to open the mould so as to remove the solidified layer as well as the prepacked coarse aggregate 2. The apparatus shown in Fig. 3, however9 can efficiently pre vent occurrence of such closed condition. Means effective for this pur-pose firstly -:

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comprises the closed tank 27 in which suitable reduced pressure condition is establi6hed on the pouring or upper side. In other words, it is pos6i-ble to commence the pouring operation by maintaining substantially the same reduced pressure condition in both the mould 1 and the closed tank 27. This can be accomplished by connecting the upper side of the tank 27 to the air-water separation tank 41 through pipe 47~
The second method of preventing the occurrence of the closed condition comprise6 the steps of commencing the pouring of the mortar while preventing further decrease of the pressure in the mould 1 and then con-tinuing the pouring by rapidly increasing the pressure in the mould. Thismethod, however, requires substantial skill and can not produce cast pro-ducts of uniform quality. However, by using the closed tank 27 it is pos-sible to select any pres6ure difference between it and the mould 1. It is also possible to start to pour by using only the head difference provided by the level of the closed tank 27, So far as the pouring operation is concerned, the pouring under the head difference and the pouring under the pressure difference may be considered the same. ~lowever, quality of the product differs considerably due to the composition of the mortar and the action of gravity. Actually, however, it is important to commence the pouring by reducing the pressure difference in the mould 1 and the inlet or pouring portion for the purpose of satisfactorily pouring without creat-ing the undesirable closing condition. It is also important to form an area not filled with the coarse aggregate by covering the exit end of the inlet pipe 26 with a metal wire . ;, , " . : ~

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, net or the like as described above. With this construction, immediately after pouring the mortar is not requlred to pass through the narrow in-terstices between the coarse aggregate. Instead, the poured in mortar is allowed to expand at the exit end and then caused to flow through the in-terstices in the coarse aggretate 2. ~or this reason9 the poured mortar does not clo~ the coarse aggregate. We have substituted a transparent member for the upper bed 22 for the purpose of observing the expansion and flow condition of the poured mortar and whether the closing phenomenon occurs or not, and found that it is advantageous to suitably control the propergation of the leading end of the mortar. More particularly, it is essential to control the propergation such that the leading end moves continuously to the forward direction. Once such propergation is stopped, the moisture in the mortar will be absorbed by the coarse aggregate and removed by the reduced pressure thus causing closing phenomena. It is necessary to carefully control the pouring operation so as to maintain con-stant speed of propergation. If the speed is too fast, water and sand separate from each other, whereas if the speed is too slow the closing phenomena would be resulted due to absorption of water by the coarse aggregate. As long as the leading end of the mortar propergates at a suitable speed, immediately after the water component of the mortar has been absorbed by the coarse aggregate 2 the mortar will successively fills the narrow interstices of the coarse aggregate thus assuring dense or void free cast products.
As the pouring operation proceeds, the pouring , : ` ~
speed due to the head difference gradually decreases and finally reduces to zero. Such gradual decrease in the pouring speed can be detected by the mortar detector 17a provided for the tank 27. Such pouring condi-tion can also be supervised by providing a transparent window for the tank 27. In any case, when the pouring speed caused by the head difference decreases to a predetermined valve~ the vent valve V4 is opened to admit the atmosphere into the tank 27 to add the atmospheric pressure to the head difference thereby increasing the pouring speed. If desired, the increase in the pouring speed caused by the admission of the atmosphere may be carried out in a plurality of steps thus assuring satisfactory il-ling of the mould without accompanying the undesirable closing condition.
After the mould has been partially filled with the mortar, the valve V4 may be fully opened for continuing the pouring operation under the atmos-pheric pressure alone~ It was fould that no closing phenomenon occurs under this condition. In the arrangement shown in Fig. 3, indicating tank 38a is connected to the mould 1 on the side opposite to the pouring side at a level higher than the mould~ This indicating tank 38 is also made of transparent material or at least provided with a transparent window for enabling to o~serve the inside condition. As described above, since the inside of this tank is also under a reduced pressure condition, when valves V5 and V6 are opened during the pouring operation of the mortar, the mortar overflowing from the mould l enters into the indicating tan~.
Due to the reduced pressure prevailing in the lndicating tank 38, the mortar e~ects thereinto. Especially,when the mortar firstly enters into .~ ~ 22_ ~

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the tank 38 a vigorous ejection occurs. However, as a sufficient quantity of the mortar is poured into the mould by using the atmospheric pressure the speed of ejection is decreased. At this time, it is evident that the mould is substantially completely filled with the mortar. Where it is de-sired to pour the mortar into the mould under pressure, valves V17, V13;
V3, V18 are closed whereas valves V7 and V15 are opened at this time to apply pressure in closed tank 27 and 38 from the cource of pressure 43 thereby apply pressure to the inside of the mould 1 through mortar the contained in these tanks.
The apparatus shown in Fig. 3 can be operated continuously.
More particularly additional moulds and beds may b~ positioned above or beneath one of the beds 22 shown in Fig. 3. In this manner, by adding a suitable number of moulds and beds and by switching the connection between respective moulds and the tanks 27 and 38 by means of couplers 33 and 34, such plurality of moulds can be operated sequentially.
The pouring device can be modified as shown in Figs. 4 through 11. As has been pointed out hereinabove, lt is essential to decrease the pressure in the mould as far as possible for the purpose of eliminating excessive water and entrained air in the mixture to be poured into the mould. However, as the pressure difference between the inside and outside of the mould increases, the ingredients of the mixture begins to separate from each other~ especially at the commencement of pouring thus resulting in undesirable closing phenomena. To obviate these phenom~na it is ad-vantageous to provide a cushion action.

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In the arrangement shown in Fig. 3, this cushion action i8 provided by the closed tank 27. Thus, by establishing a suitable reduced pressure in the tank 27, ~he pressure difference b-etween the inside and outside of the mould is decreased.
In the modification shown in Fig. 4, an open tank 29 is connected at a junction 49 to the outlet conduit 19 from the closed tank 27 via a pipe 30 including a valve V3. With this modification, when the valve Vl is closed, the castable mixture or mortar contained in tank 29 is sucked up into the closed tank 27. Then by partially or completely closing the valve V3 and by opening valve Vl, the mixture in the tank 27 is poured into the mould 1.
Fig. 5 shows another embodiment of the pouring device which does not utilize a closed tank as in the embodiments shown in Figs. 3 and 4.
Thus, a cushion member 50 in the form of an inverted U shaped tube is in-cluded in the connecting pipe 19 provided with valve Vl and the free end of the U shaped tube is immersed in the open tank 29. Similar to the em-bodiment shown in Fig. 1, the source of reduced pressure is connected;to - the mould 1. In both embodiments shown in Figs. 4 and 5, the mortar is poured into the mould by the head difference between the mould 1 and the closed tank 27 or cushion member 50. However, the cons~ruction of the pouring device shown in Fig~ 5 is more simple.
In the case shown in Fig. 6, the pouring device comprises a pressure feed mechanism such as a sealed type pump 60. However pouring of the mortar is not effected directly by the pump 60 but in the same manner as in

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the embodiment shown in Fig. 4. Thus, the mortar is once sent to the closed tank 27 and then poured into the mould 1 under the head difference.
Thus the tank 27 provides the cushlon effect required.
In the embodiment shown in ~ig. 7 the pressure feed mechanism 60 is used to provide the necessary cushion effect in corporation with the closed tank 27. More particularly, in the embodiments shown in Figs.
4 to 6, the pouring speed or pressure of the mortar is goverened by the head difference between the level of the mortar in the closed tank and that of the mould 1, whereas in the embodiment shown in Fig. 7, since the pressure feed mechanism 60 is interposed between the closed tanX 27 and the mould l,the pouring speed or pressure of the mortar is goverened essentially by the pressure feed mechanism 60~ ~ccordingly, even in a case wherein there is no head difference between the closed tank and the mould, an adequate pouring speed can be assured provided that the pressure in the closed tank is sufficiently reduced.
In the modification shown in Fig. 8, a simple cylinder 52 is used to provide the cushion effect. Thus, the mortar in the open tank 29 is transferred into cylinder 5Z by means o~ a pump 60 and the head of the mortar in the cylinder 52 is used to pour the mortar into the mould 1. ~y the suitable adjustment of the opening of valve Vl and the output of pump 60 it is possible to pour under a constant head. Further, when the head is varied during the initial stage and the final stage of the pouring operation, it is possible to obtain pouring conditions suitable for such stages. I

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In still another modification shown in Fig. 9 the desired cushion effect is provided by a bellows 53 connected between the pump 60 and the mould 1. The bellows 53 is biased by a spring 54 interposed between it and a stationary member 55. The bellows 53 expands and contracts in accordance with the variation in the output pressure of the pump 60 so as to assure a constant pouring speed of the mortar. I~here the output pres-sure of the pump varies frequently about a predetermined value, it is possible to provide means which is arranged to respond to the degree of expansion and contraction of the bellows 53 for adjusting the source of low pressure 42, that is its function to the mould 1.
In the case shown in Fig. 10 the desired cushion effect is pro-vided by disposing the mould 1 at a higher level than the open tank 29 which contains the mortar. More particularly, when the pressure in the mould 1 is reduced as described above, the injection speed of the mortar into the mould 1 is goverened by the head H. In other words, the in~ection speed can be adjusted by varying the head H, and it will be clear that due to this head, the time of actual pouring is delayed than the time of re-duction in the pressure within the mould 1.
In the modification shown in Fig. 11 although the open tank 2~
is poaitioned above the closed tank 27 in the same manner as that shown in Fig. 3, the closed tank 27 is not connected with the source of pressure 43 or source of reduced pressure 42 but instead provided with only a simple vent valve 56 which corresponds to valve V4 shown in Fig. 3. In operatlon valve Vl is closed and . ~

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valves 56 and 57 are opened. Then~ the moltar ln open tank 29 flows into tank 27 by gravity and the air in tank 27 escapes to the atmosphere through valve 56. Then valves 56 and 57 are closed whereas valve Vl is opened to cause the mortar in tank 27 to flow into the mould 1 by gravity.
The partial vacuum created at this time on the upper portion of the closed tank 27 provides the desired cushion action. If the partial vacuum becomes too high to prevent effective pouring, the valve 56 is opened slightly. When the mortar enters into indicating tank 38 ~not shown in Figo 11 but is connected to the lefthand side of the mould 1) valve 56 is opened fully to~compact the mortar poured in the mould 1 by the atmospheric pressure. It will thus be clear that in the modification shown in Fig. 11, without connecting the closed tank 27 to a source of re-duced pressure a partial vacuum is created automatically in the tank 27 as the mortar is poured into the mould and that this partial vacuum pro-vides the desired cushion effect.
Figs. 12 through 14 illustrate more preferred examples of the pressure feed mechanism for use in the pouring device, wherein a circulat-ing conduit is used for returning excess castable mixture or mortar back to the closed pouring tank for ensuring adequate pouring condition as well as adequate flow condition of the mixture in the conduit. More-over, the spacings between the closed pouring tank, open tank and mould are made to be sufficiently large and the pressure feed mechanism is also used to compact the mortar after it has been poured into the mould.
In the embodiment shown in Fig. 12, a closed type mould 1 is used and the coarse aggregate 2 is packed therein.

