Autogenous shrinkage and drying shrinkage of recycled aggregate concrete: A review

Abstract This paper comprehensively reviews the factors influencing the autogenous shrinkage and drying shrinkage of recycled aggregate concrete (RAC). Compared with natural aggregate concrete (NAC), RAC has a lower autogenous shrinkage because of the internal curing effect of recycled concrete aggregate (RCA). However, the internal curing efficiency of RCA is less than that of the lightweight aggregate because of its lower porosity and different pore structure. The drying shrinkage of RAC is larger than that of NAC, which is mainly caused by the mortar attached to the original virgin aggregate (OVA). Therefore, the methods of strengthening adhered or removing adhered mortar can reduce the drying shrinkage of RCA effectively. Some methods of strengthening adhered mortar are more environmentally friendly than removing adhered mortar. Finally, the existing autogenous shrinkage and drying shrinkage prediction models of RAC are discussed. The models obtained by seeing RCA as the two-phase composite has a higher degree of accuracy. This paper can support a better and more comprehensive understanding of the autogenous and drying shrinkages of RAC and how to reduce the cracking risk of RAC, which provides a theoretical base for future research and applications of RAC in the construction industry.