US2534580A - Reinforced building construction - Google Patents

Description

Dec. 19, 1950 H. EDWARDS 2,534,580

REINFORCED BUILDING CONSTRUCTION Filed Oct. 18, 1945 5 Sheets-Sheet 1 flilorn ey Dec. 19, 1950 I H. EDWARDS 2,534,580

REINFORCED BUILDING CONSTRUCTION Filed Oct. 18, 1945 '5 Sheets-Sheet 2 mom/0710 /0 a 2 1 0 In men for ll/JVDE/Y [fin A1905 QZZM H. MI

5 Sheets-Sheet 3 In venior v ,mroilv 0WA6D5 b 5% u-Abaw fiilorn 6y Dec. 19, 1950 H. EDWARDS REINFORCED BUILDING CONSTRUCTION Filed Oct. 18, 1945 W OOOOOOOO 000000000 0000000 ooooooooo/ 000000000 aw 000000000 mm oo0000000 ooo00oo0o 0000000 5 Sheets-Sheet 4 H. EDWARDS 10. m flilorn e5 In van for bwma/ [ow/W05 REINFORCED BUILDING CONSTRUCTION Dec. 19, 1950 Filed Oct. 18, 1945 Dec. 19, 1950 H. EDWARDS REINFORCED BUILDING CONSTRUCTION 5 Sheets-Sheet 5 Filed Oct. 18, 1945 5 W W w ZWJM H mm W pm lw nm i 1% fl Patented Dec. 19, 1950 UNITED STATES PATENT OFFICE aemroeopn BUILBEING coNsTRUcrroN Hayden Edwards, Columbus, Ohio ap licants Qctcher is, 1945, Serial No. 623 126 i i .Ciairns.

' The present invention relates to building constructions and more particularly it provides certain novel and useful forms of prefabricated slabs, sheets or plates capable of forming the principal structure of a wall, floor, roof or the like.

The principal objects of the invention are to provide structural and functional improvements in buildings and their erection and at the same time to effect substantial economies.

These objects are accomplished mainly by providing an improved type of building unit in the form of a prefabricated slab or the like having a remarkably high ratio of strength to weight which can be manufactured by rapid and economicai rolling. stampin rpu chine r y the use of permanent molds or other methods in- Volving the use .of dies and which is adapted to be set up in accordance with any .of a great variety of architectural designs quickly and inexpensively by relatively unskilled labor.

A, basic principle of the slab element is the use of a. skeleton type of construction produced by forming the slab with numerous cavities, openings, channels and indentations which eiiect economy of material and reduction of weight.

,TIhis general rinciple is not new, since the prior .art aiiords numerous examples of building slabs of skeletonized form, generally made with perforations or surface depressions, of various kinds.

the present invention which will now be briefly summarized- The slab, sheet or plate which forms a funda 1 mental element of the present invention, which will hereinafter be called a slab, comprises a foundation member in the form of a one-piece sheet or board skeletonized by surface cavities which become closed, at the site where the slab is to be erected r installed in a building or other structure, by the addition of closure elements which are made, and transported separately from the slab. In this way the handling weight of the originally separated elements of the completed slab-in-nla is materia ly reduced s t at in .many cases an individua wo kman ca eas y lift the slab base, even when it is made in large dimensions, and mount it in position, al h u h the weight of the mnleted slab-in-place m ght be too gr at for saf o ap d h nd i g w thou a helper or mechanical assistance. The open surface cavities form cqnvenient seats for therecepe t on of the app in ooks nd th i of mechanical and hand hoisting instruments whenever it is found ,necessaryor desirable to use such instruments.

