STABILIZING ADDITIVE FOR CRUSHED STONE-MASTIC ASPHALT CONCRETE BASED ON A LOW-GRADE PRODUCT AND WASTE FROM THE PRODUCTION OF CHRYSOTILE ASBESTOS

Abstract

Abstract: The results of a study of adsorption activity for bitumen and the physical and mechanical characteristics of the additive for crushed stone-mastic asphalt concrete (SMA), made on the basis of low-grade chrysotile and dusty waste from the enrichment of chrysotile-asbestos production, are presented. Structuring of the surface of layered magnesium silicates 3MgO 2SiO2 2H2O by treatment with dilute solutions of mineral acids is proposed, in which magnesium dissolution occurs only from the surface layers of magnesium silicate. At the same time, due to the structural features of the tubular structure - multilayering, the initially fibrous structure of magnesium hydrosilicate is preserved, and a layer enriched with silicon is formed on the surface of the fibers. As a result, the surface acquires a more amorphous state, which causes an increase in adsorption activity for bitumen. Based on the results of establishing the physical and mechanical characteristics of an additive made from low-grade chrysotile and powdered waste chrysotile-asbestos in the prepared crushed stone-mastic asphalt concrete mixture (ShchMAS-20), it is shown that the selected composition meets all the requirements of GOST 31015-2002 “Asphalt concrete mixtures and crushed stone asphalt concrete - mastic. Technical conditions".