Concrete Roads
and Their Construction

IN THE UNITED KINGDOM—METROPOLITAN 7 2. Tlie dipping down of both concrete and the lower reinforce- ment under the kerb and up on the inside as shown in Fig. 3 ; the kerbs are of granite. The lower reinforcement takes the stresses due to the weight of the traffic in the usual way ; the object of the upper reinforce- ment is to take the stresses due to the horizontal motion, of the traffic, the theory being that there is a tendency for the particles of concrete in. front of a moving wheel to be pusned forward, with a reverse tendency in the case of the particles behind the wheel. Between those two a tensional stress is set up, and it is to take this stress, and so prevent cracks, that the upper reinforcement . is intended. It is also considered that the double reinforcement METROPOLITAN BOROUGH OF DEPTFORD ------- ^C'infonced Concrete Road- ^Borough Engineer .F WiLKinson ffM/ CE„ ffM!ME. Fig. 3.—Transverse section of the concrete road laid in New King Street, Deptford, showing the kerbs embedded in concrete. renders expansion joints unnecessary ; these were, therefore, not provided. Construction.—No special foundation was prepared, as the sub- grade of the original road was found to be sufficiently firm for the purpose. The road was constructed in two courses, a lower, 6Jin., and an upper, 2 j in. On account of the upper reinforcement it was not possible to lay the surface coat before the concrete of the lower had set ; the former was, therefore, laid 24 hours after the latter, this being the earliest time at which the men could get on to the concrete to place the second or upper reinforcement in position.