Performance evaluation of a green mortar developed from a ternary eco-cement of industrial solid wastes

Abstract

This study evaluates the performance of green mortar incorporating an eco-cement made from various proportions of rice husk ash (RHA), ground granulated blast furnace slag (GGBFS), and circulation fluidized bed combustion fly ash (CFA). Different RHA contents of 15 wt%, 30 wt%, and 45 wt% were used to replace GGBFS (by weight), respectively, and these mixtures were activated by 15 wt%, 20 wt%, and 25 wt% CFA by the total weight of GGBFS and RHA. Engineering properties of the mortars were examined by compressive strength, splitting tensile strength, water absorption, porosity, and dynamic Young's modulus, while the sulfate resistance and scanning electron micrographs analysis were conducted to evaluate the durability and microstructure of the mortar samples. Test results demonstrated that the content of the RHA and CFA strongly impacted the properties of these samples. Based on the obtained results, the samples with 20 wt% CFA and < 30 wt% RHA showed the best performance at later ages. Also, CFA decreased the sulfate resistance of the green mortar samples, while RHA increased sulfate resistance and significantly reduced thermal conductivity. Furthermore, the scanning electron micrographs exhibited the amorphous gels and the ettringite crystal-like phase, promoting a denser microstructure of the mortars.