大掺量磷石膏路基填料的性能研究与工程应用

Performance research and engineering application of high-volume phosphogypsum subgrade filler

为探索大掺量磷石膏制备路基填料与填筑应用的可行性,开展了固化磷石膏路基填料的路用性能与浸出毒性试验,分析了磷石膏固化稳定机理。结果表明:经固化后磷石膏强度、水稳性均得到大幅提高,当固化剂掺量为2%时,试样28 d无侧限抗压强度为1.51 MPa、CBR值为65%、浸出液中的氟离子浓度为0.61~2.00 mg/L、总磷浓度<0.003 mg/L;以生成氟化物沉淀、磷酸盐沉淀化学稳定方式及水化凝胶产物(C-S-H、C-A-S-H)粘附包裹物理固化方式实现固氟除磷。填筑试验路应用验证表明,固化磷石膏路基的压实度、弯沉、回弹模量值、污染物浸出量均满足相关标准要求。

In order to explore the feasibility of preparing subgrade filler and filling application with high-volume phosphogypsum,the road performance and leaching toxicity test of solidified phosphogypsum subgrade filler were carried out,and the solidification stability mechanism of phosphogypsum was analyzed.The result shows that after curing,the strength and water stability of phosphogypsum are greatly improved,when the curing agent content is 2%,the 28 d unconfined compressive strength of samples reaches 1.51 MPa,and the CBR values are 65%,the fluoride ions in the leaching solution of the sample is 0.61~2.00 mg/L,and the total phosphorus is less than 0.003 mg/L.The fluoride precipitation,phosphate precipitation chemical stabilization method and hydration gel product(C-S-H,C-A-S-H)adhesion package physical curing method are used to achieve fluorine fixation and phosphorus removal.Through the application verification of filling test road,the compaction degree,deflection value,rebound modulus value and pollutant leaching amount of solidified phosphogypsum all meet the requirements of relevant specifications.