粘土矿物钝化改性和钝化机理初步研究

Study on Passivation of Clay Minerals and Its Mechanism

在岩土工程中 ,进行灾害防治和软基处理的一个核心问题是把粘土矿物由亲水性改造成疏水性 ,抑制和降低其含水量 ,使得粘土遇水后不再吸水膨胀 ,从而保持土壤的稳定性。岩土力学工程中以保持土壤稳定性为目的对粘土的改性称为“钝化”。所谓钝化就是用钝化剂与粘土矿物表面发生反应 ,改变粘土矿物的表面结构 ,提高憎水性 ,增加粘土整体的力学性质 ,从而达到稳定土体的目的。在粘土矿物钝化中表面活性剂是一个重要的组成部分 ,但是表面活性剂在固液界面的吸附 ,除决定于其本身的性质外 ,还决定于固体的性质、溶液的 pH值和温度等。因此 ,研究粘土矿物表面结构和性质以及与钝化剂的相互作用是提高粘土矿物钝化效果的重要途经。利用近代分析方法 (XRD、IR、Raman、MASNMR、TEM、AFM和SEM ) ,对粘土矿物 (高岭石、蒙脱石和伊利石 )钝化前后的表面结构和性质进行了系统研究 ,并结合相关的土力学、工程力学参数的测定 ,阐明粘土矿物钝化的机理 ,剖析和研制粘土矿物钝化剂 ,为解决各类工程和灾害问题中的土壤稳定提供理论依据。

Clay minerals occur extensively in various geologic enviro nments. In g eotechnical engineering a problem is always involved about the precaution again st natural calamities and the treatment of soft ground. The key of the problem i s controlling and reducing the content of water in clays, and transforming clay minerals from hydrophilic into hydrophobic. In this way the clays won't adsorb w ater an d swell as they were in contact with water, and thus the soil stability could be m aintained. We call the modification of clays for retaining the soil stability in geotechnical engineering ‘passivation’. As the surface of clay minerals inter acts with passivators during the process of passivation, the surface structure of cl a y minerals will be changed and the hydrophobility of clay minerals increased, th us the mechanical strength of clay mineral in the whole will be raised. The surf actant is a very important component in the passivator. However, the adsorption o f surfactants at the interface between solid and liquid is controlled not only b y the properties of surfactants, but also by the properties of solids, pH of sol utions and temperatures etc. So research about the surface structure and the pr operties of solids and the interaction of clay minerals with passivators is an i mport ant way to increase the passivation effect. Physical and chemical study of mineral surface is an extremely active frontier f ield of scientific research. Our study is based on the physics-chemistry of min e ral surface, and involves many analytical methods: XRD, IR, Raman, MAS NMR, SEM, TEM, AFM, and the parameter measurement of solid mechanics and engineering mec hanics. This paper systematically investigates the change of surface structu re and properties of clay minerals (kaolinite, illite and montmorillonite) befor e and after passivation. In order to clarify the mechanism of clay mineral passi vation and to provide theoretical basis for the clay stabilization in resolving various engineering and calamity problems, analyses and preparation work of pass ivators of clay minerals have been done. The work combines the basic research of mineralogy with the experimental investigation of geotechnical engineering.