Non-destructive prediction of strength of geopolymer concrete employing lightweight recycled aggregates and copper slag

This study examined the effect of various design parameters on the relationship between compressive strength and ultrasonic pulse velocity (UPV) of geopolymer concrete. To prepare the data set, a series of samples were made with increasing alkaline activator liquid to binder (AAL/B) ratios and varying densities. The variation in density was attained by partial replacement of normal weight fine and coarse aggregates by denser copper slag and lightweight recycled aggregates, respectively. The influence of AAL/B ratio and density on compressive strength and UPV was evaluated. After comprehensive analysis of results, a unified empirical equation is proposed to non-destructively compute the compressive strength of geopolymer concrete using UPV, AAL/B ratio and density. The findings demonstrated that the suggested equation could accurately predict the compressive strengths with a high determination coefficient ( D c ) of 0.97. In addition, an attempt was made to check the validity of the constructed equation by comparing it with other relevant published experimental data.