GB295545A - Improvements in or relating to concrete - Google Patents

Abstract

295,545. Glover, M. L. Jan. 17, 1928. Macadamized roads; foundations.-A concrete mass for road or floor surfaces comprises an upper layer consisting of aggregate of various sizes and cement proportioned to form interstices which are filled partly with stone chippings, gravel, or sand, and partly with bitumen, tar, or the like, applied as an emulsion, and a lower layer of dense concrete some of the aggregate of which interlocks with the aggregate of the top layer. In an example, the upper layer of a concrete road comprises 20 parts of broken stone of sizes from 1¢ inches to # of an inch, 3 parts of sand, 1¢ parts of cement and sufficient water; this is laid on a bed of unset dense concrete and is compressed by rolling until the air spaces are 20 per cent of the volume of the top layer; fine chippings, &c. are then brushed into the interstices and emulsified tar or bitumen is applied by spraying or grouting to fill the interstices and form a surface layer. In a modification, the amount of cement mixed with the aggregate is such that the greater part of the cement settles to form a dense lower layer, the upper layer having interstices, which are filled with chippings and bituminous material. This is illustrated in Fig. 1, in which the lower layer e comprises stone a, and cement mortar b only, and interstices filled with chippings and bituminous material c. Before applying the chippings and bitumen, sand may be brushed into the interstices to form a layer free from bitumen or tar.