Development of Cold-Bonded Yellow Phosphorus Slag Aggregate-Based Concrete for Heavy-Duty Construction Road

Applying high-strength artificial aggregates to temporary construction roads for large hydropower and tunnelling projects offers cost and environmental advantages. However, the link between aggregate characteristics and the mechanical properties and failure characteristics of road concrete remains unclear. This paper uses cold-bonded yellow phosphorus slag (YPS) aggregates to replace natural aggregates to prepare a novel road concrete. The coarse aggregate replacement ratio was 100%, and the fine aggregate replacement ratios were 0–30%. The physical and mechanical properties were systematically tested, and the microstructural mechanism was analyzed by XRD, SEM and acoustic emission (AE) characteristics. The results show that YPS aggregates markedly improved the slump flow and slump of concrete. However, YPS aggregates reduced the density and increased the water absorption of concrete. With increasing YPS aggregate content, both flexural strength and compressive strength decreased. The 28 d compressive strength of the YPSC0% group was 21.5% lower than that of the OC group, but the measured mean 28 d compressive strength still exceeded the nominal 50 MPa requirement of the C50 grade. AE analysis indicated that the cumulative AE energy of YPS aggregate concrete was higher than that of the OC group. The cumulative AE energy first increased and then decreased with an increasing fine aggregate replacement ratio. The failure was dominated by aggregate fracture rather than interfacial debonding. XRD and SEM results showed that the aggregate replacement did not change the hydration product types, and the aggregate–paste interface was tightly bonded. However, the porous and low-strength nature of the aggregates was the main reason for the strength reduction. The results provide a preliminary basis for producing high-strength road concrete with YPS artificial aggregates and for optimizing mix proportions; durability and field performance require further investigation.