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A closed pourlng tank 27 is connected to one side of the mould 1 through a valve Vl and a pipe 19 whereas an indicating tank 38 is connected to the other side through a pipe 28 and a valve V5. The closed tank 27 is connec-ted to an open tank 29 via a pipe 30 and a valve V3 in the same manner as in the embodiment shown in Fig. 3, and a closed pressure mechanism shown as a pump 60 is interposed between the tank 27 and the mould 1 in the same manner as in the embodiments shown in Figs. 6 and 7. A circulation con-duit 61 including a closed tank 62 utilized for pressure regulation is provided between the pipe 19 and the closed tank 27. The source of reduced pressure 42 is connected to the tank 27, pump 60 and indicating tank 38 through pipes 64, 65 and 21b respectively. These pipes are provided with valves 64v, 61v and Vg respectively. Further, tanks 27, 62 and 38 are provided with vent valves V8, respectively. In operation, after packing the coarse aggregate 2 in the mould, if desired, valves V9 and 64v are opened to connect the source of reduced pressure 42 to tanks 38 and 27 to reduce the pressure therein to a pressure of above 400 - lO0 mm Hg.
Then valve V3 is opened to suck up the mortar in tank 29 into the closed tank 27. Thereafter the pump 60 is started to pour the mortar in the tank 27 into the mould l. However, as the circulating conduit 61 is connected between pipe l9 and the closed tank 27, before valve Vl is opened the mor-tar is merely circulated through the circulating conduit 61 so that there is no fear of increasing the output pressure of the pump 60 to a danger-ous value. In other words~as it is possIble to always maiDtain a desired pouring pressure, as soon as the valve Vl is openedl the mortar is poured under an adequate condition.

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At this time it is advantageous to maintain the pressure in the mould 1 at a pressure lower than the pressure in the tank 27 by about 100 -200 mm Hg so as to assure smooth pouring of the mortar. When the mortar enters into the indicating tank 38 Erom the mould, the vent valves V8 for respective tanks 38, 62 and 27 are opened to compact the cast mortar. By operating the pump 60 while valves 61v, 64v and 65v are being closed, it is possible to increase the pouring pressure of the mortar into the mould.
The embodiment shown in Fig~ 13 is generally similar to that shown in Fig. 12 except that an inverted U shaped pipe section 66 having a suitable height is provided for pipe section 66 is connected to the c~sed tank 27 through the pressure regulating tank 62 and the circulat-ing tank 62 and the circulating conduit 61. In this case the circulating conduit 61 is connected to an intermediate point of the pressure regulat-ing tank 62, and a reduced pressure conduit 67 including a valve 67v is connected between the préssure regulating tank 62 and the source of re-duced pressure pressure 42.
In the embodiment shown in Fig. 13 when the castable mixture or mortar reaches at the level in the pressure regulating tank 62 at which the circulating conduit 61 opens the mixture is returned to the closed pouring tank 27 through conduit 61. Consequently, the pouring speed of the mortar into the mould 1 is determined essential by the difference in the levels of the opening of the conduit 61 in the tank 62 and the pipe l9 so that it is possible to pour the mortar under a desirable definite condition by selecting this level difference to a suitable ¢~

value. Where it is desired to use higher pouring pressure, the valve 61v in the circulating conduit 61 is closed thus preventing recirlation of the mortar. In this manner, it is possible to provide a definite pouring pressure irrespective of the distance between the pump 60 and the closed pouring tank 27 and open tank 29. ~his enable efficient pouring of the mortar from a distant point, for examplP a point 50 meters spaced apart.
Accordingly, it is possible to pour into a mould located at a deep position of a building or tunnel, to which a truck for conveying the mortar can not access, from the entrance of the building or tunnel.
Fin g. 14 shows still another modification of this invention where instead of using a pressure regulating tank 62 as in Fig. 13, a pressure regulating value 23 is including in the vertical portion 63 of the circulating conduit 61. The pressure regulating valve 23 is such that it opens automatically when the pressure in the pipe 19 exceeds a predetermined value thereby returning a portion of the autput of the pump 60 back to the closed tank 27.
Figs; 15 to 19 show some examples af the apparatus for removing excess water and entrained air fram the castable mixture. In the example shown in Fig. 15, a spreader 70 having a triangular cross-section is dis-posed in the closed tank 27 beneath pipe 30 from apen tank 27 (see Fig.

3). While the mortar is caused ta flow aver the surface af the spreader 70, excess water and air entrained therein are efficiently removed by the reduced created in the tank 27 by the source of reduced pressure 52 (see Fig. 3), As shown in Fig. 17 a suitable vibrator 71 may .

be provided for the spreader for enhancing the action of removing excess water and entralned air.
In the example shown in Fig. 16, lnstead of using a spreader the valve V3 is contracted as a throttle valve so as to cause tbe mortar to drop into the reduced pressure atmosphere in the closed tank~ The ex-ample shown in Fig. 18 is identical to that shown in Fig. 16 except that a vibrating mechanism 71 is mounted on the outside of the closed tank 27 so as to vibrate the same for the purpose of removing excess water and entrained air. In the example shown in Fig. 19, an inclined pipe 72 is connected to the lower end of the pouring pipe 19 through a valve l9v.
The inclined pipe is connected with the source or reduced pressure 42 (see Fig. 3) through a pipe 73 and is vibrated by a vibrating mechanism 71.
By using one of the apparatus shown in Figs. 15 to 19, as it is possible to remove excess water and entrained air from the mortar, even wehn it has a high fluidity, its fluidity is decreased during its pouring step so that it is possible to prevent such disadvantages caused by the oozing of excess water~
In the modifications shown in Figs. 20 through 23 certain im-provements are made for ensuring perfect pouring. In the arrangement shownin Fig. 3, for example, we have found that in a region 74 shown in Fig.
20, which is the end of the mould 1 connected to the indicating tank 38, the mortar is not perfectly poured~ More particularly as shown in Fig. 3, since the indicating tank 38 is connected to the source bf reduced pres-sure 42, the pressure in the region 74 is also reduced so that the mortar poured in this .;;
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region is sucked lnto the indicating tank 38, According to an aspect of this invention, in order to eliminate this difficulty a pipe 75 packed with flow resistance material 2a e.g, a coarse aggregate is interposed between the indicating tank 38 and the mould 1. As shown in Fig. 20, the coarse aggretate 2a is packed in the pipe 75 to a level slightly higher than that of the mould l. A metal wire net 76 is provided in pipe 76 the bottom of tank 38 for preventing the packed coarse aggregate 2a from filling the indicating tank 38.
In the embodimeht shown in Fig, 21 the metal wire net 76 is pro-vided in the upper portion of pipe 75.
Fig. 22 shows another embodiment which is suitable for a case where excess water still remains ln the cast mortar when :its pouring has been completed. Thus, the inner end of pipe 75 is extended in~o one end of the mould 1 and a partition plate 24 is mounted on the end of the pipe 75 thus forming an absorption chamber 80 between the partition plate 25 and the end plate 25 of the mould l. The absorption cham~er 80 is filled with a suitable absorbing material 82 e.g, sand, and is communicated with the remaining portion of the mould through a narrow gap 77 (1 mm) about the partition plate 24 for receivin~ the oo~ing water. The absorption chamber 80 is communicated with the source of reduced pressure 42 (see Fig. 3) through a pipe 81. The absorption chamber 82 is packed with fil-ter substance 82 for air and water, sand for example, Figs. 23 and 24 illustra$e another examples o~ the apparatus for preventing formation of not completely filled regions, The embodi-ment shown in Fig. 23 is identical ' - .. ~ , :
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to that shown in Fig. 22 except that a filter material ~3 comprising spongy synthetic resin, for example, is mounted in the gap 77 for passing the oozed water. In the example shown in Fig. 24 pipe 75 leading to the indi-cating chamber 38, shown in Figs. 21 - 23 is omitted, and a mortar detector 84 is mounted in the upper portion of the region where pouring is not com~
plete. In this embodiment the suction applied through the indicating tank 38 does not occur, and completion of the pouring of the mortar is detected by the mortar detector 84.
Figs. 25 through 28 show certain arrangements permitting overflow Of the mortar from the mould 1 for indicating completion of the pouring operation without using ~he indicating tank 38. In Fig. 25, the mould 1 is connected to the source of reduced pressure 42 through pipe 28 like the embodiments shown in Figs. 23 and 24, but an inverted U shaped section 85 having a substantial length is formed in pipe 28. Accordingly, after com-pletion of the pouring operation, the mortar poured into the mould has to rise through the U shaped section. By making transparent at least a por~
tion of the U shaped section or by disposing a mortar detector therein it is possible to correctly detect completion of the pouring operation. ~et the pressure in the mould can be suitably reduced by the source of reduced pressure 42. As shown in Fig. 26 such inverted U shaped section 85 may be substituted by a bellows 86. Alternatively, as shown in Fig. 27, an additional mortar detector 87 may be added to the inverted U shaped sec-tion. In the embodiment shown in Fig. 28, a coiled pipe 88 is connected between the mould 1 and the source of the reduced ~ ,~,..

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pressure 42. Where the coiled pipe 88 is made of transparent ma~erial completion of the pouring operation can be readily indica~ed.
In all embodiments described above the mould is positioned hori-zontally. However, in the embodiments shown in Figs. 29 through 33, the mould is positioned vertically. In the manufacture of cast concrete arti-cles which generally are in the form of flat plates, horizontal moulds are preferred because it is easy to load the coarse aggregate and or steel bars.
However, where the cast concrete article is especially large, a large floor space is necessary. Especially when the products are manufactured on line production system, the apparatus as a whole become extremely complicated and bulky because it is necessary to successively move along the line not only the horizontally disposed mould but also the pouring tank, the indi-cating tank, the sources of pressure and reduced pressure, etc., associ-ated with the mould.
For the purpose of eliminating these defects it has already been practiced to position the mould in the vertical position by taking into consideration the thickness of the mould relative to the available space.
- Thus, as shown in Figs~ 29 and 30 the mould 101 is held in the vertical position and a closed pouring tank 27 and a closed indicating tank 38 similar tn those described above are mounted near the opposite ends of the mould 101. These tanks are connected to a source of reduced pres-sure 42 through pipes 47 and 48, respectively and to the mould 101 respectively through pipes 26, 28 and couplings 33 and 34. Furthermore, the closed pouring tank 27 is connected to .~ .

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an open tank 29 via a plpe 30 in the same manner as in the embodiment shown in Fig. 3. Tanks 27 and 38 are also provided with vent pipes 36 and 39 including valves V4 and V8 respectively. When mortar is poured from upper into the ver~ical mould, the ~low of the mortar is generally disturbed by the coarse aggregate and the steel rods disposed in the mould with the result that voids are formed beneath the coarse aggregate and the steel rods, thus impossible to provide perfect pouring. For this reason, it is advantageous to pour the mortar into the mould through the bottom thereof~
However, where the height of the mould is large, it is necessary to pour the mortar against the large static pressure of the mortar in the mortar.
Where the mortar is poured in the mould from upper under a reduced pres-sure condition, it is possible to manufacture cast concrete articles hav-ing a height of several meters or more.
The apparatus shown in Figs. 29 and 30 and used for the upper pouring system can be simplified as shown in Fig~ 31~ Thus, by mo~mting the closed pouring tank 27 above the mould it is possible -to use the sin-gle tank 27 for pouring and indication, thus simplifying the construction.
More particularly, with ~uch simplified construction, after reducing the pressure in the tank 27 by connecting it to the source of reduced pressure, the valve V3 is opened to pour the mortar into tank 27 from tank 29. Then valves 19a and V3 are closed and valve Vl is opened for pouring the mortar into the mould from tank 27. When the mould 1 is sub-stantially filled and the pressure of the air remaining - 3~ -.-, :..

