Section of an asphalt road, 1963

Section of an asphalt road, 1963

This section of the M1 had five strata of different compositions. The formation, or sub-soil which was sometimes virgin soil, was stabilised where necessary and a six-inch deep stratum of graded stones laid and rolled on top. Next, a stratum of dry lean concrete, 7 inches deep, was laid and rolled. A lean base, three inches deep, of asphalt mixture with 65 per cent stone ingredient laid and rolled to a depth of 2 1/2 inches. The final stratum was the wearing-course in which an asphalt mixture with 30 per cent stone was laid and rolled to a depth of 1 1/2 inches. This last course formed the road surface.