【作者】 崔德山；

【导师】 项伟；

【作者基本信息】 中国地质大学 ， 地质工程， 2009， 博士

【摘要】 武汉市分布着大量冲洪积形成的第四系红色黏土，其主要黏土矿物成分为高岭石和伊利石，并含有少量绿泥石和蛭石，非黏土矿物为石英、长石和云母。由于红色黏土中含有赤铁矿，其颜色为红色。这一类红色黏土具有中等孔隙性、高塑性、中等含水率、中—低压缩性，中—微弱膨胀性等特点。随着我国经济的高速发展，红色黏土被大量用作建筑材料和地基使用。然而红色黏土地区的乡村土路，公路路基，建筑场地，水利防渗工程等，遇到下雨或雨后一段时间内，路面难以行车、行人；待到天晴，原来的路面已经面目全非。除此之外，红色黏土遇水软化还引发许多工程病害，如：由于红色黏土裂隙发育，遇水土体膨胀，地基不均匀下沉，引起基础结构断裂破坏：地表水流入裂隙性红色黏土，引起土体软化，工程性能变差；裂隙性红色黏土易发生基坑及边坡塌方、滑坡。在长期土壤固化工程中，考虑到资源节约和环境保护，人们逐步认识到，采用水泥、石灰、粉煤灰等传统土壤固化材料存在着明显不足，满足不了社会发展需要。本文研究发现，红色黏土不良物理性质与良好力学性质之间的矛盾，在很大程度上取决于红色黏土颗粒结合水膜的厚度。红色黏土结合水的性质、存在形式、厚度是控制红色黏土塑性、水化膨胀、收缩、比表面、孔隙结构、微结构、土—水特征曲线和抗剪强度等物理力学性质，电导率、吸附性、Zeta电位、阳离子的交换容量和交换性阳离子等电化学性质的重要因素，同时还是引发红色黏土地区地质灾害和地质环境破坏的重要因子。因此，对红色黏土结合水的深入研究就显得十分必要和紧迫。为了减小红色黏土结合水膜的厚度，采用离子土壤固化剂（Ionic Soil Stabilizer，简称ISS）对红色黏土进行处理。ISS是一种复合型的离子表面活性剂，在水中解离后可生成亲水基（疏油基）和疏水基（亲油基），能够显著降低水的表面张力。ISS加入红色黏土后，在土粒表面铺展开，不但润湿土粒表面和毛细管，同时也被滞止于土粒表面及毛细管。ISS与红色黏土表面交换极性阳离子和极性水分子进行离子交换，从而降低土颗粒表面电荷，减薄黏土扩散层厚度，提高水稳性，增加强度。ISS加固红色黏土具有成本低，施工方便，保护环境，强度高，收缩量小等特点，对我们国家建立一个资源节约型、环境友好型的社会，改善农村居住和生态环境，促进农村经济的发展与建立和谐社会具有重要的现实意义。目前，对红色黏土结合水的研究已经取得了一定的进展，但研究ISS对红色黏土结合水作用机理的比较少，并且存在以下几点不足：首先，ISS加固红色黏土前后结合水性质、存在界限和厚度的问题。以往对红色黏土结合水的性质、存在界限和厚度一直没有一个统一的认识，多数学者认为红色黏土的主要矿物成分为高岭石和伊利石，故其结合水主要是强结合水。在游离氧化铁胶结作用下，其性质十分稳定，结合水不容易从红色黏土中脱出，并且其厚度只有几层水分子构成。这个结论十分模糊，并没有解释以非膨胀性黏土矿物组成的红色黏土，在强结合水的作用下，怎么会有近50%的自由膨胀率。而在ISS处理后，其自由膨胀率明显降低，那ISS去掉的是什么水，其存在形式和存在界限是什么，厚度有多少?其次，ISS加固红色黏土结合水定量测量问题。以往只是从红色黏土所表现出来的物理力学性质和电化学性质来臆测其结合水膜增大或减小，显然是不科学的。在加入ISS后，这种有机红色黏土，结合水的失重量有多少，水合行为的变化对工程性质的影响有多大?要解决这个问题，必要根据工程需要建立ISS加固红色黏土结合水定量测量试验方法。再次，ISS对红色黏土结合水作用机理的认识问题。ISS加固红色黏土后，如果没有建立一个从宏观到微观的试验研究方法，其研究只能停留在表面水化和渗透水化及结合水膜变厚、变薄等简单的判断。因此，要想研究ISS加固后红色黏土结合水性质、存在形式和厚度，要想研究Zeta电位、交换性阳离子种类和数量对结合水膜厚度的作用，必须把红色黏土的物理力学性质、电化学性质和微观测试结果相结合，分析ISS对红色黏土结合水的作用机理。鉴于以上分析，为了研究ISS对武汉红色黏土结合水作用机理，本文创新性地对ISS加固红色黏土前后，进行其物理力学性质和电化学性质的系统试验，包括：塑性、水化膨胀、收缩、比表面积及孔隙分布、微结构特征、土—水特征曲线、抗剪强度、阳离子交换容量、交换性阳离子和电动性等方面，并从宏观机理和微观机理进行了初步解释。在此基础上，原创性地建立了红色黏土表面结合水定量分析方法，即热重法、差示扫描量热法和红外光谱法。利用扁平状红色黏土颗粒表面结合水的定量计算方法，计算了ISS加固红色黏土前后，红色黏土结合水膜的厚度的量变。最终创新性地建立ISS加固红色黏土的模型，分析ISS加固红色黏土结合水的性质和分布，并从ISS加固红色黏土后阳离子交换量的变化、扩散双电层结构的变化、结合水薄厚度变化等方面分析了ISS对红色黏土结合水作用机理。本文主要进行了以下研究工作：首先，进行了不同配比ISS与红色黏土作用后其物理力学性质的试验研究，对试验结果分析发现：①不同配比ISS与红色黏土的作用，能够找到反映结合水薄厚度的最低塑性指数，可以作为ISS加固红色黏土的最优配比；②ISS处理后的红色黏土X—射线衍射试验和化学组成分析结果得出，ISS加固红色黏土后并没有新的矿物晶体产生，只是矿物的晶面间距发生了很小的改变。ISS加固红色黏土的化学组成分析得出其H₂O的含量比未加固的多1．88倍。表明ISS不仅能够除掉或者减少红色黏土结合水膜的厚度，而且还能减少多水高岭石或水合多水高岭石的层间水；③ISS的加入能提高红色黏土的抗剪强度，但对滑动摩擦和咬合摩擦的贡献不大，主要是提高土颗粒之间的原始粘聚力和固化粘聚力；④ISS可以置换吸附在黏土矿物表面上的交换性阳离子和极性水分子，从而降低红色黏土的膨胀性和收缩性。红色黏土具有以收缩性为主的胀缩性的原因，并不完全归根于红色黏土中的游离氧化铁，多水高岭石或水合多水高岭石脱去层间水也有一定的贡献；⑤高岭石晶体、交换性阳离子、游离氧化铁和ISS解离的亲水基（呈阴性），在强烈的离子键作用下，形成更大的团聚体和堆叠体。这样ISS加固后，红色黏土的比表面就会减少；⑥ISS加固红色黏土的累积孔体积随着平均孔直径的减小而减小。但并不是每一个孔隙下原状土的累积孔体积都最大，在大孔隙阶段，加固红色黏土累积孔隙体积增长的较大，小于大孔隙之后，原状红色黏土的累积孔隙体积较大，这说明ISS处理红色黏土后，减小的孔隙体积主要是小于大孔隙的体积；⑦液氮冷冻真空升华干燥法可避免由水变成结晶冰而发生的约9%的体积膨胀，避免了对土的结构破坏。