. In additio to its su iiace ca es. the l b is provided with internal channels or passageways which serve not only to reduce weight and save material but also to receive and enclose various utility conduits such as pipes, wires, etc. An important feature of the invention resides in the fact t at he e in rn ope in w ic x end in a number of directionsthrough the slab body in a plane parallel to the flat surfaces of the slab, are so disposed that they can be formed in' the slab by moldinglugsor.protuberances formed on d es or the lik an pr se nwa y i ectio s no mal to the fiat s rfa of the sla Thus the use of a sand mold or other type of coring operation is rendere unnecessary, so that the slab can be fabricated in a permanent mold or by e trus o etwee c ntinu us y at o lers. or y on e o al tamp n p n h o even drop forging operations.

Th u face penings. whe c red as conemplat d in the set-up slab, fo a mu p ic y of int r-commun cat ng l e cells t ro gh which atm pheric .a r may be circula d t ae ate the s a o a wa l, floor. o r the l ma fr m ap ural ty o esla s- .In th Way the assembled slabs are kept well ventilated and dry.

In addition to their aerating function, the cells m y be used to cl seheatine'. l li hting. airpurifying or other instrumentalities, in which s th el co rs are mod fied so as to beiheaa laced together.

It is also an objectof the invention .todispose cell caviti s in sla in such. arrangement that r inforc g mesh may if des red be incorp rated in the slab without protruding into the cavities.

Another object is to arrange all the surface cavities in such a way as to leave solid portions of the slab material substantially aligned so as to act as virtual joists or piers when the slab is used as a floor or wall.

General objects of the invention are to provide a novel slab construction which may be disposed in any conventional vertical, horizontal or pitched position in a building, bridge or other structure, so that great structural strength, lightness, durability and general efiiciency will be provided at low cost.

The invention also provides means and arrangements for associating slabs together in securely bonded relation, both as the components of an individual wall, fioor, roof section or the like, and also as the adjacent members of two or more such sections.

Incidental objects are concerned with attaining novel lighting, heating, cooling, aerating and ornamental effects resulting from the use of a Single basic type of slab skeleton base completed by the addition of optionally selected adjuncts such as cell cavity covers and instrumentalities housed in the cells.

The principles of the invention are capable of being embodied in numerous specific forms, certain preferred examples of which are shown in the accompanying drawings in which Figure 1 is a front elevational view of a slab constructed in accordance with the principles of the invention, showing the interior surface, with the cell cavities uncovered, in the form in which the slab is produced by the casting or rolling operation;

Fig. 2 is a transverse sectional view of the slab taken along the line 2--2 of Fig. 1, but showing the slab completed, ready for use as a building wall, with the cell cavities covered and with a sheet of insulating material applied to the exterior surface;

Fig. 3 is an edge elevational view of the completed slab;

Fig. 4 is an elevational view, similar to the view of Fig. 1, but showing the exterior surface of the slab;

Fig. 5 is a transverse sectional view of the slab taken along the line 55 of Fig. 1, at right angles to the View of Fig. 2, but like Fig. 2 showing the slab completed by addition of cell cavity covers and insulation and differing from Fig. 2 by showing a modified form of fastening means.

Fig. 6 is a vertical sectional view through a portion of a building showin wall in interior elevation and section and showing a floor in section, with utility conduits installed in the slabs;

Fig. 7 is a front elevation of a wall slab, or a top plan view of a fioor slab, completed with cell cavity covers;

Fig. 8 is a front elevational view of a slab like that of Fig. 1, modified by inclusion of reinforcing, showin the interior surface of the slab completed by addition of cell cavity covers;

Fig. 9 is a front elevational view of the exterior surface of the reinforced slab shown in Fig. 8;

Fig. 10 is a view of the reinforced slab shown in Figs. 8 and 9, showing the right hand edge of Fig. 9 in elevation;

Fig. 11 is a transverse sectional view of the reinforced slab shown in Figs. 8, 9 and 10, taken along the line llll of Fig. 8;

Fig. 12 is a view similar to that of Fig. 10 but showing an upper or lower edge of Fig. 9;

Fig. 13 is a vertical sectional view taken 4 through the junction of a Wall and floor, showing a preferred manner of bonding slabs thereof;

