CA1168523A

CA1168523A - Method and apparatus for adjusting the quantity of liquid deposited on fine granular materials and method of preparing mortar and concrete

Info

Publication number: CA1168523A
Application number: CA000349232A
Authority: CA
Inventors: Yoshiro Higuchi; Yasuhiro Yamamoto; Yasuro Ito
Original assignee: Taisei Corp
Current assignee: Taisei Corp
Priority date: 1979-06-28
Filing date: 1980-04-03
Publication date: 1984-06-05

Abstract

ABSTRACT OF THE DISCLOSURE
A method and apparatus are provided herein for preparing hydraulic mortars or concretes. The method includes adding a quantity of water to fine aggregate particles, e.g., to sand particles, to in-crease their water content. A predetermined quantity of fine aggregate particles, e.g., such sand particles to which water has been added, are then sequentially supplied. An impact force is applied to such fine aggregate particles. e.g. such sand particles, either before or after the water has been added thereto, the force being stronger than the adhesive force of the water to such particles, thereby to remove excess water therefrom. A hydraulic substance, e.g. cement, is then mixed with the so-treated particles. The hydraulic mortar or concrete prepared from such particles has small segregation and bleeding, and products prepared therefrom have excellent mechanical strength.

Description

2 3 This invention relates to a method and apparatus for adjusting the quantity of liquid, typically water, deposited on the surfaces of fine granular materials, and a method of preparing mortar or concrete by utiliz-ing the treated granular material.
Fine aggregates comprising river or mountain sand or artiicial fine particles are widely used to prepare cement mortar or limestone type hydraulic mortar which is used to construct buildings or many other civil structures. ~len digging or crushing various ores utili~ed in metallurgy or ceramic industry and coal, fine particles or dust are formed. Further, depending upon the field of use, it is necessary to crush the ores or coal into granules having a predetermined size. I~hen pulverizing or refining these substances or when using them for chemical reactions, fine granules in the form of sludge or the like are often formed. As is well known, these fine granules contain a substantial quantity of water adhering to the surface thereof. This is true not only for river or mountain sand, but also for coal. Especially, in recent years, these substances are dug ~y using water jets so that the quantity of the deposited water is considerably large. Even with converter slag which is substantially free from ~ater when it is formed is collected using water. Moreover, as these materials are stored outdoors, they are wetted by rain, dew or snow. Such wet particles can not be used directly. For example, when sintering or converting ~hese materials to coke, and even when they are directly charged to a furnace, it is necessary preliminarily to dry them before actual use.
This requires extra heat energy, i.e., fuel. As will be described later in more detail, when a fine aggregate composed of river or mountain sand is used for the preparation of mortar or cement, the quantity of the deposited or surface water is an important factor which influences the quality of the product. Although the composition and particle si~e of the sand also influences the quality of the product, so long as sand collected from the same source is used, it is easy to utilize the sand having the 1 ~68~3 same composition and particle size and it is rare to admiY. sands from different sources. I~hen the sand contains particles of différent size, it is easy to classify the~ into fine, medium and coarse particles 7"ith a sieve and a small difference in the particle size does not result in a great difference in the quality of the product. However, the quantity o~
the surface water varies greatly depending upon the source, and the methods of collecting, conveying and storing the sand. Moreover, the specific surfac:e area of the fine particles of sand is large so that the relative quantity of the deposited water is ]arge.
In addition, sand contains water in the interstices of the sand particles which varies from time to time depending upon weather conditions.
More particularly, when sand from the same source is piled up on the ground, its water content varies at the top and the bottom, and in the morning, at noon, and in the afternoon. ~hen preparing cement mortar or concrete by using a fine aggregate, the ratio of water to cement (W/C), the ratio of cement to fine aggregate (C/g), and the ratio of cement or sand to a coarse aggregate (S/G or C/G) have a great influence upon the strength of the resulting product, and its fluidity, moldability and workability.
Thus, wl-en a excessive quantity of water is incorporated, segregation and bleeding are inevitable, thus decreasing the mechanical strength of the product. On the other hand, deficient water impairs moldability and pour-ing property, so that even when vibration or pressure is applied at the time of molding or pouring, it is difficult to obtain a dense structure which also decreases the mechanical strength. As described above, notwith-standing the fact that it is essential to select adequate W/C, etc., as the quantity of the deposited water varies greatly and as it is difficult simply and accurately to measure the quantity of the surface water, it is difficult to realize ideal ratios of WtC and S/C, etc. Although it has been proposed completely to dry the fine aggregate or to measure the weight thereof in water, such methods are not suitable in the field where a large ~ 1~8~23 quantity of sand is used. More particularly, the former method requires a large quantity of heat energy and time. The latter method requires a step of perfectly permeating water into sand to drive off air ~according to JIS (3apanese Industrial Standard), the procedure involves immersing the sand in water for 24 hours], and a step of draining the water contained in the sand.
It is therefore an object of a broad aspect of this invention , to provide an improved method and apparatus for preparing hydraulic mortar or concrete of improved quality by utilizing a fine aggregate which has had its quantity of surface water adjusted to a desired value.
By a broad aspect of this invention, a method is provided for preparing a hydraulic mortar or sand comprising the steps of: adding a quantity of water to fine aggregate particles, e.g. sand particles, to in-crease their water content; sequentially supplying a predetermined quantity of such fine aggregate particles, e.g. sand particles, to which water has been added; applying, to such fine aggregate particles, e g. such sand particles, an i~pact force stronger than the adhesive force of the water to such particles, thereby to remove excess water therefrom; and mixing a hydraulic substance, e.g. cement, with such particles.
~ By another aspect of this invention, a method is provided for preparing a hydraulic mortar or concrete comprising the steps of: supplying a predetermined quantity of fine aggregate particles having water on the surface thereof; applying, to the fine aggregate particles, an impact force stronger than the adhesive force of the water to the fine aggregate particles, thereby to remove excess water therefrom; adding a portion of water necessary to prepare the hydraulic mortar or concrete from the fine ~ 3 -aggregate particles; adding a hydraulic substance to the resulting mixture of fine aggregate particles and water to form shells of the hydraulic sub-stance about particles of the fine aggregate particles; adding the remain-ing portion of the water necessary to prepare the hydraulic mortar or con-crete; and kneading the resulting mixture.
By a variant thereof, the hydraulic ~ortar or concrete is a cement co~pound, and the fine aggregate particles are sand.
By another variant thereof, an additive is incorporatea together with the remaining portion of the water.
By a further variant, the quantity of the portion ~ water is determined according to the quantity of water remaining in the particles of the fine aggregate or sand.
By yet another variant, either one or both of a coarse aggregate and fibrous substance is added to the fine aggregate or sand.
By a still further variant, the fine aggregate or sand which has had excess water removed therefrom, and other ingredients of the hydraulic mortar or sand are conveyed to a working station by independent conveying means, and then mixed together and blasted at the working station.
According to still another aspect of this invention, a method is provided for preparing a hydraulic mortar or concrete comprising the steps of: supplying a predetermined quantity of particles of fine aggregate hav-ing water on the surface thereof; applying, to the particles, an impact force stronger than the adhesive force of the water to the particles, thereby adjusting the quantity of water remaining on the surface of the particles to a predetermined value; adding, to the particles, a quantity of water and a hydraulic substance; and then kneading the resulting mixture.

:
:~ 168~23 By a variant thereof, the hydraulic mortar or concrete is a cement compound, and wherein the fine agyregate particles are sand.
By another variant thereof, water is applied to the particles before the application of the impact force so that the particles contain water in an amount larger than the quantity of water remaining on the particles after the application of the impact force.
sy another aspect of this invention, apparatus is provided for preparing a hydraulic mortar or concrete comprising: means for removiny - excess water from a fine aggregate, e.g. from sand; and a kneading mechanism for successively adding water and a hydraulic compound, e g.
cement, to the fine aggregate, e.g. to the sand, from which the excess water has been removed; thereby preparing a hydraulic mortar or concrete.
sy a variant thereof, the means for removing excess water is specially adapted to remove excess water from sand; and the kneading mechanism is specially adapted to knead cement with sand.
By another variant thereof, the apparatus further includes:
primary and secondary water supply means; and cement supply means disposed between the primary and the secondary water supply means. ~-By yet another variant, the kneading mechanism includes: means for adding at least one of a dispersing agent, a rapid setting agent, and a delay agent.
By a further variant, the kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix.
By a variation thereof, the mixing members are divided into a plurality of sections along the shaft; and the pi~ches of the mixing . .. .
~ 5 -1 ~8523 members are varied for different sections.
By another variation, the inclination angles of the mixing mem~
bers are made different for different sections.
By a further varia-tion, the shaft is contained in a mixing chamber which is divided into a plurality of sections along the shaft;
and volumes of the sections are made to be different according to the bulk of a mixture being kneaded.
By yet another variation, the mixing members comprise large mixing chambers and small mixing members, interleaved with each other.
By a variation thereof, the large mixing chambers and the small mixing members are inclined in opposite directions.
By still another variation, the shaft is contained in a mixing chamber; and the shaft and the mixing chamber are adapted to be rotated relatively to one another.
By a variation thereof, the mixing chamber takes the form of a U-shaped member lined with a flexible member; and an elastic tube is disposed on the outside of a bottom portion of the flexible member, the elastic tube being inflatable by a pressurized fluid. --~
By a variant of such apparatus, the means for removing excess ~ water from the fine aggregate or the sand comprises: water separating ~ - ~ ~
1 168~

means for imparting an impact force to the fine aggregate or to the sand, the impact force being larger than the adhesive force of the liquid to a fine aggregate or to~the sand, thereby to re ve excess water deposited on the aggregate or on the sand; the water separating means comprising an impact plate, and a rotary disc opposing the impact plate for pro-jecting the fine aggregate or the sand against the impact plate by centrifugal force created by rotation of the rotary disc.
By a variation thereof, the rotary disc is provided with a plurality of radial vanes; and the apparatus includes means for supplying the fine aggregate or the sand to the rotary disc at a central portion thereof.
By another variation thereof, the apparatus further includes dividing means for dividing the fine aggregate or the sane projected '!
against the impact plate into two streams, namely, (a) a fine aggregate or sand stream, and ~b) a stream containing water separated from the fine aggregate or from the sand as a result of collision against the impact plate.
By another variation thereof, the dividing means is provided on an upper edge of a container of the fine aggregate or the sand from which excess water has been removed.
By another variation thereof, the impact plate is removably mounted on an inverted dish-shaped member, whereby excess water removed from the fine aggregate or from the sand as a result of collision thereof against the impact plate flows down along an inner surface of the inverted dish shaped member.
By another variation thereof, the apparatus further includes a pipe for continuously supplying the fine aggregate or the sand at a ~ ~8~23 central portion of the rotating disc; and also includes means for adding liquid to the fine aggregate or to the sand at an exit end o the pipe.
By another~variation thereof, the apparatus further includes a container for receiving treated fine aggregate or sana, an inner edge of the container being spaced from a lower edge of the inverted dish-shaped member.
By another variation thereof, the rotary disc is contained in a casing having a rectangular cross-sectional configuration; and inner sur-faces of the casing are inclined downwardly to be collided upon by the fine aggregate or by the sand projec-ted by rotation of the rotary disc.
- By another variation thereof, the apparatus further includes means for supplying cleaning-liquid to the impact plate.
By a variation thereof, the apparatus further includes a recept-acle for receiving the fine aggregate or the sand projected upon the im-pact plate; and includes means for removing the fine aggregate or the sand adhered to an upper portion of the receptacle.
By another variation thereof, the removing means comprises an elastic tube. -~
By a variation thereof, the apparatus further includes means for inflating the elastic tube.
By another variation thereof, the water separating means com-prises:~a rotary wheel adapted to rotate about a horizontal axis and pro-vided with a plurality of radial vanes; means for supplying the fine aggregate or the sand to a space between adjacent vanes; means for rotat-ing the wheel at a high speed sufficient to remove excess water from the fine aggregate or from the sand; means for discharging the fine aggregate - or the sand from the wheel substantially in a horizontal direction; and a ~ 8 -plurality of fine aggregate or sand receivers juxtaposed in the horizontal direction to classify the fine aggregate or the sand according to their size.
By another variation thereof, the impact force is applied by pressurized gas.
By another variation thereof, the impact force is applied by a conveyor belt running at a high speed.
As noted above, the impact force can be imparted by centrifugal force created by a rotating disc, a conveyor running at a high speed or pressurized gas.

