Foamed Plastic Concrete Form With Fire Resistant Tension Member

Abstract

A self-supporting concrete form of foamed polymeric material to be left in place to provide insulation for a wall the form having two side walls joined by transverse tension members of sheet metal or other thin fire resistent material. The tension members are embedded in projections provided on inner faces of the two walls to provide substantially cylindrical vertically disposed cavities for concrete. The upper and lower edges of the tension members and projections are inwardly spaced from associated edges of the two side walls so that a horizontally disposed concrete beam will also be provided when the form and adjacent similar forms are filled with liquid concrete.

Parent Case Text

This application is a continuation-in-part of U.S. Ser. No. 770,233 filed Oct. 24, 1968, now U.S. Pat. No. 3,552,076, which is a continuation-in-part of U.S. Ser. No. 580,912 filed Sept. 21, 1966, now abandoned, which is a continuation-in-part of U.S. Ser. No. 569,908 filed Aug. 3, 1966, now abandoned.

Description

This invention relates to a concrete forming system and more particularly to a form of foamed polymeric material which is left in place to provide permanent insulation and a base for wall surfaces such as plaster.

Various forming systems are used to hold concrete in place until cured. However, skilled labour is required to erect the forming systems resulting in high cost of construction. Furthermore, removal of forms requires considerable time, delaying other trades such as plumbers and electricians. If concrete is poured when the temperature drops below freezing, it is necessary to provide temporary insulation.

The object of this invention is the provision of a concrete forming system of foamed polymeric material which will provide an insulated concrete wall which has an improved fire rating.

A further object is the provision of self-supporting form which does not require bracing, tie wires or shoring.

Another object is the provision of a form which eliminates the need for heating and temporary insulation when concrete is poured at low temperatures. Furthermore the concrete cures under ideal conditions and reaches design strength in a shorter period thereby allowing construction to proceed more quickly.

A further object of the invention is the provision of a form which is left in place to perform the function of permanent insulation and a vapor barrier on both sides of the concrete in the wall. It is therefore unnecessary to provide temperature steel to take up the stresses created by a temperature differential between the inner and outer faces of the wall.

Another object is the provision of a forming system comprising units molded by machine so as to provide a high degree of accuracy at low cost so that the form can be quickly erected by unskilled workmen.

A still further object is the provision of a form which provides a base for a great variety of wall finishes such as plaster gypsum board, ceramic tiles and plywood panels.

This invention provides a self-supporting concrete form of foamed polymeric material adapted to be left in place to provide insulation for a wall constructed of a plurality of superimposed courses of said forms filled with concrete, said form comprising two spaced panels of foamed polymeric material adapted to be inter-connected by fire resistent tension members of fire resistent material, said tension members being embedded in projections integrally formed on inner faces of said panels to provide transverse walls, said walls defining at least one vertical cavity extending through said form from one major face to the other.

In the accompanying drawings which show preferred embodiments of this invention,

FIG. 1 is a perspective view of a building unit in accordance with this invention.

FIG. 2 is a top plan view of a building unit.

FIG. 3 is a sectional side elevational view taken long the line 3--3 of FIG. 1.

FIG. 4 is an end elevational view of a wall construction employing the building units of FIG. 1 and

FIG. 5 is a perspective view of a tension member for use in the building units.

Referring now in detail to the drawings a concrete form for use in constructing walls indicated generally at 10 in FIGS. 1, 2 and 3 is preferably molded in one piece of expanded polystyrene beads and comprises two longitudinal walls 11 and 12 and two integral transverse end walls 13 and 14. Three integral partition walls 15 and the end walls 13 and 14 define four substantially cylindrical bores or cavities 16. An arcuate indentation in each of the end walls 13 and 14 and the partition walls 15 provides a longitudinally extending channel 18 interconnecting the cavities 16.

