Effect of air-cooled blast furnace slag aggregates on the autogenous shrinkage of concrete

Autogenous shrinkage is one of the primary factors leading to cracking in concrete structures. To enhance the efficiency of solid waste resource utilization, this study utilizes air-cooled blast furnace slag aggregates (ACBFSAs) to prepare concrete. The impact of different combinations of coarse and fine aggregates (NS-LCR, NS-SCR, SS-LCR, and SS-SCR) on the autogenous shrinkage of concrete is investigated. The experimental results indicate that the shape of the ACBFSAs is more irregular, and the surface of the aggregates is rougher. The 112 d autogenous shrinkage of the NS-LCR group reaches −195.4 μm/m. Replacing natural aggregates with ACBFSAs effectively reduces the autogenous shrinkage of concrete, and the SS-SCR group even exhibits micro expansion (55.8 μm/m). Owing to the internal curing effect induced by ACBFSAs, the concretes obtain higher internal relative humidity and smaller autogenous shrinkage. Its multi-angular characteristics and rough surface greatly increase the bonding strength between aggregate and the matrix. This study can provide technical support for the resource utilization of ACBFSAs in concrete.