New formulations for mechanical properties of recycled aggregate concrete using gene expression programming

This paper presents new empirical models for prediction of the mechanical properties of recycled aggregate concrete (RAC) using gene expression programming (GEP) technique. A large and reliable test database containing the results of 650 compressive strength, 421 elastic modulus, 346 splitting tensile strength, and 152 flexural strength, tests of RACs containing no pozzolanic admixtures is collated through an extensive review of the literature. The performance of existing mechanical property models of RACs is then assessed using the database, and the results of this assessment are presented using selected statistical indicators. New expressions for the predictions of 28-day compressive strength, elastic modulus, flexural strength, and splitting tensile strength of RACs are developed based on the database. The assessment results indicate that the predictions of the proposed models are in close agreement with the test results, and the new models provide improved estimates of the mechanical properties of RACs compared to the existing models. (C) 2016 Elsevier Ltd. All rights reserved.