Fig. 14 is a vertical sectional view taken through a wall and roof, showing preferred modes of bonding slabs in the roof sections and to the wall slabs;

Fig. 15 is a front elevational view of a slab like that of Fig. 1, showing the cell cavities formed on the exterior surface and covered by lenses;

Fig. 16 is a vertical sectional view taken through the walls of a building, near a corner thereof showing, in vertical transverse section and in interior surface front elevation, wall slabs having their outer surface cell cavities covered by lenses and having their inner surfaces lined with sheets having pockets closed by heat-transmitting covers;

Fig. 17 is a front elevational view like that of Fig. 15 but showing the cell cavities provided on the inner or outer surface and covered by plate glass panes;

Fig. 18 is a vertical sectional view like that of Fig. 16 but showing the cell cavities and pockets provided with electric lighting, heating or air purifying means and closed by fiat covers;

Fig. 19 is a transverse sectional view, like that of Figs. 5 and 11, showing a modified type of slab in which both surfaces are provided with cell cavities;

Figs. 20 and 21 are plan views of the opposite faces of a pair of floor slabs, or elevational views of the opposite faces of a pair of wall slabs, bonded edgewise together in place in a building or the like;

Fig. 22 is a transverse sectional view, taken along the line 22-22 of Fig. 21, through the joint of Figs. 20 and 21; and

Fig. 23 is a transverse sectional view through a slab showing the openings in one of its surfaces closed by a filler applied in such a way as to leave the internal passageways open.

However, it is to be understood that the particular embodiments shown by these drawings and hereinafter explained are subject to further modification without departing from the broad principles of the invention as stated in the foregoing outline of objects and as defined by the appended claims. It is also to be understood that not all of the features incorporated in these specific embodiments need be used in the particular combinations shown and described in this application for Letters Patent.

Referring now to the drawings, Figures 1 and 4 show respectively the inner and outer surfaces of one form of basic slab unit I embodying the principles of the invention. This form, as well as the others shown by the drawings and hereinafter to be explained, is preferably made of any suitable cementitious or analogous building material capable of being poured in a plastic condition and thereafter setting to rigid condition, by hydration or otherwise, such as Portland cement concrete, burnt clay or terra cotta, fused silica, or the asbestos fiber and cement material now widely used in the building industry and sold under various trade names. However, the form of the slab is such that it is well adapted to be made also of metal, as by die-casting, or by stamping or drop-forging metal sheet or plate stock.

The slab is so shaped that one of its surfaces, hereinafter designated the inner surface 2, is provided with a plurality of substantially hemispherical cell cavities 3 arranged in lines in such a way that the cavities of adjacent lines are staggered "relatively to each other, :as is -clearly shown in Fig. "1. Each cavity penetrates the slapsome five-'sir'tl'is lmOl'e "or less of the slab thickness, so that'the opposite race 4 of the slab 'is'not broken by the cavity. However, this opposite face is broken by "a relatively small aperture forperforation 5 establishing communication between the face '4 and "the "central bottommo'st point of the cavity. The surface 4 is alsointen rupted by generally rectangular shaped openings 6 which penetrate 'suflic'ient'ly into the slab material to communicate with cylindrical "passageways I which radiate from each cavity to con nect it with each adjacent cavity. *In the ar rangem'ent shown, each cavity has six such passageways 1, spaced "approximately =60" apart around each cavity, so that "all the cavities which are aligned "in any -'direction are connected by aligned passageways I. This feature'I- regard as important because the alignment of "the passageways facilitates fishing =utility conduits and the like through them.

In order to receive lids or closuresa's *will hereinafter be explained, each cavity is "surrounded by a widened rim depression forming a shoulder 8 set slightly below the plane ofthe inner wall 2 of the slab. v

The passageways I lie all in the same general plane, which is best located parallel to and slightly outwardly from the median planeo'i the slab.

