Optimization and Modeling of 7-Day Ultra-High-Performance Concrete Comprising Desert Sand and Supplementary Cementitious Materials Using Response Surface Methodology

This research employs response surface methodology (RSM) to optimize and model ultra-high-performance concrete (UHPC) formulations, integrating desert sand and varying proportions of supplementary cementitious materials (SCMs), specifically fly ash (FA) and ground granulated blast furnace slag (GGBS). By investigating the influence of desert sand and SCM contents, the study aims to discern their impact on the workability and 7-day compressive strength of UHPC. Employing a central composite design (CCD), thirteen separate mixes were formulated. Key responses, namely workability and compressive strength, were evaluated. The developed models underscore the enhancement in UHPC performance through the partial replacement of cement with SCMs. Notably, an optimal combination of 75% desert sand and 30% SCMs resulted in a workability of 69.4 mm and a 7-day compressive strength of 46.01 MPa. The findings emphasize the potential for eco-friendly concrete in the construction industry, also prompting further exploration into long-term strength and higher SCM concentrations.