Evaluation of Fresh and Hardened Properties of Concrete made with Rice Husk Ash admixed with Snail Shell Ash

The objective of this study is to evaluate the properties of concrete incorporating Rice Husk Ash (RHA) and Snail Shell Ash (SSA) as partial replacements for cement. Cement production is a significant emission source of CO2, necessitating environmentally friendly alternatives. This research examines the combined impact of these ashes on concrete performance. RHA and SSA were employed as Supplementary Cementitious Materials (SCM) to partially replace Portland cement. The replacement levels were: RHA at 0%, 5%, 7.5%, 10%, 12.5%, and 15% and SSA at 0%, 15%, 17.5%, 20%, 22.5%, and 25% by weight. A response surface methodology was employed to design the experiments, resulting in 18 experimental runs or mixes. A number of experiments were conducted, including slump, compressive strength, flexural strength, splitting tensile strength, and water absorption tests. The results demonstrated that the workability of the fresh concrete decreased with the addition of ashes. However, the RHA-SSA concrete exhibited enhanced strengths and durability. The optimal mix, M11, which contained 15% RHA and 15% SSA, exhibited the highest strength values at both 28 and 90 days. The RHA-SSA concrete displayed reduced porosity, with M10 (15% RHA, 25% SSA) demonstrating the lowest water absorption (5.1%) compared to 13.1% for the control mix. These findings substantiate the use of RHA-SSA concrete as a sustainable alternative in construction, addressing both environmental and performance-related concerns.