经过ISS处理后的红色黏土，用该方法制样，可以看到其微结构主要为面—面和边—面聚集体，也有部分是扁平状和假六方体状高岭石颗粒，其堆叠较密实，其表面胶结物质为游离氧化物和ISS高分子链；⑧ISS加固后的红色黏土随着基质吸力的增加持水能力比红色黏土原样强。最终在500kPa基质吸力下，加固红色黏土的含水率要比不加固的少。ISS作用之后红色黏土的标准吸湿含水率要比红色黏土原样的少。其次，进行了不同配比ISS与红色黏土作用后其电化学性质的试验研究，对红色黏土试样试验结果分析得出：①红色黏土的黏土矿物的净电荷为负电荷，ISS能够置换由表面电荷吸附的阳离子和极性水分子，ISS加固后，红色黏土仍然显示出一定的负电荷；②ISS与红色黏土进行离子交换后，能够降低红色黏土溶液的pH值，而且使ISS溶液的电导率有不同程度的增加。增加后的电导率是ISS溶液的电导率加上从红色黏土中置换下来的阳离子电导率；③红色黏土白溶液中的吸附要考虑三种作用力：即红色黏土与ISS之间的作用力、红色黏土与水之间的作用力和ISS与水之间的作用力；④加入ISS后红色黏土的阳离子交换量减小，表示其带负电量减小，其水化、膨胀和分散能力减弱，所形成的结合水膜厚度减薄。交换时间越长，红色黏土可交换的阳离子越少，说明ISS加固红色黏土后阳离子的交换与交换点位置直接相关，外表面上的交换可瞬时发生，甚至一小时内达到平衡；内表面上的交换需要很长时间才能达到平衡，因为离子在到达交换点前需要在晶层间隙中运动，受离子扩散规律制约，所以往往需要很长时间才能达到平衡。⑤从四个盐基的交换结果组成来看，红色黏土的交换性阳离子以交换性Ca²⁺为主，而且交换性阳离子盐基总量低于或远低于阳离子交换量。这是因为武汉红色黏土是由冲洪积所形成的，在红色黏土红土化过程中，盐基分量K⁺、Na⁺、Ca²⁺、Mg²⁺已经被淋滤掉，对结合水的影向不大，影响结合水膜厚度和离子交换的主要是游离氧化铁，硅、铝离子及其与红色黏土的相互作用；⑥ISS溶液中含有大量高价阳离子，能够置换出土中的阳离子并使水离子化，促使结合水膜厚度减薄，电动电位势下降。这样就打开了土粒与水分子之间的“化学键”而使水分子离开土粒进入周围的自由水中，即土粒周围的大部分结合水被离子化而变成可从土体中排出的自由水。再次，利用热重分析、差示扫描量热法和傅里叶变换红外光谱技术对红色黏土中的结合水进行了定量的分析，并得出：①以热重分析法和差示扫描量热法定量计算结合水，以红外光谱法定性确定黏土表面吸附结合水性质和确定结合水类型及其界限的实验研究方法是可行的。②ISS加固红色黏土，风干状态下进行的TG/DSC曲线说明，ISS可以明显的减少红色黏土的弱结合水，最多可以从0．58%降到0．42%；强结合水也有一定程度的减少，从0．57%可以降到0．45%。③ISS处理后的红色黏土，多水高岭石或水合多水高岭石的层间水减少。④未加ISS的红色黏土其红外光谱在高步区出现三个典型的吸收谱带，即3700cm^-1，3650cm^-1，3620cm^-1，并且透射强度依次降低，这个特征说明红色黏土原样不是结晶完好的高岭石，其图谱类似多水高岭石和水合多水高岭石。加入ISS后，红色黏土的内部OH和内表层OH的结构并没有发生变化。ISS处理后红色黏土结合水吸收峰同Si—O键吸收峰比率下降，表明红色黏土中的结合水含量均有所减少，但ISS并不能完全置换红色黏土表面的强结合水。⑤根据厚度法的计算公式，计算出了ISS加固红色黏土前后弱结合水膜的厚度。在液限状态下，红色黏土原样弱结合水膜的厚度是112．97nm。ISS处理后，弱结合水膜的厚度减薄，厚度可以减小到76．74nm，降幅达20%。通过以上研究分析，得出ISS加固红色黏土的作用机理主要有以下几点：①ISS的亲水基与红色黏土质点结合，“疏水尾”则从黏土颗粒表面向外形成一保护油层围绕着红色黏土。这样，吸附在红色黏土颗粒表面的水被“疏水尾”挤出。②ISS能降低红色黏土表面结合水的表面张力。当ISS占居并吸附在黏土颗粒表面后，润湿黏土颗粒表面，降低表面结合水的表面张力，在疏水基的作用下，将红色黏土表面的结合水置换掉。③ISS处理红色黏土后，红色黏土的结合水及其中的交换性阳离子大部分被ISS解离的阳离子从红色黏土颗粒上置换下来，导致强结合水膜变得更薄，红色黏土密度更大，物理力学性质也有所提高，具有极大的抗剪强度。红色黏土变成有机红色黏土，这种有机红色黏土颗粒表面层实际上具有了疏水的碳氢化合物的属性，往往具有抗水特性。④ISS加入红色黏土，使溶液中阳离子浓度高，并与红色黏土颗粒表面的阳离子和极性水分子进行强烈交换。这种交换作用的结果是使土粒与水分子和交换性阳离子之间的作用由原来的相互吸引变为相互排斥，打开了土粒与水分子和交换性阳离子之间的“化学键”，从而释放出束缚在吸附层和扩散层内的交换性阳离子和结合水，从而降低红色黏土的电动电位，使红色黏土的结合水厚度减薄；与此同时，ISS能使溶液电解质浓度增加，在渗透力的作用下，红色黏土颗粒表面的结合水向溶液中扩散，使双电层减薄，结合水膜减薄。虽然ISS能置换红色黏土表面的交换性阳离子，使红色黏土表面双电层减薄，结合水减少，但是不会改变双电层的结构，红色黏土表面依然存在电动电位。更多还原

【Abstract】 There are lots of red clay of Quaternary from alluvial-diluvial in WuHan City. The mail components of clay mineral are kaolinite and illite, also small amount of chlorite and vermiculite; the non-clay minerals are quartz, feldspar and mica. Because of containing hematite, the red clay’s color is red. This type of red clay is characterized by medium-porosity, high-plasticity, medium-water content, medium-low compression, medium-weak expansion. With the rapid development of China’s economy, red clay was used as construction materials and foundation. However, when the village dirt roads, temporary roads, building sites, anti-seepage projects of red clay meet rain, bad road traffic is