US3464176A

US3464176A - Building construction

Info

Publication number: US3464176A
Application number: US602647A
Authority: US
Inventors: Arthur C Clements
Original assignee: INTERSTRUCT CORP
Current assignee: INTERSTRUCT CORP
Priority date: 1966-12-19
Filing date: 1966-12-19
Publication date: 1969-09-02
Anticipated expiration: 1986-09-02
Also published as: GB1199070A; BE708106A; NL6717257A

Description

Sept. 1969 A. c. CLEMENTS 3,464,176

. BUILDING CONSTRUCTION Filed Dec. 19, 1966 5 Sheets-Sheet 1 Sept. 2, 1969 A. C. CLEMENTS BUILDING CONSTRUCTION 5 Sheets-Sheet 7,

Filed Dec. 19. 1966 FIG. 6

6 MW 4, w if S p 1969 A. c. CLEMENTS BUILDING consmucnou 5 Sheets-Sheet 5 Filed Dec. 19. '1966 mm mm ow Mm mm hm mm mm P 1969 A. c. CLEMENTS 3,464,176

BUILDING CONSTRUCTION Filed Dec. 19, 1966' 5 Sheets-Sheet 4 m m M Sept- 2, 9 A. c. CLEMENTS 3,464,176

BUILDING CONSTRUCTION Filed Dec. 19. 1966 5 Sheets-Sheet 5 United States Patent 3,464,176 BUILDING CONSTRUCTION Arthur C. Clements, Santurce, Puerto Rico, assignor to Interstruct Corporation, Carolina, Puerto Rico, a corporation of Puerto Rico Filed Dec. 19, 1966, Ser. No. 602,647 Int. Cl. E0411 5/18, 5/06 us. or. 52-251 14 Claims ABSTRACT OF THE DISCLOSURE This invention relates to building construction and more particularly to a monolithic building structure of concrete or similar material.

Various construction procedures are in use at the present time for the erection of single and multi-story concrete buildings. In one type of construction, forms for the concrete are erected at the building site, and the concrete is poured in place to produce either a substantially complete building in a single operation or a wall or floor slab therefor. Other procedures utilize pre-cast concrete blocks which are transported from the factory to the site. In some cases, the blocks serve as the loadsupporting structure for the building and are cemented together through the use of a suitable mortar, while in other situations the blocks act as fillers for poured-in-place concrete and do not perform a structural function.

Heretofore, difllculties have been encountered in the provision of monolithic building structures of concrete or similar material. With respect to the poured-in-place type of construction, for example, the necessary forms for the concrete often were not readily transportable to the building site, with the result that complicated and time consuming procedures frequently were needed to construct or assemble the forms at the site. Also, although the pouring of the concrete between the forms to produce a substantially complete building in asingle operation results in a uniform monolithic structure and has other important advantages, the excessive bulk of the forms and the quantity of concrete required has limited the use of these latter techniques particularly for multistory construction. For construction procedures which utilize precast concrete blocks, one of the major difliculties encountered heretofore has been in the fastening of the blocks together to provide an integral structural unit capable of withstanding the various shear stresses which exist between adjacent blocks. In addition, and this has been of special moment in the construction of floors and walls in which the faces of the blocks are exposed, difficulties have been encountered in the proper alignment of the blocks and in the provision of a reasonably pleasing appearance to the exposed surfaces. Furthermore, it often is desirable to conceal conduits or ducts within the structure of the slabs forming the floors and walls, and many previous types of construction have proved deficient in these respects.

One general object of this invention, therefore, is to provide a new and improved monolithic structure for the floor or wall slabs of a building.

More specifically, it is an object of this invention to provide such structure utilizing both concrete blocks or other preformed members and a poured-in-place material which each form a structural, load-bearing portion of an integral building slab.

Another object of this invention is to provide a structure of the character indicated which exhibits increased resistance to shear stresses not only in the plane of the slab but also in directions perpendicular thereto.

A further object of the invention is to provide a building slab including a series of preformed members which may be quickly and easily aligned and present a pleasing and attractive appearance.

Still another object of this invention is to provide a building slab in which the necessary Wiring, plumbing, heating and cooling ducts or other conduit may be readily concealed within the slab.

A still further object of this invention is to provide a precast building block which is economical to manufacture and readily transportable to the building site.

SUMMARY formed members and the poured material have a composite structural function.

