Improvements in or relating to the production of contraction and expansion joints in concrete roads and the like

摘要

453,708. Joints in concrete roads. WINKLER, K., Lugano-Crocifisso, Casa Crocifisso, Switzerland. March 18, 1935, No. 8454. [Classes 20 (ii) and 20 (iv)] Expansion and contraction joints in concrete road surfaces are formed by inserting into the road concrete, before the latter has set, a finegrained concrete or cement strip at each place where a joint is to be formed, and cutting a joint in such strip when the fine-grained concrete has lost its plastic condition, but before it has completely hardened. The joint may be cut by cutters of the circularsaw type. In one construction, the ordinary road concrete containing coarse aggregate is cast adjacent the place at which a joint is to be formed against a mould board, and after removal of this board the fine-grained concrete strip is cast, and further road concrete is cast against the opposite side of this strip. The casting of the road concrete between adjacent joint strips is then completed and both the road concrete and fine-grained strip are mechanically worked by kneading and tamping tools. If desired, both the road concrete and the fine-grained concrete may be cast in two superposed layers a, b as shown in Fig. 3, the lower layer a being tamped and finished before casting the second layer b. A finishing and surface layer may also be provided. In another arrangement the road concrete is cast on both sides of a tapered mould h, Fig. 4, which is either in the form of a channel iron or a board covered with metal, and fine-grained concrete is cast in the channel formed on the withdrawal of the mould. The whole of the concrete is then finished by means of tamping and kneading tools. The joint strip may also be formed by means of a hollow mould formed of two tapering walls m, n as shown in Fig. 5, the road concrete being, cast and tamped on both sides of this mould, and fine-grained concrete is cast and tamped in the mould. The road concrete is banked upon each side of the mould and the fine-grained concrete is cast to a higher level than that of the finished road surface so that after withdrawal of the mould the spaces formed by the walls are filled when the road surface is tamped. The fine-grained strip may consist of cement containing no sand or sand having a grain size of from 1 to 3À5 mms.