US2548935A

US2548935A - Method of molding joints between spaced structural members

Info

Publication number: US2548935A
Application number: US772324A
Authority: US
Inventors: Karl P Billner
Original assignee: VACUUM CONCRETE Inc
Current assignee: VACUUM CONCRETE Inc
Priority date: 1947-09-05
Filing date: 1947-09-05
Publication date: 1951-04-17
Anticipated expiration: 1968-04-17

Description

April 17, 1951 K. P. BILLNER 2,548,935

METHOD OF MOLDING JOINTS BETWEEN SPACED STRUCTURAL MEMBERS Filed Sept. 5,-1.947 I 2 Sheets-Sheet 1 To Vacuum Pumr To Vacuum PUMP ToVncuum PM .511

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April 17, 1951 K. P. BILLNER 8,

METHOD OF MOLDING JOINTS BETWEEN SPACED STRUCTURAL MEMBERS 2 Sheets-Sheet 2 Filed Sept. 5, 1947 INVENTOR.

Patented Apr. 17, 1951 TENT OFFICE METHOD OF MOLDING JOINTS BETWEEN i SPACED STRUCTURAL MEMBERS Karl P. Billner, Philadelphia, Pa., assignor q to Vacuum Concrete, Inc., a corporation of Pennsylvania Application September 1947 ,-'Serial No. 772,324

Claims. 1

Whereas precast .concrete techniques have obviated the need for much of theform-work required where concrete is castin situ, current practice still requires the site erection of forms for perfecting the joints between such precast members. Inasmuch as the material andlabor required in the construction of forms represents an appreciable portion of the total cost of concrete work, it will be apparent thatthe use of prefabricated joint forms which are rapidly applicable to and removable from the structure and capable ofrepeated use, will effect tremendous the application of subatmospheric pressure to the plastic composition itselffor the purpose of removing such excess vehicle as water, to produce a more compactsolidified body in much shorter time than-would-be possible under natural atmospheric conditions.

According to themethod of the present invention for forming a. joint between spaced structural members, such members are bridged with a closure which is secured to at least one of them .by the application of subatmospheric pressure, and a plastic composition deposited-between the .members and the closure. the composition may be subjected to-subatmoS- 'pheric pressure as well. It is-also contemplated As already indicated,

that opposed closures be thus employedto bridge the structural members and that such closures be secured toat least one of the structural members. The application of subatmospheric pressure to the composition may be produced through the closure or closures, by providing them with a perforated or-foraminoussurface for contact with the composition, which may beaccomplished-by covering the open side of an otherwise closedmat with a fabric permitting the passageof a vehicle such as Water whileserving as a barrier to solid particles of the sizes employed in the composition.

As-previouslyi set forth by .the present inventor, a substantial portion of the water addedin the production of a concrete mix forcommercial use serves the solev purposepf producing workable consistencies and represents an excess insofar as the requirements for setting are concerned. It is this excess vehicle, or a substantial portion thereof which can be removed to advantage after the. concrete mix has been deposited, to produce structures which become self supporting soon after deposition and which possess superior characteristics of compactness, strength, impact resistance and uniformity, as compared with concrete structures produced by more commonly known commercial methods.

The apparatus contemplated herein for. casting a moldable plastic composition between spaced structural members, comprises a molding surface for contact with the composition, sealing means on the surface for engagement with a surface portion of the members, holding means connected with the molding surface comprising a mat having sealing means for engagement with an adjacent surface portion of the members, and means for applying subatmospherie pressure intermediate the holding means and the adjacent surface portion. It is also intended that means for applying subatmospheric pressure between the molding surface and the composition be provided. A- perforate molding surface of the type hereinabove mentioned and describedv elsewhere amongiapplicants patents and applications, may assume the form of a fabric covering for the open side of an otherwise closed mat, supported with respect to the mat by spacing means such as wire mesh or other suitable material.

The holding meansmay comprise a plurality of-matsto besecured to the structural members adjacent themolding surface. Marginal sealing means on the moldingsurface may engage adja cent-surfaces of the structural members and provide a seal between the molding surface and the holding means as well as between the composition and-atmosphere. The holding means may Ice-integral with or separable from themolding surface and the holding means may provide por- 'tions overhanging the molding surface to serve :as a bearing for properly fixing the molding surface during the moldingoperation.

' I-t'has been found'in actual practice withthe apparatus of the present invention, that shortly after the subatmospheric pressure-has been applied to the composition, the separable holding means 'can'be removed, since the composition will become self-supporting so-rapidly after a portion-of the excess vehicle has been removed that the static forces tending to displace the molding surfaceare rapidly and a'opreciably reduced. And as amatterof fact. the time required .for retaining themolding surface-itself-in position is diminished to a relatively short period becauseof the rapidity with which the composition becomes self supporting under the influence of the subatmospheric pressure to remove the excess water.