In accordance with one feature of the invention, the side wall of each of the preformed members includes a keyway having side portions which are oriented in acute angles with respect to the plane of the building slab. The cementitious material which is poured between adjacent members extends into the keyways to form twoway shear keys. The arrangement is such that the keys resist shear stresses in the plane of the slab and also in directions perpendicular thereto, with the result that the load-supporting capabilities of the slab are substantially improved.

In accordance with another feature of the invention, in certain particularly advantageous embodiments, each of the side walls for the preformed members extends in a plane which meets the plane of the building slab at an acute angle, thereby defining a generally V-shaped groove between the members which accommodates the pouredin-place material. In several good arrangements, each member includes a peripheral flange having a bevelled edge portion which greatly facilitates the alignment of the members to form the slab and also presents a pleasing appearance in cases in which the surfaces of the members are exposed.

In accordance with a further feature of certain good embodiments of the invention, the side walls of the individual preformed members are comparatively thin and form a hollow construction. The portions of the walls which define the central faces of the keyways are substantially thinner than the remaining wall portions. The members are extremely light in weight, and the central faces of the keyways may be readily removed at the construction site to gain access to the interior of the members, thus enabling the rapid and straight-forward installation of concealed conduits and ducts.

In accordance with a still further feature of the invention, in some embodiments, the preformed members are assembled into a floor slab and are supported by upright preformed columns. Each of the columns includes an integral, substantially fiat upper section which extends in the plane of the slab in contact with the peripheral flanges of the adjacent members. The columns are held in place by the poured cementitious material in a manner such that their upper sections form a part of the monolithic structure.

The present invention as well as further objects and features thereof will be understood more clearly and fully from. the following description of certain preferred embodiments, when read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a precast concrete block constructed in accordance with one illustrative embodiment of the invenion;

FIGURE 2 is a side elevational view of the block shown in FIGURE 1;

FIGURE 3 is a top plan view of the block, with a portion broken away;

FIGURE 4 is a perspective view of a precast concrete column for supporting a floor slab assembled from a series of the blocks of FIGURE 1;

FIGURE 5 is a side elevational view of the column shown in FIGURE 4, with a portion broken away, together with reinforcing rods useful in providing additional support;

FIGURE 6 is a top plan view of the column;

FIGURE 7 is a side elevational view, with certain parts shown broken away and in section, of a monolithic building structure including an assembly of blocks and columns of FIGURES 1-6, together with an assembly of reinforcing rods for the structure;

FIGURE 8 is a fragmentary top plan view of the building structure of FIGURE 7;

FIGURE 9 is a horizontal sectional view taken along the line 99 in FIGURE 5;

FIGURE 10 is a horizontal sectional view taken along the line 10-10 in FIGURE 5;

FIGURE 11 is an enlarged side elevational view of one of the reinforcing rod assemblies shown in FIG- URE 7;

FIGURE 12 is a fragmentary elevational view, with certain parts shown in section, of a monolithic building snucture including precast concrete blocks constructed in accordance with another illustrative embodiment of the invention; and

FIGURE 13 is a partially schematic elevational view of apparatus for casting the blocks.

Referring to FIGURES 1-3 of the drawings, there is shown a precast building block indicated generally at The block 20 is fabricated from concrete or similar material and in the illustrated embodiment is of square configuration. Although the dimensions of the block may vary widely depending upon the particular type and size of the building in which it is to be used, the block illustratively may be about four feet by four feet and approximately one foot thick. In order to reduce its weight and to facilitate the installation of conduits and ducts, the block is of hollow construction. Thus, an internal cavity 21 is formed between the upper face 22 and the lower face 23 of the block, in a manner that will become more fully apparent hereinafter, and a series of concrete posts 25 are disposed therein to provide additional support. The faces 22 and 23 extend in smooth flat planes and may be exposed to provide exterior and interior wall surfaces for the building.

The building block 20 includes four side walls 26. Each of the side walls 26 extends in a plane which is angularly disposed with respect to the block faces 22 and 23 and slopes downwardly and outwardly at an acute angle A with respect to the building slab in which the block is to 4 be incorporated. In the illustrative form of the block shown in FIGURES 1-3, the angle A is of the order of eighty-four degrees.

