Durability evaluation of recycled aggregate concrete through non-destructive testing and microstructural analysis

Abstract The purpose of this research is to produce sustainable concrete through the use of recycled aggregates as both fine and coarse aggregates. The use of industrially processed recycled aggregates, as opposed to laboratory-crushed materials, enables this study to generate durability and non-destructive performance data with enhanced relevance for practical construction applications. The ultrasonic pulse velocity values ranged from 4.1 to 4.89 km s −1 , indicating good to excellent concrete quality, while rebound numbers (33.8–40.4) confirmed adequate surface hardness at 28 days. Although, recycled aggregate concrete exhibited higher water penetration (11.94–48 mm), water absorption (3.5%–8.67%), and chloride permeability (1145–2992 coulombs) than natural aggregate concrete, these properties improved significantly with curing age, resulting in acceptable durability performance that remained below that of natural aggregate concrete. The microstructural and image processing results revealed higher replacement of recycled aggregates producing greater porosity and lower strength, which could negatively impact the durability characteristics of the concrete mixes. Thus, these results emphasize the critical requirements to optimize recycled aggregate content to achieve both environmental and performance efficiency.