US2096254A - Installation for pavement joints - Google Patents

Description

Oct. 19, 1937. E. MCCRADY, .JR

INSTALLATION FOR PAVEMENT JOINTS Filed Aug. 29, 1934 Patented Oct. 19, 1937 UNITED vSTATES PATENTA OFFICE Application August 29,

8 Claims.

This invention pertains to highway lor pavement joints, and more particularly, to structure for installing joints which divide a pavement into slabs.

Rigid pavements of concrete, cement, brick. etc., are materially affected by changes in temperature and moisture content and provision is generally made to take care of dimensional changes and reduce the internal stresses and strains caused by expansion and contraction.

As a result, it has been customary to divide the concrete or other paving material into smaller portions or slabs by employing longitudinal and transverse joints. In accordance with the present practice, particularly when installing the transverse joints, it has rbeen customary to provide preformed or molded sections of a suitable fibrous or felt material impregnated with some bituminous material. 'I'hese sections are normally held in place by means of a special bulkhead or wooden board known as a placing bar, until the concrete has been deposited on both sides. The bulkhead is then carefully pulled and the concrete tamped under it to prevent the filler sections from being displaced. After this, the concrete is finished.

The difficulty encountered with many such devices is the tendency to pull the iiller out along with them. Special devices are needed to hold the iiller down.

An object of my invention is to provide new and improved means for installing dimensionally extending joints.

Another object is to provide new and improved structure for installing such joints.

A further object is to provide what may be termed a permanently located bulkhead.

A still further object is to provide a more effective and/or more efficient joint installation for pavements.

These and many other objects of my invention will appear to those skilled in the art from the following description taken in view of the appended claims and the drawing, in which:

Figure 1 is a longitudinal plan view ci a structure employed in carrying out an embodiment of my invention;

Fig. 2 is a longitudinal elevational section showing the embodiment of my invention of Fig. 1 in a mounted relationship with respect to a pavement construction;

Fig. 2a is a plan lsection of a detail, taken along the line II-IIa of Fig. 2; l

Fig. 2b is a vertical elevational view of a modification of the bracket shown in Fig. 2.

1934, serial No. '141,922 (ci. 94-18) Fig. 3 is a reduced plan of a section of a roadway showing diagrammatically a transverse joint installation employing joint structure such as shown in the embodiment of Fig. 1;

Fig. 4 is a reduced longitudinal elevational section showing another structural embodiment of my invention ina mounted relationship with respect to a pavement construction, and

Fig. 5 is a vertical section of a detail taken along the line V--V of Fig. 4.

From one aspect, my invention deals broadly with an improved support structure for joint installations employed in connection with pavement constructions.

In another aspect, my invention' deals withy an improved structure for installing transverse joints in pavement constructions.

My invention involves means for interposing an expansion joint in road paving material, such as concrete and for the sake of simplifying the furtherl description of the invention, I will briefly describe the means utilized in forming or installing such an expansion joint.

In the construction of a road, the location of expansion joints is usually predetermined and designated prior to the laying of the paving material and by my invention I provide a structure which facilitates the installation of expansion joints at the designated points without materially interfering with or substantially reducing the rate of progress of pouring the concrete or road metal. My improved structure may not only be quickly assembled, but may be accurately and rigidly positioned at the designated point for the expansion joint and not only serves to support the material constituting the expansion joint, but also serve to position and hold in place the joint dowel bars which are employed for the purpose of preventing relative vertical motion between the adjacent portions of the paving slabs on opposite sides of the expansion joint'.