A keyway 30 is formed in the central portion of each of the side walls 26 of the block 20. The keyway 30 is defined by two flat side surfaces 31 and 32 and a flat central surface 33 which is parallel to the side wall. As best shown in FIGURES 2 and 3, the

surfaces

31 and 32 diverge away from one another in a direction from the center of the slab to the corresponding side wall 26, thus greatly facilitating the stripping operation described in more detail below. The

surfaces

31 and 32 are in converging relationship with each other in a direction from one face of the slab to the other and extend in planes which meet the plane of the building slab at opposite but equal acute angles B. The angles B are of the order of seventy-six degrees and preferably are slightly less than the angle A between the plane of the side wall and the plane of the slab. The thickness of the central portion 33 of the keyway 30 is substantially less than that of the corresponding side wall, for purposes that will be described more fully hereinafter.

The block 20 is provided with a square peripheral flange 35 adjacent its lower face 23. This flange includes an upper bevelled portion 36 and a lower bevelled portion 37 which slope toward each other such that the planes of the bevelled surfaces meet at a comparatively large angle. The centrally located sloping faces 38 of the upper bevelled portion 36 define the lower surfaces of the keyways 30.

FIGURES 4-6 are illustrative of a representative column 40 which is assembled with the blocks 20 in cases in which the blocks are to be used in the floor of a building. The column 40 preferably is cast in one piece from concrete or similar material and includes an upstanding portion 42 and a substantially flat upper portion 43. The upper portion 43 is of a configuration which is similar in some respects to that of the block 20. Thus, the portion 43 is provided with a square peripheral flange 45 having an upper bevel 46 and a lower bevel 47 which correspond to the

bevels

36 and 37 on the block flange 35. However, the portion 43 is substantially thinner than the block 20 and includes an extension 48 which protrudes upwardly from the columnar portion 42. The vertical dimension of the extension 48 is slightly less than the thickness of the block.

The column 40 is of square cross section, and the upstanding portion 42 thereof is provided with a series of reinforcing rods 50. The rods 50 are surrounded at intervals by straps 51 (FIGURES 9 and 10), and the upper ends 52 of the rods protrude from the column extension 48 and are bent over at right angles with respect to the major portions of the rods.

As best shown in FIGURES 7 and 8, the concrete blocks 20 are arranged at the building site in contiguous relationship with each other to form a substantially planar building slab 55. The blocks are temporarily supported at the site (by means not shown) to form a grid-like pattern with the peripheral flanges 35 of adjacent blocks in substantial contact with each other and with the side walls 26 facing one another to define a V-shaped groove 56 therebetween. In cases in which the slab 55 is to be used to form the floor of the building, the upstanding columns 40 are assembled at intervals in the pattern of blocks. The upper portion 43 of each column is arranged in the plane of the slab with its peripheral flange 45 in contact with the peripheral flanges 35 of the adjacent blocks. The extensions 48 of the columns protrude upwardly from the portions 43 to a level slightly beneath the upper faces 22 of the blocks.

A series of horizontal reinforcing rods 57 are disposed in the V-shaped grooves 56 between the adjacent blocks 20. As best shown in FIGURE 11, the rods 57 are arranged in spaced-apart pairs and are interconnected by transverse rods 58 to form a ladder-like construction. The rods 58 extend in vertical planes in directions which meet the horizontal plane of the slab 55 at acute angles. The horizontally extending end portions 59 of the rods 57 adjacent the column extensions 48 (FIGURES 5 and 7) may be suitably afiixed to the upper ends 52 of the column reinforcing rods 50.

After the reinforcing

rods

57 and 58 have been inserted in the V-shaped grooves 56, concrete 60 or other cementitious material is poured into the grooves and over the upper faces of the column portions 43. The concrete which is poured over the portions 43 is disposed around the extensions 48 of the columns and is flush with the upper faces 22 of the blocks 20, thus concealing the eX- tensions therebeneath. The concrete in the grooves 56 extends into the keyways 30 to form shear keys 62. Because of the unique configuration of the keyways 30, these shear keys, in addition to resisting shear stresses in the plane of the building slab 55, also resist such stresses in directions perpendicular to the plane of the slab. Thus, for floor slabs of the type shown in FIGURES 7 and 8, for example, the shear keys 62 resist both horizontal and vertical shear stresses. The arrangement is such that the blocks 20 are not merely fillers for the poured-in-place concrete 60 but perform an important load-supporting function, as does the concrete. The blocks and the concrete act together to provide a monolithic structural unit capable of withstanding surprisingly high shear stresses.

The

bevelled portions

36 and 37 on the peripheral flanges 35 greatly facilitate the alignment of the individual blocks 20 in substantially coplanar relationship with each other, while the bevelled

portions

46 and 47 on the columns 40 similarly facilitate the alignment of the columns with the blocks. In addition, in cases in which the lower faces 23, for example, of the blocks are to be left exposed, the

bevelled portions

37 and 47 produce a pleasing grid-like pattern on the thus formed ceiling, and the bevels have the effect of minimizing slight differences in the level of the individual blocks.

