Ready‐mix recycled aggregate concrete: Laboratory development and industrial validation at the concrete plant

Abstract Recycled aggregate concrete has been extensively studied, but the design of the experimental programs of most research on the topic does not consider the production process of ready‐mix concrete. Therefore, the findings of academic publications may not apply to industrial agents. This paper concerns the ready‐mix production of recycled aggregate concrete and covers a comprehensive description of the production process of ready‐mix concrete, the main challenges for coarse recycled aggregate use, and an experimental program defined with the managers of a ready‐mix plant, aiming at understanding the operational feasibility of ready‐mix recycled aggregate concrete production with minimal investment/adaptations at the plant. The program included experiments in the laboratory and at the ready‐mix plant. The raw materials and concrete compositions of the plant were used in all experiments and the recycled aggregates were sourced from a waste management operator and used without any treatment to improve their properties. Based on the results of the laboratory experiments, the laboratory experiments resulted in recommending replacement ratios of 50% of the aggregates 6/12 (about 10% of total aggregates). From this recommendation, the first Portuguese ready‐mix recycled aggregate concrete production was carried out to validate the incorporation ratios recommended from the laboratory productions. The ready‐mix recycled aggregate concrete compositions were successfully produced using standard equipment and procedures of ready‐mix plants. The industrial tests validated the recycled aggregate concrete compositions for the concrete specifications requested by the plants. However, it is recommended that these specific recycled aggregates are not used in concrete specified for aggressive environmental exposure conditions due to detrimental influence on durability.