Research on properties of MK–CFBCA mineral admixtures

Abstract

The main characteristic of CFBCA-MK mineral admixtures (MCMAs) is discussed in this paper. Compressive strength, fluidity and volume deformation test are measured for fresh and hardened concrete properties. With 15% usage of MCMAs, compressive strength of concrete increases 19.13% and 24.14% from 3 days to 28 days, respectively, and it can reduce shrinkage of concrete. The results of XRD, TG and IR analysis indicated that circulating fluidized bed combustion desulfurization ash (CFBCA) can provide SO 4 2 –, and metakaolin (MK) mainly provides active Al 2 O 3 and SiO 2, which provides conditions for the formation of ettringite (AFt) and C-S-H gel. When the proportion of CFBCA and MK is 3:7, it can generate more AFt and C-S-H gel in the early hydration. It indicates that MCMAs can endow concrete with good early mechanical properties and microexpansion properties.