r ~ ~ ~8~2~
The invention in its various aspects is especially suitable for ad-justing the quantity of water on sand particles which are used to prepare cement mortar or a green concrete compound. The quan~ity of water remain-ing on the surface of the sand particles is used to determine the quantit~
of water subsequently to be added to a mixture of sand, gravel and cement.
In the accompanying drawings, Figure 1 is a general side view showing one example o~ the appara-tus of one aspect o~ this invention utilized to carry out the method of another aspect of this invention;

Figure 2 is a longitudinal sectional view of the water separator A shown in Figure l;
Figure 3 is a longitudinal sectional view showing a modified water separator;
Figure 4 is a partial longitudinal sectional view showing a modification of the water separator shown in Figure 3;
Figure 5 is a side view of the water separator with au~iliary equipment;

Figure 6 is a longitudinal sectional view showing the upper portion of a modified water separator;
Figure 7 is a perspective view showing an impact frame shown in Figure 6;
Figure 8 is a plan view of the rotating disc shown in Figure 6 taken along a line VIII-VIII;
Figure 9 is a sectional plan view taken along a line IX-IX in Figure 6;
Figure 10 is a side view, partly in longitudinal section, of another embodiment of the water separator, Figure 11 is a perspective view showing a manner of attaching a section of an impact surface;

., _ g _ , 8~23 Figure 12 is an enlarged sectional view showing the relationsnip between the impact surface, a cleaning water tank, a water receiving tank and a receptacle;
Figure 13 is a partial sectional view showing means for removing deposited sand particles;

Figures 14 and 15 show modified means for removing the deposited sand particles which are simpler than that shown in Figure 13;
Figure 16 is a sectional view showing another embodiment of the water separator no~ utilizing a rotating disc;
Figures 17, 18A, 18B, 19 and 20 show still other modifications of the water separator;
Figure 21 is a graph showing the result of water removal;
Figure 22 is a longitudinal sectional view showing one example of a mixer; .
Figure 23 is a cross-sectional view of the mixing chamber shown in Figure 22;
Figure 24 is a cross-sectional view showing a modified pressure applying chamber;
Figures 25 and 26 are longitudinal sectional views showing modified mixers;

Figure 27 is a longitudinal sectional view showing still another mixer;
Figure 28 is a cross-sectional view of the mixer shown in Figure 27;
Figures 29 and 30 are perspective views showing the relative ,,;~, - 10_ arrangement of the main and auxiliary mixing members;
Figure 31 is a longitudinal view showing a modified mi~.ing chamber;
Figure 32 is a perspective view showing the modified mixing chamber shown in Figure 31; and Figures 33 and 3~l are sectional views showing modified mixing members .
Before describing in detail with reference to the accompanying drawings, the principle and advantages of aspects of this invention will first be described.
~ere excessive surface water is removed by heat or wind power, it is not only difficult accurately to adjust the quantity of water deposited on the fine aggregate, but also a large quantity of heat energy and time are required. As described above, according to aspects of this invention, the quantity of water is adjusted by applying an impact force or velocity energy to the fine aggregate. With this improved method, the q~antity of water that can be efficiently removed varies depending upon the quantity of water originally contained. For this reason the impulse, or impact, force applied to the sand must be determined depending upon the quantity of water originally contained. The impact force or shock can be applied by beating, but it is more advantageous to a~ply it as velocity energy. Where the quantity of the deposited water is relatively large, use of the velocity energy caused by gravity is effective to remove a certain amount of water. Nore advantageous, velocity energy is that utilizing wind power, rotating force, or centrifugal force. One or com-binations of two or more of these ~elocity energies can be used. It is also possible to sprinkle the particles by applying thereto the velocity energy of rotating force or celltrifugal force to cause the sprinkled particles to 5 2 ~
collide against a surface to remove the surface water. Alternatively, while the particles are at a standstill or are slowly dropping under gravity, an impact force may be applied to cause the particles to collide against a rotating body. In each case, the surface water is transferred to the surface or body colliding with the particles to adjust the quantity of water remaining on the surface thereof. Thus, the quantity of remaining water is inversely proportional to the strength of the impact force, where-by the quantity of the remaining water can be adjusted to a desired value by suitably selecting the strength of the impact force. In other words, irrespective of the particle si~e (f:ine, medium or coarse) of a fine aggre-gate which usually contains a relatively small amount of water, for example 2 to 4%, the water can be removed adequately by using a suitable impact force. More advantageously when the quantity of the deposited water is large, for example 7 - 8~ or more, water beyond a certain ~imit can be removed by the impact energy, the degree of removal being proportional to the impact energy. With a fine aggregate whose quantity of deposited water varies in a relatively small range, for example from 2.5 - 6%, it is advantageous to determine the quantities of water and cement to be incorp-orated subsequently. When the quantity of the water deposited on the particles of the fine aggregate is reduced or adjusted to a predetermined value, it is possible readily to obtain desired ratios of W/C, C/S and G/S, thus ensuring uniform quality of the resulting product.
From the standpoint of cost of installation and operating power, it is advantageous to cause the particles of the fine aggregate to collide against a stationary surface by using rotating disc, in which case the particles are supplied to the central portion of the disc to cause them to fly by centrifugal force. The sand often contains mud or clay which deposit on the surface of the sand particles, and in an extreme case the - 12 _ 1 168~2~
layer of the deposited mud or clay bonds together the particles of the fine aggregate colliding thereupon to increase the thickness of the layer.

F-rther, the deposited layer may act as a cushion layer to decrease the impact force appli.ed to the particles, thereby varying the quantity of the deposited water even with the same impact force.
In such a case, it is necessary to clean the stationary surface with water or with a rotating wiper or by rotating the surface.

In cold weather, water containing sand freezes, in which case the frozen sand is melted with steam. to separate its particles. When sea sand is used, salt contained therein can be removed when the quantity of the depos~ted water îs reduced b.y th.e method of aspects of this. inventi~on.
Now referring to the drawings, ~igure 1 îs a si~de vi`ew of one .
example utilized to carry out the method of an aspect of this invention which comprises an impact water separator A into which a fine aggregate is continuously supplied by a conveyor or the like and a mixer B. It is advantageous that the mixer B be of a continuous type and be provided with mechanisms C, D and E respectively for incorporating a powder of hydraulic substance, water and additives, e.g.., a dispersing agent.
Although any type of impact water separator A can be used in the method and apparatus of aspects of this invention, a preferred separator shown in Figure 2 comprises a hopper 1, and a rotary disc 2 disposed beneath the hopper 1. The rotary disc 2 is provided with a central opening 12 to receive the fine aggregate from the hopper and a plurality of radial vanes 7. The rotary disc 2 is supported by a rotatable sleeve 13 supported by a stationary sleeve 14 through bearings 3. The sleeve 13 is rotated by an electric motor 4 through pulleys 5 and 15 and a belt passing about these pulleys. An annular ring 6 is disposed to surround the rotary disc 2 with a suitable distance therebetween, the annular ring being detachably mounted on the inner side of a lower frusto-conical hollow casing 10.
Funnel-shaped receiver 8 is contained in the lower portion of the lower casing 10 with a suitable gap therebetween. Adjacent ~he discharge opening 18 at the lower end of the receiver 8 is disposed a conveyor 11 for receiv-ing the fine aggregate which falls down after collision against the annular ring 6. The annular ring 6 is slightly inclined, and, if desired, its upper edge may be bent inwardly in order to prevent upward sprinkling of the sand particles. By increasing the inclination angle of the annular ring, the collection of the sand particles by the receiver 8 can be improved.

A water spray pipe 16 is provided at the lower end of the hopper l, and if desired~ a screw-type or ribbon-type agitator may be provided at the lower end of the hopper uniformly to apply a suitable quantity of water to the sand particles. The water separated by the collision against the annular ring`falls down as shown by dotted line arrows to the bottom of the lower cas~ng lO.
Figure 3 shows a modified water separator A, utilized in an aspect of this invention in which the relative arrangement of the hopper 1, rotary disc 2, the motor 4, and the sleeve 13 are generally similar to that of the first embodiment. However, the annular ring or impact plate 6 against which the sand particles are ejected by the centrifugal force created by the rotary disc 2 is interposed between separated upper portions of a bell-shaped receiver 10 and reinforced by an outer ring 18a secured to the annular ring by screws 19. This construction allows ready exchange of the annular ring 6. The lower end 20 is bulged outwardly to receive the upper end of a receptacle 9 supported by a frame 22. A small gap is defined between the upper end of the receptacle 9 and the bulged out end 20 to permit passage of the separated water, whereas dehydrated sand particles 1 ~8~23 fall down into the receptacle.
Although not shown in Figure 3, it should be understood that a conveyor is installed beneath the receptacle in the same manner as in Figure 2 to convey the sand particles to the mixer B shown in Figure 1, The casing 10 of the ~ater separator shown in Figure 3 may ~e modified as shown in Figure 4 and various auxiliary equipment may be provided as shown in Figure S. Thus, as shown in Figure 4, a plurality of telescoped annular members 9a and 9b connected by connecting members 31 to the upper edge 9c of the receptacle 9 are disposed within tbe annular ring 6. ~he upper ends of respective annular members 9a, 9b and 9c are shaped to define a passage, together with the inner surface of the casing 10, for passing air and water. These knife edge shaped upper ends further function to deflect the sand particles moving along the inner surface of the casing 10 away therefrom toward the inside of the receptacle 9.
An annular rotating disc 2a slightly inclined downwardly as shown by dotted lines may be attached to the rotating disc 2 for directing the sand particles to the lower side. With this construction, the projected sand particles are blasted against the lower portion of the annular ring 6 by a centrifugal force sufficient to separate the sand particles and water by the inclined auxiliary rotating disc 2a so that the vanes 7 may be omitted. In this case, the spacings between the annular members 9a, 9b and 9c and the casing lO may be made smaller than those shown in Figure 4.
I~hen the water separator shown in Figure 4 is operated under optimum operating conditions to be described later, the substance that flows downwardly along the inner surface of the casing consists essentially of water and mud which can be discarded.

