Although recycled aggregate concrete (RAC) has been extensively studied, several critical problems about its fundamental behaviors are still urgent to be figured out. Therefore, this series of two reviews re-think fundamental behaviors of RAC based on the latest literature. In the last review (Part I), the mechanical and deformation behaviors of RAC have been intensively discussed. Here for Part II, the relationships between the replacement ratio of recycled aggregates (RA) and the durability of RAC are further presented. It is found that, due to the increase of total porosity, the resistance of RAC to freeze-thaw cycles, carbonation, and chloride ion penetration is usually decreased with the increasing replacement ratio of RA. As a result, the steel corrosion and corrosion-induced cracking in RAC are more serious than those in natural aggregate concrete (NAC). The prediction models for carbonation and chloride ion penetration of RAC and the corrosion-induced crack patterns are also presented. For addressing the degradation on the performance of RAC, several enhancement technologies such as the combined/optimization pre-treatment on RA and fiber reinforcement are put forward. Finally, the prospects of the high-performance/efficiency methodologies and applications of RAC are also shown.
Recycled aggregate concrete (RAC) has received huge attention in the past two decades. However, there are still many critical problems about fundamental behaviors of RAC which need to be figured out and otherwise limit its further sustainable popularization. Therefore, this series of two overviews re-think fundamental behaviors of RAC based on the latest literatures. In this overview (Part 1), the strength development and its mechanism as well as failure patterns of RAC under static and dynamic loadings 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 (NAC), the 28-day compressive strength of RAC is lower, whereas long-term compressive strength of RAC may be higher, which partly depends on the strength of 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 it generally develops for above 60 days. Finally, some models have been summarized to better predict the elastic modulus and long-term deformation of RAC.
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