Mechanical Performance and Shrinkage Behavior of Ultrahigh-Performance Concrete with Ferronickel Slag Under Various Curing Conditions

The main objective of this study was to evaluate the long-term mechanical performance and shrinkage behavior of ultrahigh-performance concrete (UHPC) in which the granulated ground blast-furnace slag (GGBFS), used as part of the binder, is replaced partially or fully with ferronickel slag (FNS). The aim was to identify potential strength reduction and expansion problems associated with the use of FNS powder. For steam-cured UHPC, the compressive strength of the FNS100 (124.8 MPa) was comparable to that of the control case (FNS0, 125.1 MPa), and the tensile strength showed only a 0.3 MPa difference. Under constant-temperature and constant-humidity conditions, all mixtures satisfied the design strength standard of 120 MPa by the end of the curing period. Considering constant-temperature and constant-humidity conditions, shrinkage evaluation revealed that the FNS100_NON_AD (no shrinkage-reducing and expansive agents) exhibited 3.8 times greater shrinkage compared to FNS0, while other mixtures remained within a narrow range. These results indicate that shrinkage was governed more by the presence and type of admixtures than by the FNS replacement rate itself. This study demonstrated that FNS has sufficient potential for use as a binder in UHPC and encourages further research to optimize admixture use for long-term durability and shrinkage control.