However, optimum operating conditions are not always obtained depending upon the characteristic of the sand particles. In such a case, .,~ i~.
; - 15 -., ~ ~6~523 the substance falling to the outside of the receptacle 9 thr~ugh a gap between the lower inner surface of the casing 10 and the knife-edge-s'naped portion 9c is separated into water, mud and sand particles which can be recharged into the hopper 1 by a conveyor or the like. The water component separated by the water separator may be used ta prepare concrete mortar in the subsequent step.
Figure 5 shows one example of a practical installation designed by taking into consideration the above-described factors. More particular-Iy, and elongated inclined trough 34 is installed beneath the lower end of 10. the casing lO and the receptacle 9 is formed like a funnel with its lowerend 18b faced to a conveyor ll so that a certain amount of the sand par-ticles with ad~usted water quantity accumulates in the lower portion of the receptacle 9 so as substantially to seal the same. A discharge pipe 34a is provided between the lower end of the trough 34 and funnel-shaped water receiver 36 contained in a drain water tank 35 for accumulating the separated water in the water receiver 36. An inclined centepede endless conveyor 33 with pick-up pieces 33a is provided to discharge solid components accumulated in the bottom portion of the receiver 36. Also a discharge pipe 32 having a suction port 23 is provided to discharge the water in the water tank 35 by a suitable pump, not shown, for using the water to prepare cement mortar or concrete. A water feed pipe 25 having a level detector 24 is provided for the water tank 35 so as to maintain the level of the water contained therein always at a constant level. If desired, the water feed pipe 25 may be opened in the trough 34 to clean the same or opened near the discharge end of a conveyor 30 utilized to load sand particles into the hopper 1 for adding water to the sand particles.
Although the purpose of the water s~parator of the method and apparatus of aspects of this invention is to adjust the quantity of the ; - 16 -. . .

wat~r deposiied on the sand pc)r~icics, that is the surface ,Jater, ,/hen tne sand is substantially dry, i.e., contains only a small quantity of water, it is necessary to add water to the sand contained in the hopper 1. As described above, in some cases, the sand contains mud or clay ~7hich tends to adhere to the surface of the annular ring 6 especially w'nen the water content of the sand is low, so that addition of water is effective. Thus, the added water removes the mud or clay deposited on the annular ring.
~ lere the tendency of depositing mud or clay on the inner sur-face of the annular ring 6 is large, a scraper 28 is mounted on the lower end of a shaft 27 rotated by a motor 4a at a relatively low speed, for example less than 10 rpm. A layer of mud deposited on the annular ring 6 acts as a cushion layer so that the effect of adiusting the quantity of water by using an impact force would be impaired. Moreover, the adhesive layer of the deposited mud arrests the sand particles. I~here such adhesive mud layer is removed by the scraper 28, the efficiency of adjusting the water quantity can be improved.
- A screw 29 may be mounted on the vertical shaft 27 constantly to feed the sand onto the rotating disc 2 from the hopper 1. Variation in the quantity of the sand supplied to the rotating disc 2 prevents uniform adjustment of the water content.
Details of a modified water separator are shown in Figures 6 to 9. As shown in Figure 6, a vertical supply pipe 51a connected to the bottom of a hopper 51 is directed to the central portion of a rotating disc - 52 and at the lower end of the supply pipe Sla are formed discharge openings 51b on the opposite sides. As shown in Figure 8, the rotating disc 52 is provided with a plurality of radial vanes 57 for distributing and projec-ting sand particles supplied through the discharge cpenings 51b. As shown in Figures 7 and 9, the rotating disc 52 is contained in an inverted dish-shaped rectangular impact frame 60 so that the projected sand pa{ticles collide against the inner surface 60a of the impact frame 60. The lo~er ..

end thereof surrounds the upper end of a receptacle 59 with gaps 59a therebetween, and water receiving troughs 58 are mounted near the upper ends of the shorter sides of the receptacle to receive separated water through gaps 59a ~Figure 6). A bushing 54 adapted to support the rotating disc 52 is rotatably supported by a supporting cylinder 56 at the upper center of the impact frame 60 through bearings 53, and pulley 55 is secured to the upper end of the bushing 54 for rotating the rotating disc at a predetermined speed by an electric motor, not shown, The modified embodiment shown in ~gures 6 through 9 operates as follows:

The sand particles supplied from the hopper 51 are discharged on the rotating disc 52 in the specified direction, i.e., about the middle of the longer sides of the impact frame 60 in the example shown in Figures 8 and 9 and the sand particles projected by the rotating disc 52 are directed mainly to the shorter sides of the impact frame 60. A portion of the sand particles is projected upon the longer sides but will be guided to the shorter sides by an angle between the projection and longer sides. In other words, substantially all portions of the projected sand particles would collide upon the shorter sides where excessive water is removed by the impact force, whereby sand particles with adjusted quantity of water would be collected in the receptacle. The separated water flows down along the shorter side of the inner surface 60a of the impact frame 60 and then received by troughs 58. Mud or clay contained in the orginal sand is also collected in the troughs 58. With this modification, as substantially all projected sand particles are caused to collide upon the shorter sides, the efficiency of water quantity adjustment can be improved.

Still another modification of the water separator and various modifications of its parts are shown in Figures 10 through 15. In the modification shown in Figures 10 to 12, an impact frame 60b takes the form ~ ~8~23 of an inverted frustum of a cone and is constructed such that its impact surfaces can be exchanged. The sand particles from a hopper 51 are caused to collide upon the inner surface of the impact frame to remove excess water. Since the sand particles are abrasîve, the inner surface of the impact frame 60b wears rapidly. Accordingly, an impact plate 63 is divided into a plurality of sections and each section is secured to the impact frame through a packing 68b by a fastener 68c as shown in Figures 10 and 12. To exchange a section, it is inclined by a handle 68a and then pulled out of the impact frame 60b through an opening 60c. About the lower skirt 60d, a portion of the impact frame 60b is provided with an annular water tank 62. Cleaning water is supplied into the water tank 62 through an inlet port 62a to a level higher than the upper edge of the skirt 60d by h. A small amount of the cleaning water continuously flows along the inner surface of the skirt 60d to preve~t-stagnation of mud.
The water overflows through a discarge port 62b into a water-receiving trough 58. Also the water flows along the inner surface of the skirt 62d toward the water-receiving trough 58.
When the water separator is used in the field, the sand particles tend to adhere to the inner surface of the receptacle 59. To prevent this tendency, a vibrator 61 is installed in the receptacle 59. The sand par-ticles adhere especially to the uppper portion of the receptacle, so that means for removing the deposited sand particles are provided for the upper portion as shown in Figures 139 14 and ]5.
In an example shown in Figure 13, an air bag 67 is interposed between the side wall 59a of the receptacle 59 and a hard rubber ring 66.
By periodically varying the air pressure in the air bag 67, the sand par-ticles deposited on the inner surface of the hard rubber ring 66 can be readily removed. In the example shown in Figure 14, only the hard rubber 1 16~S23 ~ing 66 is secured to the upper edge of recept~cle 59. Even with this simple construction, the hard r~bber ring 66 is caused to vibrate 'D'J the sand particles blasted thereon, thus peeling off the deposited sand part-icles. In the example shown in Figure 15, a hard rubber ring 65a is secured to the upper portion 59a of the receptacle 59 with a suitable air gap 65 therebetween. With the construction shown in Figure lS, the hard rubber ring 66a can vibrate more freely more efficiently to remove the deposited sand particles.
In the water separator described above, since the mud deposited on the skirt 60d and the sand particles deposited on the upper portion of the receptacle increases their volume with time, and since these deposited substances prevent smooth flow of water of sand particles, it will be clearly noted that use of the means for removing deposited substances is advantageous. When a rotating disc provided with vanes is used, air flow is created along the wall surfaces which is more or less effective to pre-vent deposition, but where the sand particles deposit, it will prevent smooth flow of air and grows rapidly.
Figure 16 shows another example of the water separator which removes excessive water by an impact force without utilizing the centri-fugal force created by the rotating disc. In this modification, a fineaggregate, i.e., sand, is loaded into a hopper 1 by a conveyor 7l and then supplied to a hori~ontal rotor 77 provided with a plurali~y of radial vanes 7~ by a metering device 76 which sequentially supplies a definitP quantity of sand. The rotor 77 is rotated by an electric motor 4 to apply a definite impact force to the sand particles received by the rotor. In front of the rotor 77 are disposed first to third hoppers 84, 85 and 86 to receive sand particles projected in the forward direction by the rotor 77. Each hopper is provided with a discharge damper 83 for discharging sand particles ~ ~8$2~

collected in the hopper.
More particularly, the first hopper 84 is used to receive water and mud deposited on the sand partîcles, whereas the second and third hoppers 85 and 86 are used to receive sand particles with their surface water which has been adjusted. The hopper 86 collects coarser sand par-ticles. Generally speaking, the sand particles impacted by the rotor are projected over difEerent distances depending upon the mass of the sand particles. Water content adheres to the vanes and is gathered at the tip of the vanes 79 by centrifugal force and then is discharged into the hopper 84 in the form of drops. A cover 200 is provided to cover hoppers 84~ 85 and 86 which are partitioned by adjustable partition plates 81.
As described above, with the water separator shown in Figure 16, excess water is removed by an impact force, while the sand particles are classified according to their particles sizé. Since the quantity of water remaining on the treated sand particles differs depending upon the particle size, this modified water separator is especially suitable for a fine aggregate containing particles of different sizes because the sand parti-cles are classified according to their size. Accordingly, the sand par-ticles collected in each of the hoppers 85 and 86 have substantially the same particle size and the quantity of water remaining on the sand parti-cles is also substantially constant.

