Mixture ratio optimization of polypropylene fiber recycled brick aggregate concrete based on response surface methodology

In order to obtain the optimal replacement rate of recycled brick aggregate (RBA) and the optimal volume fraction of polypropylene fiber (PPF), polypropylene fiber recycled brick aggregate concrete (PPFRBAC) with good mechanical properties was prepared. On the basis of the three-factor three-level orthogonal test, the response surface methodology (RSM) was used to establish the regression model to study the effects of water-cement ratio, RBA replacement rate and PPF contents on compressive strength and splitting tensile strength of PPFRBAC. The desirability function was used to optimize the PPFRBAC mixture ratio, and the optimized results were verified by experiment. The results show that the regression model established by RSM has high accuracy and reliability. The influence of water-cement ratio on the compressive strength and splitting tensile strength of PPFRBAC is most significant. At three different water-cement ratios, the optimal replacement rate of RBA predicted by the model is 100%, the optimal PPF content is 0.9%, and the absolute relative errors between the predicted values and the experimental values of strength are all less than 5%, which indicates that the proposed model can provide reference for multi-objective optimization of mix ratio of fiber recycled brick aggregate concrete. © 2022 Central South University of Technology. All rights reserved.