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in the mould increases, the pressure in the mould can be reduced by con-necting it to the source of reduced pressure 42 by opening valves 3a and l9a.
Although it was considered that when mortar i9 poured from upper into a vertical mould, the mortar can reach freely to the bottom of the mould without being resisted by the air in the mould. However, we have found that the poured mortar spreads about the pouring port in the upper portion of the mould and then descends downwardly as diagrammatically shown in Fig. 32, especially when the mould is loaded with coarse aggre-gate andsor steel rods. As a result, there is a tendency that the remain-ing air is sealed in the bottom portion of the mould. By constructing a portion of the vertical mould from transparent material, it was noted that when the pressure in the upper portion of the mould is reduced as described above, the air sealed in the bottom portion rised upwardly through the poured mortar, thus increasing voids therein and degrading the product. Further, this hinders smooth pouring of the mortar.
To obviate this difficulty, in the modification shown in Fig.
32, an intermediate tank 102 is connected to the bottom of the mould lOl through a pipe 1~3, and the tank 102 is connected to the source or reduced 20 pressure 42 through a pipe 104 including a valve 104v. Further, a pair of small closed tanks 105 are disposed on the opposite sides of the upper portion of the vertical mould 101. The tanks 105 are connected to the mould through valves 110 and to the source of reduced pressure ~0 through a pipe 106 and valves 106v.

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The operation of this modification is as follows. The roarse aggregate 2 is prepacked in the mould 1 and then valves Vl7, 106v, 110 and 103v are opened to reduce the pressure in tank 27 and mould 101 by the source of reduced pressure 42, whereby the air in the interstices between the coarse ag8regate 2 is removed. Then valve V3 is opened to transfer the mortar in tank 29 into tank 27. Thereafte~, valve Vl is opened to pour the mortar in tank 27 into the mould 101. Since the pres-sure in the bottom portion of the mould is also reduced by the action of the source of reduced pressure 42 through pipes 103 and 104 and valve 103v, there is no fear of sealing the air in the bottom portion and hence rising of such sealed air. Although the mortar is poured while being dehydraged and deairated, 30 minutes after completion of the pouring operation, cer-tain amount of oozing water often collects in the upper portion of the mould. In other words, where the height of the poured mortar is relative-ly large, and where the area of the upper portion of poured mortar is re-latively small, the oozed water may be separated notwithstanding of the pouring under a reduced pressure condition. Accordingly, for an interval of 30 to 60 minutes after completion of the pouring operation, valves 106v and llO as00ciated with small tanks 105 are maintained in the opened state to reduce the pressure in the upper portion of the mould 101 by the action of the source of reduced pressure 42. By supplementing the mortar from tank 27 under these conditions, it is possible to obtain solid, that is void free products irrespective of the separation of the oo~ed water.
Since the method and apparatus utilizes a reduced ~ .

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~ ~ ~ t-~pressure condition in the mould, it is also possible to obtain satisfactory products even when the mortar is poured into a vertical mould through the bottom thereof. Fig. 33 illustrates one example of such modification in which an open tank 29 containing mortar or other castable material 100 is connected to the bottom of a vertical mould through a pipe 107 including a valve 107v. An indicating tank 38 is connected to the upper plate of the mould lOl through a pipe 37 including a valve V5 and two small tanks 105 are connected to the opposite sides of the upper plates through valves llO. The small tanks 105, and the indicating tanks 38 are also connected to a source of reduced pressure respectively through pipes 106, 48 and valves 106v and Vl8. In operatlon, at first, valve 107v is closed and valve V5 is opened to reduce the pressure in the vertical mould by the action of the source of reduced pressure 42. Then valve 107v is opened to pour the mortar lO0 into the mould as shown by arrows by the pressure differ-ence on the inside and outside of the mould. Since the head of the poured mortar in the mould gradually increases the pouring speed is gradually de-creased thereby providing a type of the cushion effect. For this reason, - it is possible to minimize creation of the closed condition of the mortar at the inlet end caused by the separation of water. When the level of the poured mortar reaches a predetermined level it is possible to con-tinuously maintain the adequate pouring condition by further extending the pouring pipe 107 into the mould thereby decreasing the head difference or by increasing the vacuum in ~he mould. Moreover9 as the mortar is poured into the bottom while exhausting the upper portion of the mould, it is possible : ;, , j .
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to steadily pour the mortar without sealing the air ln the bottom portion and hence forming voids caused by rising alr as has been described in connection with the embodiment shown in Fig. 32.
The method of an aspect of this in-ention is also useful where it is desired to manufacture products having openings or recesses. I~ere large structural members are prepared by precast technique it is essential to provide openings or recesses in the structural members for the purpose of ventilation or forming windows or passages. In such a case as th'e construction of the mould becomes complicated, it becomes considerably difficult to maintain the desired reduced pressure- condition. Moreover, it is necessary to increase the mechanical strength of the mould to with-stand against the pressure difference on the inside and outside of t~e mould. Moreover, handling of such large mould is extremely difficult.
Figs. 34, 35 and 36 illustrate another embodiments of this invention suitable for such application which enable to manufacture pro-ducts'requiring moulds of complicated construction under reduced pressure condition in the same manner as simple products not including openings or recesses. These embodiments also enable to maintain the pressure in the openings or recesses at the same pressure in the solid moulded por-tion.
The mould shown in Fig. 34 comprises an outer rectangular frame111, and an inner rectangular frame 112 provided with an opening corres-ponding to the opening or recess ~ in the cast article A. These outer and inner frames are clamped between a upper plate 113 and a bottom plate' 114 for defining a chamber adapted to accommodate F'`'' 39 _ :~
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coarse aggregate 2. The chamber for moulding the product is connected to the pouring tank 27 through a pipe including a valve Vl. The tank 27 is connected to a source of reduced pressure 42 shown as a vacuum pump through a pipe 47 and a tank 41. An overflow or indicating tank 38 is also connec-ted to the mould chamber through a pipe 37 including a coupling 34 and a valve V6. The opening B is also connected to vacuum tank 41 through pipe lOg including valve 108v. The pipe 108 is also provided with a vent valve lO9v.
In operation after packing coarse aggregate in the space corres-ponding to the cast product A, valves V7, V16 and 108v are opened to de-crease the pressure in the spaces A and B and tank 27. Then valve V3 is opened to transfer the mortar into tank 27 from tank 29. The mortar transferred into tank 27 is spreaded and removed of its excess water and entrained air. Thereafter valve Vl is opened to pour the mortar into the mould. By continuously supplementing mortar into tank 29 it is possible to continuous by cast the product. Upon completion of the pouring opera-tion, the mortar enters into the indicating tank 38 via pipe 37. When~
such overflow of the mortar is detected by visual observation or by means of a suitable detector, valve Vl is closed to terminate the pouring opera-tion thereby gradually increasing the pressure in tanks 27 and 38 until finally atmospheric pressure is reached. Accordingly, the mortar ls poured into the mould under atmospheric pressure thus producing more compact and void free product. At this time the vent valve 209 is also opened so as to make the pressure in area B to be always . . .

equal to the pressure in area A. This eliminate the necesslty of providing a special sealing member to the inner ~rame 112 and of imparting a suffici-ent strength to the inner frame to withstand against a large pressure dif-ference. Moreover, after completion of the moulding operation, it is possible to readily remove the top or bottom plate 113 or 114 without being interfered by the pressure difference on the inside and outside of the mould.
Fig. 36 shows an embodiment similar to that shown in Fig. 34 ex-cept that the cast product A is a tubular article~ Although the volume of the opening B is increased greatly, the same advantageous features can be provided~ Where it is desired to obtain thin walled products e.g. cylin-ders, the coarse aggregate 2 may be substituted by fibers of metal or glass.
In addition, according to this embodiment it is possible to obtain dense tubular products without using centrifugal moulding operation which accom-panies noise.
As has been described above, in connection with the embodiment shown in Fig. 1, in accordance with an aspect of this invention it is possible to cast while the mould 1 is contained in~the reduced pressure chamber ll. Utilization of such reduced pressure chamber is especially advantageous where articles of complicated constructions are to be manu-factured. Figs. 37 and 38 illustrate such application. In the embodiment shown in Fig. 37, a hood shaped reduced pressure chamber ll is mounted on a base plate 115. Preferably a sealing member 116 is interposed between the chamber 11 and the base plate 115. The mould 120 - :: . ...

.
, ~:: - ~: .

disposed in the cha~ber 11 i8 illustrated to have a cross-section of a rail.
However, it will be clear that the construction of the mould ls not limi~ed to any particular configuration, and that it may take any irregular and complicated construction. Any conventional mould of the composite con-struction may also be used, and no air tight seal is necessary although the pressure in the mould is reduced below ~he atmospheric pressure. A closed pouring tank 27, preferably provided with means for spreading the mortar as described above,and an open tank 29 are provided for pouring the mortar 100 in tank 29 into the mould 120 through pipe 30, valve V39 tank 27, valve Vl and pipe 117. An overflow or indicating tank 38 is also connec-ted to the mould 120 through a pipe 117 including a valve V5. Tanks 27 and 38 are connected to a vacuum pump 42, or a source of reduced pressure and a vacuum tank 41 through pipes 47 and 48. As before, tanks 27, 38 and 41 are provided with vent valves 36, 39 and ll9v. Further, the vacuum tank 41 is connected to the mould 120 through a pipe 118. Of course the reduced pressure chamber 11 should have sufficient strength to with-stand the pressure difference between its inside and outside.
The apparatus shown in Fig~ 37 operates as follows. The vacuum tank 41 is connected to the reduced pressure chamber 11 through pipes 47, 48 and 118 to reduce the pressure in the reduced pressure chamber and the mould 120. When coarse aggregate 2 is prepacked in the mould 120 the air in the interstices in the coarse aggregate can be removed. Then the pressure in ~he tanks 27 and 38 si also reduced by connecting them to the vacuum tank 41. Thereafter .P, j ~

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valve V3 is opened to introduce the mortar 100 into tank 27 from tank Z9.
The mortar admitted into tank 27 is spreaded in a manner described in connection with Fig. 15 for removing excess water and entrained air. ~len, valve Vl is opened to pour the mortàr into mould 120. Thereafter, the operation proceeds in the same manner as described above. After ~he pour-ing and compacting of the cast mortar have been completed, connections 117 are removed from the cast mould and then connected to the next empty mould.
Fig. 38 shows still another embodiment of this invention which 10 is simpler than that shown in Fig. 37. In this embodiment, the closed pouring tank 27, overflow tank 38 and connections between the reduced pres-sure chamber 11 and the mould 120 are omitted. Thus, the open tank 29 and the vacuum tank 41 exhausted by vacuum pump 42 are connected directly to the reduced pressure chamber 11, and the pipe 30 including valve 121 and extending from open tank 29 opens directly in the upper plate of the reduced pressure chamber 11 and the pipe 122 leading from the vacuum tank 41 is also connected to a suitable portion of the reduced pressure cham-ber 11. The mould 123 is provided with two funnels 123 and 124 at its upper surface. One of the funnels 123 is positioned beneath the opening 20 of pipe 30 whereas the other funnel 124 is made of transparent material and a window 125 is provided for the side wall of the chamber 11 for supervising overflow of the mortar which occurs when the pouring operation of the mortar 100 has been completed~
In operation, while valve 121 is being closed9 the pressure in chamber 11 is reduced by connecting it to the vacuum chamber 41. Then valve 121 is opened to pour , ~