Similarly, the underside of the foam 10 is provided with a longitudinally extending channel 18a of semi-circular cross section whereby, in use, a horizontally extending concrete beam is formed in the space provided by the associated channels 18 and 18a of two forms 10 when one form is placed on top of the other as shown in FIG. 4.

It will be noted that the top, bottom and end edges of the walls 11 and 12 are provided with tongues 20 or grooves 21 respectively to mate with grooves and tongues of adjacent similar forms 10. The tongues and grooves have a taper of about 5.degree. to provide a more water tight joint.

It will be noted that the end walls 13 and 14 are provided with ribs 24 adjacent their side edges and that the tongues 20 and grooves 21 at the ends of the form 10 are provided on these ribs 24, thus ensuring that mating tongues 20 and grooves 21 adjacent blocks 10 will not be prevented from fully engaging by engagement of the major surfaces of the end walls 13 and 14.

The tongues 20 and grooves 21 provide for accurate alignment of the form vertically as well as horizontally. This alignment of the forms is facilitated by the accuracy which can be maintained in molding the forms 10 of expanded beads of polystyrene.

The walls 13, 14 and 15 are provided with recesses 17 to hold horizontal reinforcing steel 29 in place without tying.

The vertically disposed reinforcing steel 36 shown in FIG. 4, in the form 10 is conveniently held in position by a strap 30 having depending pointed portions 31 adapted to be embedded in the longitudinal walls 11 and 12. The straps 30 are received in notches 32 in the tongues 20 which are centered with respect to the cavities 16. The vertical reinforcing rods extend through apertures 33 provided in the strap 30. Dovetail grooves 35 provided in the side walls of the form serve as plaster keys.

It will also be noted that the grooves 21 in the underside of the form 10 are not continuous and that portions 37 which do not have a groove are adapted to mate with the notches 32 in the tongues 20 of an underlying form 10. Thus relative horizontal movement of superimposed forms is prevented.

While it is possible to mold the form 10 entirely of foamed plastic it is desirable particularly in multiple family dwellings to provide a more fire proof wall. This has been accomplished by using a thin fire resistent tension member 40 to interconnect adjacent portions of the foamed plastic end walls 13 and 14 and partition walls 15.

The tension member 40 particularly described and illustrated herein is sheet metal plate having right angle flanges 42 (see FIG. 2). However, other suitable materials such as wire mesh, asbestos, glass fibre cloth or fire resistent polymeric materials. It should be appreciated that if the material used for the tension member is thin enough fire will not penetrate the concrete wall even though the tension member is not completely fire proof.

In FIG. 5 a modified form of tension member is shown generally at 50 comprising two plates 52 and 53 adapted to be secured together by fastening means passing through apertures 54 therein. Additional rows of apertures 54 may be provided so that the width of the form 10 can be adjusted. The outer edges of the plates 52 and 53 are provided with flanges 55 which are disposed at right angles to the major surface of the plate. The flanges 55 alternate so that the plastic foam of the projecting wall portions 13, 14 and 15 will not be unduly weakened.

It will be readily apparent that when the form 10 is filled with concrete a fire stop is formed between the plastic foam of the inwardly projecting portions of the walls 13, 14 and 15.

The form 10 is conveniently formed in a mold by inserting tension members 40 in the mold prior to filling the mold with pre-expanded beads of polystyrene. The form 10 is thus molded in one piece to provide the desired accuracy. However, it is possible to mold the form in two pieces with plate 52 and 53 embedded in the respective inner faces thereof. The mating portions of the form 10 can then be secured together by suitable fastening means prior to being laid up in a wall.

It will be noted that concrete will flow into the space between outer faces of tension members 40 of forms 10 placed in end abutting relationship. A fire stop is thus created at each end of the form 10. However, to ensure that concrete completely seals the ends of the abutting forms, the two tension members 40 or 50 at the ends of the form 10 are preferably foraminous.

In use, a first course of form units 10 are positioned on a footing (not shown) containing vertical dowels extending into the cavities 16. The cavities 16 are then filled with concrete to the height of the recesses and the concrete in each hole is vibrated. Horizontal reinforcing is laid, and vertical reinforcing rods about 58 inches long are inserted into the wet concrete approximately 12 inches.

