Abstract: To promote the resource utilization of industrial waste and enhance the performance of road concrete, the effects of rice husk ash (RHA) on the performance of low-fineness self-compacting concrete (LF-SCC) for road applications were systematically evaluated. With cement replacement rates ranging from 0% to 50%, the workability, mechanical properties, and durability tests were conducted, and the mechanisms were explored through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and mercury intrusion porosimetry (MIP). The results showed that the 20% RHA replacement rate yield the best performance. At 28 days, compressive strength, splitting tensile strength, and flexural strength are increased by 5.73%, 2.48%, and 2.50%, respectively. The chloride ion permeability reach an “extremely low” level, while water absorption and penetration depth are reduced by 75% and 60%, respectively. SEM and EDS analyses indicated that an appropriate amount of RHA promote pozzolanic reactions, resulting in the formation of large amounts of C—S—H gel, which significantly optimize the pore structure. MIP tests revealed that the total porosity with 20% RHA replacement rate at 28 days is only 5.34%, with the most probable pore diameter is reduced to 28.9 nm, and the proportion of harmful pores significantly is decreased. However, excessive incorporation of RHA lead to performance degradation due to the accumulation of unreacted SiO₂. Therefore, the 20% RHA replacement rate is recommended as the optimal dosage.

Key words: rice husk ash, self-compacting concrete, pavement performance, durability