Still other ernbodiments of the water separator are illustrated in Figures 17 and 18. In Figure 17, the fine aggregare, i.e., sand, is caused to drop between a pair of parallel spaced-apart hard rubber rotors 75, which are rotated at a speed higher than the falling speed of the sand, and then discharged downwardly to impinge upon an inclined impact plate 78 secured by a fastener 78c. Then, the water deposited on the surface of the sand particles is separated and the sand particles are reflected towards 1 ~8~2~
the leEt as shown by solid arrows, to be taken out through a discharge port 73. The separated water and mud are collected in a trough 74. Cleaning water is supplied and discharged from a storage tank 62 through inlet and outlet ports 62a and 62b in the same manner as in the embodiment shown in Figure 12 to wash away mud accumulated on the rear side of the skirt 62d.
Trough 87 is provided to collect the separated water. The sand particles may be projected in the horizontal direction or slightly downwardly in the same manner as in Figures 6 to 15.
Furthermore, two or pairs of the rotors 75 may be juxtaposed to increase the quantity of the sand to be treated.
In still another modification shown in Figure 18A, the sand particles dropping from the hopper are projected at a high speed against an inclined impact plate 78 secured by a fastener 78e by means of a pair of conveyors 72 and 72a running at a high speed, and cleaning water is supplied to a skirt 62d at a lower position than the impact plate 78 to prevent mud from adhering to the inner surface of the skirt. By the high speed belt conveyors 72 and 72a, a large velocity energy is applied to the sand particles regardless of the quantity thereof. Where it is not desired to run the belt conveyors at a high speed, the upper belt conveyor 72a is replaced by a rotating member 80 (Figure 18B) situated at the discharge end of the lower belt conveyor so as to impart the re~uired velocity energy. Where the belt conveyors are run at a high speed, the sand particles tend to jump and splash, thereby decreasing the efficiency of imparting the velocity energy. With the construction shcwn in Figure 18B, it is possible efficiently to remove water without dropping the sand particles away from the conveyor. Where it .~

~ 8523 is not desirable to project the sand particles in the horizontal direction against gravity, the sand paricles may be projected downwardly in the same manner as in ~igure 17.
In a modification shown in Figure 19, the sand par-ticles from the hopper 1 are supplied to a high pressure air nozzle 98 via a metering device 97 to eject the particles against the impact plate 78 by the velocity energy of the high pressure air, thereby removing excess surface water. As before, the inner surface of the skirt is cleaned by the cleaning water.
According to the embodiments described above, since substantially all sand particles imparted with a high velocity energy are caused to collide upon the impact plate, the impact plate wears quickly so that it is necessary frequently to ex-change the same. The modification shown in Figure 20, is con-structed to obviate this problem, comprises a pair of spaced belt conveyors 235 and rotating members 240 driven by motors 203 adapted to impart high velocity energy to the sand par-ticles so that sand particles projected by the belt conveyors collide with each other in a space between the conveyors, thus sprinkling the water removed from the sand particles in the space. A motor driven blower 241 is used to exhaust air en-training the sprinkled water to the outside through a duct ~42 which may contain a mist separator, not shown. With this con-struction, although all projected sand particles do not collide with each other, only a small amount of the projected sand par-ticles collide upon an inverted funnel-shaped impact plate 212a so that the wear thereof is small.
With the embodiment shown in Figure 20, the impact force is different for respective sand particles so that the ,. ~

~, - 23 -:~ ~ 6~523 quantity of the water remaining on the sand paricles is not always constant. To eliminate this problem, an impact plate 234 shown by dot and dash lines may be positioned between the belt conveyors 235. Where sand particles containing mud are projected, the impact plate 94 is taken out through a window, not shown, and cleaned. The impact plate 94 may be a thick casting.
In any of the embodiments described above, substant-ially uniform impact force is imparted to the fine aggregate so as to remove excess water. So long as the impact force is larger than the adhering force of the water to the particles of the fine aggregate, it is possible to remove surplus water.
The removed water flows down along the impact plate while the particles of the fine aggregate are permitted to fall down or move outwardly.
The result of water separation effected by the water separator according to aspects of this invention is shown in Figure 21. As can be noted from the curves shown in Figure 21, irrespective of the difference in the quantity of the surface water which differs dependent upon the ~ - 23a -particle size, so long as the quantity of the surface water exceeds a pre-determined limit before treatment, substantially constant quantity of water remains on the sànd particles after the treatment. Even wnen the quantity of the initial water is less than the predetermined limit, a quantity of water proportional to the initial water quantity can be removed.
When the impulse force is increased by increàsing the speed of the ~ota-ting disc, the quantity of the water remaining after the treatment decreases and vice versa, but the shape of the resulting curves resembles that shown in Figure 21. ~or this reason, in order to make the quantity of water remaining after the treatment uniform, a quantity of water is added to the fine aggregate to adjust its initial water quantity to be higher than, for example, 15%.
In the embodiment shown in Figure l, water is added to the mixer ~ in two stages to be admixed with the fine aggregate treated by the water remover A.
More particularly, at the first stage, water is added to the treated fine aggregate with a water sprinkler Dl and the aggregate is thoroughly mixed together to apply a uniform quantity of water on respec-tive particles. Then, a powder of hydraulic substance, e.g., cement, is added by an adder C and is admixed with the fine aggregate to form shells of cement about the particles of the fine aggregate. An additional quan-tity of water is added by a water adder D2 and the mixture is then kneaded.
The shells thus formed are stable enough to withstand the subsequent addi-tion of water and kneadlng. Accordingly, the structure molded with this mixture has a large mechanical strength. After incorporation of the hydraulic substance, the mixture can be conveyed to a remote station.
It should be noted that, according to aspects of this invention, it is not always necessary to add water in two stages and to add the hydraulic substances between the additions of water. Thus, water may be added at one time. The fine aggregate whose quantity of surface water is adjusted to a predetermined value subsequently to be added to prepare a kneaded compound, thereby reasonably determining the water to cement ratio W/C, the ratio of sand to cement S/C and other factors of compoundlng to cause uniform particles and to increase the mechanical strength of the products. Although coarse aggregate may be added at any stage, it is advantageous to add it immediately prior to the addition of the primary water.
A preferred example of the mixer is illustrated in Figure 22, which comprises a mixing chamber 110 corltaining a screw mechanism 104. As shown in Figure 23, the mixing chamber 110 has a ~-shaped cross-sectional configuration lined with a resilient film 105. Pressure applying chambers 106 are pro-vided on the outside of the resilient film 105 to urge inwardly the resilient film 105. Fine aggregate, whose surface water has been adjusted, and coarse aggregate are fed into the mixing chamber 110 at its left-hand end from hoppers l01 and 103, re-spectively, by a belt conveyor 111. A predetermined quantity of water is then added from a water tank 114 through a pipe 115 including a valve 115v. Secondary water is admitted into an intermediate section of the mixing chamber 110 from water tank 114 via a branch pipe 116 including a valve 116v. One or more additives, e.g., a dispersing agent9 a delay agent, a quick-setting agent, etc., are supplied to the branch pipe 116 from a tank 117 through a pipe 118 including a valve 118v. Where it is not desirable simultaneously ~o incorporate a plurality of types of additives, a plurality of independent tanks each containing an additive of one type may be installed. At the rear or right-hand end is formed an exhaust port 109 to 1 1~8~23 discharge kneaded compound into a receiver 120. The compound in the receiver is conveyed to a working station by a tank car, a pipe, a conveyor or the like.
The pressure applying chamber 106 is sealed and is supplied with pressuri~ed air or water. When pulsating pre-ssuri~ed fluid is applied, it is easy to remove the compound adhered to the resilient film 105. The pressure applying chambers 106 contain elastic tubes 108. The tubes 108 can be substituted by sponge rubber or a hair rock (a mixture of hairs of humans or animals bonded by latex or an artificial resin binder and having a substantial elasticity). Although the pre-ssure applying chamber 106 can be provided along the entire bottom length of the mixing chamber llO, it is advantageous to install a plurality of spaced-apart pressure applying chambers 106 as shown in Figure 22. This construction prevents the res-ilient film from excessively bulging into the mixing chamber to interfere with the operation of the screw m~chanism 104.
Where the mixer shown in Figure 22 is used to prepare compounds, e.g., mortar or concrete, a powder of cement is supplied to the mixing chamber 110 from a cement tank 102 through -a metering device 112. An operation between sand hopper 101 and the cement tank 102 comprises a first step 1, an oper-ation between the cement tank 102 and the secondary water supply pipe 116 comprises a second step II, and an operation between the pipe 116 and the discharge port lO9 comprises a third step III. More particularly, to prepare mortar or cement, in the first step I, a portion of water necessary to prepare the final compound is added to a mixture of sand and gravel through pipe 115 and the water content of the mixture is made uniform by ;~ - 26 -7 ~ ~852~
the screw mechanism 104. Then, a measured quantity of cement is incorporated in the mixture to form stable shells of cement about respectlve sand particles in the second step II.
When preparing cement mortar, in the third step, the secondary water is added through pipe 116 together with one or more desired additives. With the connection shown in ~igure 22, the additive is first admixed with a large quantity of the sec-ondary water in pipe 116 so that even an additi~e having a high viscosity can be uniformly admixed.
Instead of using a single resilient tube 108 as shown in Figure 23, a plurality of juxtaposed tubes 108 may be used, as shown in Figure 24. With this construction, it is not nec-essary to construct the pressure applying chamber 106 to be sufficiently air tight. Furthermore, the tubes 108 which should be air tight would not be damaged by the friction caused by the screw mechanism 104. Where water is filled into the tubes 108, their internal pressure can readily be adjusted by merely changing the level of a water tank. For example, the water tank may be positioned at a position higher than that of the tubes 108 by 1.5 to 2 meters. It was found that this level of the water tank is sufficient to prepare satisfactory cement mortar or concrete.
~s shown in Figure 23, additional pressure applying chambers 126 each containing a resilient tubes 128 not only assist the action of the resilient tube 108 at the bottom of the mixing chamber, but also reinforce the U-shaped resilient film 105, especially when it is more or less aged or elongated, thus maintaining a desirable sealing relationship to the screw mechanism 104.

8 ~ 2 3 The discharge port 109 can be formed at one side of the mixing chamber 110 as shown in ~igure 22 because this con-struction can contain the compound throughout the entire length of the mixing chamber so that even when the compound has a con-siderably high fluidity, the entire length of the mixing chamber can be efficiently utilized.
Figures 25 and 26 show modified mixers, Thus, while in Figure 22 the mixing chamber 110 is made of a single integral member, in ~igures 25 and 26 the mixing chamber 110 is made up 1~ of a plurality of sections. More particularly, in the example shown in Figure 25, the mixing chamber 110 comprises a plurality of cascade-connected sections llOa, llOb and llOc which are disposed at different levels. A sand tank 101, a water tank 121 and a first screw section 104a driven by a motor Ml are provided for the first section llOa. A water content measuring device 122 is provided for the sand tank 101 to measure the water content of the sand treated by the water remover A des-cribed above (Figure 1) so as to control the quality of water supplied from the water tank 121. The second section llOb com-prises a second section 104b of the screw mechanism and a hopperllOe adapted to receive the mixture of sand and water from the first section llOa and a measured quantity of cement from the cement tank 102 via paddle wheel 112. The third section llOc is provided with a hopper llOd adapted to receive kneaded mix-ture from the second section llOb and secondary water from a water tank 123, and a discharge port 109 at the end of the third section and connected to a discharge pipe 124 for con-veying the resulting compound to a receiver 120.

