高镁镍渣-磷石膏基胶凝材料固化和改良盐渍土的性能

Properties of Solidified and Modified Saline Soil by High MagnesiumNickel Slag-Phosphogypsum Based Cementitious Materials

本工作以高镁镍渣(HMNS)和磷石膏(PG)等工业固体废弃物为主要胶凝材料,针对盐渍淤泥的处理难点,同时固化和改良处理盐渍淤泥。评价了高镁镍渣-磷石膏基胶凝材料固化和改良盐渍土的工程性能和理化性能,并对固化作用机制进行了分析。通过现场试验进一步验证高镁镍渣-磷石膏基胶凝材料固化和改良盐渍土的可行性。结果表明:HMNS-PG基胶凝材料固化盐渍土路用性能优于传统水泥固化土。掺20%HMNS-PG基胶凝材料固化土饱水1 d、3 d、5 d、7 d后的水稳系数分别为0.84、0.81、0.8、0.79。冻融循环15次后固化体抗压强度损失率和质量损失率分别为13.2%和2.9%,试件完整性良好。同时磷石膏改良盐渍土使得盐分析出,土壤颗粒团聚,减少了盐胀等病害。HMNS-PG基胶凝材料改良盐渍土后,盐渍土的pH值降低,浸出液电导率EC值提高,钠的吸附比(Sodium adsorption ratio,SAR)降低。现场固化试验中,试段取两组试样测得无侧限强度分别为3.4 MPa和2.8 MPa,压实度分别为94.7%和94.1%,240 d电导率提高了约118.1%,pH值下降了约6.13%,理化性能明显得到改善。

In this work,industrial solid waste such as high magnesium nickel slag(HMNS)and phosphogypsum(PG)was used as the main cementitious material for the treatment of salted sludge,the salted sludge was treated by solidification and improvement at the same time.The physical and chemical properties of high magnesium nickel slag-phosphogypsum based cementitious materials for solidify and modify saline soil were evaluated,and the mechanism of solidification was analyzed.Finally,the feasibility of solidification and modification of saline soil by high magnesium nickel slag-phosphogypsum based cementitious material was verified by field test.The results showed that the road performance of solidified saline soil with HMNS-PG based cementitious material was better than that of traditional cement solidified soil.The water stability coefficients of the soil after 1 d,3 d,5 d and 7 d solidification with 20%HMNS-PG-based cementitious materials were 0.84,0.81,0.8 and 0.79,respectively.After 15 freeze-thaw cycles,the compressive strength loss rate and mass loss rate of the solidified body were 13.2%and 2.9%,respectively,and the integrity of the test piece was good.At the same time,the phosphogypsum improved the saline soil,so that the salt was precipitated,the soil particles were agglomerated,and the salt swelling and other diseases were reduced.After improving the saline soil with HMNS-PG-based cementitious material,the pH value of the saline soil decreased,the EC value of the conductivity of the leachate increased,and the sodium adsorption ratio(SAR)decreased.In the on-site curing test,the unconfined strengths of the two groups were 3.4 MPa and 2.8 MPa,the compaction degrees were 94.7%and 94.1%,respectively,and the conductivity of 240 d was increased by about 118.1%.The pH value fell by about 6.13%,the physical and chemical properties were obviously improved.