A Review on the Influence of Recycled Aggregate on the Shrinkage Performance of Concrete

To promote the resource utilization of construction waste and alleviate the shortage of natural aggregates, this paper reviews the influence of modified recycled coarse aggregates on the shrinkage performance of concrete. Research findings indicate that recycled aggregates, due to the adhered old cement mortar on their surfaces, have low apparent density, high water absorption rate, and large porosity, leading to a decline in workability as the replacement rate increases, and their compressive and tensile mechanical properties are generally lower than those of ordinary concrete. Regarding shrinkage performance, autogenous shrinkage is affected by the moisture state of the aggregates, water-binder ratio, and mineral admixtures; pre-wetting treatment and the addition of fly ash can suppress autogenous shrinkage. Dry shrinkage intensifies with the increase in the replacement rate of recycled aggregates and the decrease in initial moisture content, and it accounts for a higher proportion of total shrinkage. Pretreatment technologies for recycled aggregates can optimize the pore structure and interfacial transition zone, thereby improving shrinkage performance, but they are associated with high costs and complex operations. Existing shrinkage prediction models do not fully consider the characteristics of recycled aggregates, resulting in insufficient accuracy. In the future, it is necessary to develop low-cost and environmentally friendly modification technologies, deepen the research on shrinkage mechanisms, and establish dedicated prediction models to provide support for the engineering application of recycled concrete.