Dynamic mechanical properties of ferronickel slag powder-modified soil-cement using split-hopkinson pressure bar testing

Ferronickel slag is an industrial waste, ranking as the fourth largest smelting slag in China, with an annual discharge of about 30 million tons. However, only 8% to 10% of this slag is utilized, leaving a substantial amount of ferronickel slag unutilized. This not only pollutes the environment, but also results in a significant waste of resources. Recycling ferronickel slag wastes allows for the optimum use of resources, which benefits initiatives in ferronickel slag powder production and environmental protection. In light of this, ferronickel slag powder (FSP) and mineral powder (MP) are mixed here to achieve the optimal proportion when incorporated into soil-cement (the mixture is simplified as FSMP) for application in subgrade reinforcement. In the subgrade soil of airport runways, in fact, it often endures the impact of loads, therefore, to study the influence of added ferronickel slag powder on the mechanical behavior of soil-cement after impact compression, the Split-Hopkinson pressure bar (SHPB) testing was conducted on a series of soil-cement samples with varying FSMP replacement ratios (0, 10%, 20%, 30%, 40%, 50%, and 60%). The failure mode, compression after impact (CAI) strength, and dynamic stress-strain relationship of the soil-cement samples were studied. The results indicate that, as the FSMP replacement ratio increases from 0 to 60%, the rate of peak stress growth at 60-day age are 11.39%, 12.08%, 12.57%, 16.11%, -16.83%, and -13.20% respectively. This implies that the dynamic stress first increases as FSMP increases and then decreases after the peak is reached at 40% FSMP replacement. Moreover, as the curing ages, the peak dynamic stress gradually increases. The rate of this increase is significantly higher between the curing age of 7d and 28d than between 28d and M60d. The addition of a suitable amount of ferronickel slag powder can enhance the impact resistance of soil-cement. These findings can serve as a foundation for understanding the application of soil-cement in engineering under impact.