Effective use of agricultural by products in cement and concrete a comprehensive bibliometric and systematic review of their potential to promote a circular economy

The growing demand for sustainable construction materials has intensified research into the utilization of agricultural ashes as supplementary cementitious materials (SCMs) in cement and concrete. Agricultural by-products such as sugarcane bagasse ash (SCBA), rice husk and straw ash (RHA), wheat straw ash (WSA), and maize-based ashes have demonstrated significant potential to enhance mechanical performance, durability, and environmental sustainability when used at optimized replacement levels and the selection of these four agricultural ashes is primarily driven by their global abundance, high amorphous silica content, and established pozzolanic reactivity. This review critically synthesizes existing literature on the effects of agricultural ashes on the mechanical properties, durability performance, pozzolanic behavior, microstructural development, and environmental impacts of cementitious systems. Findings consistently indicate that partial cement replacement, typically within the range of 5–20% by mass, improves compressive, tensile, and flexural strength through pozzolanic reactions and filler effects, leading to refined pore structures and increased formation of secondary calcium silicate hydrate (C–S–H) gel. Durability enhancements, including reduced permeability, lower water absorption, and improved resistance to sulfate, acid, and chloride attacks, are widely reported, particularly when ashes are thermally treated and finely ground. In addition, incorporating agricultural ashes leads to substantial reductions in carbon dioxide emissions, energy consumption, and material costs, while addressing agro-waste disposal challenges and supporting circular economy principles. However, performance variability arising from differences in ash source, processing methods, chemical composition, fineness, and curing conditions remains a major challenge. This review identifies optimal replacement ranges, highlights critical research gaps, particularly in long-term durability and standardization and provides guidance for future research and practical implementation, positioning agricultural ashes as viable, eco-friendly alternatives for sustainable cement and concrete production.