Evaluation of performance and statistical analysis of rigid pavement incorporating recycled aggregate concrete through the BBD methodology

Abstract The incorporation of recycled concrete aggregate (RCA) in the construction of rigid pavements has attracted considerable interest due to its environmental and economic benefits. A statistical method known as Response Surface Methodology (RSM) serves as an effective tool for optimizing concrete mix designs by adjusting independent variables to achieve desired characteristics. However, there is a lack of extensive research that combines modified mix designs with statistical modeling to predict the mechanical properties of concrete. Furthermore, many existing studies fail to consider the combined impacts of various factors, including cement content, water-to-cement ratio, and fine-to-coarse aggregate ratio, on the performance of concrete mixtures. This study aims to develop and optimize concrete mixtures that incorporate RCA for rigid pavements using the Box-Behnken Design method. The main goals were to forecast water absorption, compressive strength, flexural strength, split tensile strength, and slump of fiber-reinforced concrete, as well as to identify optimal mix designs that fulfill specific strength requirements. A total of 30 mixtures were tested, varying in four factors: cement content (300, 350, and 400 kg m −3 ), water/cementitious ratios (0.3, 0.4, and 0.5), fine/coarse aggregate ratios (0.3, 0.4, and 0.5), and silica fume content (0%, 5%, and 10% by weight of cement). RSM was employed to create predictive equations for the mechanical properties of the concrete mixtures, revealing that cement content and silica fume ratios had a significant impact on these properties, followed by the fine-to-coarse aggregate and water-to-cementitious ratios. The correlation coefficients (R 2 ) for all predictive models exceeded 0.95, indicating a strong relationship between the independent variables and the mechanical properties. The optimal mix identified for achieving a compressive strength greater than 30 MPa and a flexural strength exceeding 4.1 MPa consisted of 365 kg m −3 of cement.