US3460447A

US3460447A - Unitary joint-forming structure

Info

Publication number: US3460447A
Application number: US647358A
Authority: US
Inventors: Robert J Grenzeback
Original assignee: ROBERT J GRENZEBACK
Current assignee: ROBERT J GRENZEBACK
Priority date: 1967-06-20
Filing date: 1967-06-20
Publication date: 1969-08-12
Anticipated expiration: 1986-08-12

Description

Aug. 12, 1969 R. J. GRENZEBAC'K 3,460,447

UNITARY JOINT-FORMING STRUCTURE Filed June 2o, 1967 MN 24) l 22) 4o FIGA gg ed 5e' ATTORNEYS aired States Patent t 3,460,447 UNITARY .IOIN'B-IFGRMING STRUCTURE Robert J. Grenzeback, 16 Mason St., Winchester, Mass. 01890 Filed .lune 2%, 1967, Ser. No. 647,353 Int. Cl. Eii1c 1.1/10, 1]/12 U.S. Cl. 941-18 5 Claims ABSTRACT OF THE IHSCLOSURE BACKGROUND OF THE INVENTION In the construction of roads, bridges, and other types of structures in which a viscous hardenable material such as concrete, asphalt, or the like is poured within forms and allowed to set, it is often desirable to provide expansion joints between adjacent sections of the construction in order to allow for expansion and contraction of the sections due to variations in load and atmospheric conditions. These expansion joints are generally of relatively small dimensions (often of the order of fractions of an inch) and therefore cannot readily be formed by the usual technique of inserting a standard wooden form between the adjacent sections while pouring them and subsequently removing the form, since the small spacing severely restricts access to the form which tightly adheres to both sections after they have set. On the other hand, the form, being relatively incompressible, cannot permanently be left in place since this would prevent the necessary expansion and contraction of the sections relative to each other.

Present construction techniques utilize what is known as a hopscotch method of construction to solve the problem of forming expansion joints. In this method, alternate construction sections are poured within wooden forms erected for this purpose, the sections are allowed to set, and the forms are then removed; spacing elements such as slabs of cork are next positioned adjacent the hardened sections and the sections which have been skipped over are then poured. The cork slabs may then be left in place if it is desired to form an expansion joint of the type having a partially limited expansion capability (cork being a material which may be classified as partially compressible) or may be chipped out by hand and the joint lled with sealant if it is desired to form a joint having a greater expansion capability. Such techniques are quite time consuming, and unduly lengthen the time spent in construction. Further, in cases in which sealant is to be introduced into open-bottom joints of the type found in bridges and similar structures, special preparations for retaining the sealant must be made and these preparations often further lengthen the construction time. It is therefore desirable that a more efficient and more economical method of constructing expansion joints be found.

SUMMARY OF THE INVENTION I have found that expansion joints in structures formed from viscous hardenable materials may readily be formed SAAl? through the utilization of a simple yet elicient unitary joint-forming structure consisting of a core member, preferably of cork or of a foamed, closed celled, polystyrene plastic, and a pair of wall members which are attached to the core member on opposite sides of the core to form a modular sandwich The wall members, which may advantageously be formed from a light Weight, relatively strong, non-corroding material such as ber glass, may be reinforced with a number of stress-carrying rods which provide additional rigidity to the unitary structure and which can subsequently serve as attaching members for lirmly bonding the walls to the opposite sides of the expansion joint which is being formed. The core member may, if desired, be removed after the expansion joint has been formed; the wall members, on the other hand, which isolate the core member from the adhesive viscous material, are permanently bonded to opposing sections of the joint. A retaining lip for sealant-retaining gaskets may be directly incorporated into structures made in accordance with my invention to provide a `rapid means of forming sealant-retaining joints. Such structures as these allow the formation of poured sections sequentially as well as simultaneously and thus greatly reduce construction time.

