Comparative assessment of limestone-calcined clay blend and fly ash as binders in roller-compacted concrete pavement: evaluation of fresh and hardened properties

This study presents a comparative analysis of cement replacement with a limestone-calcined clay blend (LC2) and fly ash (FA) in roller-compacted concrete pavements (RCCP) at substitution levels of 25–80%. The results indicate that increasing replacement levels raised optimal moisture content, with LC2 mixes requiring less water than FA mixes, ranging from 7.13% to 21.77% compared to 16.38% to 28.71%. As a result, LC2 provided a controlled increase in consistency, air content, and density loss, ensuring a well-compacted matrix. In contrast, FA led to higher moisture sensitivity, greater air retention, and increased density loss. At 28 days, RCCP mixes with 50% LC2 exhibited a minimal compressive strength reduction of 3.52%, significantly outperforming those with 25% FA, which suffered a 19.20% reduction. While FA maintained RCCP strength requirements only up to 25% replacement, LC2 remained effective even at 60%, demonstrating its viability as a superior cement alternative in RCCP applications.Highlights LC2 as a cement substitute in RCCP.Fresh and hardened properties of RCCP.LC2 mixes at 50% replacement offer optimal sustainability and performance in RCCP.Statistical analysis confirmed the significant impact of LC2 on RCCP properties.