The Influence of Silica Fume on The Strength and Permeability Characteristics of Pervious Concrete

Pervious concrete is recognized for its significant permeability and ecological advantages; yet, its strength and durability are constrained, limiting its structural uses. This research examines the effects of different silica fume concentrations on the mechanical characteristics and permeability of pervious concrete to enhance its performance and practical applicability. The accessibility of diverse equipment resulted in the adoption of British Standards and American Society for Testing and Materials (ASTM) regulations. This study used the Department of Environment (DOE) approach to enhance pervious concrete mixes by using silica fume substitutes of 3%, 6%, and 9% by cement weight. To assess the impact of silica fume on the characteristics of pervious concrete, all mixtures maintained a consistent water-cement ratio of 0.4. The workability, compressive strength, tensile strength, and infiltration rate of pervious concrete, accompanied by varied silica fume concentrations, were evaluated according to ASTM and British Standards. The slump test findings for mixtures with 0-9% silica fume replacement indicated a significant reduction in workability, especially between 0% and 3%, measuring 15 mm and 10 mm, respectively. The compressive strength of pervious concrete improved with extended curing time, reaching a maximum of 28.33 MPa at 28 days with a 3% replacement of silica fume. On the 28th day of concrete maturation, the tensile strength exhibited a similar trend, with a 3% substitution of cement by silica fume resulting in strength of 3.11 MPa. Pervious concrete mixtures with 0%, 3%, 6%, and 9% silica fume substitution exhibited differing infiltration rates, with the 9% silica replacement mixture demonstrating the highest rate. The 3% silica fume mix (PC3) attained the optimal strength-permeability ratio by improving particle packing and minimizing micro-voids. This research found that a 3% silica fume substitution surpasses larger silica fume replacements in optimizing the equilibrium of workability, compressive strength, tensile strength, and permeability in concrete.