Accordingly, it is an object of my invention to provide a unitary joint-forming structure. Further, it is an object of my invention to provide a unitary joint-forming structure which is simple and economical to make and which may be left in place, or which may be partially removed, after the joint has been formed. Yet a further object of my invention is to provide a unitary joint-forming structure in which a retaining lip for sealant-retaining gaskets is formed directly. Still a further object of my invention is to provide a unitary joint-forming str-ucture which allows the pouring of adjacent sections in sequence.

`One feature of my invention resides in the provision of a pair of relatively thin non-corroding wall members surrounding a central core, the walls being adapted to remain in place after the sections have been formed. Another feature of my invention resides in the provision of stiifening bars attached to the wall members and spaced from the members to provide increased resistance to buckling of the walls during the pouring or section-forming operation. Still another feature of my invention resides in the provision of either a partially or a fully compressible central core which is isolated from the poured sections by the wall members and which provides both stiffening and spacing between the sections during the pouring operation. A further feature of my invention resides in the provision of a removable core member which provides rigidity to the structure during pouring but which is readily removable after the sections have been formed.

SPECIFICATION The above and other and further objects and features of my invention will become more readily apparent when considered in connection with the following detailed description of the drawings in which:

FIG. l is a pictoral View of a preferred form of unitary joint-forming structure constructed in accordance with my invention, the structure shown being especially adapted to form expansion joints of the fully expanding type;

FIG. 2 is an end sectional view of the structure of FIG. 1 shown positioned between adjacent sections to form an expansion joint, one of the sections being fully poured and the other only partially so;

FIG. 3 is an end sectional View of the structure of FIG. 2 showing the core member partially removed and replaced with a sealing gasket supporting a layer of sealing compound after the poured sections have hardened; and

FIG. 4 is an end sectional view of an alternative form of unitary joint-forming structure shown positioned between adjacent poured sections, the structure shown being especially adapted to form expansion joints of the partiallyexpanding type.

In FIG. 1, a unitary joint-forming structure constructed in accordance with my invention comprises a core member 12 which is preferably formed from a foamed, closed-celled, polystyrene material attached on opposite faces to

walls

14 and 16. The latter may advantageously be formed from a light-weight, non-corrodable material such as fiberglass which may be formed in relatively thin but strong sections. As may be seen from FIGS. 1 and 2 of the drawing, the wall 14- comprises a first relatively flat section 18 having a flange 20 positioned adjacent the upper portion and extending substantially at right angles to the wall. An inwardly extending wall section 22 connects the outer portion of the flange to a second at wall section 24. The flange and the inwardly extending wall section form a triangle extending outwardly of the structure for purposes which will subsequently be described. A line of weakening 25 may be formed in the upper portion of the core member 12. An angled wall section 26 terminating in a horizontal flange 2S is provided at the bottom of the wall 14 to provide a footing for the structure. The wall 16 is constructed similar to the Wall 14 and need not be described in detail.

A number of standoffs 30 are positioned along the

Walls

14 and 16 and are secured to these walls by adhesive or the like. In the embodiment shown in the drawings, the standoffs are secured to the walls by means of strands of fiber glass-reinforced plastic material which are bonded to the walls and which are subsequently allowed to set. Reinforcing bars 32 are spot-welded to the standoifs 30 and act as longitudinal stiifening elements to prevent buckling of the

walls

14 and 16.

The dimensions of the structure of my invention will depend on the desired dimensions of the expansion joint and on the materials being utilized. For typical expansion joints in concrete bridge structures and the like, a closed celled, polystyrene core 11/2 inches thick and 14 inches high is appropriate; the width of the core is, of course, dependent on the width of the bridge section. The

walls

14 and 16 may be formed from a single 11/2 ounce mat of iiber glass with resin bonding; additional layers may be used as reinforcement if desired.

FIG. 2 of the drawings shows the structure 10 positioned intermediate adjacent sections of Vicous hardenable material which are being poured to form a solid structure on hardening; for purposes of illustration, this material is shown as being concrete. At the stage illustrated in FIG. 2, one section 34 has already been fully poured, while another section 36 is still in the process of being poured. The structure 10 serves as an end closure wall for the

sections

34 and 36 during the pouring and hardening operation.

