Design of experiment and multi-criteria decision applied to concrete mixture with crushed brick and tile as aggregate

To study the impact of crushed clay brick and tile as aggregate on the properties of concrete for precast concrete products, a comprehensive testing program was conducted. Thereby, the Box-Behnken design of experiment was used with a view to the economic and time constraints. Properties of concrete are modelled as second- order functions using the response surface method based on 62 different concrete mixtures tested in their hardened state. Selection of acceptable concrete mixtures was made according to experimental results and mathematical models of required properties (density, compressive strength, tensile strength). Finally, optimal concrete mixture for precast concrete beam and block floor system was chosen according to a multi-criteria decision.