Mechanism development of strength contributed by CPB with rice husk ash

Rice husk ash (RHA) is currently utilized as a supplementary cementitious material in cement products due to its pozzolanic properties. This study aims to investigate the pozzolanic effect (PE) and filler effect (FE) of RHA on the mechanical properties and microstructure of cemented paste backfill (CPB). The effects of RHA content, cement-to-tailings ratio, and mass concentration on the unconfined compressive strength (UCS) of the CPB were investigated. The proportion of UCS that could be attributed to the PE was 67.30%–87.92% higher than the FE in CPB with RHA contents ranging from 10% to 20%. The FE of RHA exerted stronger influence at lower curing times, but the PE played more crucial roles at curing times of more than 3 d. These results provide new insights into the potential use of RHA as a cementitious material for use in backfilling during mining operations.