水泥-磷石膏稳定碎石路面基层材料的研究与应用

Research and Application of Cement-Phosphogypsum Stabilized Crushed Stone Pavement Base Material

为了促进磷石膏的综合利用,改善水泥稳定碎石的抗裂性能。本文通过磷石膏部分取代细集料制备了一种水泥-磷石膏稳定碎石材料,系统地分析了材料强度、水稳性能和抗裂性能的影响因素。结果表明,水泥剂量、磷石膏掺量和集料级配均对水泥-磷石膏稳定碎石材料的强度有较大影响。适当将细集料的质量分数降低5%~10%,更有利于材料形成骨架密实型结构。磷石膏除了具有细集料的填充作用,还可以促进膨胀性钙矾石(AFt)晶体生长。磷石膏掺量为8%(质量分数)的水泥-磷石膏稳定碎石泡水养护7 d的强度保持率为73.4%,水稳性能良好,与水泥稳定碎石相比,其7 d强度提高了26.7%,28 d干缩应变降低了40.3%。在贵州省某二级路进行了工程应用,试验段检测的合格率为100%,验证了生产配合比的可行性。

In order to promote the comprehensive utilization of phosphogypsum(PG) and improve the crack resistance of cement stabilized crushed stone,the cement-PG stabilized crushed stone material was prepared by partially replacing fine aggregate with PG.The factors affecting the strength,water stability,and crack resistance of the material were systematically analyzed.The results show that the cement dosage,PG content,and aggregate gradation have a significant impact on the strength of cement-PG stabilized crushed stone material.Properly reducing the mass fraction of fine aggregate by 5%~10% is more conducive to the formation of the framework dense structure.PG has a filling effect of fine aggregate and promotes the growth of expansive ettringite(AFt) crystals.When the content of PG is 8%(mass fraction),the strength retention rate of cement-PG stabilized crushed stone after soaking in water for 7 d is 73.4%,showing the fine water stability.Compared with cement stabilized crushed stone,its 7 d strength increases by 26.7% and 28 d dry shrinkage strain is reduced by 40.3%.An engineering application is carried out on a secondary road in Guizhou Province,and the pass rate of the test section is 100%,verifying the feasibility of the mix proportion.