A more complete understanding of the invention will follow from a detailed description based upon the accompanying drawings wherein:

Fig. 1 is a fragmentary perspective illustrating the invention as applied to wall construction;

Fig. 2 is a fragmentary section taken along the line 22 of Fig. 1;

Fig. 3 is an elevation of one of the forms shown at the right of Fig. 1; and

Fig. 4 is a section taken along line 44 of Fig. 3.

The precast concrete wall members H! and I2 define a corner of the structure under consideration and an adjacent structural member l4 coplanar with one of the corner forming members [2 cooperates in forming a portion of one of the walls. An external closure 161 is shown as bridging the corner forming members, retained in posotion by a holder [8 applied to a portion of the member in and a holder 20 applied to a. portion of the member l2. An internal corner closure 22 is similarly positioned to bridge the corner forming members by a holder 24 applied to a portion of the member Ill and a holder 26 applied to a portion of the member I2. These corner closures are depicted as separable from their respective holders while the closures 28 employed for producing the running joint between the elements [2 and 14 have been illustrated as unitary with their holders 30, and applied to opposite surface portions of the spaced elements I 2 and I 4.

Each of the holders is provided with marginal sealing means 32 to exclude atmosphere when it defines a closed chamber with the surface of the structural member to which it is applied for producing therein a subatmospheric pressure through i a line 34 communicating with a suitable source of such pressure, such as a vacuum pump.

Each of the closure members is likewise illustrated as having communication with a source of subatmospheric pressure through a line 36 for ner joint or column is illustrated in more detail in Fig. 2 wherein the precast structural members 10 and I2 are shown as having enlarged ends 38 containing grooves 40 with which the deposited concrete 42 will become interlocked. The closure member It may be formed from two sections of plywood or the like arranged at right angles and reinforced by an angle M. The internal or molding surface of the closure I 6 is bounded by a sealing member 46 of strip rubber or the like which bears upon the adjacent edge portions of the spaced precast structural members between which the joint is to be produced. The portion of the closure molding surface intermediate this marginal sealing means is faced with a woven fabric 48 pervious to wate or other vehicle to be withdrawn but impervious to the solid particles of the composition being molded. The fabric is supported out of contact with the closure body by means of woven wire mesh 50 or the like so that the subatmospheric pressure produced through a projecting nipple 52, by means of a vacuum pump connected therewith by a conduit 36, will be substantially uniformly distributed over the adjacent surfaceof the composition 42.

Since the concrete or other plastic composition is usually quite plastic when first deposited, its static head requires appreciable force for retention of the closures at the outset, produced in this case by the use of vacuum operated holders. For this purpose the closures l8 and 20, which may be constructed of a suitable number of layers of plywood are applied to portions of the structural members adjacent the closure by means of subatmospheric pressures produced through a suitable number of nipples 54 and conduits 34 leading to a vacuum pump. The wall engaging surfaces of these holders carry yieldable sealing members 58 formed of sponge rubber or the like retained between suitable strips or beads 58. Similar sponge rubber supports 60 are provided intermediate the sealing members, particularly where the spans involved would otherwise produce excessive stresses upon the holder body under the subatmospheric pressures encountered. To assure a quick and positive seal between the holders and the wall surfaces to which they are applied, even where such surfaces are somewhat rough, thin rubber sealing flaps 62 are secured to the sealing members 56 to extend therebeyond for engagement with an appreciable area of the wall, which flaps may assume the form of limp resilient and thin material such as yellow balloon rubber. overhanging portions of these holders provide projections 64 which engage a portion of the closure to force it into its operative position when the holder is applied to the wall and its sponge rubber sealing members and supports yield under the influence of the sub-atmospheric pressure produced between the holder and the wall as shown in Fig. 2.

The internal corner closure 22 is likewise provided with a marginal rubber sealing gasket 46 and faced with a fabric backed with woven wire mesh or the like in the same manner as described with respect to the external closure. The

internal holders

24 and 26 are inturn similar to the external holders i8 and 20 except for such physical dimensions as may vary to accommodate the configuration of particular structural members. In the case illustrated in Fig. 2, the internal holders are somewhat narrower and somewhat thicker than the external holders.

In applying the invention, with the structural members I 0 and H2 in erected position, the internal and external closures are applied, the separable holders positioned to bear upon them, and subatmospheric pressure is then introduced between the holders and the structural members through the conduits and nipples provided for this purpose. This will result in securing the closures in position, whereupon the plastic mix is introduced into the form thus defined and subatmospheric pressure is applied to the mix through the perforate surfaces of one or both of the closures. As soon as a predetermined portion of the excess vehicle has been withdrawn from the mix, the composition begins to become self supporting and the static head becomes reduced sufficiently to permit discontinuance of the subatmospheric pressures applied between the holders and the structural members and the holders themselves canthen be removed. In due time, the subatmospheric pressure applied to the composition through the closure or closures can also be discontinued and the closures removed.