In accomplishing this, I provide a inetal plate so formed that it is capable of being quickly and rigidly installed at the point of the expansion joint and which is of such character that it may be retained in position after the pouring operation is completed. This plate is preferably of such length that it extends along or across the paving material to be subsequently poured and is of such form that it is readily held in a vertical position by means of stakes driven into the subgrade of the road. As herein illustrated, the plate is of a width equal to the thickness of the concrete slab to be produced and its upper edge material when that material is subsequentlyV ofthe slab. t, J

The plate is alsovso formed as to provide stake receiving apertures thereinl which are preferably equally spaced .longitudinally'ofl the plate and are so located that they do not interfere with or in anyv manner vimpede the operation of securing the expansible material to one side of the plate. In addition, the plate is provided with dowel bar positioning means which are so formed and located that they not only do not interfere with the operation of pouring the road metal, but also are of such form and construction that they hold the `dowel bars rigidly in the desired and designated positions.`

From the foregoing it will be apparent that the procedure here contemplated not only involves the rapid and accurate positioning of the exparlslble material at the point ofthe expansion joint, but it also involves the rapid and accurate positioning of the dowel bars so as to insure that both the expansible material and the dowel bars are properly located and positioned in the paving poured. The plate and the dowel-positioning means secured to it remain in position vafter the road pouring operation is completed.

'I'he dowel bar positioning means is preferably so proportioned, constructed, and/or located that it will give during movement between the slabs of the pavement which-lie' adjacent the joint.

It( will appear that the joint structure is designed and installed in such a manner as to support and maintain itself in alignment during the pouringand setting of theconcrete road metal. As seen in the diagrammatic view of Fig. 3, the joint is laid out. or installed, and then, concrete road metal from a mixer 4I) is discharged from a chute 4I against both sides of the line of the proposed joint until the desired depth of road metal has been obtained. In this figure the work is advancing from the right to the left.

I have been able to'eliminate the disadvantages of the commonly employed bulkhead joint structure by providing a structure that may be permanently retained in position. This structure is so positioned and located that it adds to the strength of the adjoining slabs as well as to the strength of the joint itself. Then, too, the procedure employed is materially simplified and there is very little, if any opportunity to spoil the concrete work as frequently occurs when th bulkhead is pulled out. v

Referring to the drawing, I will designate somewhat similar parts of the illustrated embodiments of my invention by the same numerals, but will differentiate between embodiments by prime sufxes.

As shown in Fig. 2, I provide a brous strip IU which in height corresponds to the depth of height can be made slightly greater and the ller cut ofi' after the pavement has been iinished.` In this connection, although each joint plate II also. has a height such that its top edge aligns exactly with the concrete or cement slabs, it may be desirable in certain installations to shorten the height of the plate and to position it slightly below' the surface. This permits the edges of the slabs to chip, but protects the plate from tramc wear. Bituminous material can be employed` as a filler to protect the edges of the slabs adjoining such a plate, in such a case. In the illustrated embodiment of my inventio 'shown in Figs. 1 and 2, I have provided the joint is so formed as to conform to the surface contour plate vstructure II with a somewhat centrallylocated, angle-like or V-shaped projection I2 and withan outwardly extending base portion I5; the projection I2'is, and the portion I5 may be suit-v ably punched'out, in order to receive a verticallyextending positioning pin 30 which' is preferably driven into the sub-grade 1. 'Ihe pin 30, as shown particularly in Fig. 2, extends downwardly in abutment with the .edges of a verticallyextending hole in the projection I2, and may extend through a punched-out portion in the base projection I5 to align and rigidly secure the plate II in position. For a joint installation having a considerable length, it is preferable to locate a plurality of positioning pins 3l lat a number of spaced points along the length of the plate II. The pins need not necessarily extend through the brackets I4, but may be driven down in abutment with side edges thereof or at a spaced position therefrom, see the pin 30a. represented by dotted lines in Fig. l.

As seen, the joint plate II is also provided with associated means for supporting one or more longitudinally and horizontally extending dowel bars 20. This means includes a horizontal punched-out portion of the V-shaped projection I2 and a horizontal punched-out portion I6 of an upwardly projecting bracket I4. In like manner, the fibrous strip I0 is also punched out to permit the dowel bars 20 to pass therethrough.

