In this study, ground fly ash (GFA) and steel sag powder (SSP) were applied to mass concrete to explore its workability, temperature rise during cement hydrating and the resistance to sulphate and chloride attacks. The results show that a composite of SSP and GFA can retain a moderate workability. SSP and GFA can effectively reduce the temperature rise during concrete hardening. Replacing SSP with GFA could increase the hydration degree of concrete, decrease the content of Ca(OH)(2) (CH) and its carbonation, and refine the pore structure of concrete, especially under high temperature curing conditions. Replacing OPC with SSP has a negative effect on the strength and the durability of concrete, and replacing SSP with GFA can offset this negative due to the higher pozzolanic activity of GFA. The improved effect is better under high temperature curing conditions and at later ages. (C) 2020 Elsevier B.V. All rights reserved.