Ideally, the left and right hand sections on opposite sides of the structure are poured at an equal rate so that counter-balancing forces in opposite directions are applied to the structure 10. Under these conditions, the core member 12 compresses slightly due to the applied lforces. In practice, however, it is desirable to pour the

sections

34 and 36 serially, the pouring of the section 34 being completed before the poring of the section 36 is begun. This introduces a large force on the right hand wall which would cause this wall to buckle outwardly (toward the left in this case) were it not for the strength introduced in my structure by the modular sandwich construction and by the stiffening elements 32 which resist any bending moment causing the Wall to buckle.

After the

sections

34 and 36 have been formed and hardened, they are spaced a xed distance apart by the core member 12 and the

walls

14 and 16. The latter are Ltirmly bonded to the

opposite sections

34 and 36 when these sections harden and serve as end faces for the respective sections; the core member 12 is then no longer needed to space the wall members and accordingly may be removed if desired. This may be accomplished in any of several ways` Thus, the upper portion only of the core member may be removed by separating it along the line of weakening 25. This allows the introduction of sealant material in the upper portion as is described more fully below. Further, it may be chipped out by hand if made from a brittle, easily breakable material. Note in this connection that the core is isolated from the poured sections by the

walls

14 and 16. If the core member 12 is constructed of a foamed polystyrene material, it may readily be removed by treating it with a suitable solvent to dissolve the material. This treatment completely dissolves the core member and leaves a void space which serves as the desired expansion joint between the

sections

32 and 34. Alternatively, since the closed-celled polystyrene core is relatively highly compressible, it may be left in place Without adverse consequences. This is in strong contrast to prior forms of wood or the like which had to be removed to allow operation of the expansion joint.

When the member 12 is removed, it is often desirable to protect the expansion joint from extraneous substances such as water which may seep into the joint and cause subsequent damage on freezing, or from pebbles or other material which may become trapped in the joint and prevent its expansion. Accordingly, in FIG. 3, which is an end sectional view of the structure of FIG. 2 showing both sections fully poured and hardened, the upper portion of the core member 12 is removed along the line of weakening 25 and a gasket 38 is positioned on the flange 20 and adjacent the inwardly sloping wall 22; the remaining portion of the compressible polystyrene core may be left in place. In practice, this gasket may be formed from a rectangular sheet of neoprene one-eight of an inch thick and 41/2 inches wide doubled back on itself to form a U-shaped closure for the expansion joint as shown. A ller material such as an asphalt compound 40 is then poured over the gasket 36 and allowed to set. After the filling compound is hardened, it rises or falls slightly in the expansion joint as the width of the joint decreases or increases in accordance with the forces and environmental conditions operating on the

sections

34 and 36. The gasket 38 deforms accordingly, with the result that the expansion joint is sealed and remains so under all conditions.

It will be noted that a portion of the core member 12 remains in the joint after it has been formed; this core portion, being relatively strongly compressible, does not limit the expansion and contraction of the joint in any way. If the vmaterial used in the core is polystyrene or the like, it will be found that the core member will fragment after continued expansion and contraction of the joint and will eventually drop through the bottom of the joint if the latter is of the open-joint type such as is used in bridge construction.

So far I have illustrated an expansion joint of the openjoint type such as is used in bridges. In this type of joint, a strongly compressible material is used to allow essentially unlimited joint expansion.

In some types of construction, such as that encountered in roadways or bridges, it is often desired to limit the range of expansion through which an expansion joint is allowed to operate. In such cases, it is desirable that material such as cork, which is only partially compressible, be utilized in the expansion joint to provide the necessary limiting action, the cork remaining in the joint after the sections are formed. In joints of this type, the desired sealant material may be spread directly on the core member, since this member is to remain in place at all times. In this case, the sealing gasket may be omitted and the joint-forming structure may then be somewhat simplified.