The section 104b of the screw mechanism is secured to a hollow tube comprising the second section, the hollow tube bein& rotated by a motor M2 through a pinion and a ring gear 134 secured to the tube. A horizontal shaft 135 extends through the third section llOc and is driven by a motor M3.
The horizontal shaft 135 is provided with a plurality of paddles 136 which are set at a predetermined angle to assure uniform mixing.
In the modification shown in Figure 26, the sections llOa, llOb and llOc are arranged coaxially to form a continuous mixing chamber. Sections 104a, 104b and 104c are mounted on a common shaft 140 driven by a motor N4 located at the lefthand end of the mixing chamber. The second and third sections llOb and llOc are rotated by motors M2 and M3 respectively in a dir-ection opposite to that of the screw sections 104b and 104c for the purpose of improving the mixing efficiency. For the purpose of adding the secondary water at the same position as that shown in Figure 25, the shaft 140, at least in the third section, is made hollow to feed water from a water tank 133 through per-forations 133a at one end of the third section llOc.
Although the multiple sectlon construction of themixing chamber shown in Figures 25 and 26 is more or less com-plicated, since the volume of the contents of respective sec-tion varyby the ingredients added in respective sections, it is possible to construct respective sections to contain contents of varying volume. Mixers of different types may be used as shown inrespective sections.
Another example of the mixer utilized in aspects of this invention is illustrated in Figures 27 and 28. As shown, a mixing chamber has a U-shaped sectional configuration and a length sufficient to complete the entire mixing and kneading operations. A horizontal rotatable shaft 159 extends.through the mixing chamber 160 and is provided with a plurality of mixing member 158 which are arranged generally along a helix, The angles of inclination and the pitches of the respective mixing members are varied in accordance with the mixing steps.
Sand with its water content which has been adjusted by the water separator Adescribed above is supplied to the lefthand end of the first section I by a belt conveyor 151. The primary water isadded at substantially the same position through a water pipe155. Coarse aggregate~ i.e., gravel, is added from a gravel tank 155a at a joint between the first and second sections I and II, while cement is added from a cement tank 155c adjacent the gravel tank 155a. The secondary water and the additive are incorporated at a joint between the second and third sections II and III through pipes 155b and 155d respect-ively. In addition to the mixing member 158, relatively small auxiliary mixing members 157 are also mounted on the portions of the shaft 159 in the first and second sections I and II.

These auxiliary mixing members 158. If the direction of the auxiliary mixing members is the same as that of the main mix-ing members, the angle of inclination of the auxiliary mixing members is made to be larger than that of the main mixing mem-bers~ The main and auxiliary mixing members are inclined and are arranged along continuous helical lines respectively. As shown in Figures 29, 30, 33 and 34, the main mixing members are separated more than 30 about the periphery of the rotating shaft 159 and constructed such that each main mixing member does not extend over an angle of at least 360~.
As shown in ~igures 29 and 30, the auxiliary mixing members 157 have a smaller height than the main mixing members 158 and in the case shownin Figure 30, the auxiliary mixing members 157 utili~ed to support the main mixing members 158.
As shown in Figures 33 and 34, both main and auxiliary mixing members 158 and 157 are secured to the rotating shaft 159 by means of suitable fasteners 156.

In the construction shown in Figures 27 through 34, the speed of moving the mixture towaId the discharge opening 166 varies depending upon the angle of inclination of the mix-ing members 157and 158 with respect to the rotating shaft 159 corresponding to the variation in the bulk of the mixed compos-ition charged. Considering only the weigh~, the speed of move-ment is the minimum at the charging end, while it is the maxi-mum at the discharge end, but in the method of aspects of this invention, where the water content of the mixture varies, the problem is not so simple. Thus, the volume varies between a case wherein sand having a relatively small quantity of water, e.g., 2 - 3%s and a case wherein said contains much more water.

In a relatively dry mixture incorporated with cement which forms-shells, its volume shows a maximum, whereas when water is added to increase the fluidity of the mixture, the weight therof in-creases but its volume decreases greatly. In the step shown in Figure 27, in which the primary water is added to make the sur-face water uniform, the angle of inclination of the-main mix-ing members 157 is made to be a standard, whereas the auxiliary mixing members 157 are inclined in the opposite direction to , ~
~ - 31 -~ ~ fi8S23 realize a relatively slow feed speed. In the second step II, the angle of inclination of the main mixing members 158 is made larger so as to obtain higher feed speed, thus allowing an increase in the bulk in step II~ In step III, after incorpor-ation of the secondary water, the fluidity increases, thus further decreasing the volume. For this reasorl, in step III, the angle of inclination of the main mixing members 158 is made to standard to decrease the feed speed than that of sec-tion II. For the reason described above, with a mixing chamber 160 having a uniform cross-sectional area, the mixture can be mixed together with a constant surface level irrespective of the variation in the bulk. At the discharge port 166, the sur-face level of the mixture decreases rapidly as the mixture is discharged so that it is advantageous to provide an auxiliary mixing member 157a at this position to make the residence time of the mixture at this position as long as possible. The com-pound discharged through the port 166 is received by the rec-eiver 170,but the discharged mixture can be conveyed by a con-duit or a pump.

While in the embodiment shown in Figures 27 - 30 the variation in the bulk is coped with by varying the angle of in-clination of the mixing members 158, in the embodiment shown inFigures 31 and 32 the variation in the bulk is coped with by varying the volume of the mixing chamber 160. More particularly, the height of the side walls 160d of the mixing chamber 160 at section II is increased to increase the volume thereof. Be-cause inthe step in which shells of cement are formed about sand particles and the quantity of water between the sand par-,~
. :, ~, -ticles is very small, even when the volume of the mixture increases, its fluidity is small so that the variation of the bulk can be coped with by merely increasing the height of the side walls 160d~ Even when the high side walls 160d are pro-vided~ the cross-sectional configuration of the ~ixing chamber 160 is generally ~-shaped so that transfer of the mixture can be performed efficiently by the inclined mixing members 158, and the portion of the mixture bulged upwardly in section II i5 subjected to efficient mixing operation. When the pitch of the mixing member in section II is suitably selected, efficient mixing and kneading of the mixture can be assured with a re-latively short length of the section II.
Th.e embodiments shown in Figures 27 - 30 are suit-able for preparing a large quantity of cement mortar or cement compound of excellent characteristics.
To have a better understanding of aspects of this invention, the ff~
- ~ 32a -following Examples are given.
Exampl In this example, the apparatus shown in Figure 2 was used which is provided with a rotating disc 2 having a diameter of 400 mm and driven by motor 4 at a speed of 1100 rpm. Fine river sand containing 3.98% of water and having a fineness modulus (F.M.~ of 1.28 mm, ~the F.'.~. being determined according to the equation F.M. = -1 P /100, where P is weight percent of aggregate remaining in a mesh of 0.15, 0.3, 0.6, 1.2, 2.5 or 5.0 mm after meshing, the quantity of surface water varying from 4% to 25%) was supplied to the rotating disc 2 to cause the sand particles to collide upon the impact plate 6. The rate of supply of the water containing sand to the hopper 1 was varied in a range of 50 to 160 Kg/min. and the water content of the sand conveyed by the conveyor 11 was measured to be 9.4 -10.1% showing that the quantity of the surface water is substantially con-stant.
I~here the speed of the rotating disc 2 was increased to 5000 rpm, the quantity of the surface water was measured to be 6.06 - 6.38% which shows that the quantity of the surface water was substantially reduced than that when the rotating disc was rotated at a lower speed and the variation in the quantity of the surface water is much smaller.
Example 2 l~ith the same apparatus utilized in Example 1, sand particles of medium size and containing 2.25% of water and having F.M. of 2.28 mm was treated in the same manner. In this example, however, water was added to the sand at the exit of the hopper 1 at a rate of 4 ~/min. I~hen the rota-ting disc 2 was rotated at a speed of 1100 rpm, the water content of the treated sand was 4.7 _ 5.3C/ showing that the quantity of the surface water has been decreased because the treated sand had a larger particle size.
However, it was found that the range in which the quantity of the surface water varies has been narrowed. In c~ntrast, when the speed of the rotating P~
~ - 33 -disc 2 was increased to 5~000 rpm, the quantity of tne surface water varied in a narrower range of 4.33 to 4.85%.
Example 3 Coarse sand produced from a different origin from that utilized in ~xample 1 and having a Jater content of 3.31% and F.M. of 2.96 rmn was treated in the same manner as in Example 2. More particularly, when the rotating disc 2 was rotated at a relatively low speed of 1100 rpm, the quantity of the surface water was 3.3 - 4.2%, whereas at a higher rotating speed of 5000 rpm, ~he quantity of the surface water was 3.2 to 3.52%
showing a narrower range.
Example 4 In this example, the apparatus shown in Figures 4 and 5 was used in which the rotating disc 2 having a diameter of 450 mm was rotated by motor 4 at a speed of 1250 rpm. ~Iedium size river sand having a water content of 2.25% and F.M. of 3.27% was caused to collide against the impact plate 6. I!ater containing sand was fed into the hopper 1 at a rate of 25 m3/hour. 5-40 ~ /mln. of water was sprinkled onto the sand while it was being conveyed by conveyor 30. The treated sand collected in the bottom portionof the receptacle 9 was conveyed by the conveyor 11. The conveyed sand was sampled at each minute to measure the water content of the treated sand. The water content measured was in a range of 8.79 - 8.93%
and it was found that the quantity of the surface water was substantially constant, i.e., from 6.54 to 6.58%. The quantity of the recovered sand after the treatment was 24.1 m3/hour, showing a high yield of 96.2%. The unrecovered quantity consisted essentially of mud.
~len the speed of the rotating disc 2 was increased to 1500 rpm, the water content of the treated sand was 6.92 - 7.04% ~the quantity of the surface water is 4.66 - 4.77~). At a higher speed of 1750 rpm, the water content of the treated sand was 5.79 - 5.88% (the quantity of the surface water was 3.53 - 3.62%). Thus, in each case the quantity of the - 34 _ ~ L ~ 3 surface water was reduced and is su~stantially constant. The quantity of the treated and recovered sand was 24.28 m3/hour for 1500 rp~, and 24.52 m3/hour for 1750 rpm.
_xample 5 The same apparatus utilized in Example 4 was used to treat medium size sea sand having a water content of 2.46%, a salt content of 0.33%, and F.M. of 2.62%. In this example, 30 ~ /min. of water was added to the sand while it was being conveyed by the conveyor.
In this example, when the rotating disc was rotated at a lor,7er speed, the water content of the treated sand was 8.56 - 8.71% (the quan-tity of the surface water was 6.40 - 6.55%). Even with the same rotation speed of the disc, since the sand is coarse, its quantity of surface water has been decreased. Although the treated sand still contains 0.03~ of salt, it can be used for preparing green mortar or green concrete because of the formation of the cement shells, and the quantity of the recovered sànd was 23.8 m3/hour.
I~hen the rotating disc 2 was rotated at a speed of 1500 rp~, the water content of the treated sand was 6.76 - 6.83% (the quantity of the surface water was 4.30 - 4.37%), whereas when the speed of the rotating 20 disc was increased to 1750 rpm, the water content of the treated sand was 5.51 - 5.58~ (the quantity of the surface water was 3.05 - 3.12) which shows that the variation in the water quantity is also small. The salt contents were 0.028% and 0.027% for 1500 rpm and 1750 rpm respectively and such salt-containing sand could be used to prepare a concrete compound.
To remove salt, it is necessary to use clean water of a quantity at least equal to that of sea sand, so that to remove salt from 25 m3 of sea sand, it is ne~essary to use 25 - 80 m3 of clean water. In contrast, according to this example, the quantity of water added to the sea sand is only 30~ /min., or 1.8 m /hour.
~hen salt is removed by sprinkling water on~o sea sand, the sal~

i - 35 -` 1 i~85~3 , . .
is not removed uniformly, For example~ eYen though the a~erage quantity of the remaining water is 0.03%, it varies between 0.002 and 0.150%, mean-ing that a considerable quantity of washed water contained more than 0.04%
of the remaining salt whic~ is the permissible upper limit. According to this example, when water is added to the sea sand being conveyed by the conveyor at a rate of only 30 ~/min., since the separation of water is efficiently performed by the impact force, the quantity of the remaining salt is only 0.007 - 0.038%.
Example_ Fine particles of a slag pulverized by water and having F.M. of 2.53 1mn and containing 2.90~ of water ~as treated in the same manner as in Example 4.
More particularly, when water is removed at the rotating speed of 1250 rpm of the disc 2, the water content of the slag particles was 8.99 - 9.27% tthe quantity of the surface water was 6.09 - 6.37%), whereas at the speed of 1750 rpm, the water content was decreased to 6.19 - 6.28%
(the quantity of the surface water was 4.29 - 4.38%) and the quantity of recovered sand was 24.0 m3, 24.3 m3 and 24.51 m3 at the speeds of 1250, 1500 and 1750 rpm respectively.
~ e~

In this example, the apparatus shown in Figures 6 - 9 was used.
Coal dust having a particle si~e of 0.15 - 5 mm and containing 3 - 15%
of the surface water was treated by the apparahus. The feed speed was selected in a range of from 80 to 200 Kg/min.
The rotating member 52 was provided with vanes having a length ~ of 250 mm between the axis and the outer end and the rotating member was rotated at a speed of 1500 rpm to remove water from the coat dust. After treat~nent, the coal dust contained 4.2 - 4.3~ of the surface water, showing uniform water removal. Mud on the particles of the coal dust was also efficiently separated.

