Hydration and microstructure of concrete containing high volume lithium slag

Due to requirements for environmental protection, saving of resources and sustainable construction in the future, investigation on the use of high volume mineral admixtures as supplementary cementitious materials in concrete was carried out in this study. The effect of high volume lithium slag (LS) to partially replace cement by weight on compressive strengths of concrete was experimentally investigated, and the hydration of hardened paste was measured by non-evaporable water. Moreover, the microstructure of concrete was determined by mercury intrusion porosimetry and scanning electron microscope methods. Results showed that the use of high volume LS reduced compressive strengths of concrete at early ages, and compressive strengths were remarkably improved at later ages, with concrete containing 40% LS being close to that of the control concrete. Hydration of hardened paste showed similar variation trends with compressive strengths. The high-volume LS degraded concrete microstructure at early ages, and 40% LS improved concrete microstructure at the later ages, due to the filling effect and pozzolanic reaction of LS. However, there still existed defects in microstructure of concrete containing 60% LS, with increased harmful porosity, especially interfacial transition zone.