Performance and Durability of Chemically Activated Lime-Based Cement Blended With Rice Husk Ash

Abstract

Lime–pozzolana binders ofer a low-carbon alternative to conventional materials; however, their practical application is limited by slow strength development and insufcient durability, particularly under aggressive chemical environments. In addition, existing studies on chemical activation have largely focused on OPC-based systems, with limited attention to lime-based binders and their durability performance. This study investigates the efect of chemical activation on the performance and durability of lime–rice husk ash (RHA) mortars. The objective was to evaluate how sodium hydroxide (NaOH) and sodium sulfate (Na2SO4) infuence compressive strength, porosity, and resistance to sulfuric acid attack of lime mortars. Physicochemical characterization confrmed that the RHA contained 94.95% SiO2 with high amorphous content and strong pozzolanic reactivity (> 60% conductivity loss). Results showed that RHA incorporation improved lime mortar performance, while chemical activation signifcantly enhanced

these properties. NaOH activation increased compressive strength by 132%, compared to 53% for Na2SO4, relative to the non- activated system. Porosity decreased progressively across the systems, with the lowest values observed in NaOH-activated mortars.

Under acid exposure, all RHA-containing mortars outperformed pure lime, which disintegrated completely. Strength and mass losses were lower in activated systems, particularly with NaOH. Deterioration was more severe in 3% H2SO4 than in a 0.5% solution. The fndings indicate that chemical activation improves the short-term performance of lime–RHA mortars, although reaction

products were not directly quantifed. These results highlight the potential of chemically activated lime–RHA mortars as sus- tainable construction materials, particularly in resource-constrained regions.