Utilizing Stearic-Acid-Coated Marble Dust for the Production of Eco-Friendly Self-Cleaning Concrete: RSM Modeling and Optimization

With the growing demands of the construction industry, the need for manufacturing cement increases, and it causes challenges to the climate as one ton of cement results in the release of around one ton of CO2. Therefore, it is essential to find an alternative to reduce the environmental impact. This study aims to optimize the properties of concrete containing marble dust and stearic acid to produce eco-friendly and self-cleaning concrete. Stearic acid induces a self-cleaning property in concrete to make it free from moisture, leading to its prolonged service life. Thirteen mixes are designed, using marble dust as a partial replacement of cement by weight (at 10%, 20%, and 30%) and stearic acid by cement weight (at 0.5%, 1%, and 1.5%) in this eco-friendly self-cleaning concrete. Nine mixes were developed using response surface methodology (RSM), where two variable inputs were considered. The compressive, tensile, and flexural strengths were assessed. Other tests such as ultrasonic pulse velocity, Young's modulus of elasticity, density, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and self-cleaning property have been conducted and evaluated. At 10% replacement of marble dust by the weight of cement and with a 0.5% coating of stearic acid, the compressive, tensile, and flexural strength of concrete increases by 12.68%, 21.71%, and 16.73% over the control mix, whereas the best self-cleaning property is observed at 30% partial replacement of cement with marble dust coated with 1.5% of stearic acid.