Performance evaluation of barley husk ash as a pozzolanic supplementary material

The construction sector carries a heavy environmental burden, much of it linked to Ordinary Portland Cement production, which is responsible for about 7–8% of global CO₂ emissions. In response, this study explores a more sustainable alternative by turning an abundant agro-industrial byproduct, barley husk ash (BHA), into a partial cement replacement in mortar. Mortar mixes incorporating 0–25% BHA were produced at fixed water-to-cement and cement-to-sand ratios of 0.48 and 1:2.75, respectively. Fresh properties, mechanical performance, durability, and microstructural behavior were assessed at curing periods of 3, 7, 28, and 56 days. Powder analysis revealed BHA contains 72.88% combined SiO 2 , Al 2 O 3 , and Fe 2 O 3 , with crystalline silica and irregular surfaces, meeting ASTM Class N pozzolanic standards. While workability slightly decreased, BHA promoted pozzolanic reactions forming secondary C–S–H gel, densifying the microstructure. At 20% replacement, BHA enhanced bulk density (7.8%), compressive strength (20.6%), flexural strength (21.3%), and durability by reducing porosity, water absorption, length change, and improving corrosion and acid resistance. These findings highlight BHA as a sustainable, performance-enhancing cement substitute for eco-friendly construction. Further studies are recommended to assess its behavior under severe exposure conditions and within cement-free binder systems such as alkali-activated and geopolymer matrices.