Mechanical and durability performance of reactive powder concrete under acidic conditions: Role of nano‐silica, pozzolanic admixtures, and curing methods

Abstract

This study evaluates the improvement performance and durability of reactive powder concrete (RPC) using a synergistic combination of silica fume (SF), metakaolin (MK), nano‐silica and hooked‐end steel fibers, under two distinct curing methods: standard water curing and elevated temperature heat curing. Four RPC mixes were prepared with a constant fiber volume fraction (0.4%) and a total binder replacement of 25% by SF, MK, or their combination. Experimental investigations included compressive strength, indirect tensile strength, ultrasonic pulse velocity, bulk density, and durability against sulfuric acid exposure for 60 days. The results confirmed that heat curing substantially enhanced all performance parameters, with up to an 83% increase in compressive strength after 7 days. Mixes containing SF demonstrated superior strength and acid resistance compared to those with MK, due to the denser microstructure and higher pozzolanic activity of SF. Moreover, the integration of 1% nano‐silica further improved performance by increasing compressive strength (up to 11.6% at 7 days) and reducing water absorption (up to 5% at 28 days), attributed to improved microstructure density and accelerated early pozzolanic reactions. These findings highlight that durability is governed by microstructural characteristics and overall quality of cementitious matrix rather than strength alone, while also emphasizing the critical role of optimizing binder composition, curing method, and nano‐modification to produce high‐performance, durable RPC mixes suitable for aggressive environments and long‐term infrastructure applications.