Influence and mechanism of micro/nano-mineral admixtures on the abrasion resistance of concrete

Abstract

The abrasion resistances of concrete in which the cement was partially replaced by 40 wt% super fine slag (SFS), 5 wt% nano-SiO2 (NS), 5 wt% NS and 25 wt% fly ash (FA) were tested. Mechanisms responsible for the affection of these micro/nano-mineral admixtures on the abrasion resistance of the concrete were analyzed through measurements of the micro-hardness of the interfacial transition zone (ITZ) of the aggregate-cement matrix and the cement matrix, the hydration products of the paste, and the degree of polymerization of the silicate chains of C-S-H in the paste. Results indicated that the addition of SFS, NS, or NS and FA improved the abrasion resistance of the surface mortar layer by 82%, 73% and 68%, respectively, and that of the concrete by 20%, 16% and 13%, respectively. Because of the addition of SFS, NS, or NS and FA, Ca(OH)2 was consumed to produce more calcium silicate hydrate (C-S-H) and other aluminiferous hydration products, and the degree of polymerization of silicate chains in C-S-H was increased. Therefore, the micro-mechanical properties of the ITZ and the cement matrix were strengthened, improving the abrasion resistance of the concrete.