Fundamental behaviour of recycled aggregate concrete - Overview I: strength and deformation

Recycled aggregate concrete (RAC) has received huge amounts of attention in the past two decades. However, there are still many critical problems about fundamental behaviours of RAC, which need to be figured out and which otherwise limit its further sustainable popularisation. Therefore, this series of two overviews rethinks fundamental behaviours of RAC based on the latest literature. In this overview (part I), the strength development and its mechanism, as well as failure patterns of RAC under static and dynamic loading, are explored. Then, the influencing factors and prediction models of elastic modulus, shrinkage and creep of RAC are intensively discussed. It is found that, compared with natural aggregate concrete, the 28 day compressive strength of RAC is lower, whereas the long-term compressive strength of RAC may be higher, which partly depends on the strength of the parent concrete. Furthermore, because the elastic modulus of RAC is often decreased, the drying shrinkage and creep of RAC are always increased. However, the autogenous shrinkage of RAC can be decreased, and also generally develops for above 60 days. Finally, some models have been summarised to better predict the elastic modulus and long-term deformation of RAC.

Automated summary

Recycled aggregate concrete (RAC) has received significant attention in the past two decades. In this overview, the strength development and failure patterns of RAC under static and dynamic loading are explored. Factors influencing elastic modulus, shrinkage, and creep of RAC are discussed, and prediction models are summarized. The study finds that RAC has lower compressive strength at 28 days compared to natural aggregate concrete, but may have higher long-term compressive strength. The elastic modulus of RAC is often decreased, leading to increased shrinkage and creep. However, autogenous shrinkage of RAC can be reduced.