GB205887A - Improvements in bituminous concrete pavements and method of making same - Google Patents

Abstract

205,887. Jackson, W. J. Mellersh-, (Hacker, W. E.). July 25, 1922. Macadamized roads.- Relates to bituminous macadamized roads of the kind in which a superficial layer C of fine mineral aggregate coated with bituminous material is laid upon, and bonded by compression to, a primary layer B of coarse mineral aggregate coated with bituminous material laid upon an ordinary foundation A; and consists in grading the aggregate of the primary layer so that it shall contain not more than 18 per cent of voids. An aggregate of which 40-70 per cent is too large to pass through a sieve having half-inch round openings, 15-40 per cent passes through the first sieve but is retained on a No. 10 mesh sieve, and 15-28 per cent passes the No. 10 mesh sieve, is stated to be suitable. Instead of the intermediate size aggregate, a mixture in which material retained on a No. 4 mesh sieve forms 10-25 per cent of the total aggregate while material passing through the No. 4 mesh sieve but retained on the No. 10 mesh sieve forms the remaining 5-15 per cent, may be substituted. The layer C contains 8-17 per cent of bitumen. Specification 18518/14 is referred to.