~ - 36 -~ - ~
_xample 8 1~6~523 In this example, the apparatus shown in Figures 10, 11 and 12 was used to remove water from blast furnace slag containing 20.5 - 57.5%
of the surface water.
The rotating member 52 had a radius of 300 mm and rotated a~ a speed of 2000 rpm. The treated slag contained 12 - 15% of the surface water. The particle size of the slag was larger than O.l mm which can be classified.
~ æle 9 The apparatus shown in Figures 6 - 9 was used, and in this example, mineral particles having an oil content of 28 - 46~/. and a grain si~e o~ less than 3 mm was preheated to 80C. and then supplied to the hoipper 1.
The rotating member 52 was provided with blades having a length of 250 mm between the axis and the ends of the blades. The rotating body was rotated at a speed of 1850 rpm, and the impact plate 60a was heated to 60C. After the treatment, the quantity of oil remaining on the mineral particles was 4.8 - 5.3~ showing substantially uniform removal of oil.
According to a prior art method of removing oil contained in mineral particles, the oil was removed by evaporation. To this end, it has been necessary to heat the particles at a high temperature of 500DC.
for a considerable period while agitating~ Furthermore, it is necessary to recover evaporated oil by condensation which requires an expensive equlpment. In contrast, the apparatus of an aspect of this invention is simple in construction and consumes less operating energy.
The following examples show the use of the fine particles removed with water by the method and apparatus of aspects of this invention as des-cribed above.
Example lO
To prepare cement mortar according to a conventional method, :

g8523 nearly perfectly dried medium size river sand, water and 956 Kg of cement were used at a C/S ratio of 1:1 and at a W/C ratio of 35%. 765 Kg of a lignin sulphonic acid-type dispersing agent was added and the mixture ~as kneaded. The resulting mixture evolved a considerable number of air bubbles and had a fluidity of 42 sec. when measured with a J funnel which have 6.5 cm in diameter of feed side, 45 cm in hieght and 1.0 cm in dia-meter of discharge side. The percentage of breezing after 3 hours was 6%.
The product molded with this mortar had a compression strength of 375 Kg/
cm2, 489 Kg/cm and 563 Kg/cm2 respectively after 3, 7 and 28 days. The coefficient of variation after 28 days was 15.3%.
The same sand was dehydrated according to the process of Example 4 by using the apparatus shown in Figure 4. When the rotating disc was rotated at a speed of 1750 rpm, the quantity of the surface water after the treatment was 3.53%. Cement, water (total water minus the remaining water)and a dispersion agent were added to the treated sand in quantities to ôbtain the same W/S and W/C ratios described above. After kneading for two minutes, a cement mortar was obtained having a fluidity of 13 seconds when measured with a J funnel and the percentage of breezing of 0.5% after

3 hours. Products molded with this mortar had a compreSSiOn strength of 532 Kg/cm , 698 Kg/cm and 790 Kg/cm respectively after 3, 7 and 28 days, the variation coefficient being 4.8%.
The water content of the same medium size sand was reduced at a rotating speed of 1750 rpm of the rotating disc to adjust the quantity o~
the surface water to 3.53%. After uniformly incorporating 16.47% of primary water to the sand thus treated a quantity of cement sufficieint to obtain a ratio C/S = 1:1 and the mixture was admixed to form cement shells have a W/C ratio of 20% about the sand particles. After adding 15~ of the secondary water and 0.8% of a dispersing agent, the mixture was kneaded to obtain cement mortar having a fluidity of 19 sec., and zero breezing per-centage after 3 hours. The compression strength of the products molded " .-- .
~ - 38 -`- 1 168~23 with this mortar was 619 Y~g/Cm ~ 739 Kg/cm and 855 Kglcm respectiyely after 3, 7 and 28 days, the variation coefficient being 2.2%; ~en rom-pared with products prepared by the prior method, the products prepared according to the method of ~spects of this invention have higher compres-sion strength and are more stable.
Example 11 The same quantity of the same sand as that of Example 10 but not dehydrated according to the method of an aspect of this inveniton, 347 Kg of cement, 3.5 Kg of a dispersing agent and water were mixed together to obtain mortar having ratios C/S = 1:2, C/G = 1:3.6 and WJc = 42% to pre-pare mortar having a slump value of 2.1 cm and appreciable breezing and air bubbles. The compressive strength of the products molded with this mortar was 208 Kg/cm , 284 Kg/cm and 334 Kg/cm respectively after 3, 7 and 28 days, the variation coefficieng being 17.4%.
Similar mortar was prepared except that the surface water was reduced to 3.53%. The mortar, less than 2.5 minutes after kneading, had a slump value of 8.2 cm and showed certain segregation and breezing. The products molded with this mortar had a compression strength of 274 Kg/cm2, 348 Kg/cm2 and 482 Kg/cm after 3. 8 amd 29 days respectively and a varia-tion coefficient of 8.2% showing an increase in the strength by 50% anduniform quality.
6.47% of the primary water was added to the same river sand which had its quantity of the surface water adjusted to 3.53% and the same quantity as described above of sand was added to form cement shells whose W/C content was 20%. Thereafter, gravel, 22% of the secondary water and 1% of a dispersing agent based on the quantity of cement were incorporated and kneaded together to obtain a concrete compound having a slump value of 11.6 cm. The product molded with this concrete compound had a compression strength of 308 Kg/cm j 382 Kg/cm and 513 Kg/cm2 respectively after 3, 7 and 28 days and a variation coefficieint of 5.1% showing an increase of 50%
Y P~
- 39 _ 1 1 ~8523 of the compression strength and uniformity of the products.

Example 12 ___ _ ___ To a concrete compound having the same formulation as that of Example 11 was added 1.5% by volume of steel fibers. In this example, the sand was not dehydrated according to the method of aspects of this inven-tion. The resulting concrete compo-md had a slump value of 1.5 cm and showed large segregation and breezing. The bending strength of the con-crete product molded with this concrete compound ~as 58 Kg/cm after 28 days.
10In contrast,a similar concrete compound utilizing the same sand dehydrated by the method of aspects of this invention had a slump value of 7.4 cm immediately after the kneading and showed a slight segregation and breezing. A concrete product molded with this concrete composition showed a bending strength of 75 Kg/cm after 28 days.
A concrete compound utilizing dehydrated sand particles formed with cement shells having a ratio of W/C of 20% and incorporated with the steel fibers had a slump value of 12.~ cm, and showed no breezing. The concrete product molded with this concrete compound had a bending strength of 92 Kg/cm after 28 days.
Exampl The same river sand as that used in Examples 10 - 12 was used.
350 Kg of cement, 1120 Kg of sand~ 700 Kg of a coarse aggregate, and 10.5 Kg of a quick-setting agent were admixed under dry state. The resulting mixture was conveyed by high pressure air to a working station where water was added in an amount to obtain~a ~/C ratio of 50~. The resulting concrete compound was blasted against a vertical wall through a blasting nozzle.
The quantity of rebound was above 35~ hen blasted against the wall of a tunnel, the quantity of dust generated was 750 CPPI. 28 days after blasting the concrete had a compression strength of 232 Kg/cm and a variation coefficient of 14.5%.
. . .

~- 40 ----` 1 g 6~2~
The concrete compound haying the same compositionas in E~amples 10 - 12 except that the quantity of the surface water was ad~usted to be 3.53% was prepared and the concrete compound was blasted under the same conditions. It was found that the quantity of rebound was 18% and the quantity of dust generated was 340 CPM. The-blasted concrete had a compres-sion strength of 363 Kg/cm2 after 28 days and a variation coefficient of 5.3%.
The same sand with its surface water adjusted to be~ 3.53% and a quantity of cement were mixed together to form cement shells having a W/C
ratio of 20~. Then a quantity of water to ensure a ratio ~/C = 34.2~ and 0.6% based on the weight of cement, of a dispersing agent were added to prepare a mortar having a high fluidity. The mortar was conveyed under pressure through a pipe. Another dry compound was prepared having ratios C/S = 1:3.01 and S/A (A represents a coarse aggregate) of 56% and conveyed under pressure through another pipe. The two compounds were admixed at the working station at a ratio of 1:1.75 by volume together with a suitable quantity of a quick-setting agent. The concrete composition suitable for blasting had a ratio W/C of 42% and contained 352 Kg of cement, and blasted against a wall. The amount of rebound at the time of blasting was 8.9% and the quantity of dust generated was 72 CPM. The compression strength of the blasted concrete after 28 days was 542 Kg/cm2 and the variation coeffi-cient was 3.2~. The compression strength was increased by 100~ and the variation coefficient was reduced to 1/5 when compared with conventional concrete compound.
Example 14 In this example, the water remover A sho~ in Figure 16 was com-bined with the mixer B shown in Figure 27. A medium size river sand (containing 23% of water and a quantity of surface water of 3 - 27%~ and having F.M. of 2.1 was treated by the water removPr ~.
The rotating member 77 was provided with vanes 79 having a length ~ - 41 -~ ' &8~23 of 225 mm and rotated at a speed of 1250 rpm. The water con-taining sand was supplied to the hopper 1 at a rate of 50 -120 Kg/min~ The sand in the hopper 85 contained 6.7 - 6.9% of the surface water, and that in the hopper 86 contained 6.4 -6.8~ of the surface water. The quantity of the surface water of the sand contained in the hopper 86 corresponds to that of the medium size sand.
~ here the speed of the rotating member was increased to 1500 rpm, the water content of the sand in the hopper 85 was 5.6 - 5.9%, that of the sand in the hopper 86 was 5.2 - 5.4%.
When the speed is increased further to 1750 rpm, the water con-tent of the sand in the hopper 85 was 3.9 - 4.2~ and that of the sandin the hopper 86 was 4.1 - 4.3%, showing substantially equal water content.
Cement, ~ter and 1% of a dispersing agent based on the volume of cement were added to the sand thus treated to obtain ratios of C/S = 1:2 and W/C = 43%. The quantity of water added corresponds to the difference between the added water and surface water. The kneaded mixture had such fluidity that the shearing strength F of 1.54 g/cm , a relative viscos-ity coefficient ~ of 0.86 g/sec.cm4, a relative closure coeffic-ient ~F of 0.0034g/cm and a segregation and breezing of 0.05%.
The compression strength of a molded product utiliæing the mor-tar thus prepared had a compression strength of 438 - 452 Kg/cm (average 447 Kg/cm ) and 521 - 545 ~g/cm (average 534 Kglcm ) after 7 and 28 days respectively. Although a little segregation and breezing were noted, the product had uniform strength.
In addition to the kneading operation in which all _ 41a -1 ~8t~23 quantity of water is added at a time, another process was also performed which includes the shell forming step and water S~as added through pipe 155 to ensure surface water of 10%, then a quantity of Portland cement was added to obtain a ratio ~/C
of 20%. Finally, 153 Kg of the secondary water and 1% based on the volume of the cement of a dispersing agent were incorporated to prepare cement mortar - 41b -,. ..

