GB1270974A - Bituminous materials - Google Patents

Abstract

1,270,974. Bituminous composition. WIBAU WESTDEUTSCHE INDUSTRIEUND STRASSENBAUMASCHINEN G.m.b.H. 17 April, 1969 [19 April, 1968; 16 May, 1968], No. 19581/69. Heading C3N. A bituminous surfacing material comprises a mineral grain mixture and bitumen, as binding agent, in which the mineral grain mixture comprises more than 55% by weight of a gravel fraction having a grain size of 2-12 mm. together with a filler fraction having a grain size of less than 0À09 mm. and a graded sand having a grain size of 0À09-2 mm., the filler fraction forming up to 20% by weight of the mineral grain mixture and the graded sand forming up to 25% by weight of the mineral grain mixture, the amount of binding agent being such that the hollow spaces in the vibrated mineral mixture are completely filled or there is a slight excess, not more than 4% by volume, of binding agent. Examples specify as the mineral grain mixture (a) filler 18%, fine gravel 60%, and sand 22%; and (b) filler 15À5%, fine gravel 65%, and sand 19À5%. In general, the composition may comprise 90-94% by weight of mineral grain mixture and 10-6% by weight of bitumen. The sand used may be crushed. For a filler content of less than 20% by weight, the consistency and composition of the mortar (filler + sand + bitumen) are the same as for " mastic asphalt," the composition of which is referred to in the Specification. The gravel used suitably has a maximum grain size approximately corresponding to the dimensions of the voids in the gravel component of the material, normally 1À5-4 mm. The surfacing material may be laid using the conventional vibrating beam apparatus.