Performance of Silica Fume Modified Concrete in Aggressive Environment

Abstract

Concrete structures in industrial and wastewater environments are often exposed to aggressive chemical attacks, particularly from sulfuric acid, which significantly degrades their mechanical properties and service life. This study investigates the effect of partially replacing Ordinary Portland Cement (OPC) with Silica Fume (SF) at ratios of 0%, 5%, 10%, and 15% on the mechanical and physical properties of cement mortar specimens exposed to a sulfuric acid solution (5 G/L). A total of 100 standard prismatic specimens (4*4*16 cm) were prepared, cured in both water (as a reference) and acid medium, and tested at ages of 7, 28, 56, and 90 days. Key performance indicators included mass change, flexural strength, and compressive strength. The results were Sulfate-Resisting Cement (SRC) under identical conditions. The findings revealed that the 10% SF replacement ratio exhibited the optimal performance, achieving the highest compressive strength (29.01MPa1.17%) and flexural strength (8.61 MPa) at 90 days in the acidic medium – an increase of 15% over the reference specimens – while demonstrating the lowest mass loss (-1.17%). Moreover, the OPC+10%SF mixture outperformed SRC in terms of weight stability and overall chemical resistance. Statistical analysis (ANOVA) confirmed significant differences between replacement ratios, with a coefficient of variation below 0.05, ensuring high experimental reliability. The study concludes that incorporating 10% silica fume into OPC effectively enhances the durability of concrete in sulfuric acid environments, offering a cost-effective and technically superior alternative to SRC for aggressive exposure conditions) and flexural strength (8.61 MPa) at 90 days in the acidic medium –an increase of 15% over the reference specimens- while demonstrating the lowest mass lose.