too bad to use. When the weather is fine, the original road surface has changed dramatically. In addition, the red clay softened by the water has also arisen lot of project diseases, for example, because of fracture of red clay, the red clay swells when meeting water, which will cause inhomogeneous subsidence damage and infrastructure faults; when surface water flows into cracks of red clay, it will soften the soil, decrease the work performance; the foundation and slope of crack red clay are prone to collapse, landslides. At the long-term of soil-reinforcement project, taking into account the resource conservation and environmental protection, people gradually realized that the use of cement, lime, fly ash and other traditional soil-reinforcement material have a lot of shortage, which can not meet the needs of social development.The study shows that the conflict between the adverse physical properties and good mechanical properties of red clay mainly depends on the thickness of adsorbed water film of red clay granules. The property, type and thickness of adsorbed water film of red clay not only has correlation with plasticity index, hydration-expansion, shrinkage, specific surface area, pore structure, micro-structure, soil-water characteristic curve and shear strength etc. physical and mechanical properties, but also pH, conductivity rate, absorption, Zeta potential, cation exchange capacity and exchangeable cation etc. electrochemical properties. At the same time the adsorbed water of red clay is an essential factor to trigger geological disasters and environmental damage. Therefore, research on the adsorbed water of red clay is very necessary and urgent. In order to reduce the thickness of adsorbed water film. Ion Soil Stabilizer （ISS） is used to deal with red clay. ISS is a complex of ion surfactant. The hydrophilic group and hydrophobic group of ISS can significantly reduce the surface tension of water. Added into the red clay, ISS can not only occupy and wet the surface of soil and capillary, but also exist on the surface and capillary. ISS can exchange with polarity water molecules and exchangeable cations of the red clay surface, thus ISS can decrease the charge of the soil particle surface, thin the thickness of diffusion layer, improve water stability and the intensity of red clay. ISS reinforces the red clay, which has the characteristics of low cost, easy construction, environmental protection, high intensity and small amount of shrinkage. For China to build a resource-saving and environment-friendly society, to improve rural living and ecological environment, to promote rural economic development and the establishment of a harmonious society is an important practical significance.At present, the study of red clay adsorbed water have made some progress, but the study