The dowel bar 20 is positioned to extend across the joint substantially centrally of the depth of the adjacent or opposite slabs 8 and 9, and longitudinally into each slab. 'I'he dowel bar 20 has what may be termed a spaced-three-point suspension or support. In order to prevent aA bond between the dowel bars 20 and the immediately associated concrete or cement slab, the bar is preferably painted and then greased, or merely greased. 'Ihis permits the slabs to expand and contract without breaking the dowels or chipping the concrete. f

In addition, I provide end spacing for permitting the bar to slide, in and out with respect to at least onekof the slabs which, in this case, is the slab 9. This calls for the provision of an open space in the slab the size of the bar 20 which is long enough to permit movement of one or both ends of the bar. Thus, I provide a cap or sleeve 2l in the form of a metal or ber tube, which in this oase is shown as the latter and is mountedv over an end of the dowel bar 2li, and has a space between its end and' the end of the bar to permit movement of the former.

The joint plate may be constructed in any other suitable form or pattern and any suitable material may be employed such as a wire mesh, or a solid or patterned piece of metal.

If the dowel bar and the joint plate do not have thel exact positioning desired, for example, the dowel bar may incline from one slab to thel other, then unequal stresses and strains may be set up, the joint will not function as it should, and the bar may soon break or the concrete chip out on top of it. Thus, it is highly important that the dowel bar and the joint plate as well as the fiber stripbe positively aligned and held in the desired position during the pouring of the pavement material and during its setting process.

I have found that the problem may be solved by providing a bracket structure such as Il which, in itself, forms a part of the joint plate. It may be secured thereto adjacent its bottom center portion I5 and extend upwardly therefrom in order to receive the longitudinally and horizontally exjoint plate I I.

tending dowel bar. In this way, the joint plate, the bracket and the dowel bar form a closed figure whose parts are held in alignment by their relationship with respect to each other, and additionally, by the stake-like element or pin 30 lwhich may cooperate with thevclosed structure.

In the embodiment of my invention shown in Figs. 1 and 2, the bracket has what may be termed a U or V-shape, and in the embodiments of Figs. 4 and 5 has what may be termed an M- shape.

The M-shaped structure I4' of. Fig. 4, like the V-shaped structure I4 of Fig. 2, has a central portion I5' secured to the bottom of the associated joint plate II by some suitable means such as a Weld I3', but unlike the previously discussed embodiment, is provided with a pair of oppositely and downwardly extending legs or stake-like pins I6. which may be and preferably are, driven into the sub-grade 'I. As seen the portion I5 of the embodiment of Figs. 1 and 2 presents a flat support surface, while the portion I5' of the embodiments of Figs. 4 and 5 presents an angular or inclined support surface. The bracketstructure I4' is preferably of a channel shape, see Fig. 5, in order to more readily support the dowel bar 20. A sleeve or ring I'I' extends upwardly from the bracket adjacent each of its body portions I4' and forms a positioning loop through which a dowel bar may extend. As seen in Fig. 5, the dowel bar 20 may be notched adjacent one side 2I in order that the ring I1' may be pulled tightly thereagainst to prevent a turn of such dowel bar with respect to the bracket I4.

Further, in accordance with my invention, I contemplate the employment of support bracket structure which will allow for relative move- -ment between the slabs 8 and 9, and since the dowel bars 20 prevent much vertical movement, which will particularly allow for horizontal expansion between the slabs.

Since the bracket structure need not be retained in a unitary form after the concrete has set, its portion I5 lying adjacent the joint may be so proportioned as to break or shear off during relative movement between the slabs. If portions I5have a slender outline (see their strap-like thickness in Fig. 2), no further provision need be made. However, as seenin Fig. 2a, the portion I5 may be provided with transverse perforations, or a slot or groove I5a', in order to facilitate braking.

In the modified form of bracket IlIa shown in Fig. 2b, the base portion I5b has a somewhat U-shaped outline and is adapted to clamp over bottom portions of the filler strip I0 and the This form of bracket need not be secured to the plate II, but in any event, if it is secured to the latter, it will preferably be welded to it adjacent its base edge. Since the portion I5b ts over the bottom portions of the filler strip and the joint plate with a spring-like clamping action, it follows that it will also permit relative expansion between the slabs 8 and 9 with a spring-like action and no provision need be made for deliberately breaking such a type of bracket into two or more parts.

