Prediction and Optimization of Flexural Strength of Cement Concrete Containing Reclaimed Asphalt Pavement Using Box-Behnken Design

This research paper presents a comprehensive analysis of the prediction and optimization of flexural strength in
cement concrete incorporating Reclaimed Asphalt Pavement (RAP) as a partial replacement for natural coarse
aggregates, utilizing the Box-Behnken Design (BBD) of Response Surface Methodology (RSM). The study
investigates the influence of five critical mix design parameters, water content, cement content, sharp sand, RAP
content, and natural coarse aggregates on the flexural strength development of concrete. Through a systematic
experimental program employing a full quadratic model, the research develops a statistically significant regression
equation capable of predicting flexural strength with acceptable accuracy. The model demonstrated adequate fit
with a Lack-of-Fit F-value of 1.03 and p-value of 0.047, indicating statistical significance at the 95% confidence
level. Optimization of the model yielded a maximum flexural strength of 3.7829 N/mm². Additionally, the study
explores the effects of varying RAP replacement percentages (0%, 25%, 50%, 75%, and 100%) on flexural
strength at 28 days of curing, identifying an optimal replacement level of 75% achieving 2.45 N/mm². The findings
contribute to the growing body of knowledge on sustainable concrete production, offering engineers and
researchers a validated predictive tool for designing RAP-incorporated concrete mixtures with optimized flexural
performance.

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