Concrete Roads
and Their Construction

J CONCRETE ROADS ago, the filling consisting of broken chalk several feet in thickness and overlying the original river mud. The site of the road had, however, been in use for about twenty years, so that the ground was fairly well consolidated. Before the new concrete was laid down the road paving had consisted of water-bound macadam resting on about 1 ft. of hard core, which again rested on the chalk filling. The latter had settled so much that in places it was necessary to raise the road as much as a foot. This was effected by covering the old macadam with ashes, which were consolidated by watering and rolling with a 10-ton roller, the surface being finished off with a camber ready to receive the concrete. The Fig. 29.—Reinforced concrete Dock Road, Southampton, for London and South-Western Railway. new pavement was macle with Portland cement, and sea gravel dredged from Langston harbour. As no machine mixer was available it was all turned by hand three times dry and three times wet to ensure good mixing. It was 6 in. thick in all, the lower 4 in. being mixed in the proportion of 1 to 6. and the upper 2 in. in the proportion of 1 to 3. For this upper layer, the gravel was all passed through a g in. square mesh screen so as to avoid the possibility of the road surface being pitted by the splintering