Application of Response Surface Methodology for Predicting the Compressive Strength of Mortars Containing Natural Pozzolan

Abstract

In this paper, the effect of the inclusion of natural pozzolan (NP) on the compressive strength of cement mortar is investigated. Prediction models of compressive strength of cement mortars having NP were developed utilizing response surface methodology (RSM). In addition, multi-objective optimization has been performed by maximizing the compressive strength with natural pozzolan replacing cement (NPC) in ranges between 0 and 40% by weight of cement and natural pozzolan replacing sand (NPS) in ranges between 0 and 40% by volume of sand. To reduce the negative impact of NP on the compressive strength, silica fume (SF) was used as a partial replacement for cement by weight with ratios of 5% and 10%. The experimental data comprises the 28-day compressive strength of twenty-three mortar mixes. The specimens have cubic shapes with dimensions of 50×50×50 mm. The experimental results were used as the database for developing prediction models to evaluate the impact of doses of NP and SF on NP mortar's compressive strength. Developed models were assessed and validated to check significance and suitability of these combinations in mortar. The involvement of every parameter was analyzed using ANOVA and other statistical measures. Optimal relationships were identified between compressive strength and NPC and/or NPS ratios. The ideal replacement levels of NP for enhancing the NP mortars compressive strength were determined by numerical optimization. Constructed models’ outcomes aligned well with experimental data. The predicting NP mortars compressive strength quadratic model outperforms the linear model. Models established in this study can predict compressive strength of cement mortars using NP and SF, the results of which will be highly useful for engineering community.