An Experimental Study on Durability Properties of Reactive Powder Concrete Containing Silica Fume and Fly Ash as Supplementary Cementitious Materials

The paper reports the influence of using silica fume (SF) and fly ash (FA) as supplementary cementitious materials (SCMs) on the durability properties of reactive powder concrete (RPC), focusing on sorptivity, ultrasonic pulse velocity (UPV), and carbonation depth. The study additionally compares the performance of RPC with highstrength concrete (HSC) to assess the relative benefits of RPC. A total of 19 mixtures, including 17 RPC and 2 HSC mixtures, were evaluated. Parameters such as volume of binder content (45%, 50%, 55%, and 60%), water-binder ratios (20%, 25%, and 30%), and SCM proportions (0%, 10%, 20%, and 30%) were varied; these parameters were examined experimentally to evaluate their effect on durability. Results showed that increasing the binder volume ratio from 40% to 60% reduces water absorption up to 60%, with SF mixtures outperforming FA mixtures in water resistance. The sorptivity and water absorption are increased by 78% and 46.6%, respectively, when the W/B ratio is increased from 20% to 30% for FA mixtures, whereas for SF mixtures, the optimal performance occurs at a 25% W/B ratio. The highest reduction in water absorption and sorptivity occurred at a 20% SCM replacement for SF. UPV increased with higher binder content and SCM replacement, SF mixtures showing superior results. Further, RPC with SF exhibits minimal resistance to CO₂ penetration. In comparison to HSC, RPC with SF demonstrates significantly lower sorptivity, up to 63.4%, 8.12% higher UPV, and minimal carbonation depth, while HSC shows a 62.5% greater carbonation depth compared to RPC with FA.