An advantageous form of joint-forming structure for joints of the partially expansible type is shown in FIG. 4 of the drawings. In this iigure, a unitary joint-forming structure 42 is composed of a core member 44 and a pair of wall members 46 and 48 respectively. The structure 42 is positioned intermediate

adjacent construction sections

50 and 52 which are being formed. As was the case with the structure I10, standots 54 and strengthening rods 56 are positioned on the walls of the structure to provide additional resistance to buckling. Flanges 58 and 60 are provided at the bottom of the walls 46 and 48 respectively to provide footing for the structure while the expansion joint is being formed.

In contrast to the

walls

14 and 16 of the structure 10, the walls 46 and 48 of the structure 42 are relatively ilat and planar, and do not have a projecting flange for receiving a sealing gasket. instead, a rather shallow strip 62 of wood or other material is attached to the core member 44 between the walls 46 and 48 of the upper portion of the structure. In FIG. 4, the attaching means are shown as being nails 64 which are driven through the strip 48 into the core member 44; it will be apparent, however, that other attaching means such as adhesive or the like may also be utilized.

The strip 62 serves to maintain the spacing of the walls 46 and 48 while the

sections

50 and 52 are hardening, and forms a narrow channel between the walls for the reception of the sealant material when removed. Although the strong compressive forces acting on the walls of the structure will pinch strip 62 to a certain extent, its removal is aided by the fact this strip is of relatively shallow height and is thus more readily removable from the structure than is a comparable strip of greater depth.

So far I have described how the structures of my invention may be utilized to form joints in such structures as bridges, roadways, culverts, etc. It will be apparent that my invention is not so limited but may be utilized to form joints in any structure in which sections of a viscous, hardenable material are to be poured in sequence or Simultaneously with a gap between the sections to provide an expansion joint. Further, it will be apparent that various changes may be made in the structure of my invention without departing from the spirit and scope of my in vention. Thus, for example, the standoffs and reinforcing rods may be replaced by other reinforcing means such as small I-beam sections extending parallel to the wall with the web of the I-beam extending perpendicular to the wall. Further, core members other than cork or polystyrene may be used, the particular type of core members selected being dependent on the compressibility of the core member and the expansion characteristics desired `for the joint. Other changes within the scope and spirit of my invention may also be made, and it is intended that all the material described and shown herein be taken as illustrative only and not in a limiting sense.

Having described and illustrated a preferred embodiment of my invention, what I claim is new and desire to secure by Letters Patent is:

1. A joint-forming structure for separation during casting of adjacent sections of a hardenable material having, in combination:

a non-metallic core member appreciably more cornpressible than said material in the hardened state, said core member having walls adhesive to said material in the hardened state,

a rod-like elongated metallic stitening member generally parallel to and spaced laterally from a wall of the core member and having its principal dimension along a line subjected to a bending moment by said cast material before hardening thereof,

a plurality of standois secured to said stiening member and spacing it laterally from said wall to permit said material to surround it completely during casting, and

means to attach said standoffs rigidly to said Wall.

2. The combination according to claim 1, in which the last-mentioned means comprise flexibly conformable material covering portions of the standofs and adhesively bonded to said wall.

3. The combination according to claim 1, in which the standofs are metallic and the last-mentioned means are fibrous non-metallic strands covering portions ofthe standois and adhesively bonded to said wall.

4. The combination according to claim 3, in which the standotfs are welded to the stiffening member.

5. The combination according to claim 1, in which the core member comprises a core appreciably more compressible than the hardenable material in the hardened state and wall members adhesive to said material in the hardened state.

References Cited UNITED STATES PATENTS 1,880,725 10/1932 Bleck 94-18 2,198,084 4/ 1940 Jacobson 94-18 2,301,137 1l/1942 Musall 94-18 2,352,314 6/1944 Fischer 94-18 2,540,251 2/ 1951 Fischer 94-18 2,967,467 1/ 1961 Maude 94-18 3,060,817 10/1962 Daum 94-18 3,124,047 3/ 1964 Graham 94-l8 3,234,860 2/1966i Laly 94-18 3,330,187 7/1967 Kohler 94--18 3,334,557 S/1967 Fitzgibbon 94-18 2,078,280 4/1937 Robertson 94-18 NILE C. BYERS, JR., Primary Examiner