Reliability-Based Design Optimization of Recycled Coarse Aggregates Used in Corrosive Environment

Abstract

In this study, coarse aggregates extracted from waste concrete were used as recycled coarse aggregates in a concrete mixture. Such durability properties of concrete samples as water absorption, porosity, and electrical resistance as corrosion evaluation indicators were assessed. First, estimation models for the mechanical and durability parameters of concrete were obtained using the kriging surrogate model; then, these models were evaluated using a metaheuristic optimization algorithm coupled with a simple and fast new method of reliability evaluation. Ultimately, the probabilistic optimal values of using recycled coarse aggregates to achieve an environmentally friendly concrete were calculated. The probabilistic single-objective optimization results revealed that in an environment with 70% humidity, a temperature of 23°C, and chloride ion concentrations of 0%, 3%, 5%, and 8%, the replacement ratio of recycled coarse aggregates for the different chloride ion concentrations listed above is limited to 39.12%, 38.08%, 37.21%, and 22.68%, respectively, in a water-to-cement ratio of 0.40.