Study on the Mechanical Properties and Micro-Mechanisms of All-Solid Waste Cementitious Materials with Tire Particle Solidified Slag

The large-scale stockpiling of construction waste and industrial solid waste poses a severe threat to the ecological environment, necessitating the development of economically and efficient pathways for resource utilisation. In order to validate the efficacy of industrial solid waste as a solidification agent, this study employs a slag-alkali slag-phosphogypsum (SAP) solid waste system in conjunction with waste tire particles (TPs) for the synergistic solidification of construction waste. The strength of the resulting solidified material is compared with that of conventional cement-stabilised soil. Response surface experiments determined the optimal ratio of SAP solidification agent as m (slag)∶m (alkali slag)∶m (phosphogypsum)=16.2%∶3.8%∶4.6%. On this basis, 2.5%, 5% and 7.5% of the tire particles were added to investigate their impact on solidified soil properties. It indicates that the SAP-solidified soil exhibits unconfined compressive strengths of 3 412 kPa and 11 893 kPa at 7 days and 28 days respectively, with water stability coefficients of 0.85 and 0.90. A tire particle content of 2.5% can increase soil strength, comparing to cement-stabilized soil. However, if the proportion exceeds 5%, both the strength and stability of solidfied soil are decline. Microscopic analysis reveals that the SAP system generates a calcium silicate hydrate (C-S-H) gel with spatial network structure and acicular-rod-shaped ettringite (AFt). Excessive tire particle content can disrupt this structure. This research demonstrates that SAP solidification agent can effectively substitute cement, and incorporating a small amount of tire particles enhances soil stabilisation strength. This provides a viable pathway for resource utilisation of industrial solid waste and disused tires in soil stabilisation applications.