As indicated heretofore, each of the blocks 20 is provided with an internal cavity 21 (FIGURE 2) to form a hollow construction. With this arrangement, the blocks are comparatively light in weight and may be readily transported from the factory to the building site. The cavities 21 illustratively are formed through the use of cardboard boxes or suitable foam materials which serve as internal molds and are retained in the blocks. The boxes, foam materials or other internal molds may be provided with suitable sleeves which define openings for the posts 25. The resulting hollow construction produces relatively thin side walls 26 for the blocks and even thinner central portions 33 as a result of the keyways 30. At the construction site, selected ones of the portions 33 may' be readily removed prior to the pouring of the concrete 60 to provide convenient access to the interiors of the blocks. The necessary electrical wiring, plumbing and heating and cooling ducts for the building may be quickly and easily inserted through the thus formed openings in the blocks and concealed between the opposed block faces 22 and 23.

In certain advantageous embodiments of the invention, the peripheral flanges on the blocks are notched to provide even further resistance to shear stresses in the plane of the building slab. In the embodiment shown in FIG- URE 12, for example, adjacent concrete blocks 65 include peripheral flanges 66 which each have three bevelled

surfaces

67, 68 and 69 thereon. The

surfaces

67 and 68 correspond to the bevelled surfaces 36 and 37 (FIGURE 1) of the building blocks 20 described above, while the surface 69 slopes upwardly from the side wall of the block to form an abrupt edge 70 with the surface 68. The edge 70, together with the surface 69 of the adjacent side wall, defines a notch 72. Upon the pouring of cementitious material 73 between the adjacent blocks, the material extends into the notch 72 to provide a positive lock between the blocks and thereby further reduce the possibility of the blocks becoming separated as a result of excessive shear stresses in the plane of the building slab.

FIGURE 13 is illustrative of one form of apparatus useful in the manufacture of the preformed building blocks at the factory. Although the apparatus may be arranged to produce either the blocks 20. of FIGURE 1 or the blocks 65 of FIGURE 12, in the specific form shown in FIGURE 13 the apparatus is adapted to manu facture blocks of the type indicated at 75. The blocks 75 are generally similar to the blocks 20 (FIGURES 1-3) but are somewhat thicker and do not include the lower faces 23, the blocks 75 being left open to provide a honeycomb appearance in cases in which they are assembled into an exposed floor slab, for example.

The blocks 75 are formed through the use of a series of core molds 76 which define internal cavities 77 for the blocks. Successive molds 76 are automatically led by an infeed conveyor belt 78 to a vertically movable platform 80 which may be raised or lowered through the use of hydraulic jacks 81. Upon the receipt of each successive mold on the platform 80, the platform is lifted by the jacks 81 from the level of the infeed conveyor 78 to a position (the position shown) immediately beneath a pouring chute 85. The chute 85 includes an upper section 86 and two telescoping

conical sections

87 and 88 disposed therebeneath.

The external side walls, keyways and flanges of the block 75 are formed by four plates 89. The plates 89 advantageously comprise vacuum mats of a type well known in the art and are connected by conduits 95 to a suitable vacuum pump (not shown). Each plate is movable toward and away from the core mold 76 by a hydraulic jack 96. As the platform 80 reaches its upper position, the jacks 96 move the plates 89 toward the mold 76 to position the plates in spaced juxtaposition therewith.

Concrete is then poured into the pouring chute 85. The concrete flows through the chute section 86 and is directed outwardly along the conical surfaces of the

sections

87 and 88 into the spaces between the vacuum plates 89 and the core mold 86, thereby forming the completed block. During the pouring of the concrete, the platform 80 and the mold 86 advantageously are vibrated by a vibrator of conventional construction.

After the pouring operation has been completed, the vacuum pump is energized to apply suction through the conduits to the side plates 89 and thereby facilitate the curing of the concrete by the removal of excess moisture therefrom. The plates 89 are then stripped outwardly away from the completed block by the jacks 96, and the jacks 81 are energized to return the platform 80 to its initial position at the level of the infeed conveyor 78. The completed block is carried from the apparatus by an outfeed conveyor 97 for storage and eventual transportation to the building site.

