Multi-objective Optimization of Mix Proportion for Volcanic Scoria Concrete Using Response Surface Methodology

Abstract Due to the scarcity of natural sand resources and the abundance of volcanic scoria sand, volcanic scoria sand concrete is becoming increasingly popular. Therefore, this paper aims to study the mix proportion of new sustainable steel fiber reinforced volcanic scoria sand concrete (SFVSSC). Response surface methodology (RSM) was used to design the mix proportion according to the recommendations of EFNARC 2005 using the proportion of water-to-cement ratio (w/c) (0.35, 0.4, and 0.45), the volcanic scoria sand replacement rate (Rvs) (25, 50, and 75%), and steel fiber volume content (Vsf) (0.5, 1, and 1.5%) as input variables. To assess the workability and mechanical properties of SFVSSC using RSM, slump, thermal conductivity, specific strength, compressive strength, and splitting tensile strength were determined. The results show that the quadratic polynomial regression equation can be used to predict the effect of different composition factors on the performance of SFVSSC with high accuracy and confidence. In addition, stress–strain curves were obtained for mixtures with different Rvs and Vsf. Finally, multi-objective optimization produced optimal mix proportions for SFVSSC: w/c of 0.35, Rvs of 52.8%, and Vsf of 1.15%. The optimization results were verified experimentally, and the absolute value of the relative error between the predicted and tested strength values was less than 5%. This paper shows that it is feasible to use SFVSSC and suggests the potential application of RSM in concrete proportioning.