An important feature of the invention resides in the capacity'of the slab to be cast-or 'ro'lledby fixed, solid molding or roll surfaces, or to be punched, pressed or stamped from plain sheet or plate stock. To this end I make a ll'the cavities, passageways and openings in "suchform and relationship that all portions of all of them are directly open to one or another of the surfaces '2 and 4 of theslabby straight lines normal to such surfaces. "This willbe evident from Fig. '2, where it will be appreciated that a single --specially shaped molding protuberance or die projection maybe used to form each cavity 3 and those portions of its six passageways 1 which are il'odated between each dotted line -9 and the cavity, while another, differently shaped protuberance or projection on a cooperating molding surface or die "forms the opening '6 and that "portion of the adjacent passageway "1 which lies between the dotted lines '9. 0i course suitable projections on oneor another of the two molding'or die surfaces will be provided 'to form the perforations 5.

The presently preferred material for the slab I is one o'f-the 'cementitio'us or plastic type, and the drawings illustrate the saw in the relatively thick form in which such "material' is best cast, molded or rolled. *However, it istobe understood that cooperating dies, configured in the same way as the molding or rolling surfaces, may -be set up in a dropforging, "punching or stamping press and operated on plain 'meta'l sheets or plates of any appropriate gauge to produce 'a metallic slab of the same general surface and internal contours as the cemen'titious or plastic slab. The metallic slab can, however, be made somewhat thinner, and it will 'be -found convenient in many cases to make it longer "and/or wider :because the metal product can be handled with'less danger of breakage, cracking or distortion.

It is thussapparent' thatthe particular arrangement hereinabove described and shown in Figs. 1 "and 2 combines various functional surface de- 6 pressicns and internal passageways in a slap in such awvay'thatthe slab need not beeX-pensively molded or cored :out but can be cast by the use o ia permanent Torin or can be extruded between rotating rollers, or can be die-stamped, die-cast or'drop iorged. For-this reason coupled with the inexpensive material which may be used, the slab is extremely economical to make.

The slab isalso unusually light, since the ratio of its voids to its solid material is very high. Notwithstanding this lightness, the slab is structurallystrong because of the staggered arrangement of the 'lineso-f cavities which leaves a substantially straight or only slightly sinuous line of solid slab material running in one direction betweenadjacent rows of cavities. Two such lines are seen in Fig. l, o-ne'on-eachside of the vertical central line of cavities. These lines act in vertical compression as virtual piers or studding when the slab is used "as a wall, and when such lines "are disposed lengthwise between supports, when a slab is disposed horizontally, they act as 'virtual joists.

Thestructure thus far-described is made in one integral piece and is of course very light because it is skele'tonized by the openings, cavities and passageways. It can be made light enough,-even when made in slabs of appreciable length and width, for one workman to carry and sets. slab without'ass'istance. The'sur'fac'e openings-arcint'en'ded tobe covered after the slab is installed in a building or other structure, and this covering may'beaccomplished intwo principal ways which will now be described.

The surface 2,which is generally and preferably employed as the interior face of a building vvall, originally presents the series-of cavities3. These are covered by-discs it which more orless accurately fit "against the shoulders *8 and may be held in place in any convenient way, as by the cement or other plastic keys indicated at H. Each-cover disc ill may be made'in the form of a fairly thin circular plate cast, stamped or otherwise'formed from the same material as the slab itself or from any other suitable material. A-s'lab completed'by the addition of cover plates [6 resents 'a'suriace "-2 which is continuous, unbroken and substantially smooth. If this surface be arranged as the interior of a wall or as ace'iling it may be faced by plaster, wall'board or any other conventional interior sheathing, or the slab and its covers iii may be made with such accuracy as to present "a'sm'ooth, even, finished surface, as is W6l1 shoWn in Fig.7, which requires no plastering or'other preparation prior to receiving adecorative finishof paper, paint or the like.

