煤系固废协同固化盐渍土的力学特征与机理研究

以干旱半干旱地区固体废弃物资源化利用为研究背景，利用煤系固废煤矸石(CG)、煤系偏高岭土(CMK)联合干旱区易获取的固废材料电石渣(CS)协同普通硅酸盐水泥(OPC)开发一种新型固化材料，探讨其固化干旱半干旱区盐渍土的力学性能与微观变化机理。基于室内实验，对比100%OPC固化盐渍土，研究不同矿区产出的CG以及煤矸石-煤系偏高岭土-电石渣协同固化剂(CGCMK-CS)替代52%、60%、68%、72%、84%OPC后各龄期的无侧限抗压强度(UCS)特征，并取特征组进行有害阴离子(Cl-、SO42-)浸出试验与微观测试，从微观角度对其强度变化机理进行探讨。结果表明，煤矸石–电石渣–煤系偏高岭土–普通硅酸盐水泥协同固化(CG-CMK-CS-OPC)体系具有良好的Cl-与SO42-结合能力，固化盐渍土后Cl-与SO42-浸出量是100%OPC的一半，其水化产物铝酸三钙能与盐渍土中的Cl-与SO42-生成AFm相产物，并使体系中的团粒内孔隙与团粒间孔隙向颗粒内与颗粒间孔隙转化，由此降低了盐渍土中盐分带来的危害。根据7 d UCS试验结果，使用山西运城CG固化体系的效果最佳，这与其活性钙质和铁铝...

Mechanical properties and mechanism of co-curing saline soil with coal solid waste

Under the research background of resource utilization of solid wastes in the arid and semiarid regions, a new curing material was developed with the coal wastes (such as the coal gangue (CG) and coal metakaolin (CMK)), the carbide slag (CS) that is a waste material readily available in the arid region, and the ordinary Portland cement (OPC). Besides, its mechanical properties and microscopic change mechanism in curing of saline soil in the arid and semi-arid regions were discussed. Based on the laboratory experiment, the unconfined compressive strength (UCS) characteristics of curing saline soil in different ages were studied by replacing 52%, 60%, 68%, 72% and 84% OPC with CG from different mines and CG-CMK-CS, and comparison was made with the saline soil cured with 100% OPC. Then, the characteristic groups were taken for the leaching tests of harmful anions (Cl? and SO₄ 2?) and microscopic tests to investigate the strength change mechanism from a microscopic perspective. The results show that the CG-CS-CMK-OPC system has a good ability of binding Cl? and SO₄ 2?, with the leaching amount of Cl? and SO₄ 2? equivalent to only half of that cured by 100% OPC. Further, the hydration product tricalcium aluminate could form AFm with Cl? and SO₄ 2? in the saline soil, and thus the intra-agglomerate and inter-agglomerate pores in the system are transformed into intra-granular and inter-granular pores, reducing the hazard caused by salt in saline soil. The results of the 7d UCS test show that Shanxi Yuncheng CG curing system has the best strength, which is related to its high content of active calcium and ferroaluminum, as well as the low content of biomass. Shaanxi Yulin CG takes the second place and Shaanxi Xianyang CG has the worst performance. After replacing 52% OPC for curing saline soil with CG-CMK-CS, the compression strength of some test groups q_u exceeded that of curing saline soil with 100%OPC. Even after the replacement of 84%OPC, CG-CMK-CS-OPC can still meet the strength requirements of cement and fly ash material for highway base. Therefore, CG-CS-CMK-OPC can be used as a green, economic, environmental friendly and low-carbon curing material and promoted in the application of saline soil road subgrade engineering in the arid and semi-arid regions.