The apparatus of FIGURE 13 preferably is arranged for semi-automatic operation, with the conveyor speeds, the actuation of the jacks 81 to raise the platform 80, the movement of the side plates 89 into casting position by the jacks 96, the energization of the vibrator 90, the pouring of the concrete, the application of low pressure to the plates 89, the stripping of the plates, the lowering of the completed block by the jacks 81 and the discharge of the blocks onto the outfeed conveyor 97 all coordinated in sequential, timed relationship with each other.

In each of the illustrated embodiments of the invention, the precast building blocks advantageously are of square configuration. In other good arrangements, however, the blocks may be triangular, hexagonal or of other suitable shape consistent with the provisions of keyways in the side walls thereof which enable the formation of shear keys having the unique features described above.

What is claimed is:

1. In a monolithic building structure, in combination, a plurality of preformed members having substantially parallel faces and having side walls arranged in contiguous relationship with each other to form a substantially planar building slab, the side walls of adjacent members being angularly disposed with respect to the plane of one face of said slab and facing each other to define a groove therebetween, each of said facing side walls including a keyway having side portions which extend in uniform fiat planes from adjacent said one face of the slab to the other at acute angles with respect to the plane of said one face, each of said acute angles being of the order of seventy-six degrees, and a body of pouredin-place cementitions material for holding said members together, said cementitions material being disposed in the grooves between adjacent members and extending into said keyways to form shear keys, said shear keys resisting shear stresses in the plane of said slab and also in directions perpendicular thereto.-

2. In a monolithic building structure of the character set forth in claim 1, said facing side walls being comparatively thin to form a hollow space within each of said members, a portion of each of said side Walls being thinner than the remaining portion thereof.

3. 'In a monolithic building structure, in combination, a plurality of preformed members arranged in contiguous relationship with each other to form a substantially planar building slab, each of said preformed members having substantially parallel faces and having a side wall extending in a plane which meets the plane of one face of said slab at an acute angle, the side walls of adjacent members facing each other to define a generally V-shaped groove therebetween, each of said facing side walls including a keyway having converging side portions which extend in uniform fiat planes from adjacent said one face of the slab to the other at acute angles with respect to the plane of said one face, each of the acute angles between the planes of the side portions and said one face being less than the acute angle between the plane of said side wall and said one face, and a body of pouredin-place cementitions material for holding said members together, said cementitions material being disposed in the V-shaped grooves between adjacent members and extending into said keyways to form shear keys, said shear keys resisting shear stresses in the plane of said slab and also in directions perpendicular thereto.

4. In a monolithic building structure in combination, a plurality of preformed members arranged in contiguous relationship with each other to form a substantially planar building slab, each of said preformed members having substantially parallel faces and a peripheral flange adjacent one of said faces, each said member including a side wall extending in a plane which meets the plane of said one face at an acute angle, the peripheral flanges of adjacent members being in substantial contact with one another and the side walls of adjacent members facing each other to define a generally V-shaped groove therebetween, each of said facing side walls including a keyway having side portions which intersect the other face of the corresponding member and extend in uniform flat planes from said other face to said peripheral flange at acute angles with respect to the plane of said one face, each of the acute angles between the planes of the side portions and said one face being less than the acute angle between the plane of said side wall and said one face, and a body of poured-in-place cementitions material for holding said members together, said cementitions material being disposed in the V-shaped grooves between adjacent members and extending into said keyways to form shear keys, said shear keys resisting shear stresses in the plane of said slab and also in directions perpendicular thereto.

5. In a monolithic building structure of the character set forth in claim 4, the peripheral flange of each of said preformed members being beveled to form at least one sloping surface on each flange.

6. A precast building block adapted to be assembled for cementitions interlock with other blocks in a substantially planar building slab, said block being of integral, one-piece construction and having substantially parallel faces and a plurality of side walls extending in planes which are each disposed at an acute angle with respect to the plane of one face of said slab, each of said side walls defining a keyway having a fiat central portion parallel to the corresponding side wall and having converging side portions which extend in uniform flat planes from adjacent said one face of the slab to the other at acute angles with respect to the plane of said one face, each of the acute angles between the planes of the side portions and said one face being less than the acute angle between the plane of the corresponding side wall and said one face, said side walls being comparatively thin to form a hollow space within said block and said central portions being thinner than said side walls, whereby when cementitions material is inserted in said keyway a shear key is formed between juxtaposed such blocks which resists shear stresses in the plane of said slab and also in directions perpendicular thereto.