In the embodiment of my invention shown in Fig. 4, the bottom portion I5 of the bracket will more readily shear off along the base line of its relatively sharp or acute angle.

As previously pointed out, in Fig. 3, I diagrammatically show a cement or concrete mixer 40 having a. feed or discharge chute 4I. This view procedure employed in constructing a concrete pavement or highway having a transverse joint embodying the principles of my invention. 'I'his gure diagrammatically points out the relationship or spacing between a plurality of dowel bars such as shown in the embodiments of Figs. 2 and 4, each of which has been represented generally by the letter a. After a plurality 'of such bars have been aligned transversely and longitudinally as shown, then the concrete may be poured or placed around them to finish the two adjacent slabs 8 and 9.

VIn this connection, by way of example, the pavement may be provided with a or 1/" joint spacing; and, each dowel bar a may have approximately a 21 inch spacing with respect to adjacent bars.

While various modiiic'ations and changes may be made in the structure herein disclosed, it will be apparent to those skilled in the art that such changes may be made without departing either from the spirit or the scope of the invention. Itv

is desired, therefore, that only such limitations shall be placed on the invention as are imposed by the prior art and the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a structure for installing a joint in a pavement, the combination of a treated brous strip, means adapted to abut against said strip for holding it in position during a pouring of pavementmetal, said means having a length substantially corresponding to the length of the proposed joint and bracket and dowel means for permanently securing said holding means with relation to the pavement.

2. In a structure for installing a joint in a pavement, the combination of at least one plate adapted to extend upwardly the depth of the proposed pavement, support means secured to the bottom of said plate and extending upwardly therefrom, said support means being positioned in such a manner that it will be embedded when pavement metal is poured to form the joint, a hole punched in said plate and at least one hole punched in said support means in alignment with the hole in said plate, and a longitudinally extending dowel bar mounted in said punched holes.

3. In a positioning plate for a pavement joint which is adapted to be permanently mounted as a part of the pavement structure, the combination of a body portion having a vertical dimension corresponding substantially to the proposed depth of a. pavement slab, a V-shaped bracket portion centrally secured to a base of said body portion and extending outwardly therefrom, said body portion and said bracket portion having portions for supporting a dowel bar.

4. In a.- positioning plate for a pavement joint which is adapted to be permanently mounted as a part of a pavement structure, the combination of a body portion having a vertical dimension corresponding substantially to the proposed depth of a pavement slab, an M-shaped bracket portion centrally secured to a base of said body portion and extending outwardly therefrom, said body portion and said bracket portion having portions for supporting a horizontally-extending dowel bar, the legs of said M-shaped bracket being pointed for driving into a sub-grade of a. roadway upon which the pavement is to be constructed.

5. In a structure for installing a joint in' a pavement which includes, a dowel bar and means extending across the proposed joint and supporting said holding means with relation to the pavement, means cooperating with said strip and said holding means and being supported by the latter,

said last-mentioned means having oppositely extending portions for supporting a dowel bar during a pouring of pavement metal, said last-mentioned means having a yieldable portion for permitting relative movement between slabs of the pavement adjacent the joint after the metal has set.

'7. In a positioning structure Afor a pavement joint, the combination of a plate-like body portion having a depth corresponding substantially to the depth of a proposed pavement slab, a

bracket portion secured to the base of said bodyportion and having a pair of arms extending upwardly therefrom. a dowel bar, means on each -of said arms for receiving and aligning said dowel bar, said bracket portion having downwardly extending portions for driving into a subgrade. v

8. In a pavement construction having a pair of oppositely-positioned slabs connected by a suitable joint, the combination of a joint plate extending along the joint and between said slabs, said joint plate having a vertical dimension corresponding substantially to the vertical dimension of said slabs, a bracket means having a central portion secured to the bottom of said joint plate, said bracket means extending up-V ,wardly from said joint 'plate into each of the slabs, a horizontally-positioned dowel bar mounted upon said bracket means and extending through said joint plate for connecting up the slabs, a vertically-positioned dowel bar extending downwardly through said joint plate into a subgrade of the pavement.

EDWARD MCCRADY, J R.

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