of mechanism of ISS with red clay adsorbed water is relatively low and there are some storages such as following: First of all, the water nature, existence boundary and thickness of red clay adsorbed water before and after treating with ISS. In the past it has not been a unified understanding, the majority of scholars believe that the main mineral compositions of red clay are kaolinite and illite, so its adsorbed water is strong adsorbed water. In the role of free iron oxide, it is very stable in nature. Adsorbed water is not easy to break away from the red clay and the thickness is several layers of water molecules only. This conclusion is very vague, and did not explain that non-swelling clay mineral composition of the red clay, in the role of strong adsorbed water, how the free-swell reaches nearly 50%. After treatment with the ISS, the free expansion rate decreased significantly. What water ISS remove, what is the existence forms, exist boundary and the thickness? Secondly, the problem of quantitative measurement of red clay adsorbed water after treatment with ISS. In the past, the guessing results of increase or decrease the adsorbed water film according to the physical and mechanical properties and electrochemical properties is clearly unscientific. After joining ISS, what is the number of weight loss of adsorbed water, how the hydration behavior impact on the project property. In order to resolve this problem, it is necessary to set up adsorbed water test method of quantitative measurement. Once again, the problem of research on the mechanism of ISS with red clay adsorbed water. After ISS reinforcing the red clay, if not set up a mechod from a macro to micro-research, the research will remain at the surface hydration and penetration. Therefore, in order to research on the nature, existence limit and thichness of red clay adsorbed water film, to study of Zeta potential, the type and quantity of cation exchange, combination of physical and mechanical properties, electric chemical nature and micro-test results are necessary to analysis the mechanism of ISS-reinforcing adsorbed water of red clay.In view of the above analysis, in order to research on the mechanism of ISS treating adsorbed water, the article firstly revolutionary carry on the following physical, mechanical and electrochemical properties test of red clay treated by ISS, for example, plastic, hydration expansion, shrinkage, specific surface area and pore size distribution, micro-structural characteristics, soil-water characteristic curve, shear strength, cation exchange capacity, exchangeable cation and Zeta potential, etc. ,from the macro to micro-mechanism to give preliminary explanation. On this basis, the mechods of quantitative analysis of red clay adsorbed water was established, that is thermogravimetry, differential