Low-carbon cement strategy: utilizing fly ash to enhance jarosite-modified OPC performance
摘要
The cement industry is a significant contributor to global carbon dioxide emissions, primarily due to its high clinker content and energy-intensive manufacturing processes. The utilization of industrial by-products as supplementary cementitious materials offers a practical route to reduce clinker consumption while maintaining performance. In this study, the feasibility of using raw jarosite, processed jarosite, and fly ash as partial replacements for clinker and mineral gypsum in OPC-43 grade cement was investigated. Cement mortars were prepared in accordance with the Bureau of Indian Standards (BIS) and optimum evaluation for normal consistency (32.8), setting time (130 min for IST and 170 min for FST), soundness (0.8%), drying shrinkage (0.2% for 7 days and 0.17% for 28 days), compressive strength (27.5 MPa for 3 days, 39.8 MPa for 7 days and 51.6 MPa for 28 days), flexural strength (5.97 MPa for 7 days and 12.6 MPa for 28 days), water absorption (4%), and durability under aggressive environmental conditions. The results indicate that jarosite alone reduces strength due to sulphate-rich composition; however, the combined incorporation of processed jarosite and fly ash improves strength and durability by promoting secondary hydration and pore refinement. Optimized blends exhibited improved mechanical performance, reduced water absorption, and enhanced resistance to chemical attack compared to the control mix. The study demonstrates that controlled use of jarosite with fly ash can partially replace clinker and gypsum, contributing to sustainable cement production with reduced environmental impact.