Rheology, shrinkage and pore structure of alkali-activated slag-fly ash mortar incorporating copper slag as fine aggregate

his study was conducted to investigate the effect of the use of copper slag (CS) as fine aggregate to replace natural sand (NS) at different volume replacement levels (namely, 0%, 20%, 40% and 60%) on the properties of alkali-activated slag-fly ash (AASF) mortars. In addition, both low calcium (LC) and high calcium (HC) alkali-activated slag-fly ash (AASF) mortars were used to studied the influence of the mass ratio of fly ash to fly ash and slag on the properties of mortars. The workability, mechanical properties, autogenous and drying shrinkage and pore structure of mortars were investigated. Results show that using CS to replace NS in AASF mortars at appropriate levels (i.e. 20% and 40%) slightly increases the fluidity, yield stress, consistency, and mechanical strength, while restraining the drying shrinkage and refining the pore structure of mortars. However, when the replacement ratio is increased to 60%, the mortar becomes inhomogeneous due to the high density of CS particles, leading to poor performance of mortars. The use of CS as fine aggregate at a suitable level in AASF mortars can reduce NS consumption while also providing an avenue for value added use of CS. (C) 2020 Elsevier Ltd. All rights reserved.