Concrete Roads
and Their Construction

IN THE UNITED KINGDOM—PROVINCIAL 55 Brecon and Abergavenny Main Road.—Work was commenced on this road at a point near the Brecon boundary in September, 1919, under the supervision of Mr. S. A. Bennett, A.M.I.C.E., the County Surveyor, one-half width being laid at a time. After about 100 yds. had been laid this portion was fenced off for twenty-eight days, after which the traffic was turned on to it while the other half of the road was being constructed. No longitudinal joint was made in the concrete, but a double layer of the reinforcing fabric about 18 ins. wide was laid at the centre of the road where the two halves met. Expansion joints were provided, but instead of being placed at right angles to the direction of the road, these were laid diagonally at intervals, and were filled with bituminous material. The concrete, which is 6 in. in thickness, was laid in one course and consisted of crushed furnace slag, graded from 2 in. to I in., sharp freshwater sand, and Portland cement, in the proportion of 4| slag, 1| sand and 1 cement. Before being opened to traffic the surface was tarred and spread with a |-in. coating of granite chippings. On account of the water-logged subsoil, diagonal cross drains were laid in the road, with 4-in. pipes, open jointed, the trenches being filled in with 6-in. broken slag. These cross drains are connected to a 6-in. longitudinal drain under the footpath, the drainage water being discharged into watercourses. The width of the roadway is 20 ft., and the length so far completed is about 800 yards. The nature of the traffic over the road is both heavy and con- tinuous, and consists of heavy steam tractors with trailers, commercial motor lorries, and a frequent omnibus service, in addition to the ordinary local traffic. Prior to the concrete being laid, the road was constructed with most of the known pro- prietary materials, but on account of the soft nature of the subsoil it became almost impassable on account of corrugations and depressions. Latest Report.—The County Surveyor, reporting on the condi- tion of the road in November, 1920, says: “So far the concrete road has been a complete success, having withstood the traffic, and showing no signs of disintegration or of any cracks.”