Mechanical and durability performance of sustainable cement mortars: Experimental optimization and multi-regression modelling

With the growing environmental impact of ordinary Portland cement (OPC) production, sustainable cementitious materials based on using an industrial by-product are of considerable interest and the use of ground granulated blast furnace slag (GGBFS) is one such candidate. Alkali activation of GGBFS with sodium hydroxide (NaOH) is a favorable strategy to optimize the performance of blended cementitious systems and mitigate cement consumption along with CO 2 emissions. This study investigated the mechanical and durability-related parameters of cement mortars from experimental data while establishing a statistical model on how partially replacing OPC with GGBFS under discrete (low, medium, high) NaOH activation levels affects the strengths. Seventeen mortar mixtures were prepared using GGBFS replacement ratios ranging from 0% to 40% and NaOH concentrations of 0%, 8%, 10%, and 12%. The findings revealed that activation using NaOH could enhance the efficiency of GGBFS-blended mortars depending on replacement level, reducing absorption and void ratio values thereby. Among the investigated mixtures, the formulation incorporating 30% GGBFS along with 10% NaOH showed the best overall behavior. The developed multi-regression models offered moderate predictions of flexural strength, absorption and void ratio but were inadequate for estimating compressive strength (R 2 = 0.206) attributed to non-linear complexity. Then instead of using regression modeling, the experimental optimization of mix design was performed. These results add to the research of more sustainable cementitious materials, and also provide practical information on optimal conditions for NaOH-activated GGBFS blended cement mortars in engineering applications.