scanning Calorimetry and infrared spectroscopy; use of the flat model of red clay particle to calculate the adsorbed water with the quantitative method. Finally the model of ISS-reinforcing red clay is set up to analysis the nature and distribution of red clay adsorbed water. The reaction mechanism of 1SS with adsorbed water is analyzed from cation exchange capacity, double-layer changes and thickness of adsorbed water.In this paper, the following research works have been done.First of all, physical and mechanical properties test of a different ratio of ISS on red clay was carried on, the test results show:①Different proportions of ISS added, red clay can be found the minimum plastic index that can be used as the optimal ratio of reinforcing red clay;②X-ray diffraction and chemical composition analysis results show, after adding ISS, there is no new mineral or crystal, only small distances of crystalline surface changes. The chemical composition of red clay adding ISS has no change; the H₂O content is 1.88 times than the unreinforcement soil. That is to say ISS will not only be able to get rid of or reduce the thickness of adsorbed water of red clay, but also to reduce the number of interlayer water of halloysite;③The red clay added ISS can improve the shear strength, but no contribution to the sliding friction and occlusion friction, mainly enhance original cohesion and reinforcing cohesion of soil particles;④ISS can replace the exchangeable cation and the polar water molecules of particle surface, thereby reducing the the expansion and shringkage of red clay. Red clay with a shrinkage, the main reasons is not fully explained of free iron oxide, halloysite’s inter layer water must have the contribution;⑤Kaolinite crystals, exchangeable cation, free iron oxide and hydrophilic group （negative） of ISS, in the role of a strong ionic bond, can form a larger aggregates and stacked body. By this way, the specific surface area of red clay treated by ISS will be reduced;⑥The cumulative pore volume decreased with average pore diameter decreased of red clay treated with ISS. Using ISS to deal with red clay, only the pore size is less than the size of large pores can by decrease;⑦Liquid nitrogen freeze- vacuum drying can avoid the crystallization of water into ice and will not appear about 9% of the volume expansion to prevent destroy the structure of soil. After adding ISS, it can be seen that micro-structure of red clay is face to face and the edge to face aggregates. Some particles are flat and like-hexahedron kaolinite particles, the stack is very compaction. Cementation material of surface is free oxides and ISS’s polymer chain;⑧After added ISS, the red clay’s water-holding capacity increase with the matrix suction increase. At 500kPa, the water content of reinforced red clay is less