7. A precast building block adapted to be assembled for cementitions interlock with other blocks in a substantially planar building slab, said block being of integral, one-piece construction and including substantially parallel faces, said block having a peripheral flange including a beveled edge portion adjacent one of said faces and a plurality of side walls extending in planes which are each disposed at an acute angle with respect to the plane of said one face, each of said side walls defining a keyway having a flat central portion parallel to the corresponding side wall and having converging side portions which intersect the other of said faces and extend in uniform fiat planes from said other face to said peripheral flange at acute angles with respect to the plane of said one face, each of the acute angles between the planes of the side portions and said one face being less than the acute angle between the plane of said side wall and said one face, said keyway forming a shear key upon the insertion of cementitions material therein, and between juxtaposed such blocks which resists shear stresses in the plane of said slba and also in directions perpendicular thereto.

8. A precast building block of the character set forth in claim 7, the beveled edge portion of said peripheral flange forming a plurality of flat sloping surfaces in converging relationship with each other.

9. A precast building block of the character set forth in claim 8, the portion of said peripheral flange adjacent each side wall including first and second upwardly sloping surfaces on opposite sides thereof and a downwardly sloping surface which intersects one of said upwardly sloping surfaces to form a peripheral notch on said flange.

10. A monolithic building structure comprising, in combination, a plurality of preformed members arranged in contiguous relationship with each other to form a substantially planar building slab, each of said preformed members having substantially parallel faces and having a sloping side wall extending in a plane which meets the plane of one face of said slab at an acute angle, the side walls of adjacent members facing each other to define a generally V-shaped groove therebetween, each of said facing side walls including a keyway having converging side portions which extend in uniform flat planes from adjacent said one face of the slab to the other at acute angles with respect to the plane of said one face, each of the acute angles between the planes of the side portions and said one face being less than the acute angle between the plane of the corresponding side wall and said one face, means including a plurality of upright preformed columns for supporting said slab, each of said columns including an upper section extending in the plane of said slab, and a body of poured-in-place cementitious material for holding said members and said columns together, said cementitions material being disposed in the V-shaped grooves between adjacent members and extending into said keyways to form shear keys,

said shear keys resisting shear stresses in the plane of said slab and also in directions perpendicular thereto.

11. A monolithic building structure of the character set forth in claim 10, in combination, reinforcing means disposed in said V-shaped grooves, said reinforcing means including a first series of reinforcing rods extending in directions parallel to the plane of said slab and a second series of reinforcing rods which are angularly disposed with respect to the plane of said slab.

12. A monolithic building structure comprising, in combination, a plurality of precast concrete blocks having substantially parallel faces arranged in contiguous relationship with each other to form a substantially planar floor slab for a building, each of said concrete blocks having a substantially square peripheral flange and a plurality of oppositely disposed side walls extending in planes which meet the plane of said slab at an acute angle A, the peripheral flanges of adjacent blocks being in contact with one another and the side walls of adjacent blocks facing each other to define a generally V-shaped groove therebetween, each of said facing side walls including a keyway having a fiat central portion parallel to the corresponding side wall and having converging side portions which each extend in uniform flat planes from adjacent one face of the corresponding block to the other at an acuate angle B with respect to the plane of said slab, said acute angle -B being less than said acute angle A, said side walls being comparatively thin to form a hollow space within each of said blocks and said central portions being thinner than said side walls,

disposed in the V-shaped grooves between adjacent members and extending into said keyways to form shear keys, said shear keys resisting shear stresses in the plane of said slab and also in directions perpendicular thereto.

13. A monolithic building structure of the character set forth in claim 12, each of said columns including an extension disposed above said upper section, said cementitious material being disposed on said upper section and surrounding said extension to rigidly bond the same to the adjacent blocks.

14. A monolithic building structure of the character set forth in claim 12, in which the flange on each of said blocks and the upper section of each of said columns are provided with beveled peripheral portions, the beveled peripheral portion of each column being in abutting relationship with the beveled peripheral portions of the adjacent blocks.

References Cited UNITED STATES PATENTS 1,353,373 9/ 1920 Allbright 52-337 X 1,389,404 8/ 1921 White 52-577 X 1,397,147 11/1921 Sawyer 52-324 X 1,776,572 9/ 1930 Tise 52-440 FOREIGN PATENTS 878,395 10/1942 France.

805,071 5/1951 Germany.

547,340 5/ 1956 Belgium.

FRANK L. ABBOTT, Primary Examiner P. C. FAW, JR., Assistant Examiner U.S. Cl. X.R.