;: : , ~ . ' ' ,. : .

the mortar 100 in tank 29 lnto the ~ould 120 through the funl~el 123. ~om-pletion of the pouring operation can be detected by viewing overflow of the mortar in funnel 124 through the window 125. Then valve 121 is closed and vent valve ll9v is opened to compact the cast mortar by the atmospheric pressure.
The method of an aspect of this invention can also be used to a mould which is not made to be especially rigid. Fig. 39 shows such embodi-ment in which the mould 126 is constituted by a recess formed in a base 127 and a hood 90 covering the recess. Two closed pouring tanks 27 each connected to open tank 29 containing mortar 100, and a vacuum tank 41 eva-cuated by a vacuum pump 42 are provided to act in the same manner as the embodiment shown in Fig. 37. The number of the pouring tank 27 is not limited to two but may be one, three or more than three depending upon the size of the cast product. Generally speaking, the area of the mould that can be efEiciently poured with mortar Erom one pouring tank is approximate-ly 10 m . The mould 126 may be a portion of a road or the basement of a building. The bottom surface of the mould 126 is covered by an air imper-vious layer 130 e.g. an artificial ~esin film and the upper peripheral edge 130a of the film is overlayed by the bottom flange 90a of the hood 90. The mould 126 ls packed with coarse aggregate 2 and or steel bars not shown. The coarse aggregate 2 is covered by a metal wire net 128 or the like for preventing floating up or movement of the coarse aggregate.
The operation of the embodiDent is generally the same as that of previous embodiment. However, in this case it is advantageous to reduce the pressure in the hood ~ , , rJ;,I"~

90 to 0.3 Kg/cm2 or less. In some casesj lt is possible to deposit a portion of the mortar on the coarse aggregate 2 to form an overflow layer lOOa and then the pressure in the hood 90 is reduced to cause the de-posited layer to impregnate the coarse aggregate 2 Thereafter, valve 129 is opened to add the remaining portion of the mortar onto the im-2regnated coarse aggregate. According to this method, since the mortar is spreaded widely on the coarse aggregate, excess water and entrained air can be removed efficiently. Since it is possible to continuously supplement mortar into pouring tanks 27 by opening the valves V3, it is possible to cast extremely large building foundation or load in a sealed chamber and under reduced pressure~ After pouring, by breaking the vacuum in the hood 90 it is possible to COmpact the cast product thus obtaining dense and void free products. Although a completely closed rigid cubic mould is not used it is still possible to obtain well defined product because the floating up and movement of the coarse aggregate are prevented by the membér 128.
Fig. 40 illustrates a more specific and advantageous embodiment of this invention which is useful to repair cracks formed in a concrete structure. Cracks are often formed in a concrete building or the like due to deformation of the foundation or temperature variation, and such crack enlarges with time, thus causing leakage oof rain water or in the worst case r~pture of the building. Accordingly, it is necessary to promptly repair the crack. However, in the past an effective method of repairing the crack has not been available. More particularly it is common to apply a cement paste or mortar to cracks appearing on the surface of ~ .

the concrete structure, but such method can not repair the cracks formed in the inner portion of the concrete structure, and the cement paste or mortar applied only to the surface cracks will soon be broken. To obvi-ate this disadvantage~ it has recently been proposed to inject epoxide resin or the like into the cracks. Even with this met hod it is impossi-ble to completely fill small and deep cracks of complicated construction.
Such resin requires a special and expensive solvent. Further, as the resin has different physical and chemical characteristics from thos of concrete, satisfactory repair can not be expected.
As has been pointed out before, a crack 132 visible on the sur-face of a concrete structure 131 generally extends into deep portions of the structure, and at deep portions, the crack has narrow width and compli-cated configuration. In the embodiment shown in Fig. 40, a cover plate 133 having an area sufficient to cover the crack is applied. Where the crack presents in only one surface of the concrete structure only one cover plate is used whereas when the crack extends between opposite sur-faces of the structure at least two cover plates should be used. The cover plate is secured to the surface of the structure through an air tight sealing member 134, which may be a rubber tube, an adhesive tape or putty. The inside of the cover plate 133 is communicated with pouring tank 27 through valve Vl and the pouring tank 27 is connected to a vacuum tank 41 through pipe 47 and to the open tank 29 (whlch contains mortar) through a pipe 30. As before, an overflow or indicating tank 38 is con-nected to the cover plate 133. The overflow tank 38 is positioned at a level higher than a crack at the highest level. The overflow ;
,, .
.

. . .

tank 38 is provided with a vent pipe 39 and connected to the vacuum tank 41. In operation, the inside of the cover plate 133 is connected to the source of reduced pressure through the vacuum tank 41 ta remove air in the gap 132. Thereafter valve Vl is opened to in~ect mortar or paste into every portion of the gap 133. After injection, atmospheric air is admitted into the tanks 27 and 38 thus applying atmospheric pressure to the mortar or paste thus compacting the same. Thus, this embodiment enables the mortar or paste completely to fill into every detail of the gap. Such repair has been impossible by any prior art apparatus or method.
Fig. 41 shows another embodiment of this invention which is suitable for field application and does not require to use any special mould. The embodiments shown in Fig. 41 and succeeding figures are suitable to connect together a pair of concrete structures or blocks by moulding mortar between them. These embodiments are suitable to inter-connect different portions of a concrete structure, or to fill a gap be-tween the base of a machine and its foundation thus forming a rigid sup-porting structure or a force transmitting struc~ure. More particularly, when constructing a concrete structure, a building for example, it is usual to fabricate also a subground structure. In such a case, instead of dig-ging a deep opening having a depth egual to the height of several stories, in some cases concurrently with the ~abrication of the structure above the ground surface, the ground is gradually dug downwardly to successively fabricate pillars, beams or floors from the ground surface toward lower.
In such method of fabrication, it is difficult . _ . ., 6~

to perfectly fill concrete in all corners between the upper portion of a subsequently fabricated pillar and the~-bottom portion of a previously fabricated pillar. Further, as the concrete is set, oozing water collects on the upper portion of the subsequently fabricated pillar and such later fabricated pillar tends to sink. The previously fabricated upper pillar dries and shrinks so that it is inevitable to form a sllbstantial gap be-tween the upper and lower pillars. For this reason, it is usual to suitably space apart the upper and lower pillars and fill concrete in the gap after removing irregularities at the opposing surfaces. However~
there was no satisfactory method of connecting upper and lower concrete pillars by filling concrete between them, so that in many cases the opera-tor fills the gap with concrete by a hand tool. 0f course this method can not interconnect two pillars with sufficiently strong joint. More particularly, although it is possible to fill the outer portion of the gap, the inner portions will not~be completely filled with concrete. In concrete buildings it is essential to strongly joint the upper structure to the underground structure, for the purpose of providing desired strength, rigidity and safeness.
According to the embodiment of this inVentiOn shown in Fig. 41, a gap 144 is formed between the upper portion of a foundation or a pillar 141 supported thereby and the supporting member 142 for a upper structure 143~ Coarse aggregate 2 is filled in the gap 144 around steel bars or beams 145. The gap 144 is surrounded by a porous cover 147, e.g. an expanded metal, which may be applied in position by merely wrapping lt about the gap 144 and ~ ,............................ . .

the coarse aggregate contained therein. The cover is not required to be air tight or adhesive. Thereafter a relatively thin coating 148 of concrete is formed to seal the gap 144. Since the coating 148 is lined with the expanded metal it is firmly supported by the pillars. The interior of the concrete coating 148 is connected to a closed pouring tank 27 through a pipe 19 and a valve Vl and to an overflow or indicating tank 38 through a pipe 37 and a valve V5. Tanks ~7 and 38 are connected to a source of reduced pressure,:through valves and the tank 150 is also connected to an open tank 29 containing mortar through a valve V3 and a pipe 30 ln the same manner as lQ in the previous embodiments. Accordingly, this embodiment also operates in the same manner. More particularly, at first valves Vl, V5 and V3 are opened to reduce the p~essure in the gap 144 by the operation of the source of reduced pressure 42. Thereafter valve V3 is opened to transer the mortar contained in the tank 29 into tank 27. The mortar is subjected to the ac-tion of the reduced pressure to remove excess water and entrained air and then poured into the gap 144. I~en the gap 144 is filled with mortar, a portion thereof overflows into the indicating tank 38 thus informing to the operator that the pouring operation has completed. Thereafter valve V3 is closed and the pressure in tanks 27 and 38 are increased gradually to atmospheric pressure so as to compact the poured mortar. According to this embodiment, it is possible to pour mortar in all spaces in the gap and the concrete join~ thus formed has sufficient mechanical strength, and is dense and void free.
The method described in connection with Fig. 41 . ~ .: :

is also applicable where one of the members to be ~oined compri~es a metal member. Fig. 42 illustrates such application. Thus, a fitructure 152 e.g.
a steel pillar or a supporting leg of a machine, not shown, is mounted on a support or foundatlon 141 wlth a suitable gap 144 therebetween. The structure 152 is secured to the foundation by anchor bolts 151. In the same manner as in Fig. 41~ the gap is packed with coarse aggregate 2 which is surrounded by perforated cover 147. A coating of concrete or mortar 148 is applied to cover the perforated cover 147. Mortar is poured into the gap 144 in the same manner as has been described in connection with the embodiment shown in Fig. 41.
Fig. 43 shows modified concrete joints. Although in the embodi-ments shown in Figs. 41 and 42, no special mould is used, it takes a cer-tain curing time for setting the concrete of mortar cover 148. To obviate this defect, according to the embodiment shown in Fig. 43, the gap 144 be-tween the upper structure 142 and the lower structure 141 is surrounded by plates 150 of metal or wood to form a mould. An air sealing member is interposed between the upper portion of the plates 150 and the upper structure 142, whereas a mortar sealing member 156 is interposed between the lower portion of the plates 150 and the lower structure 141. ~ pipe 33 leading to the closed pouring tank 27 (see Fig. 41) and a pipe 34 lead-ing to the overflow tank 38 are connected ~o the space within the plates 150. By the same method as has been described in connection with Figs.
41 and 42, the mortar is poured into the gap 144.

