Pozzolanic activity and fatigue response of roller compacted concrete containing zeolite powder with different size distribution

This study investigated the impact of zeolite powder particle size on the fatigue resistance of roller-compacted concrete (RCC) mixtures, emphasizing its role as a supplementary cementitious material (SCM) under dynamic loading. The study used three different zeolite powder sizes: Z1 (maximum 75 µm), Z2 (maximum 45 µm), and Z3 (maximum 37 µm). The mixtures were tested with 5, 10, 15, and 20% zeolite replacement by total cementitious materials. The study found a strong correlation between particle size and the pozzolanic reaction's progress, evaluated by thermogravimetric analysis (TGA). Z3 (the finest particle size) showed significant pozzolanic activity in cement pastes at 28 days, even at higher replacement levels. Z2 and Z1, with larger particle sizes, exhibited suitable activity at 28 days only up to 10% replacement. As curing time extended to 90 days, more pozzolan was activated across all particle sizes and replacement levels. Fatigue resistance tests largely mirrored these findings, indicating that smaller particle sizes generally led to better performance. For 28-day specimens, Z3 with 10% replacement yielded the best fatigue performance, while Z1 and Z2 often performed worse than the reference mix containing no zeolite powder. The optimal zeolite content for fatigue performance was generally lower than that suggested by pozzolanic activity alone. Based on VIKOR analysis, the Z3-15 mix (15% Z3 zeolite) was identified as the most suitable, followed by Z3-10 and Z2-15, improving fatigue life by 15% to 30%. Practically, the ideal amount of Z3 zeolite was between 15% and 20%, and for Z1 and Z2, between 10% and 15%. • Zeolite powder (ZP) was used as partial replacement of Portland cement in RCC mixture. • The effect of zeolite powder size on pozzolanic activity and fatigue life of RCC was investigated. • The optimal percentage of zeolite powder was determined based on the above two criteria. • Pozzolanic activity in the smallest size powder started earlier and grew faster. • Fatigue life was investigated up to 90 days, but 28 days curing was sufficient even for zeolite RCCs.