1 ~ 6 8 ~ j ~ 3 having ratios S/C = 2 and ~/C = 43%. The fluidity of the mortar ,7as s1~ch that the initial shear strength F of 2.63 g/cm3, a relative visco^,ity coefficient A of 1.08 g-sectcm4 and a relative closing coefficient ~ Fo of 0.0072 g/cm4. No segregation and breezing were noted. The molded pro-duct had a compression strength of 521 - 545 Kg/cm2 (average 535 Kg/cm ) and 628 - 656 Kg/cm2(average 642 Kg/cm ) after 7 and 28 days respectively.
A portion of piled up sand, 285 Kg of water, 664 Kg of cement were admixed and kneaded to obtain a mortar having F of 0.74 g/cm , ~ of 1.37 g-sec/cm4, ~ ~ of 0.014 g/cm4, and a segregation and breezing of 1.4%. The product molded with this mortar had a compression strength of 268 - 367 Kg/cm (avera~e 332 Kg/cm ) and 353 - 501 Xg/cm (average 397 Rg/cm ) respectively after 7 and 28 days. Thus the mechanical strength is substantially lower and varies a great deal.
_xample 15 A mixer A shown in Figures 6 to 9 was used for dehydration. Fine water containing sand (the quantity of the surface water of 3 to 27%, percentage of water absorption of 2.8~, and F.M. of 1.93) was supplied to the upper portion of the hopper 51 and water was sprinkled onto the sand at a rate of 30 ~/min., while the sand is being conveyed. The rotating member 52 was rotated at a speed of 1500 rpm to project the sand at a rate of 360 - 450 Kg/min. The quantity of water remaining on the sand particles after the dehydration treatment was 8.3 - 8.5% showing a small variation.
This means the even when the rotating speed is varied more or less, it is possible to adjust the quantity of the surface water as desired.
Cement,gravel and water were added to the dehydrated sand in such amounts to obtain ratios S/C = 1:2, S/G = 38.5% and W/C = 43%. 1.2% based on the volume of the cement of a dispersing agent was added and then kneaded. The resulting concrete had an excellent fluidity and a slump value of 15.6 and only a slight segregation and breezing were noted. The product molded with this concrete compound had an average compression 'r~/ ' ~

strength of 285 Kg/cm2 and 412 Kg/cm2 after 7 and 28 days respectively, the variation coefficient thereof being 8.8%.
I~ere the mixer sho~m in Figure 27 was used, the primary water was added to the treated sand to adjust its surface water to be 10%, 1150 Kg of gravel and a powder of Portland cement were then added to adjust the ratio W/C to be 20%. Then 83 Kg of the secondary water and 1.2% based on the volume of the cement of a dispersing agent were added to obtain a concrete compound having ratios S/C = 2, S/A = 38.5, and ~/C = 43% and a high fluidity of 17.2 cm in terms of the slump value. The product molded with this concrete compound had an average compression strength of 351 Kg/cm after 7 days and 468 Kg/cm after 28 days showing only 5% variation coefficient.
As a control, the water content of the same sand was measured and corrected, Then, 360 Kg of cmeent, 155 Kg of water, 720 Kg of sand and 1150 Kg of gravel were admixed with a mixer to produce a concrete compound having the same formulation as described above, and a slump value of 12 cm.
The average compression strength of a molded product was 197 Kg/cm2 and 343 Kg/cm after 7 and 28 days respectively. Thus, not only the variation coefficient is 15.6%, but also the strength is lower and varies.
Example 16 The water separator shown in Figures 10 to 12 was used to treat a coarse river sand containing 3.8 - 26% of water (percentage of absorption of 1.7%) and coarseness of 3.35.
The rotating member 52 was rotated at a speed of 1750 rpm to adjust the surface water to 3.2 - 3.3% of the sand supplied from the hopper 51 at a rate of 360 to 450 Kg/min. After incorporating the primary water to the treated sand to adjust its surface water to 14%~ a powder of Port-land cement was added to product a W/C ratio of 20%. Thereafter, 290 ~g of the secondary water and 1.2% based on the volume of the cement of a disper-sing agent were added and kneaded to obtain a mortar having ratios S/C = l.;, 8~2~
W/C = 38~ and such fluidity that the initial shear strengt'n F of 0.69 g/cm , a relative viscosity coefficient ~ of 0.35 g sec/cm4, and a r la-tive closing coefficient ~ of 0.0032 g/cm4. The mortar was transported by a pump to a station 120 m apart through a pipe having an inner dia~eter of 5 cm at a speed of 67 m/min. At the station 1 part of the sand, the surface thereof having been adjusted to 3.2 - 3.3%, 0.95 part of gravel having a siæe of 1 - 15 mm and a powder of cement were incorporated to form cement shells in which W/C is 18% at a point 5 m before a blasting nozzle. The concrete compound was then blasted agains~ ~he inner wall of a funnel.
The quantity of the blasted concrete composition was 8 m3 per hour, the ratio W/C thereof was 33.4% and the quantity of cement was 509 Kg/m3. The amount of rebound at the time of blasting was 6.5% and the quantity of dust generated was 1.21 mg/m3. The round upper wall of the funnel was satisfactorily blasted to a thickness of 120 mm without any peeling. The average compression strength of the blasted concrete was 329 Kg/cm2 and 603 Kg/cm2 after 3 and 8 days respectively. The variation coefficient was 3.2% and the average strength was higher by 1.4 times the prior art concrete having the same ormulation, while the variation coefficieint was reduced to 115.
Where the quantity of the surface water of all portions of the sand was not adjusted but only a sampied portion was adjusted, concrete was prepared by admi~ing the sand and then blasted according to the prior art wet or dry process. The amount of dust generated at the time of wet blasting was 6 - 10 m/m whereas that of the dry blasting was 6 - 10 mg/m .
The quantity of dust, i.e., 1.21 mg/m3, of the concrete prepared using the method of an aspect of this invention is much lower than these values.
l~hile with conventional concrete the amount of rebound is 20 - 30~, in both wet and dry blasting of the concrete prepared using the method of an aspect of this invention, the amount of rebound was reduced to a fraction of these ~ 44 -2.3 amounts. I~loreover, the reaction applied to the nozzle is much s~al~er than blasting prior art concrete compounds. Theconveyed quantity of 3 - 4 m /hour of the prior art concrete could be doubled when a pipe line having an inner diameter of 5 cm was used.
_xample 17 In this example, the water separator shown in Figure 10 ~,?as used to treat a river sand containing 3 - 15% of the surface water (percentage of water absorption Z.3% and coraseness of 2.1). In this example, water was added to the sand at a rate of 32 ~ /min. while the sand is being conveyed by the conveyor. The rotating member 52 was rotated at a speed of 1780 rpm and the sand was supplied thereto at a rate of 360 - 450 Kg/min.
The quantity of the surface water reamining on the sand particles was 4.6 -

4.7% showing uniform water removal.
After adding the primary water to the treated sand such that its surface water would be 7.6%, 1196 Kg of gravel and a quantity of Portland cement were added such that the ratio W/C would be 18%. The resulting mixture was transported by trucks to a working station spaced by 2 hour driving-time distance. 92.4 Kg of the secondary water and 1.2% based on the volume of the cement of a dispersing agent were incorporated into the mixutre at the working station to prepare a concrete compound having ratios of W/C = 2.34, S/A = 38.5% and W/C = 46.8%. The concrete had a high fluidity as evidenced by its slump value of 12.5 cm and no segregation and breezing were noted. ~he roduct molded with the concrete compound had an average compression strength of 303 Kg/cm2 and 420 Kg/cm2 after 7 and 28 days respectively and a variation coefficient of 4.3%.
On the other hand, a green concrete having the same formulation but prepared according to the prior art method decreases its slump value in proportion to the time required for transportation, thus degrading workability. For this reason, it is necessary to agitate the green concrete during transportation. In addition, after transporting over a long dis-~ 45 -

5 ~ 3 tance, it has been necessary further to add water at the ~Jorking sta~ion which decreases the mechanical strength of the product. For example~ the compression strength after 28 days of the product prepared with such green concrete was only 300 Kg/cm2 and its variation coefficieint was 15% w'nich should be compared with 4.3% of the product prepared ~y the method of an aspect of this invention. In addition, according to aspects of this invention, it is not necessary to transport the total quantity of the water.
Example 18 In this example, the mixer shown in Figure 22 was used having an inner diameter of 350 mm of the mixing chamber 110 and a total length of 40 m. The shaft or screw 190 was rotated at a speed of 70 rpm. River sand with its surface water adjusted to 3.8 - 4.2% by the water remover shown in Figures 4 and 5 was supplied to the mixing chamber from the hopper 101 at a rate of 232 Kg/min. and gravel was supplied from the hopper 103 at a rate of 412 ICg/min. Then water was supplied through pipe 115 at a rate of 11.25 ~7/min. to adjust the surface water of the aggregates to 11.6 - 12.6%. Then cement was added to the aggregate from tank 102 at a rate of 115 ~g/min. to form cement shells ~hose W/C ratio was adjusted to be 24%. To the mixture were added the secondary water and a mixture of lignin and sulphonic acid through pipe 116 at rates of 18.6 ~ /min. and 1.13 ~ /min. respectively followed by continuous kneading to form a green concrete at a rate of 20 m3/hour in which ~/C = 42%, C/S = 1:2 and S/G =
1:1.78.
This green concrete had a slump value of 12 cm and showed no segregation and 'Dreezing. The product molded with this green concrete had a compression strength of 254 ICg/cm2, 345 Kg/cm2 and 442 Kg/cm2 respecti~7e-ly after 3, 7 and 28 days.
Example 19 The mixer shown in Figure 25 was used. An artificial light weight 3~2~
fine aggregate (specific gravity 1.4) containing 8~ of surface water, and the other artificial light weight coarse aggregate (specific gravity 1.6) having a particle size of 15 mm and containing 1% of the surface water were prepared, The fine aggregate was charged into the hopper 101 at a rate of 159 Kg/min. 9 while the coarse aggregate was charged into the hopper 101 at the same rate. Water ~as sprinkled upon the aggregates from tank 121 at a rate of 11 ~/min, to adjust the surface ~7ater of the aggre-gates to 15%.
~ powder of cement was added to the mixture of the fine and coarse aggregates from hopper 102 at a rate of 117 Kg/min. to form cement shells about the aggregates. Then water and naphthalene sulphonate-type water decreasing agent were incorporated from tank 123 at the rates of 31 ~/mirl. and 6 ~ /min. respectively.
The resultant concrete had an excellent flui~ity as evidenced by its slump value of 15 cm, and no segregation and bleeding were noted. The composition of the green concrete comprised 350 ~g of cerent, 4~t~ ~g o+
sand, 162 ~ of water and 18~ of water decreasing agent, each per cubic meter. Its W/C ratio was 46~, and the percentage of the coarse aggregate was 50%. The product molded with this green concrete had a compression strength of 216 Kg/cm and 386 Kg/cm respectively after 7 and 28 days.
The product prepared by the prior art method had a compression strength of 173 Kg/cm and 331 Kg/cm after 7 and 28 days respectively.
Example _ In this example, the mixer shown in Figure 26 was used. ~lore particularly, sand having a particle size of less than 5 mm and containing

