US2172042A - Process and device for producing expansion joints in concrete - Google Patents

Description

j [@NENNWk J G. 'WIELAND Sept. 5, 1939'.

I PROCESS AND DEVICE FOR PRODUCING EXPANSION JOINTS IN CONCRETE Filed Nov. 14, 1935 Patented Sept. 5, 1939 UNITED STATES PROCESS AND DEVICE FOR PRODUCING EXPANSION JOINTS IN CONCRETE Georg Wieland, Berlin-Iichterfelde, Germany Application November 14, 1935, Serial No. 49,840 In Germany November 16.1934

8 Claims.

The invention relates to a process and device for the production of expansion joints in concrete pavements.

In the production of streets paved with concrete, the expansion joints have been produced as narrow gaps in the pavement in order that the separate parts of the pavement could move easily and independently. In the lower part of the gaps, asphalt cardboard, wooden boards, or wooden fiber sheets were inserted. The upper portion of the joints have been provided temporarily with insert peces of iron or the like which were placed with their upper edges even with the finished street surface. As soon as the concrete had stifiened a little, the inserts were lifted out before the concrete had set. The edges were then smoothed. In spite of careful lifting of the insert pieces, the tamped concrete was also lifted and loosened. It was impossible to restore the loosened structure of themass to its original condition of cohesion as the repairing would take more time than the setting of the concrete. Thus, the concrete was disturbed in its process of getting hard. The consequence was that the concrete bodies became cracked at the edges of the joints.

According to the present invention, in the production of such bodies or constructions, insert bodies of heat conducting materials are used. The insert bodies are enveloped by a fusible material which gets soft or liquid upon being heated. Such insert bodies are embedded in the concrete pavement with their upper edges even with the upper surface of the pavement. After the hardening of the concrete has begun, the bodies are heated temporarily and then drawn out.

This manner of working enables the insert bodies to be drawn out instantly after their heating while still hot. The envelope which has become soft or liquid provides the necessary loosening of the embedded insert bodies and serves besides as a lubricant.

As melting materials for the envelope, bitumen, wax, or paramn will serve.

The insert bodies may be hollow and heated by bodies.

The invention is described in more detail in steam or hot air which is passed through the cement shall take place without being disturbed ,Fig. 3 shows an instrument for drawing out the joint inserts; and

Figs. 4 and 5 are front views in reduced scale of elongated insert bodes having inlet and outlet openings. 6 In the lower concrete layer 6, the expansion joint is filled with a wooden board or wooden fiber plate I. The latter carries a holder 4 which serves for positioning and holding the hollow joint insert l. The joint insert member I formed of two pieces is advantageously welded together. Numerals l8 l8 indicate the welding seams.

The joint inserts consist suitably of iron, aluminum or other metal. They have a trapezoidal cross-section and have a breadth, for instance, 15

of 15 mm. and an inner hollow space 3 of 'a breadth of 5 mm. They are provided with openenings I! for entrance and exit of steam. For this purpose it may suffice that the hollow space be left open at both ends, as shown in Fig. 5, 20 or the ends may be closed and openings provided in the upper edge, as shown in Fig. 4. Before the insert body is put in place, it is provided with a bituminous film 2, for instance of asphalt bitumen, on its outer surfaces. Then it is placed 25 in the holder 4. The upper concrete layer 5 is then formed by tamping or rolling. The joint insert l remains embedded when the concrete has set and become hard. After a period of, for instance, two or three days, steam or hot air is passed through the hollow space of the joint insert I. At about 55 C. the bituminous fllm becomes liquid and the joint insert can be easily drawn out. The bitumen is then absorbed by the concrete wall. Thus the painting of the concrete wall is saved, so that the joint can be filled immediately with bituminous material.

In the'production of the upper concrete layer 5, the joint insert I may be completely embedded. 40 By heating the insert body, the thin concrete covering over the joint insert breaks oil automatically and in a straight line. v

As seen in Fig. 2, the joint insert may be placed with its upper edge even with the finished pavement and the edges of the joints may be rounded with the aid of a suitable masons trowel.

The use of insert bodies with two hollow spaces according to Fig. 2 enables letting steam in and out at the same end. When using solid insert bodies, the heating may take place electrically.

The insert bodies may also be pressed into the concrete masses, when the latterare formed. It is... only essential that the initial setting of the lever l grips into the space H of the joint insert 1, Whilst the other gripping lever carries a movable part l2 which is provided with a handle ,8, a bore l3 and a shutting valve M. Part l2 seats in the cavity 16 of the joint insert I. Into the solidly constructed edge part l5 of the joint insert leads achannel I! from the cavity I6 to the inner space of the joint insert.

When the tongs are placed in position, the valve I4 is opened and the steam from a steam lead connected thereto passes into the joint insert. When the latter is heated sufficiently, the valve lfi'is closed and the joint insert may be pulled out with the aid of the tongs.

As the jointinsert is ;completely loosened by heating and lies separated in the concrete mass before it is drawn out, the joint insert may have any shape, for instance a zig-zag-, arch-, or S-form. In this way expansion joints may be produced,- over which the wheels of a vehicle always roll on after another. The joints can be produced of any depth.

In the claims:

1. Process of forming expansion joints in conorete pavements comprising forming the pavement with insert bodies of heat conducting material having their side walls covered with fusible material embedded in the pavement with their upper edges substantially even with the upper surface of the pavement, heating the insert body for a short time to above the fusing point of the fusible covering material after the concrete has become hard, and withdrawing the insert body from the pavement when its covering has become fused.

2. Expansion joint insert body for use in concrete pavements comprising a closed, hollow metallic body having an entrance opening and a discharge opening for a hot fluid, and having a coating of bitumen on its outer surface.

GEORG WIELAND.

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