Study on compressive strength and durability of alkali-activated coal gangue-slag concrete and its mechanism

In this paper, AACGS concrete was prepared by using raw and 700 degrees C calcined coal gangue as the coarse aggregate and alkali-activated coal gangue-slag (AACGS) as the cementitious material. The variation of compressive strength and durability of AACGS concrete was studied, and the durability damage mechanism of AACGS concrete is analyzed in depth by SEM. The research results showed that coal gangue as coarse aggregate shows high compressive strength and good durability in AACGS concrete. AACGS concrete with calcined CGCA shows great advantages in compressive strength and sulfate attack resistance. Under the condition of large content, its long-term frost resistance durability and chloride ion permeability resistance are not as good as that of raw CGCA. If AACGS concrete is applied to the freeze-thaw environment, the content range of CGCA should be 30%-50%. This study provides an experimental basis for the large-scale utilization of coal gangue. (C) 2020 Elsevier B.V. All rights reserved.