Utilizing spend garnets as sand replacement in alkali-activated mortars containing fly ash and GBFS

Abstract

This paper investigates the possibility of using garnet waste as river sand replacement in high-strength alkali-activated mortars (AAMs) containing fly ash (FA) and ground blast furnace slag (GBFS). The garnet waste replacing river sand was used at varying levels of 0, 25, 50, 75, and 100%, by weight. In this study, the ratios of binder to aggregate (B:A), alkaline activator solution to binder (S:B) and the activator solution modulus (Ms) remained the same in all samples tested. The tests conducted were slump flow, compressive strength, flexural strength, drying-shrinkage, porosity, and resistance to acid, etc., which indicated the impacts of using garnet waste on the mechanical and durability performance characteristics of AAMs. The tests data revealed that as the level of waste garnet content increased in AAMs, there was a corresponding improvement in the workability of said samples. Notably, when the garnet waste content level exceeded 25% in the tested samples, there was a decrease in flexural and compressive strength in comparison with the control sample. Therefore, it would appear that the garnet waste could act as a potential replacement of river sand up to a maximum of 25% without any strength loss. It also meets the need for a cost-effective alternative which is eco-friendly and a renewable resource. It is recommended that spend garnets waste should be used in AAMs as river sand replacement to minimize the environmental problems, cost and natural resources depletion.