Synergy of inert granite powder and active mineral admixture in manufactured sand mortar: The effect on mechanical properties, chloride permeability and water absorption properties

Granite powder (GP) and active mineral admixture including ground granulated blast furnace slag (GGBFS), metakaolin (MK) and fly ash (FA) were used to partially replace granite manufactured sand (GMS) and cement to prepare manufactured sand mortar (MSM). Synergistic effect of four mineral admixtures in MSM on mechanical properties, water absorption properties and chloride permeability was studied. Combined with the analysis of cementitious materials hydration and pore characteristics, the synergistic mechanism of four mineral admixtures was comprehensively expounded. The results show that although the synergy of GP can improve the performance of MSM, the replacement of cement by GGBFS and FA leads to the increase of water absorption and chloride diffusion coefficient and the decrease of mechanical properties. Synergistic effect of GP, GGBFS, FA and MK is greater than that of the three of them due to the complementarity of particle size and chemical composition of the four materials, which ends the situation of MSM performance reduction.