Concrete Roads
and Their Construction

 86 CONCRETE ROADS and it was for this reason that it was decided to try reinforced concrete for the road down to the lake. The ground is boggy, but was drained by a system of field drains and ditches. The road was laid directly on top of the grass, which was fairly level, and any small hollows were filled up with stones, but there was no pitching and no rolling. It was understood at th© tim© that the road was entirely experimental, and nobody expected it to carry the heavy traffic without showing some defects, although it was hoped that it would be better than the macadam road. The result has exceeded all expectations, as the road has carried all the traffic in connection with dismantling the camp at the Loch Doon Aerial Gunnery School and does not show the slightest defect. The surface is coated with tar spray and granite chips. The concrete, which is reinforced, is 7 in. to 9 in. thick. London, Brighton and South Coast Railway Goods Yard, East Croydon. —These roads, two in number, have been laid in the sidings which are used mainly for the discharge of coal, with the result that the traffic is of a very heavy order and comprises vehicles of all descriptions up to heavy steam wagons. The base of the new road was prepared by scouring off to the required depth the top surface of the old road and consolidating to shape with a 10-ton roller. Before concreting, test blocks were made and were broken at 7 and 28 days, the results being found to be satisfactory. The thickness of the concrete is 6 inches, and the proportions adopted were 1 : 2 : 4, the larger aggregate being beach shingle obtained from Newhaven Harbour. The reinforcing mesh was laid 2 inches from the under surface of the slab. After the concrete had been laid, the sui'face screeded and the material allowed to set, the road was covered with sand which was kept wet for, approximately, three weeks, at the end of which period the sand was removed, and the surface allowed thoroughly to dry. It was then covered with a thin layer of tar and fine granite chippings. Fig. 57 shows the sub-grade prepared to receive the concrete, and Fig. 58 is a view of the finished road. The work was carried out under the superintendence of Mr. J. Petrie, O.B.E., the district engineer. The first of these roads was opened on 24th June, 1920, and the second on 29th September, 1920.