The surface '4 is brok'enby the openings i5 "and the small perforations 5. It is generally desirable to'affix'sheet insulation, shown at l2' in the drawings, to this surface when used as the exterior of 'awvall. "One wayof accomplishing this aflixation is by inserting plugs l3 of any nailable material, such as wood, plastic or the like, into certain of the openings 56 and then nailing the sheets [2 to these plugs. Thus the exterior surface of the'wall is'finished, and o'f'course any'conventional surfacing trim may be'app'liedsuch as stucco, board sheathingor the like.

The slabs may be made in any convenient length and width, but it is best to make their dimensions in multiples of each other and 'in multiples of the distance from center to center of the cell cavities. It will also be found desirable in most cases to provide two intersecting edgeso'f eachslab with-a tongue f4 andthe other assmsq,

two edges with a complemental groove 15 so that adjacent slabs can be interfitted together. Of course all the edges might be grooved and the mating grooves of adjacent slabs be filled with some independent keying material.

A plurality of slabs, as cast, rolled or pressed in the skeletonized form which has been described, are set edge to edge in vertical position to form a wall, with the tongues it interfitted into the grooves l and with the cell cavities 3 open to the interior surface. These cavities are then closed by the cover plates l6, and the exterior surface of the wall is sheathed by installing plugs l3 at selected intervals and nailing or'otherwise securing sheets of insulation i2 to these plugs. Optionally, the insulation may be mounted by means of bolts l5 passing through the perforations 5 and engaged with nuts and washers ll in the cells, as shown in Fig. 5, These bolts may be conveniently extended beyond the insulating material surface as shown in Fig. 5 as a means for tying exterior facing.

Fig. 6 illustrates a corner of a. building in which two intersecting walls are formed of completed slabs and in which a floor is similarly formed and tied into the walls. In this figure the bolts I6 are used to mount sheets of insulation, and furring it is interposed between the insulation and any conventional type of exterior sheathing l9.

Fig. 6 also shows a convenient mode of supporting a floor, generally designated 28, on a wall, generally designated 2|. In this arrangement the wall is laid up to desired height, so as to terminate in a single course of slabs providing a continuous horizontal top edge surface. This surface provides a bearing for the margins of a floor slab which is laid on it, and the upper edge of this floor slab in turn provides a footing for the course of slabs which are then laid up to continue the wall. In this way the floor is securely keyed into the wall.

It will be understood, with reference to Figs. 6 and 1, that the floor slabs are laid in such a way that the aligned cell cavities shown extending in vertical lines in Fig. l extend across the span between the walls which serve as bearings for these slabs. Thus the solid slab material, lying in almost straight lines between the aligned cell cavities, serves as virtual joists from bearing to bearing and renders unnecessary the use of actual joists, beams or any other supporting means.

Fig. 6 also shows certain of the passageways I employed to house utility conduits 22 which can easily be fished through those of the passageways 1 which are continuously aligned in any direction. Thus, as shown in Fig. 6, the conduits may extend in a vertical direction through the walls, in a horizontal direction through the floor, or in any inclined or diagonal direction through the floor or walls. These conduits may be led into or out of the wall through the surface 2, from any of the cavities 3, by omitting the cover disc Ill from such cavity or by providing a hole in it, and'they may be led through the surface 4 from any of the openings 6 or perforations 5.

When used as a floor I prefer to dispose the slabs with their cavity surface 2 uppermost. The cavities may if desired be subsequently closed by covers It] to provide a foundation for any conventional type of flooring 23.

The surface 4 of the floor slab forms the foundation for a ceiling which may be built up in some such way as is indicated in Fig. 6, where a sheet ofinsulation 24 is hung from the slab by f of the openings.

means of bolts 25 passing through some of the perforations 5. This insulation may be covered by any suitable ceilin surface material, as indicated at 26, being fastened in place by the same bolts.

If desired or thought necessary, the quarterspherical or half cavities which open to the edge of the top course of slabs in the wall 2| (one of such cavities being shown at the top center of Fig. 1) may be filled with cement to assist in bonding the wall and floor margins together. Such bonding is employed in Fig. 14 at 21 to secure together the two sections 28 of a pitched roof and also at 29 to secure the lower edge of cavities and the adjacent floor half cavity as shown in Fig. 13.

