A Review: The Modification Methods of Concrete Recycled Coarse Aggregates

In recent years, the rapid development of the construction industry has led to the abandonment or demolition of numerous buildings, resulting in an increasingly prominent issue of waste concrete accumulation. However, the recycling rate of construction waste remains low. Recycled coarse aggregates are coated with a significant amount of old cement mortar, which increases their water absorption and introduces numerous weak interfacial transition zones (ITZs) in recycled concrete. These weak ITZs significantly impair the mechanical properties of recycled concrete. This paper reviews methods for removing old cement mortar from recycled coarse aggregates and enhancing the weak interfaces in recycled concrete, analyzing their advantages, disadvantages, applicability, and environmental-economic benefits.