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,_ The embodiment shown in Fig. 44 i8 identical to that shown in Fig. 43 except that mould plates 160 of steel or plastic are interposed between the upper structure 142 and the lower structure 141 in flush with their outer surfaces. At the interfaces between the mould plates 160 and the upper and lower structures are provided plastic filling members 159 which may comprise putty or the like. As the filling members 159 have a wedge shaped cross-sectional configuration, when the pressure in the gap 144 is reduced the filling members are pressed inwardly by the atmospheric pressure thus increasing the sealing effect.
As the mould plates 160 are secured to be flush it is possible to manufacture them beforehand in a factory of metal or concrete, thus enabling the formation of the concrete joint in a short time.
Figs~ 45 and 46 show a modification of the embodiment shown in Fig. 43. However the embodiment shown in Figs. 45 and 46 are improved to be more suitable for practical application. More particularly, in the embodiment shown in Fig. 43 it is necessary to form the mould con-stituted by plates as a split type so that it is neces~ary to provide a suitable sealing member between split halves. In the embodiment shown in Figs. 43 and 44, the mould plates is divided into a plurality of unit plates 164 of the same number as the number of side faces o the lower structure 141. Sealing members similar to sealing members 155 and 156 sho~m in Fig. 43 are provided between the upper and lower ends of respec-tive unit plates 150 and the upper and lower structures 142 and 141.
Angle corner members 161 made of rubber or soft synthetic resin are pro-vided to . " .;, , : :; :~:: ,,: . , :.;" : , :

cover corners between ad~acent longltudinal edges of the unit plates 164.
Opposing unit plates 164 are connected together by t1e bars 162 thus form-ing a closed mould. Although tie bars 162 remain in the cast concrete joint, as they are used merely to assemble the closed mould, the tie bars may have relatively small diameter~ The operation and arrangement of the pouring tank 27, indicating tank 38 and the source of reduced pressure are the same as has been described with reference to Fig. 41.
To have better understanding of aspects of this invention some examples are given.
Example 1 Coarse aggregate consisting of crushed stone having a grain size of 10 to 20 mm (specific gravity 2.6) was packed in the mould 1 shown in Fig. 1 and then the perforated plate 3 was placed on the coarse aggregate 2. The pressure in the chamber 11 was reduced to 0.1 Kg/cm by the opera-tion of the pressure reducing mechanism 6. Cement mortar consisting of a mixture of 91 Kg/m3 of cement, 791 Kg/m3 of sand, 356 Kg/m3 of water, and 15.8 ~/m3 of a dispersion agent and having a flow rate of 17.8/sec. and a specific weight of 1.962 Kg/,C was poured in hopper 5. Then the valve 7 was opened to pour the mortar into the mould 1. Pouring was continued for 2 to 3 seconds, and the valve 7 was closed when the level of the mortar rised 10 mm above the perforated plate 3. Then valve 10 was opened to restore the pressure in the reduced pressure chamber to the atmospheric pressure for forcing the mor~ar above the perforatéd plate 3 into the mould 1.
The cast concrete block was subjected to a curing `~ - 52 -, .

:

treatment for 7 days at a temperature of 20C in wet air. The resulting product had a compression strength of 292 ~g/cm2 whereas a concrete block manufactured by the conventional prepacking process utillzing the same coarse aggregate and the same curing treatment had a compression strength of 252 Kg/cm2 showing substantial increase in the compression strength.
Further, the surface appearance of the product was excellent.
Example 2 Apparatus identical to that used in Example 1 was used. Light coarse aggregate produced at ~aruna and having a grain size of less than 20 mm and a specific gravity of 0.8 was used. Mortar consisting of 960 Kg/m3 of cement, 78 Kg/m3 of light fine aggregate having a particle size of less than 1 mm, 533 Kg/m3 of water, and 4.8 Kg/m3 of a dispersion agent and having a W/C ratio of 5.7% flow rate of 16.0/sec. and a specific weight of 1.58 Kg/J~ was poured into the mould under a reduced pressure of 0.1 Kg/cm until the level of the mortar reached a level a~out 30 mm above the perforated plate 3. Thereafter valve 10 was opened to push back the mor-tar to the space beneath the perforated plate thus producing a dense con--crete block. After steam curing for ~ hours at a temperature of 60C, compression strength of 80 Kg/cm was obtained. On the other hand the concrete block prepared by the conventional prepacking process and utiliz-ing the same light coarse aggregate and the same curing condition as in Example 1 showed a specific weight of 1.35 and a compression strength of 43 Kg.cm2. This shows that the compressiOn strength was increased greatly.

Example 3 The method of Examples 1 and 2 was repeated except that a light coarse aggregate produced at Oshima and having a grain si~e of from 10 to 20 mm (specific gravity 1.6) ~as used. In this Example mortar was rose 20 mm above the perforated plate 3. The resulting concrete block had a specific weight of 1.91 Kg/~ and a compression strength of 228 Rg/cm .
On the contrary, a concrete block manufactured by the conventional pre-pack method and by utilizing the same material and curing condition as this example showed a specific weight of 1.743 Kg/~ and a compression strength of 186 Kg/cm .
Example 4 The apparatus shown in Fig. 2 was used and the mould had di-mensions of 50 ~ ~50 x 650 cm. One side of the mould 1 was made of a transparent plate for observing the manner of rising the mortar during pouring. The same coarse aggregate and mortar as in Example 2 were used.
Only a single pouring pipe 4 was used. During pouring the pressure in the mould 1 was reduced to 0.1 Kg/cm2 and the pressure in the indicating tank 13 was also reduced slightly. It was noted that the mortar rises with its level always maintained horizontal. The time required for the pouring operation was 20 seconds.
When the mortar is cast by the conventional method it is necessary to use two or more pouring tubes and a pouring time of 2 to 3 minutes. On the other hand, according to an aspect of this invention it is possible to pour in shorter time with a single pouring tube be-cause the pressure in the mould is reduced at the time of pouring.

::,, : .

When vibration is imparted to the mould for one to two seconds after pouring and while the mould is still subjected to reduced pressure, it was noted that air voids along the inner surface of the mould were com-pletely eliminated. It will thus be noted that the vibration imparted not only enhances impregnation of the mDrtar into the structure o~ the coarse aggregate but also imprcves the surface characteristic o~ the product.
When subjected to the same curing treabment as in Example 2, the product had a specific weight of 1.41 Kg/~ , and a compression strength of 81.5 Kg/cm~ which is to be compared with 43.5 Kg/cm2 of the product manu-factured by the conventional method.
The surface condition of the product was also inspected. The product of the conventional method contained 3 to 5 voids or recesses of 2 to 10 mm per lOOcm2 of the surface, but in the product produced by the method of an aspect of this invention the number and size of such voids were reduced greatly.
Example 5 In this example, the apparatus shown in Fig. 3 was used. A
layer of mortar having the same composition as the mortar moulded subse-quently (to be described later) was formed in a closed mould having di-mensions of 1400 x 600 x 150 mm, and then coa~se aggregate comprising No. 5 crushed stone (having a diameter of 13 to 20 mm and a specific gravity of 2.6 was packed ln the mould. The volume of the interstices in the coarse aggregate was 55.4~ . Thereafter the upper bed was mounted on the mould.
Mortar was prepared by admixing 1 part of cement, l part of sand having a particle size of less than 2.5 mm, 0.44$ part of ~' ' ! ', ' ' ' ' '~
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water, 0.25% based on the volume of the cement of a dispersion agent and 0.01% of aluminum powder. The mortar had a flow rate of 26 seconds. The mortar in the open tank 29 was transferred into a closed pouring tank 27 made of transparent acrylic resin. The pressure in the tank 27 and the mould was reduced to -70 cm Hg and then pouring of the mortar was commenced.
Thereafter, the pressure in the tank 27 was gradually decreased to -60 cm Hg, then to - 55 cm Hg, and when the pouring opera~ion is completed, that is when the mortar overflowed into tank 38, the pressure in the tanks 27 and 38 was restored to normal atmospheric pressure. When a pouring tube lQ having an inner diameter of 2.5 cm was used, the time required for pour-ing was 5 minutes and 45 seconds. One hour after pouring, the cast mor-tar was cured by increasing the temperature from 7C at a rate of 20~C/
hour and maintained at a temperature of 60C for four hours. Thereafter the cured product was removed from the mould. Immediately after such re-moval, the product had a compression strength of 183 Kg/cm which was increased to 293 Kg/cm after one week and to 380.5 Kg/cm after 4 weeks.
The surface condition was flat like a mirror thus requiring no surface finishing. A cylindrical sample was cut from the product and its internal structure was examined~ It was noted that the mortar was completely filled in the coarse aggregate thus providing dense and void free struc-ture.
Example 6 Again the apparatus shown in Fig. 3 was used. ~ortar similar to that used in Example 5 was prepared except that aluminum powder was not used. The mortar had a flow rate of 24.6 seconds. This mortar was poured into the mould 1 ,:

:.

, - -and the closed tank 27 while the pressure in this was reduced to -65 cm Hg. Pouring was continued while the pressure in tank 27 was stepwisely reduced to -50 cm Hg and -45 cm Hg. When the mortar appeared in the indi-cating tank 38, pouring of the mortar was terminated and the pressure in the tank 27 was restored to the stmospheric pressure. The time required for pouring was 4 minutes and 5 seconds.
Immediately after pouring the concrete block was cured. Thus the temperature was elevated at a rate of 20C per hour and maintained at 60C for 4 hours. When removed from the mould the product showed a compression strength of 175/cm2 which was increased to 227 kg/cm after 7 days and to 323 Kg/cm2 after 4 weeks. The surface appearance and inside structure were similar to those of Example 5.
Example 7 In this Example, the apparatus shown in Fig. 3 was used.
Crushed stone No. 4 having a grain si~e of 20 to 30 mm and a specific gravity of 2.6 was used as th~ coarse aggregate 2 packed in the mould 1 to leave a unoccupied space o~ 52.2~ in the mould. The mortar used comprised 1 part of cement, 1.5 parts of sand, 0.60 part of water and 1.0% of a dehydrating agent which was used to provide the desired strength as far as possible, and the mortar had a flow speed of 34 seconds.
After reducing the pressure in the mould 1 20 - 70 cm Hg and the pressure in the closed tank 27 to -65 cm Hg, pouring of the mortar was commenced.
Pouring was continued while the pressure in tank 27 was increased to -55 c.m Hg then to -35 cm Hg and when the mortar appeared in the indicating tank 38, pouring was terminated and the pressure in tank 27 was increased to the atmospheric '' ', ' ', ~ ; ~ ' ~"'';''''`'' ':

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pressure. The total time requlred for the pouring was 3 minutes and 8 seconds. Then the cast block was subjected to the same curing treatment as in Example 6 and then removed from the mould to obtain a product. The surface appearance of the product was the same as that of previous exam-ples, and only few small voids were noted insidP the product. These re-sults show that the product of this example has much excellent properties than a product preparPd by the conventional prepack process wherein vi-bration was applied to the mould, and the mortar was poured under a pres-sure of 3 Kg/cm2 through a plurality of parallel pouring pipes spaced each other by 20 cm.
Example 8 Again the apparatus shown in Fig. 3 was used. The light coarse aggregate having a grain size of larger than 15 mm and a fipecific gravity of 1.2, which is the same as that used in Example 4, was used. The com-position of the mortar was 1 part (all in weight ratio) of cement, 0.1 part of perlite, 0.575 part of water and 0.05 part of dehydrating agent.
lhe pouring of the mor~ar was started with the pressure in the mould 1 and the closed tank 27 reduced as described in Example 7. Then the pour-ing was continued while the pressure in the closed tank 27 was increased to 50 cm Hg and then -30 cm Hg. The pouring was completed within a per-iod of about 4 minutes. Thereafter the cast block was sub~ected to a steam curlng treatment for 4 hours to obtain a product. rrhe compression strength of the product was about 80 Kg/cm2 immediately after removal from the mould, and increased to 110 Kg/cm2 after 7 days and 140 Kg/cm after

4 weeks. It was found that the mortar .