Figs. 20 and 21 show the joint by which a pair of adjacent slabs are bonded together in a wall, floor or roof section. It will be observed that the half-openings 6, open to the edges of the two slabs, become aligned with each other and provide keyways for receiving fills 32 of bonding material, preferably a cement introduced in plastic condition and subsequently setting, thus providing a laced bond for the joint. In order to keep such plastic bonding material from filling the passageways '1 I form a shoulder 33 along the plane at which each opening 6 meets the adjacent passageway 1 along the long dimensions Plates 34 of some suitable thin sheet material, which may be as inexpensive as cardboard, are laid on these shoulders to support the cement until it hardens and thus prevent it from entering and obstructing the passageways I. If desired or thought necessary, the'joint can be strengthened by tying adjacent slabs together by bolts or the like passed through the mating passageways l which are intersected by the joint line.

Figs. 8-12 show a modification of the slab structure in which reinforcing is incorporated. This reinforcing, designated 35, may take the form of a series of wires or rods or coarse woven wire mesh so dimensioned that all the wires will lie in the solid portions of the slab and none of it will protrude into any of the cavities, passageways or openings. Such a reinforced slab is fabricated, installed and completed in the same way as has been described in connection with the unreinforced slab.

Fig. 19 shows a further modified type of slab in which both surfaces are provided with open cavities 36. All the cavities are staggered with relation to each other so that maximum strength of the skeleton structure is preserved. Each cavity may be closed after the slab is installed by addition of a closure disc or plate It. Slabs made in this form are primarily useful as the walls of structures which do not require insulation or other type of outer sheathing, and they are useful also in horizontal position as girders or as the floors of short span bridges, culverts and the like, or in horizontal or pitched position as a roof, in all of which uses some plastic surfacing material oan be inserted or poured into the cavities after the structure is mounted in place. In this way the weight of the slab or the like is kept low for ease in handling, transportation and installation.

Figs. 15 and 16 show a modification in which slabs used to form walls are positioned with their cavity surfaces 2 on the outside and in which assum the. cavities,- are, closed; by double convex lenses 31' eachheldinplace against the shoulder- 8 by some such. means; as.v a, bezel. These lenses. concentrate, solar rays at focal points in: the cavities where the heat is absorbed; by an appropriate fluidin one terminal; portion, 38 ofa coi139 which extends through the perforation 5; at the base of the cavity and terminates in a portion on or in they interior surface of; the. wall. It is convenient to mounttheterminal portion 40 of'each coil in a pocket 4| f'ormediin interior wall sheathing and covered by a perforated closure plate 42. Heat generated in the coil is thus transmitted through, the wall and; into the. interior of the building by' passing; through, the perforations in, time.v plates, 40,.

The coils may be connectedinseries witheach other and, with a, pump andreservoir in which sun heat, canbestored for recirculation after sundown.

Figs. 17' and 18 illustrate a further modification in, which transparent or translucent panes 43; are substituted for the lenses 31' and for the perforated closure plates 42; Such' awall is intended to be impermeable by heat and air and" hence may include a sheet; of" insulation interposed between the wall slab and its outer sheathing 44, closing the perforations 5;. Electric light bulbs 45 and 46 may be positioned in the, sheathing pockets 4| and in the cavities 3 to give various illuminating effects to both the'insid'e and outside surfaces of" the walls Such a wall, and of course also a ceiling similarly constructed, may be used in the form of. an isolated panel to give novel effect to a store front, theater lobbyor the like, or the interior surface arrangement may be employed with a plainexterior, made as in; Fig. 6," to provide ceiling or wall lighting.

