Utilization of Brick Dust and Rice Husk Ash for Sustainable Cement Replacement in M20 and M25 Grade Concrete

The study evaluates the influence of replacing cement with Fly Ash, Brick Dust, and Rice Husk Ash on the compressive strength of concrete. Cement replacement was conducted at varying percentages (5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40%) for M20 and M25 grade concrete, and compressive strength was assessed at 7, 28, 90, and 180 days. The results demonstrate that partial cement replacement can achieve comparable or improved strength performance up to an optimal level, beyond which strength reduction occurs. For M20 grade concrete, the highest 28-day compressive strength of 43.94 MPa was recorded at 5% Fly Ash replacement, surpassing the control mix (43.46 MPa). Similarly, Brick Dust replacement at 5% resulted in a peak 28-day strength of 44.94 MPa, while Rice Husk Ash exhibited an optimum replacement level of 5%, achieving 44.42 MPa. However, higher replacement levels beyond 20% led to a decline in strength. For M25 grade concrete, the optimal 28-day strength of 52.60 MPa was obtained at 10% Fly Ash replacement, while 5% Brick Dust replacement resulted in a peak strength of 50.00 MPa. In contrast, Rice Husk Ash replacement showed the highest strength of 50.38 MPa at 5% replacement. A steady decline was observed beyond 20% replacement, indicating a threshold limit for effective utilization of these supplementary cementitious materials. The study concludes that partial cement replacement using industrial and agricultural by-products can enhance concrete sustainability without compromising strength. This research contributes to the development of cost-effective and environmentally friendly construction materials suitable for sustainable infrastructure.