关键词: 磷石膏, 硫铝系高活性材料, 路面基层材料, 无侧限抗压强度, 水稳定性

Abstract: In order to solve the problem of large-scale resource utilization of phosphogypsum and consider the economy of engineering application. Sulfoaluminate high-activity material (SHAM) clinker prepared from total solid waste with advantages of early strength, high strength and low cost was used as the main cementing material. Phosphogypsum was modified by admixture such as distribution stone slag and mineral powder to prepare SHAM stable phosphogypsum mixture (SSPM), and the experimental research of SSPM used as pavement base material was carried out. The unconfined compressive strength test, water stability test and microstructure test of SSPM were carried out. The effects of carbide slag and mineral powder on the mechanical properties and water stability of SSPM were studied, and the action mechanism was analyzed. The effects of different SHAM clinker ratios on the mechanical properties of SSPM were studied. The results showed that the 7d unconfined compressive strength of SSPM was up to 6.02 MPa, which could be used as pavement base material. Admixture could promote the formation and stability of hydration products, adding 1% carbide slag and 3% mineral powder could improve the unconfined compressive strength of SSPM at any age. SSPM had good water stability, the softening coefficient was not less than 0.85, and the water-soaked strength could still meet the strength requirements of roadbed materials. With the increase of solid waste-based SHAM clinker content, the 7 d and 28 d strength of SSPM increased significantly, but the later strength of SSPM decreased when the content was more than 15%. This study could provide a feasible technological path for expanding the resource utilization of phosphogypsum and promote the development of low carbon cycle in society.

Key words: phosphogypsum, sulfoaluminate high activity material, pavement base material, unconfined compressive strength, water stability