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impregnated lnto substantially all interstices of the light coarse aggre-gate.
Example 9 Again the apparatus shown in Fig. 3 was used. The same coarse aggregate and mortar as those disclosed in Example 6 were used and the mortar was poured under the same conditions as in Example 6. Then the pressure in tanks 27 and 28 was increased to about 5 Kg/cm2 by the source of pressure 43, thus completing the pouring operation. The cast block was subjected to the same curing treatment as in Example 6 and then re-moved from the mould. The compression strength of the product immediately after removal from the mould was 228 Kg/cm2 which was increased to about 373 Kg/cm2 after 7 days and to 466 Kg/cm2 after 4 weeks which is much higher than that shown in Example 6.
Example 10 This example relates to the repair of cracks shown in Fig. 40.
The crack 132 had a length of 188 cm on~one surface of a concrete wall and obliquely extended toward the opposite surface. Plates 133 having a length of 2 meters were applied to cover the crack and the peripheries of the plates were air tightly sealed by means of an adhesive tape. The pressure 20 in the crack was reduced to 0.15 Kg/cm2 by means of the vacuum tank 41 and then a cement paste prepared by admixing 5 parts of Portland cement and 2 parts of water was poured into the crack from open tank 29 through closed tank 27. When the poured paste appeared in the indicating tank 38 pouring of the pasté was terminated. Then the valves V~ and V8 in the vent pipes 36 and 39 were opened gradually to restore the pressure in tanks 27 and 38 to the atmospheric ~ 59 .. ,: " ' i : :~

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pressure. After setting the poured cement paste the plates 133 were re-moved.
7 days after repair an opening was drilled in the direction of the crack to inspect the manner of filling the crack and it was found that the cement paste had impregnated substantially all portions of the crack.
Example 11 A crack having a maximum width of 11 mm and extended through the thickness of a concrete structure 131 was air tightly sealed by applying cement mortar to the surface portion the crack and then curingO The pres-sure in the crack was reduced to 0.12 Kg/cm2 and then mortar prepared by admixing 5 parts of cement, 5 parts of sand and 2.5 parts of water was poured into the crack. Where the crack had a length of 200 cm and a depth of 350 mm, the time required for the pouring was about 1 minute. There-after, the pressure in the crack was increased in the same manner as in Example 10 and the layer of the cement mortar firstly applied was removed.
10 days after an opening was drilled through the concrete structure in the direction of the crack and it was found that the crack was substantially completely filled.
Example 12 This example relates to the embodiment shown in Fig. 41.
The foundation pillar 141 had a square cross-sectional configura-tion in which the length of one side was 1200 mm. The coarse aggregate 2 used was No. 4 crushed s~one having a ,specific gravity of 2.6, and the gap 144 was surrounded by an expanded metal 147. A mortar layer 148 .
'. ' ' ~' `' rB~

was applied to the outside of the expanded metal 147 to a thickness of 20 mm. After setting the mortar layer, the pressure in the gap 144 was reduced to 0.2 Kg/cm2~ and mortar prepared by admixing 100 parts of cement, 100 parts of sand and 45 parts of water was poured into the gap 144. When the mortar appeared in the overflow tank 38 positioned 1 meter above the gap 144, the pouring of the mortar was terminated. Then the pressure in tanks 27 and 3~ was increased gradually to the atmospheric pressure.
The filled gap was maintained at normal temperature for 28 days and the strength of the joint was measured to be 330 Kg/cm . By drilling a hole through the joint it was found that all interstices in the coarse aggregate were filled with the mortar.
Example 13 This example relates to the embodiment shown in Fig. 42. The foundation 141 shown in Fig. 42 had a square cross-sectional configuration in which the length of one side was 1000 mm, and the height of the gap 144 was 100 mm. The time required to fill the same mortar as in Example 12 in the gap 14~ was 3 minutes, and the joint thus obtained was quite satis-factory.

Example 14 This example relates to the embodiment shown in Fig. 43 except that the coarse aggregate was not prepacked. After reducing the pressure in gap 144 to 0.1 Kg/cm , a concrete mixture was poured therein through pipe 151 by means o a concrete pump. The time required for the pouring was 5 minutes. An opening was drilled through the interface between the joint and the foundation 142 for , ...

. - , . . . .

. , t;~
.

inspecting the inside structure and it was found that the mortar substanti-ally completely filled the gap.
Example 15 This example relates to the embodiment shown in Fig. 44. con-crete moulded plate mem~ers 160 each having a thickness of 15 mm were applied to surround the gap 144 and putty was used as sealing members 159.
Coarse aggregate consisting of No. 4 crushed stone described above was prepacked in the gap 144. After reducing the pressure in gap 144 to 0.2 Kg/cm , cement mortar similar to that used in Example 12 was poured into the gap 144 to form a joint. The interface between the joint and the upper pillar 142 was drilled for inspection. It was found that a dense struc-ture similar to those of Examples 12 to 14 was formed.
Example 16 This example relates to the embodiment shown in Figs. 45 and 46. Rubber corner members 161 having a thickness of 15mm and tie bars 162 having a diameter of 9 mm were used to assemble plates 164 into a mould. Thereafter the same process steps as in Example 15 were followed~
- to obtain a joint. It was found that the joint was strongly bonded to the upper and lower structures 142 and 141.
We have also modified the embodiments shown in Figo 3, 12 - 14 and 29 - 33 such that the pouring side thereof was changed to that shown in Figs. 4 to 11, that spreading means shown in Figs. 15 to l~ were associated w~th the pouring tank 27, that the overf-ow tank 38 side shown in Fig. 3 was changed to that shown in Figs. 25 to 28, and that the pipe leading to the overflow tank was changed to those shown in Figs. 20 to 24.
In each case, it was '~ - 62 : . , ' .
'' ' .:

r,3 confirmed that so long as the pressure in the mould ls reduced to a pressure less than 0.8 Kg/cm , the mechanical strength of the cast product could be improved greatly, and that maximum improvement could be obtained when the pressure is decreased below 0.7 Kg/cm . Accordingly, it is ad-vantageous to use a vacuum higher than these values in all cases, the maximum vacuum being determined by the design and operating conditions of the apparatus. Further, it was found that the radius of the area that can be effectively poured with a single pouring tube varies depending upon such factors as the inside diameter of the pouring tube, the flow rate and composition of the mortar, the grain si2e and characteristic of the prepacked coa~se aggregate. Where the inner diameter of the pouring tube is 25.4 mm and where No~ 5 crushed stone is used as the coarse aggregate, the radius of the area in which satisfactory pouring is possible by a single pouring tube ranges from 2 to 3 meters. Generally speaking, a sin-gle pouring tube is sufficient for an area up to 10 m2.

,

Claims (135)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of moulding a hydraulic substance comprising aggregate and a cement and water mixture, utilizing an injection zone, a moulding zone and an overflow zone, said overflow zone being separate from the moulding zone, which comprises filling the moulding zone with aggre-gate, reducing the pressure in the injection zone, in the moulding zone and in the overflow zone to a vacuum, introducing said cement and water mixture into the moulding zone in sufficient excess quanity to cause said mixture to overflow from the moulding zone into the overflow zone, return-ing the overflow zone to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow zone is returned to the moulding zone to eliminate the voids between the aggregate in the moulding zone created by moving the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow zone to avoid the in-troduction of air into the moulding zone.

2. The method of claim 1, wherein the overflow zone is posi-tioned higher than the moulding zone.

3. The method of claim 1, wherein the overflow zone is a separate overflow tank which is positioned higher than the moulding zone.

4. The method of claim 1, wherein the injection zone is re-turned to at least atmospheric pressure at the same time as that of the overflow zone.

5. The method of claim 1, wherein the area at the inlet to the moulding zone from the injection zone is increased to provide a smooth transition between said zones and reduce the tendency of the aggregate to block and reduce the effective area of transition between said zones.

6. The method of claim 1, wherein the injection zone is dis-posed above the moulding zone.

7. The method of claim 1, wherein the zone adjacent the moulding zone is evacuated, so that said moulding zone is subjected to a vacuum within the moulding zone and a vacuum surrounding the moulding zone.

8. The met hod of claim 7, wherein the zones adjacent the moulding zone are closed tanks disposed between the moulding zone and the injection and overflow zones, respectively, and the pressure in said closed tanks is reduced prior to introducing the cement and water mixture into the moulding zone and increased after the completion of said introduction and said cement and water mixture is introduced into said moulding zone through said closed tank.

9. The method of claim 1, wherein the injection zone and the moulding zone are closed zones and the pressure difference between the zones is regulated to control the flow of the cement and water mixture from the injection zone to the moulding zone.

10. The method of claim 1, wherein the pressure in the moulding zone is reduced to less than 0.8 Kg/cm2.

11. The method of claim 1, wherein the pressure in the moulding zone is reduced to less than 0.7 Kg/cm2.

12. The method of claim 1, wherein coarse aggregate is prepacked in the moulding zone.

13. The method of claim 2, wherein said coarse aggregate is selected from the group consisting of crushed stone and gravel.

14. The method of claim 2, wherein said coarse aggregate com-prises lightweight coarse aggregate.

15. The method of claim 1, wherein the cement and water mixture is strongly bonded to the inner surface of the moulding zone.

16. The method of claim 1, wherein the moulding zone is air-tight sealed by a sealing member, and the cement and water mixture is sequentially poured into the moulding zone to substantially fill the voids created by removing excess water and entrained air from the mixture under reduced pressure.

17. The method of claim 1, wherein a cushioning effect is achieved by providing a reduced pressure on the cement and water mixture, said mixture being disposed intermediate the injection zone and the point of introduction of the cement and water mixture into the moulding zone, thereby alleviating the pressure difference between the inside and outside of said moulding zone.

18. The method of claim 17, wherein said cushioning effect is achieved by providing a closed tank which is operatively connected be-tween the injection zone which houses the cement and water mixture and moulding zone, the pressure in said closed tank being reduced at the time of introducing the cement and water mixture into the moulding zone and in-creased after the completion of said introduction, and said cement and water mixture is introduced into said moulding zone through said closed tank whereby said mixture is subjected to the reduced pressure in said closed tank.

19. The method of claim 18, wherein the injection zone con-taining the cement and water mixture is open to the environment and is connected to said closed tank by a pipe for transferring said cement and water mixture to said closed tank.

20. The method of claim 18, wherein said closed tank is vibrated for spreading the cement and water mixture and for removing excess water and entrained air from the cement and water mixture,

21. The method of claim 1, wherein pressure feed means are pro-vided downstream of the injection zone and circulating passage provides communication between the downstream side of the pressure feed means and the injection zone whereby when the pressure of the cement and water mix-ture on the downstream or output side of the pressure feed means exceeds a predetermined value, said cement and water mixture is returned to the upstream or input side of the pressure feed means through said circulating passage.

22. The method of claim 21, wherein the circulating passage is provided with a closed tank and wherein the pressure in said closed tank can be reduced.

23. The method of claim 22, wherein said circulating passage leading to the input side of said pressure feed means is open at an in-termediate point of the length of said closed tank whereby said cement and water mixture is introduced into said mould under the head difference be-tween said intermediate point and said mould.