6~ of the surface water and gravel having a grain size oi 25 mm and contain-ing 1% of the surface water were prepared and charged into hopper 101 at rates of 260 Kg/min. and 348 Kg/min. respectively. Itater was supplied to the tank lOl from tank 121 at a rate of 8 ~ /min. to adjust the surface water of the aggregates. Then cement was added to the mixture of the sand and gravel from hopper 102 at a rate of 117 Kg/min. to form cement shells about the aggregates.
A mixture of water (at a rate of 31 /min.) and lignin sulphon-ate-type water decreasing agent (at a rate of 6 /min.) ~7as supplied to the mixing chamber from hopper 133. The green concrete discharged in~o the receiver 120 had a slump value of 17 cm and no segregation and bree~-ing were noted, showing high fluidity. The composition of the green con-crete was: 350 Kg of cement, 780 Kg of sand, 1043 Kg of gravel, 162 of water, 18 of the water decreasing agent, each per cubic meter and its W/C ratio ~7as 46%.
The product molded with this green concrete had a compression strength of 224 Kg/cm and 403 Kg/cm2 after 7 and 28 days respectively.
The concrete products prepared by the prior art method had a compression strength of 183 Kg/cm2 and 348 Kg/cm respectively after 7 and 28 days respectively, ~hich proves the excellent properties of the product prepared by the method of aspects of this invention.

~ _ 48 -

Claims

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

1. A method of preparing a hydraulic mortar or concrete comprising the steps of: adding a quantity of water to fine aggregate particles to increase their water-content; sequentially supplying a predetermined quantity of said fine aggregate particles to which water has been added; applying, to said fine aggregate particles, an impact force stronger than the adhesive force of the water to said fine aggre-gate particles, thereby to remove excess water therefrom; and mixing a hydraulic substance with said fine aggregate particles.

2. The method of claim 1 wherein said hydraulic mortar or concrete is a cement compound, and wherein said fine aggregate particles are sand.

3. A method of preparing a hydraulic mortar or concrete comprising the steps of: supplying a predetermined quantity of fine aggregate particles having water on the surface thereof; applying, to said fine aggregate particles, an impact force stronger than the adhesive force of the water to said fine aggregate particles, thereby to remove excess water therefrom; adding a portion of water necessary to prepare said hydraulic mortar or concrete from said fine aggregate particles; adding a hydraulic substance to the resulting mixture of fine aggregate particles and water to form shells of said hydraulic substance about particles of said fine aggregate particles; adding the remaining portion of said water necessary to prepare said hydraulic mortar or concrete; and kneading the resulting mixture.

4. The method of claim 3 wherein said hydraulic mortar or concrete is a cement compound, and wherein said fine aggregate particles are sand.

5. The method according to claims 1, 3 or 4 wherein an additive is incorporated together with said remaining portion of said water.

6. The method according to claims 1, 3 or 4 wherein the quanti-ty of said portion of water is determined according to the quantity of water remaining on the particles of said fine aggregate.

7. The method according to claims 1, 3 or 4 wherein either one or both of a coarse aggregate and fibrous substance is added to said fine aggregate or sand.

8. The method according to claims 1, 3 or 4 wherein said fine aggregate or sand has an excess of water removed therefrom, and other in-gredients of the hydraulic mortar or concrete are conveyed to a working station by independent conveying means, and then are mixed together and blasted at said working station.

9. A method of preparing a hydraulic mortar or concrete comprising the steps of: supplying a predetermined quantity of particles of fine aggregate having water on the surface thereof; applying, to said particles, an impact force stronger than the adhesive force of the water to said particles, thereby adjusting the quantity of water remaining on the surface of said particles to a predetermined value; adding, to said particles, a quantity of water and a hydraulic substance; and then kneading the resulting mixture.

10. The method according to claim 9 wherein water is applied to said particles before the application of said impact force so that said particles contain water in an amount larger than a quantity of water remaining on said particles after the application of said impact force.

11. The method of claims 9 or 10 wherein said hydraulic mortar or concrete is a cement compound, and wherein said fine aggregate particles are sand.

12. Apparatus for preparing a hydraulic mortar or concrete comprising: means for removing excess water from a fine aggregate; and a kneading mechanism for successively adding water and a hydraulic com-pound to said fine aggregate from which said excess water has been removed;
thereby preparing a hydraulic mortar or concrete.

13. The apparatus of claim 12 wherein said means for removing excess water is specially adapted to remove excess water from sand; and said kneading mechanism is specially adapted to knead cement with sand.

14. The apparatus according to claims 12 or 13 which further includes: primary and secondary water supply means; and cement supply means disposed between said primary and said secondary water supply means.

15. The apparatus according to claims 12 or 13 wherein said kneading mechanism includes: means for adding at least one of a dispersing agent, a rapid setting agent, and a delay agent.

16. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix.

17. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix wherein said mixing members are divided into a plurality of sections along said shaft; and wherein pitches of said mixing members are varied for different sections

18. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix,and wherein inclination angles of said mixing members are made different for different sections.

19. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix; wherein said shaft is contained in a mixing chamber which is divided into a plurality of sections along said shaft; and wherein volumes of said sections are made to be different according to the bulk of a mixture being kneaded.

20. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix; and wherein said mixing members comprise a plurality of large mixing chambers and a plurality of small mixing members, interleaved with each other.

21. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix; wherein said mixing members comprise a plurality of large mixing chambers and a plurality of small mixing members, interleaved with each other; and wherein the large mixing chambers and the small mixing members are inclined in opposite direction.

22. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix; wherein said shaft is contained in a mixing chamber; and wherein said shaft and said mixing chamber are adapted to be rotated relatively to one another.

23. The apparatus according to claims 12 or 13 wherein said kneading mechanism comprises a shaft provided with a plurality of mixing members which are disposed along a helix; wherein said shaft is contained in a mixing chamber; wherein said shaft and said mixing chamber are adapted to be rotated relatively to one another; further with a flexible member; and still further wherein an elastic tube is disposed on the out-side of a bottom portion of said flexible member, said elastic tube being inflatable by a pressurized fluid.

24. The apparatus of claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises-water separating means for imparting an impact force to said fine aggre-gate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate ot to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate, or said sand against said impact plate by centrifugal force created by rotation of said rotary disc.

25. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate, or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; wherein said rotary disc is provided with a plurality of radial vanes; and including means for supplying said fine aggregate or sand sand to said rotary disc at a central portion thereof.

26. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; said water separating means further includ-ing means for dividing fine aggregate or sand projected against said im-pact plate into two streams: (a) a fine aggregate or sand stream, and (b) a stream of water separated from said fine aggregate or from said sand as a result of collision against said impact plate.

27. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; said water separating means further includ-ing dividing means for dividing fine aggregate or sand projected against said impact plate into two streams, (a) a fine aggregate or sand stream and (b) a stream of water separated from said fine aggregate or from said sand as a result of collision against said impact plate; said dividing means being provided on an upper edge of a container of the fine aggre-gate or the sand, from which excess water has been removed.

28. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate ot to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; wherein said impact plate is removably mounted on an inverted dish-shaped member, whereby excess water removed from said fine aggregate or from said sand as a result of collision thereof against said impact plate flows down along an inner surface of said inverted dish-shaped member.

29. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; wherein said impact plate is removably mounted on an inverted dish-shaped member, whereby excess water is removed from said fine aggregate or from said sand as a result of collision thereof against said impact plate flows down along an inner surface of said inverted shaped member; and further including a container for receiving treated fine aggregate or sand, an inner edge of said container being spaced from a lower edge of said inverted dish-shaped member.

30. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggre-gate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; said water separating means further including a pipe for continuously supplying said fine aggregate or said sand at a central portion on said rotating disc, and means for adding liquid to said fine aggregate or to said sand at an exit end of said pipe.

31. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate on said said against said impact plate by centrifugal force created by rotation of said rotary disc; wherein said rotary disc is contained in a casing having a rectangular cross-sectional configuration; and wherein inner surfaces of said casing are inclined downwardly to be collided upon by said fine aggregate or sand projected by rotation of said rotary disc.

32. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation rotation of said rotary disc; said water separating means further including means for supplying cleaning liquid to said impact plate.

33. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said-fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; said water separating means which further including a receptacle for receiving said fine aggregate or sand projec-ted upon said sand impact plate; and means for removing said fine aggre-gate or sand adhered to an upper portion of said receptacle.

34. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggre-gate or said sand against said impact plate by centrifugal force created by rotation of said-rotary disc; said water separating means further including a receptacle for receiving said fine aggregate or said sand projected upon said impact plate; and means for removing said fine aggregate or sand adhered to an upper portion of said receptacle, said removing means comprising an elastic tube.

35. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate on said sand against said impact plate by centrifugal force created by rotation of said rotary disc; said water separating means further includ-ing a receptacle for receiving said fine aggregate or said sand projected upon said impact plate; and means for removing said fine aggregate or said sand adhered to an upper portion of said receptacle, said removing means comprising an elastic tube; and further including means for inflating said elastic tube.

36. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate to to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggre-gate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc; wherein said water separating means comprises: a rotary wheel adapted to rotate about a horizontal axis and provided with a plurality of radial vanes; means for rotating said wheel at a high speed sufficient to remove excess water from said fine aggregate or from said sand; means for discharging said fine or said sand from said wheel substantially in a horizontal direction; and a plurality of fine aggregate or sand receivers juxtaposed in the horizontal direction to classify said fine aggregate or said sand according to their size.

37. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rota-tion of said rotary disc, said impact force being applied by pressurized gas.

38. The apparatus according to claims 12 or 13 wherein said means for removing excess water from the fine aggregate or from the the sand comprises: water separating means for imparting an impact force to said fine aggregate or to said sand, said impact force being larger than the adhesive force of said liquid to said fine aggregate or to said sand, thereby to remove excess water deposited on said aggregate or on said sand; said water separating means comprising an impact plate, and a rotary disc opposing said impact plate for projecting said fine aggregate or said sand against said impact plate by centrifugal force created by rotation of said rotary disc, said impact force being oppied by a con-veyor belt running at a high speed.