Performance of Concrete Using Water Hyacinth Ash as a Partial Cement Substitute

Concrete is one of the most widely used construction materials, with cement as its primary component. However, cement production significantly contributes to CO 2 emissions, posing environmental challenges. This study investigates the use of water hyacinth ash (WHA) as a sustainable partial replacement for cement in C‐30 grade concrete. WHA was incorporated at 0%, 5%, 10%, 15%, and 20% by volume. Concrete samples were cast in cubes, cylinders, and beams using standard steel molds and a mechanical compaction process. The mix included ordinary Portland cement, clean river sand, crushed stone aggregates, and potable water. Compressive strength was tested at 7, 14, and 28 days, while split tensile strength, flexural strength, and water penetration were evaluated at 28 days. Results indicated that up to 10% WHA replacement enhanced compressive strength by 16.67%, flexural strength by 73.45%, and split tensile strength by 64.2%, while water penetration remained below 4 mm. A multivariate nonlinear model was developed to predict 28‐day compressive strength and optimize WHA content, identifying 14.3% as the optimal replacement level. These findings suggest that incorporating WHA into concrete can improve structural performance, reduce cement consumption, and lower CO 2 emissions, making it a viable sustainable construction material for environmental and economic benefits.