24. The method of claim 21, wherein the pressure is measured in the circulating passage for returning the cement and water mixture to the input side of the pressure feed means from the output side thereof, whereby the cement and water mixture can be introduced into the moulding zone at a pressure less than a predetermined value.

25. The method of claim 1, wherein the overflow zone is a closed zone and wherein the overflow zone is connected to the moulding zone through a pipe which is prepacked with a material which resists the flow of the cement and water mixture.

26. The method of claim 1, wherein the cement and water mixture is introduced into the closed moulding zone while it is held in a vertical position.

27. The method of claim 7, wherein the zone adjacent the mould-ing zone is reduced during the moulding process and increased after the moulding process.

28. The method of claim 1, wherein the injection zone, the moulding zone and the overflow zone are closed zones and said closed moulding zone is formed to surround a crack disposed in a concrete struc-ture said cement and water mixture being introduced into said crack.

29. The method of claim 1, wherein the injection zone, the moulding zone and the overflow zone are closed zones and said closed mould-ing zone is formed to surround a gap disposed between a pair of concrete structures, said cement and water mixture being introduced into said gap.

30. The method of claim 3, wherein the overflow tank is trans-parent or provided with a transparent window and the quantity of overflow into the overflow tank is observed and controlled to avoid the introduction of air into the moulding zone when a quantity of the overflow from the over-flow tank is reintroduced into the moulding zone.

31. The method of claim 1, wherein after moulding the product is subjected to a curing treatment.

32. The method of claim 1, wherein after the moulding zone is filled with aggregate, a perforated plate is inserted into the moulding zone for preventing the floating and displacement of the aggregate when the cement and water mixture is introduced into the mould.

33. The method of claim 1, wherein in order to eliminate the occurrence of a coarse surface in the moulded product, a thin coating of the cement and water mixture is applied to the bottom of the mould and then the aggregate is packed in the mould to a level slightly lower than the top edge of the mould.

34. The method of claim l,wherein the cement and water mixture is introduced from the injection zone to the mouldlng zone by a pressure difference.

35. The method of claim 1, wherein when the speed of introduc-tion of the cement and water mixture into the moulding zone decreases the injection zone is open to atmospheric pressure to increase the speed of introduction of said mixture.

36. The method of claim 1, wherein the speed of introduction of the cement and water mixture from the injection zone into the moulding zone is determined by the head difference between the injection zone and the moulding zone.

37. The method of claim 1, wherein the speed of introduction of the cement and water mixture from the injection zone into the moulding zone is controlled by a pressure feed means.

38. The method of claim 37, wherein the speed of introduction of the cement and water mixture from the injection zone into the moulding zone is maintained constant by varying the pressure of the pressure feed.
means.

39. An apparatus for moulding a hydraulic substance comprising an injection tank, a moulding tank,and an overflow zone, said moulding tank being adapted to contain an aggregate, means for reducing the pressure in the moulding tank and in the overflow zone to a vacuum, means for in-troducing a cement and water mixture into the injection tank, means for transferring said mixture from the injection tank into the moulding tank in sufficient excess quantity to cause said mixture to overflow from the moulding tank into the overflow zone, and means for returning the overflow zone to at least atmospheric pressure, whereby at least a portion of said excess quantity of said mixture in the overflow zone is returned to the moulding tank to eliminate the voids between the aggregate in the moulding tank created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free produce, said mixture being maintained in sufficient quantity in said overflow zone to avoid the introduction of air into the moulding tank.

40. The apparatus of claim 39, wherein the overflow zone is positioned above the moulding tank.

41. The apparatus of claim 40, wherein a perforated plate is disposed between the overflow zone and the moulding tank.

42. The apparatus of claim 39, wherein the overflow zone is a separate overflow tank which is positioned higher than the moulding tank.

43. The apparatus of claim 39, wherein the moulding tank and the overflow zone are disposed in a closed container and the means for reduc-ing the pressure in the moulding tank and the overflow zone is a vacuum means which is operatively connected with the closed container.

44. The apparatus of claim 43, wherein the closed container is provided with a vent means which is closed by a valve means operatively associated therewith.

45. The apparatus of claim 42, wherein the overflow tank is provided with a vent means which is closed by a valve means operatively associated therewith.

46. The apparatus of claim 39, wherein a means is disposed at the point of introduction of the cement and water mixture to the moulding tank from the injection tank, said means functioning to increase the area at the inlet to the moulding tank to provide a smooth transition between the injection tank and the moulding tank and to reduce the tendency of the aggregate to block and reduce the effective area of transition between said tanks.

47. The apparatus of claim 46, wherein said means is a screen-like member.

48. The apparatus of claim 42, wherein the injection tank is disposed above the moulding tank.

49. The apparatus of claim 39, wherein the moulding tank is surrounded by an enclosure, and means are provided for evacuating the en-closure, said enclosure functioning as an intermediate chamber of reduced pressure formed between the atmosphere and the moulding tank, thereby protecting the environment in the moulding tank.

50. The apparatus of claim 42, wherein the injection tank is a closed tank and means are provided for evacuating said injection tank.

51. The apparatus of claim 39, wherein the injection tank is an open tank and a cushioning means is operatively disposed between the injec-tion tank and the moulding tank.

52. The apparatus of claim 51, wherein the cushioning means is a closed tank and means are provided for evacuating said closed tank.

53. The apparatus of claim 52, wherein conduit means provide communication between the injection tank and the closed tank and between the closed tank and the moulding tank and valve means are provided in said conduit means between said tanks.

54. The apparatus of claim 51, wherein the cushioning means is an inverted U-shape tube which provides communication between the injection tank and the moulding tank, said inverted U-shape tube provided with a valve means.

55. The apparatus of claim 53, wherein a pump means is disposed in the conduit means between the injection tank and the closed tank.

56. The apparatus of claim 53, wherein a pump means is disposed in the conduit means between the closed tank and the moulding tank.

57. The apparatus of claim 51, wherein the cushioning means is closed cylinder means and means are provided for evacuating said cylinder means.

58. The apparatus of claim 57, wherein conduit means provide communication between the injection tank and the closed cylinder and be-tween the closed cylinder and the moulding tank and valve means are pro-vided in said conduit means.

59. The apparatus of claim 58, wherein pump means are disposed in said conduit means between the injection tank and the closed cylinder.

60. The apparatus of claim 51, wherein the cushioning means is a bellows means and means are provided for evacuating said bellows means.

61. The apparatus of claim 60, wherein conduit means provide communication between the injection tank and the bellows means and between the bellow means and the moulding tank and valve means are provided in said conduit means.

62. An apparatus for moulding a hydraulic substance comprising a closed injection tank, a closed moulding tank and a closed overflow tank, said moulding tank being adapted to contain an aggregate, means for reduc-ing the pressure in said tanks, conduit means connecting said pressure-reducing means to said tanks, an open supply tank operatively connected to the injection tank by conduit means, conduit means providing communi-cation between said injection tank and said moulding tank, said conduit means containing a closed pump means which is also operatively connected with said pressure-reducing means, and a circulation conduit containing a pressure-regulating means, said circulation conduit being connected at one end to the injection tank and at the other end to the conduit between the moulding tank and the pump means, wherein a cement and water mixture is transferred from the open supply tank to the closed injection tank and, in turn, to the moulding tank in sufficient excess quantity to cause said mixture to overflow from the moulding tank into the overflow tank, and and means are provided for returning the overflow tank to at least atmos-pheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the moulding tank to eliminate the voids between the aggregate in the moulding tank created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the moulding tank.

63. The apparatus of claim 62, wherein the pressure regulating means is a pressure-regulating tank.

64. The apparatus of claim 62, wherein the pressure-regulating means is a pressure-regulating valve.

65. The apparatus of claim 50, wherein a spreader means is dis-posed in the injection tank at a position beneath an opening for admitting said hydraulic substance, for removing excess water and entrained air from said hydraulic substance.

66. The apparatus of claim 65, wherein the spreader means is a triangular baffle plate,

67. The apparatus of claim 65, wherein the spreader means is pro-vided with a vibrating means,

68. The apparatus of claim 50, wherein an open tank containing the hydraulic substance is connected to the injection tank and a throttle valve is positioned above the injection tank between said open tank and said injection tank for causing the hydraulic substance to drop into the reduced pressure atmosphere of the closed injection tank.

69. The apparatus of claim 50, wherein a vibrating means is mounted to the outside of the closed injection tank for vibrating the same to remove excess water and entrained air from the hydraulic substance,

70. The apparatus of claim 50, wherein the injection tank is an elongated, inclined, pipe-like element which is provided with an evacuating means and a vibrating means.

71. The apparatus of claim 39, wherein the overflow tank is con-nected to the moulding tank by a conduit means and said conduit means is filled with aggregate to a level higher than the moulding tank.

72. The apparatus of claim 71. wherein the conduit means con-tains a wire to prevent the coarse aggregate from filling the overflow tank.

73. The apparatus of claim 39, wherein the overflow tank is con-nected to the moulding tank by a conduit means and said conduit means and the lower portion of said overflow tank are filled with aggregate.

74. The apparatus of claim 73, wherein a wire is disposed above the aggregate to hold it in position.

75. An apparatus for moulding a hydraulic substance comprising an injection tank, a moulding tank, and an overflow chamber, said moulding tank being provided with double-walled end portions which divide the mould-ing tank into a central moulding tank and two lateral absorption chambers, said central moulding tank being adapted to contain an aggregate and said lateral absorption chambers being adapted to contain an absorption mater-ial, said lateral chambers communicating with the central moulding tank, means for reducing the pressure in the injection tank, the central mould-ing chamber, and the overflow chamber, means for evacuating the lateral absorption chambers, means for introducing a cement and water mixture into the injection tank, means for transferring said mixture from the injection tank into the central moulding tank in sufficient excess quantity to cause said mixture to overflow from the central moulding tank to the overflow chamber and means for returning said overflow chamber to at least atmos-pheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow chamber is returned to the central moulding tank to eliminate the voids between the aggregate in the central moulding tank created by removing the excess water and entrained air under reduced pres-sure, and replacing said voids with said cement and water mixture to pro-duce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow chamber to avoid the introduction of air into the central moulding tank.

76. The apparatus of claim 75, wherein the inner wall of said double-walled end portion contains an aperture which provides said communi-cation between said lateral chambers and said central moulding tank.

77. The apparatus of claim 76, wherein said aperture contains a filter material.

78. The apparatus of claim 76, wherein said aperture contains a hydraulic substance detector.

79. The apparatus of claim 75, wherein said overflow chamber is an inverted U-shaped tube.

80. The apparatus of claim 75, wherein the overflow chamber is a transparent chamber.

81. The apparatus of claim 75, wherein said overflow chamber is a bellows-type device.

82. The apparatus of claim 75, wherein the overflow chamber is a coiled pipe.

83. The apparatus of claim 75, wherein the overflow chamber is a tank.

84. The apparatus of claim 50, wherein vacuum means are operative-ly associated with both the upper and lower portions of the moulding tank.

85. The apparatus of claim 50, wherein means are provided for introducing the cement and water mixture from the injection tank into the bottom of the moulding tank.