A second course of form units 10 is installed by slipping them over the vertical rods and aligning the holes 16 in the first and second courses. Two additional courses, including horizontal reinforcing, may then be installed before filling the second and third courses and the remaining space in the first course with concrete. Building of the wall is then continued three form unit courses per pour (approximately 4 feet).

When form units, in accordance with this invention, are used below ground, it is recommended that two coats of plaster and a bituminous coating be applied on the exterior face.

The form units 10 have a length of 4 feet and are 16 inches high. The width of the form varies to suit the load bearing requirements. It has been found that blocks having cores of 6, 8 and 10 inches in width provide a reasonable range of sizes for structures up to approximately 10 storeys in height.

Expandable beads of polystyrene known as Pelaspan is a preferred material. This material is manufactured in the form of small beads or granules containing an expanding agent. These particles are expanded in a mold by the application of heat to the desired shape. Pelaspan, because of its ability to be molded, provides an ideal material for molding this plastic building component. Furthermore, Pelaspan has desirable properties such as light weight, high strength to weight ratios, ideal surface to carry plaster, low moisture absorption and good insulating properties. Typical values of the material are shown below:

Test Value Procedure Density 1.3-1.5 lbs/cu.ft. Shear Strength 22-25 p.s.i. ASTM C273 Compressive Strength 20-22 p.s.i. ASTM D1621 at 10% deformation Flexural Strength 60-62 p.s.i. ASTM C203 Tensile Strength 48-52 p.s.i. ASTM D 1623 K-Factor 0.242-0.243 Dow Method BTU in/hr. sq.ft. Water absorption 0.03 lb/sq.ft. MIL-P-19644A Water Vapour 3.0-3.4 Transmission gm/24hr/100 sq.in. ASTM E96E

above values are obtained from lab moulded samples in the density range specified.

The expandable polystyrene beads are pre-expanded to the desired density (approximately 11/2 lbs. per cubic foot) before being placed in the mold. It is also recommended that a self-extinguishing type of polystyrene bead be used in the molding of the forms to provide a more fire-resistent structure.

Other expanded polymeric materials may be used provided that the desired tensile strength can be obtained without adversely affecting the insulation value and weight of the form. the material must also be capable of being molded to the desired shape. Examples of such alternate materials are polyurethane foam or a foamed polymeric material sold under the trade name Polcat by Nioteric Chemical Systems Limited.

Claims

I claim:

1. A self-supporting concrete form of foamed polymeric material capable of containing liquid concrete without additional shoring, said polymeric material being of uniform low density throughout so as to be resiliently deformable, said form including two spaced longitudinal walls terminating adjacent two spaced transverse end walls, said end walls extending from one longitudinal wall to the other, at least one partition wall intermediate said end walls extending from one longitudinal wall to the other, at least one of said end walls and said partition wall having a tension member of fire resistant material integral therewith to provide a fire stop between said longitudinal walls, said partition wall and end walls defining holes extending through said form, each said hole being vertically disposed when said form is in use and tapering toward a smaller cross-section at its lower end, corresponding edges of said transverse walls and said partition wall being inwardly spaced from adjacent edges of said longitudinal walls so as to provide a longitudinal beam of concrete integral with a column of concrete in each said vertical hole when concrete is poured into a plurality of assembled forms and a recess in a lower edge of each longitudinal wall and a projection provided on an upper edge of each longitudinal wall so that projections and recesses of superimposed similar forms cooperate to position said forms, said polymeric material being deformable to provide a seal thereby minimizing seepage of concrete between forms.

2. A concrete form as claimed in claim 1 wherein the tension member is embedded in said end walls or partition wall.

3. A concrete form as claimed in claim 2 wherein each of said end walls and partition wall of said form comprises said tension member.

