Hybrid Pervious Concrete Incorporating Micro Rice Husk Ash for Improved Mechanical Properties and Ecological Benefits

To improve mechanical qualities and sustainability, this study explores the creation of hybrid pervious concrete that partially substitutes micro-rice husk ash (MRHA) for ordinary Portland cement (OPC). MRHA replacement levels of 0, 5, 10, and 15% by weight of cement were used to create four different concrete mixtures. At 10% MRHA, the compressive strength improved by 16%, from 36.5 MPa (control) to a maximum of 42.3 MPa. At 10% MRHA, water permeability dropped from 5.8 × 10⁻⁷ m/s (control) to 4.7 × 10⁻⁷ m/s, suggesting better matrix densification. At 15% MRHA, the water absorption decreased by 15.4% from 7.8% to 6.6%. As MRHA has a lower specific gravity, the hardened density at 15% MRHA decreased slightly from 2340 kg/m³ (control) to 2298 kg/m³. The results showed that 10% MRHA replacement offers the best results in terms of strength, permeability, durability, and environmental benefits. Thus, MRHA is a viable sustainable material for environment-friendly concrete applications.