86. An apparatus for moulding a hydraulic substance comprising a closed injection tank, a mould adapted to contain an aggregate, and a closed overflow tank, said mould being disposed in a vacuum chamber, means for evacuating the injection tank, the vacuum chamber and the overflow tank, means for introducing a cement and water mixture into the injection tank, means for transferring said mixture from the injection tank into the mould disposed in the vacuum chamber in sufficient excess quantity to cause said mixture to overflow from the mould into the overflow tank and means for returning the overflow tank to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the mould disposed in said vacuum chamber to eliminate the voids between the aggregate in the mould created by removing the ex-cess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free, moulded porduct, said mixture being maintained in sufficient quanti-ty in said overflow tank to avoid the introduction of air into the mould.

87. The apparatus of claim 86, wherein the overflow tank is transparent so that the quantity of cement and water mixture which over-flows the mould can be monitored.

88. An apparatus for repairing a crack in a concrete structure which comprises providing a cover plate on all sides of said crack to seal the crack from the atmosphere, providing an injection tank and an overflow tank in the vicinity of said crack. means for reducing the pressure in said crack and in the injection and overflow tanks, means for introducing a cement and water mixture into the injection tank? means for transferring said mixture from the injection tank into the crack in sufficient excess quantity to cause said mixture to overflow from the crack into the over-flow tank, means for returning the overflow tank to at least atmospheric pressure whereby at least a portion of said excess quantity of said mix-ture in the overflow tank is returned to the crack to eliminate any voids which may have been produced in the mixture, by removing excess water .

and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the crack.

89. An apparatus for interconnecting different portions of a concrete structure wherein a gap exists between said concrete structure which comprises disposing a coarse aggregate in said gap, providing a porous cover around siad aggregate disposed in said gap, applying a thin coating of concrete to said porous cover to seal said gap, disposing an injection tank and an overflow tank in the vicinity of said gap, means for reducing the pressure in said gap and in the injection and overflow tanks, means for introducing a cement and water mixture into the injection tank, means for transferring said mixture from the injection tank to the gap in sufficient excess quantity to cause said mixture to overflow from the gap into the overflow tank, returning the overflow tank to at least at-mospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the gap to eliminate the voids between the aggregate in the gap created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the gap.

90. The apparatus of claim 89, wherein the porous cover is an -xpanded metal.

91. The apparatus of claim 88, wherein the cover plate is a flat plate which extends across all sides of the crack and is flush with the outer surface of the concrete structure, said plate being provided with an air sealing member and a mortar sealing member.

92. The apparatus of claim 91, wherein the flat plates are provided with wedge-shaped filling members, said filling members being drawn toward the crack when a vacuum is applied to said crack, thereby in-creasing the sealing effect of the crack.

93. The apparatus of claim 92, wherein corner plates are disposed at the corners of the concrete structure between the flat plates and said concrete structure and tie bars are provided to connect opposing flat plates together.

94. An apparatus for moulding a hydraulic substance comprising an aggregate and a cement and water mixture, utilizing an injection tank, a moulding tank adapted to contain an aggregate and an overflow tank, which comprises means for reducing the pressure in the injection tank, in the moulding tank, and in the overflow tank to a vacuum, means for introducing the cement and water mixture into the injection tank, means for transfer-ring said mixture from the injection tank into the moulding tank in sufficient excess quantity to cause said mixture to overflow from the moulding tank into the overflow tank, and means for returning the over-flow tank to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow tank is returned to the moulding tank to eliminate voids between the aggregate in the moulding tank created by removing the excess water and entrained air under reduced pressure, and replacing said voids with said cement and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow tank to avoid the introduction of air into the moulding tank.

95. The apparatus of claim 94, wherein the overflow tank is disposed at a lever above the moulding tank.

96. The apparatus of claim 95, wherein the overflow tank is transparent.

97. The apparatus of claim 94, wherein the moulding tank com-prises an air impervious sheet disposed in a recess formed in the surface of the ground and a hood mounted to the periphery of said sheet above said recess.

98. A method of moulding a hydraulic substance comprising aggregate and a cement and water mixture, utilizing an injection zone, a moulding zone and an overflow zone, said overflow zone being separate from the moulding zone, which comprises filling the moulding zone with aggre-gate, reducing the pressure in the injection zone, in the moulding zone and in the overflow zone to a vacuum, introducing said cement and water mixture into the injection zone, transferring said mixture from the injec-tion zone into the moulding zone in sufficient excess quantity to cause said mixture to overflow from the moulding zone into the overflow zone, returning the overflow zone to at least atmospheric pressure whereby at least a portion of said excess quantity of said mixture in the overflow zone is returned to the moulding zone to eliminate the voids between the aggregate in the moulding zone created by removing the excess water and en-trained air under reduced pressure, and replacing said voids with said ce-ment and water mixture to produce a substantially void-free product, said mixture being maintained in sufficient quantity in said overflow zone to avoid the introduction of air into the moulding zone.

99. The method of claim 98, wherein the overflow zone is posi-tioned higher than the moulding zone.

100. The method of claim 981 wherein the overflow zone is a separate overflow tank which is positioned higher than the moulding zone.

101. The method of claim 98, wherein the injection zone is re-turned to at least atmospheric pressure at the same time as that of the overflow zone.

102. The method of claim 98, wherein the area at the inlet to the moulding zone from the injection zone is increased to provide a smooth transition between said zones and reduce the tendency of the aggregate to block and reduce the effective area of transition between said zones.

103. The method of claim 98, wherein the injection zone is dis-posed above the moulding zone.

104. The method of claim 98, wherein the zone adjacent the mould-ing zone is evacuated, so that said moulding zone is subjected to a vacuum within the moulding zone and a vacuum surrounding the moulding zone.

105. The method of claim 104, wherein the zones adjacent the mould-ing zone are closed tanks disposed between the moulding zone and the injec-tion and overflow zones, respectively, and the pressure in said closed tanks is reduced prior to introducing the cement and water mixture into the moulding zone and increased after the completion of said introduction and said cement and water mixture is introduced into said moulding zone through said closed tank.

106. The method of claim 98, wherein the injection zone and the moulding zone are closed zones and the pressure difference between the zones is regulated to control the flow of the cement and water mixture from the injection zone to the moulding zone.

107. The method of claim 98, wherein the pressure in the moulding zone is reduced to less than 0.8 Kg/cm2.

108. The method of claim 98, wherein the pressure in the moulding zone is reduced to less than 0.7 Kg/cm2.

109. The method of claim 98, wherein coarse aggregate is prepacked in the moulding zone.

11O. The method of claim 1O9, wherein said coarse aggregate is selected from the group consisting of crushed stone and gravel.

111. The method of claim 109, wherein said coarse aggregate com-prises lightweight coarse aggregate.

112. The method of claim 98, wherein the cement and water mixture is strongly bonded to the inner surface of the moulding zone.

113. The method of claim 98, wherein the moulding zone is air-tight sealed by a sealing member, and the cement and water mixture is sequentially poured into the moulding zone to substantially fill the voids created by removing excess water and entrained air from the mixture under reduced pressure.

114. The method of claim 98, wherein a cushioning effect is achieved by providing a reduced pressure on the cement and water mixture, said mixture being disposed intermediate the injection zone and the point of introduction of the cement and water mixture into the moulding zone, thereby alleviating the pressure difference between the inside and outside of said moulding zone.

115. The method of claim 114, wherein said cushioning effect is achieved by providing a closed tank which is operatively connected between the injection zone which houses the cement and water mixture and moulding zone, the pressure in said closed tank being reduced at the time of introducing the cement and water mixture into the moulding zone and in-creased after the completion of said introduction, and said cement and water mixture is introduced into said moulding zone through said closed tank whereby said mixture is subjected to the reduced pressure in said closed tank.

116. The method of claim 115, wherein the injection zone con-taining the cement and water mixture is open to the environment and is connected to said closed tank by a pipe for transferring said cement and water mixture to said closed tank.

117. The method of claim 115, wherein said closed tank is vibra-ted for spreading the cement and water mixture and for removing excess water and entrained air from the cement and water mixture.

118. The method of claim 98, wherein pressure feed means are provided downstream of the injection zone and a circulating passage pro-vides communication between the downstream side of the pressure feed means and the injection zone whereby when the pressure of the cement and water mixture on the downstream or output side of the pressure feed means ex-ceeds a predetermined value, said cement and water mixture is returned to the upstream or input side of the pressure feed means through said cir-culating passage.

119. The method of claim 118, wherein the circulating passage is provided with a closed tank and wherein the pressure in said closed tank can be reduced.

120. The method of claim 119, wherein said circulating passage leading to the input side of said pressure feed means is open at an in-termediate point of the length of said closed tank whereby said cement and water mixture is introduced into said mould under the head difference be-tween said intermediate point and said mould.

121. The method of claim 118, wherein the pressure is measured in the circulating passage for returning the cement and water mixture to the input side of the pressure feed means from the output side thereof, whereby the cement and water mixture can be introduced into the moulding zone at a pressure less than a predetermined value.

122. The method of claim 98, wherein the overflow zone is a closed zone and wherein the overflow zone is connected to the moulding zone through a pipe which is prepacked with a material which resists the flow of the cement and water mixture.

123. The method of claim 98, wherein the cement and water mixture is introduced into the closed moulding zone while it is held in a vertical position.

124. The method of claim 104, wherein the zone adjacent the mould-ing zone is reduced during the moulding process and increased after the moulding process.

125. The method of claim 98, wherein the injection zone, the moulding zone and the overflow zone are closed zones and said closed moulding zone is formed to surround a crack disposed in a concrete struc-ture said cement and water mixture being introduced into said crack.

126. The method of claim 98, wherein the injection zone, the moulding zone and the overflow zone are closed zones and said closed moulding zone is formed to surround a gap disposed between a pair of con-crete structures, said cement and water mixture being introduced into said gap.

127. The method of claim 100, wherein the overflow tank is transparent or provided with a transparent window and the quantity of overflow into the overflow tank is observed and controlled to avoid the introduction of air into the moulding zone when a quantity of the overflow from the overflow tank is reintroduced into the moulding zone.

128. The method of claim 98, wherein after moulding, the moulded product is subjected to a curing treatment.

129. The method of claim 98, wherein after the moulding zone is filled with aggregate, a perforated plate is inserted into the moulding zone for preventing the floating and displacement of the aggregate when the cement and water mixture is introduced into the mould.

130. The method of claim 98, wherein in order to eliminate the occurrence of a coarse surface in the moulded porduct, a thin coating of the cement and water mixture is applied to the bottom of the mould and then the aggregate is packed in the mould to a level slightly lower than the top edge of the mould.

131. The method of claim 98, wherein the cement and water mixture is introduced from the injection zone to the moulding zone by a pressure difference.

132. The method of claim 98, wherein when the speed of introduc-tion of the cement and water mixture into the moulding zone decreases the injection zone is open to atmospheric pressure to increase the speed of introduction of said mixture.

133. The method of claim 989 wherein the speed of introduction of the cement and water mixture from the injection zone into the moulding zone is determined by the head difference between the injection zone and the moulding zone.

134. The method of claim 98, wherein the speed of introduction of the cement and water mixture from the injection zone into the moulding zone is controlled by a pressure feed means.

135. The method of claim 134, wherein the speed of introduction of the cement and water mixture from the injection zone into the moulding zone is maintained constant by varying the pressure of the pressure feed means.