Microstructure and Performance Optimization of Barley Husk Ash–Blended Mortars: A Sustainable Approach to Cement Substitution

The research investigates barley husk ash (BHA)—an abundant agriculture byproduct—as a partial cement substitute in mortar production. Chemical composition analysis revealed that BHA comprises 72.88% combined SiO 2 , Al 2 O 3 , and Fe 2 O 3 , with crystalline silica (quartz) and fibrous, irregular morphologies, meeting ASTM Class N pozzolanic standards. Mortar mixes incorporating 0%–25% BHA were prepared with constant water‐to‐cement and cement‐to‐sand ratios of 0.48 and 1:2.75, respectively. Hardened properties were systematically evaluated at curing periods of 3, 7, 28, and 56 days. Statistical modeling using analysis of variance (ANOVA) and response surface methodology (RSM) demonstrated excellent predictive capability ( R 2 = 0.92–0.99). Optimization identified 22.75% BHA with a curing period of 37.23 days as the optimal mix, yielding superior mechanical and durability performance with a desirability score of 82.6%. Experimental validation confirmed the accuracy of predictions, with errors consistently below 5%. The findings establish BHA as a viable, performance‐enhancing, and a sustainable cement substitute, contributing to eco‐efficient construction.