For the illuminating bulbs of Fig. 18 there, may be substituted ultra-violet ray bulbs or their equivalent for, sterilizing the; air in the. cavities,

and thisv air may be circulated, by way of the In. all forms of the invention, the slabs which are associated in edge to, edge relation provide continuous communicating passageways. through them. I have explained that. any set of such passageways which are aligned in any direction may be: selected to house, Wiring, piping orthe. like. These passageways andthe, remaining ones may-beused also to conduct. heated or cooled air through. the walls from some point. or level selected as an inlet to some other point or level serving as; an outlet. It will, readily be appreciated that walls, ceilingsaor'floors may in this way have their temperature modified and. controlled, in: any desired way. The warmed or cooled air may be recirculated from the passageways to a heating orrefrigerating means andv bacle: again to the passageways, or it maybe exhausted into thebuildinginterior or to the outside, in any way desired, It; is recognized, also that. the. cell. cavities may, havelm un ediinqthem individual heat radiators, such as those of the electric filament type, which will warm theslabs and; theair contained; in them, and that this-air may; be kept out of, the building interior by the useofimperforate closure discs ID, or it may be discharged into the building interior by the use of perforated discs 42. Obviously, individual cooling coil units, may-be substitutedfor theheating; elements. A desirable arrangement would include the use of both heatingand cooling; units disposed in different selected cells for operation at different seasons of the year.

It is thought: to be clear from the foregoing description and, the, drawings that the slab provided by the invention may be embodied in the form, of a single standard type of skeletonized body to which any of the variety of cell cavity covering elements i8; 31 42', 43, or others may be selectivelyappli'edi While I prefer to make the cell cavities substantially hemi-spherical as 20" adapted to be impressed in thebasi'cmaterial of the bodybydie protuberancesin casting, rolling, forging, stamping and like processes.

In the appended claims, which point out the broadly novel principles of the invention the term building walls and the like" is intended to include not only vertical walls properly so called; whether bearing, non-bearing or backup, but also such elements as floors, roofs, ceilingsand' the like, and the utility of the-invention is not limited to buildings per se but is recognized: as being applicable to such analogous structures as bridges, decking, bulkheads, etc. The invention is broadly capable of being' embodied in numerous forms other thanthose specifically illustrated and described in the foregoing specification and thedrawings and all such modifications are intended to be covered by; the broaderof the appended claims.

I claim v 1. A building slab comprising a skeletonized body having each of two opposed outer surfaces provided with a set of indentations having their inner portions staggered with relation tothe inner portions of the indentations of the other set and intersecting said inner portions, the interior of said slab being provided with passage- .ways formed by said intersecting portions and extending laterally through the body and through the end Walls thereof in a plane parallel to the indented surfaces.

2: A building slab; comprising a skeletonized body having each of two opposed outer surfaces provided with a set of; indentations having their inner portions staggered, with relation to the inner portions of the indentations, of the other set: and: intersecting said, inner portions, the interior' of said slab being provided with passageways formed by said intersecting portions and extending laterally through the body and through the end walls thereof in a plane parallel to the indented surfaces, in combination with closures for covering said indentations.

3. A building slab comprising a skeletonized body having each oftwo opposed outer surfaces provided with a set of indentations having their inner portions staggered with relation to the inner portions of the indentations of, the other set and; intersecting said inner portions, all points. on the bottom. of each indentation of each set lying directly beneath points within said in- 31 dentation in the plane of one of said surfaces, whereby none of said bottoms is directly covered by any of the material of the body between said bottom and one of said surfaces, the inner portions of the indentations of each set interseeting the inner portions of the indentations of the other set, and the interior of the slab being provided with passageways formed by said intersecting portions and extending laterally through the body and through the end walls thereof in a plane parallel to the indented surfaces, where- ..by all of the indentations can be formed by die projections pressed vertically to the planes of said surfaces.

in which the closures for said indentations are in the planes 7 of said respective surfaces, leaving said passage- -ways unobstructed.