In some instances, particularly where the thickness of the column or joint is small, it may be unnecessary to apply subambient pressure both internally and externally of the concrete,

in which case one of the closures may serve merely as a barrier to retain the mix in position while the subatmospheric pressure is applied to the opposite surface alone. In such a case, one of the closures may assume a simpler form.

It will be understood that the running joints or columns may be produced with similarly separable closures and holders, difiering in configuration to accommodate the shape which it is desired to impart to the molded material. It is contemplated for some applications of the invention, to construct the closures and holders in a unitary fashion, as distinguished from separably, as has been depicted in Figs. 3 and 4. In these figures, the closure 28 and the holders 30 are suitably joined together by bolts, screws, or the like, so that the assembly may be applied as a unit to the spaced structural members between which it is desired to produce a molded joint. Inasmuch as the elements composing this formof the invention are similar to those described with reference to the preceding figures, they have been similarly identified and will require no extended discussion. It will be noted that the intermediate supports 60 best shown in Fig. 3 can be terminated or extended as desired to best suit the surface to which it is applied. It will be understood that the closures and holders for such running joints might well be separable in the manner described with reference to the corner joint previously described, bearing in mind that where the construction is unitary, the entire assembly must be retained in position until the composition has become sufficiently self supporting to permit its removal.

The subatmospheric pressures applicable to the plastic composition will assume values in the ranges disclosed in the Billner Patent No. 2,046,- 867, dated July 7, 1936, and the subatmospheric pressures applied to the holders will be as great or greater. The effective area of the holder or holders for a given closure opposed to a coopcrating surface will be computed in each application to exceed that necessary to retain the form equipment and plastic composition in position for the valve of subatmospheric pressure to be used.

Whereas but two specific embodiments of the invention have been described with reference to the drawings, many variations will occur to those skilled in the art as they have been recognized already by the present inventor, rendering it important that these examples should not be construed to restrict the invention beyond the scope of the appended claims.

I claim:

1. A method of forming a joint between spaced structural members comprising bridging said members with a closure, securing the closure in fluid tight relationship to at least one of said members by the application of subatmospheric pressure, and depositing a plastic composition between said members and closure.

2. A method of forming a joint between spaced structural members comprising bridging said members with a closure, securing the closure to at least one of said members by the application of subatmospheric pressure, depositing a plastic composition between said members and closure, and subjecting said composition to subatmospheric pressure.

3. A method of forming a joint between spaced structural members comprising bridging said members with opposed closures, securing said closures in fluid tight relationship to at least one of said members by the application of subatmospheric pressure, and depositing a plasticcomposition between said members and closures.

4. A method of forming a joint between spaced structural members comprising bridging said members with opposedclosures, securing at least one of said closures in fluid tight relationship to at least one of said members by the application of subatmospheric pressure and depositing a plastic composition between said members and closures.

5. A method of forming a joint between spaced structural members comprising bridging said members with opposed closures, securing said closures in fluid tight relationship to said members by the application of subatmospheric pressure, and depositing a plastic composition between said members and closures.

- 6. A method of forming a joint between spaced structural members comprising bridging said members with a closure, securing the closureto at least one of said members by the application of subatmospheric pressure, depositing a plastic composition between said members and closure, and applying subatmospheric pressure to said composition through said closure.

7. A method of forming a joint between spaced structural members comprising bridging said members with 'a closure, securing the closure to at least one of said members by the application of subatmospheric pressure, depositing a plastic composition containing excess vehicle between said members and closure, and removing a portion of said vehicle under subatmospheric pressure conditions.

8. A method of formin a joint between spaced structural members comprising bridging said members with a closure, securing the closure in fluid tight relationship to said members by the application of subatmospheric pressure, and depositing a plastic composition between said members and closure.

9. A method of forming a joint between spaced structural members comprising bridging said members with a closure, securing the closure to said members by the application of subatmospheric pressure, depositing a plastic composition between said members and closure, and applying subatmospheric pressure to said composition through said closure.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 882,196 Hahn Mar. 17, 1908 958,419 Mowat May 17, 1910 1,500,121 Fontaine July 8, 1924 1,630,801 Persons 1. 1 May 31, 1927 2,046,867 Billner July 7, 1936. 2,239,989 Britten Apr. 29, 1941 2,317,997 Lapidus May 4, 1943 Billner June 28, 1949