Utilization of Tunnel Waste Slag for Cement-Stabilized Base Layers in Highway Engineering

The rapid expansion of highway infrastructure in the mountainous regions of China has led to a significant increase in tunnel construction, generating substantial amounts of tunnel waste slag. Concurrently, the development of transportation infrastructure has created a critical shortage of natural aggregates, necessitating the exploration of alternative sustainable sources. This study aimed to conduct a comprehensive evaluation of the physical and mechanical properties of tunnel waste slag and explore its potential for utilization in cement-stabilized base courses for highway engineering applications. The uniaxial compressive strength of the parent rock (tunnel waste slag) ranged from 81 MPa to 89 MPa in the desiccated state, indicating its suitability for use as a construction material. This study also determined the maximum dry density (2.432 g/cm³) and optimal moisture content (5.4%) of cement-stabilized mixtures incorporating recycled aggregates derived from tunnel waste slag. The splitting tensile strength of these mixtures at 28 days varied from 0.48 MPa to 0.73 MPa, demonstrating robust mechanical performance. Moreover, the unconfined compressive strength of these mixtures escalated from 7.0 MPa at 7 days to 11.0 MPa at 90 days, signifying a substantial enhancement in strength over time. These results validate the viability of utilizing tunnel waste slag in highway engineering and furnish valuable insights for designers, concrete manufacturers, and construction firms engaged in the development of cement-stabilized aggregate base courses.