1. The slab claimed in claim 2,

said indentations being open to an edge of the slab in angularly diverging relation, whereby two similar slabs may be laid edge to edge in stag- .gered relation with an indentation of one pair formed in one slab aligned with the corresponding other indentation of a pair formed in the other slab so that the aligned indentations combine to provide a plurality of openings crossing the line of joint between the two slabs at alternately different oblique angles and are adapted to receive and hold keying material to bond the two slabs together and by their different angularity to the line of joint resist separating forces normal to said line.

7. The slab claimed in claim 1, in which certain of the indentations formed in one oi. said surfaces have spaced parallel side walls intersecting the edges of the slab, adjacent pairs of said indentations being open to an edge of the slab in angularly diverging relation, whereby two similar slabs may be laid edge to edge in staggered relation with an indentation of one pair formed in one slab aligned with the corresponding other indentation of a pair formed in the other slab so that the aligned indentations combine to provide a plurality of openings crossing the line of joint between the two slabs at alternately different oblique angles, in combination with closure plates 1 disposed in the aligned indentations bonding the I two slabs together and by their diiferent angularity to the line of joint resisting separating forces normai to said line.

8. A building slab comprising a body having separated substantially hemi-spherical cavities formed in one surface in a plurality of parallel lines with the cavities of laterally adjacent lines staggered with relation to each other and having its opposite surface provided with rectangular indentations arranged in groups extending in directions radiating from the axis of each of the cavities which is normal to the plane of the first named surface, said indentations intersecting said cavities and the intersections forming passageways extending laterally through the body and radial relatively to the cavities and establishing communication between ad acent cavities.

9. The slab claimed in claim 8, in which the cavities and indentations are closed by separate individual covers disposed between the bottoms of the cavities and indentations respectively and the adjacent surfaces of the body, leaving the passageways open inside the body.

10. A building slab comprising a body having separated substantially hemi-spherical cavities formed in one surface and having its opposite surface provided with rectangular indentations arranged in groups extending in directions radiating from the axis of each of the cavities which is normal to the plane of the first named surface, each of said indentations extending into and intersecting a pair of adjacentv cavities and the intersections constituting passageways wholly within the body establishing communication between adjacent cavities.

11. The slab claimed in claim 10, in which ad. jacent pairs of the passageways are aligned so that utility conduits can be projected through the interior of the body.

12. The slab claimed in claim 10, in which six indentations radiate from each cavity and opposite pairs of passageways of the same group are aligned so that utility conduits can be projected through the interior of the body in any of three different straight line directions.

13. A building slab comprising a cementitious bodyhaving a plurality of spaced separated cavities formed in one surface and arranged in parallel lines with the cavities of adjacent lines staggered relatively to each other, in combination with elongated metallic reinforcing elements embedded in the body in straight lines between adjacent cavities.

A building slab comprising a cementitiou body having a plurality of spaced separated substantial helm-spherical cavities formed in one surface and arranged in parallel lines with the cavities of adjacent lines staggered relatively to each other, in combination with elongated metalc reinforcing elements embedded in the body in straight lines between adjacent cavities.

HAYDEN EDWARDS.

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

v UNITED STATES PATENTS Number Name Date 528,636 Kupper Nov. 6, 1894 689,523 Trumbull Dec. 24, 1901 706,974 Lyle Aug. 12, 1902 783,448 Merrill Feb. 28, 1905 836,017 Douglass Nov. 13, 1906 901,833 Rettig Oct. 20, 1908 995,940 Meier June 20, 1911 1,043,701 Freeman Nov. 5, 1912 1,171,191 Gronert et al Feb. 8,1916 1,277,829 Baum Sept. 3, 1918 1,305,294 McIntyre June 3, 1919 1,597,167 Pace Aug. 24, 1926 1,670,095 Boes May 15, 1928 1,991,459 Slayter Feb. 19, 1935 2,908,370 Schwalbe July 16, 1935 2,196,177 Hultquist Jan. 25, 1938 2,298,001. Fay Oct. 6,1942

FOREIGN PATENTS Number Country Date 5,352 Great Britain of 1899 278,299 Germany of 1914 739,273 France of 1932

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