4. A concrete form as claimed in claim 3 wherein said transverse walls are inwardly curved so as to provide a longitudinal beam of at least partly curved cross-section.

5. A concrete form as claimed in claim 3 wherein said projection on the upper edge of each longitudinal wall is a tongue and said recess on a lower edge of each longitudinal wall is a groove adapted to receive a tongue of an adjacent similar form when said forms are superimposed.

6. A concrete form as claimed in claim 5 wherein tongues are provided on the end edges of longitudinal walls and grooves are provided in end edges disposed on opposed end edges of the said longitudinal walls so that tongues and grooves of adjacent similar forms cooperate to position said forms and provide a substantially liquid tight joint when forms are placed in end abutting relationship.

7. A concrete form as claimed in claim 6 wherein said tension members comprise foraminous material and said longitudinal walls comprise integrally molded expanded beads of polystyrene.

8. A concrete form as claimed in claim 6 wherein said tension members comprise a mesh at least partly composed of synthetic plastic material.

9. A concrete form as claimed in claim 6 wherein at least one notch is provided in each tongue on the upper edges of the longitudinal walls to cooperate with mating raised portions in the grooves in the lower edges of longitudinal walls thereby assisting in the positioning of said form in horizontal rows.

10. In a wall structure, a plurality of molded form blocks of foamed synthetic plastic material having a substantially uniform low density, each said block having two spaced longitudinal walls terminating adjacent two transverse end walls extending from one longitudinal wall to the other, at least one partition wall intermediate said end walls extending from one longitudinal wall to the other, at least one of said end walls and said partition wall having a tension member of fire resistant material integral therewith to provide a fire stop between said longitudinal walls, said end walls and partition wall interconnecting said longitudinal walls to provide a sufficiently rigid structure for holding the liquid concrete and defining vertical holes extending through said form, each said hole tapering toward a smaller cross-section at its lower end, upper and lower edges of said transverse walls and said partition wall being inwardly spaced from adjacent edges of said longitudinal walls so as to provide a longitudinally extending beam of concrete integral with columns of concrete in said vertical holes and a projection being provided along an upper edge of each longitudinal wall and a recess being provided along a lower edge of each longitudinal wall so that projections and recesses of superimposed forms cooperate to position said forms, said projections being compressed in said recesses to minimize seepage of liquid concrete, similar projections being provided along end edges of longitudinal walls and recesses along opposed end edges of each said form whereby projections and recesses on the ends of adjacent similar forms cooperate to provide a substantially liquid-tight joint.

11. A wall structure as claimed in claim 10 wherein the tension member is embedded in said end walls or partition wall.

12. A wall structure as claimed in claim 11 wherein each of said end walls and partition wall of said form comprises said tension member.

13. A wall structure as claimed in claim 12 wherein said transverse walls are inwardly curved so as to provide a longitudinal beam of at least partly curved cross-section.

14. A wall structure as claimed in cliam 12 wherein said projection on the upper edge of each longitudinal wall is a tongue and said recess on a lower edge of each longitudinal wall is a groove adapted to receive a tongue of an adjacent similar form when said forms are superimposed.

15. A wall structure as claimed in claim 14 wherein tongues are provided on the end edges of longitudinal walls and grooves are provided in end edges disposed on opposed end edges of the said longitudinal walls so that tongues and grooves of adjacent similar forms cooperate to position said forms and provide a substantially liquid tight joint when forms are placed in end abutting relationship.

16. A wall structure as claimed in claim 15 wherein said tension members comprise foraminous material and said longitudinal walls comprise integrally molded expanded beads of polystyrene.

17. A wall structure as claimed in claim 15 wherein said tension members comprise a mesh at least partly composed of synthetic plastic material.

18. A wall structure as claimed in claim 15 wherein at least one notch is provided in each tongue on the upper edges of the longitudinal walls to cooperate with mating raised portions in the grooves in the lower edges of longitudinal walls thereby assisting in the positioning of said form in horizontal rows.