than the non-reinforcement red clay. Standard moisture absorption water content of red clay reinforced by ISS is less than the non-reinforcement red clay.Secondly, The electrochemical properties test was carried on a different ratio of ISS, and the results analysis is as following:①The net charge of red clay’s clay minerals is negative charge, ISS can replace cation and the polar water molecules, after that, the red clay particle still show the negative charge;②After ion exchange of ISS with the red clay, the pH of red clay solution decrease, and the conductivity of ISS solution increase;③The adsorption of red clay from solution have to consider three types of force: the red clay with ISS, red clay and water, ISS and water;④After treatment with ISS, the cation exchange capacity of red clay decrease, which will indicate its negative electricity decrease, the hydration, swelling and dispersion decline, the thickness of adsorbed water film thin. The exchangeable cation of red clay decrease with the time increase, which indicates the cation exchange capacity is different in the surface and interlayer. The surface can be instantaneous exchange; on the interlayer surface, it wil take a long time to achieve the required balance, because the exchangable ions before arrival at the purpose will move in the interlayer. Constrained by the laws of ion diffusion, it often requires a long time to achieve balance.⑤From the results of cation exchange of four components, the exchangeable cation of the red clay is mainly Ca²⁺, and the total amount of exchangeable cations is lower or much lower than the cation exchange capacity. Because red clay is alluvial-diluvial, in the process of laterization, the ion of K⁺, Na⁺, Ca²⁺, Mg²⁺ has been filtered, and has little effect on the thickness of adsorbed water film, but free iron oxide, silicon, aluminum ion and its interaction with the red clay have great impact on adsorbed water;⑥ISS solution contains a large number of high charge cation which can exchange the cation in the red clay and make the thickness of adsorbed water film thin, Zeta potential drop. That will open the force between soil and water molecules, and make the water molecules leave from the soil surface into the surrounding water freely. At last, most of the adsorbed water of soil can become discharged from the soil into free water.Thirdly, the thermogravimetric analysis, differential scanning Calorimetry and Fourier transform infrared spectroscopy technology is use to quantitative analysis the adsorbed water of the red clay , the results show:①The combination of thermogravimetric analysis and differential scanning Calorimetry to quantitatively calculate the adsorbed water, and Fourier transform infrared spectroscopy to determine the nature, type and limit of adsorbed water of red clay surface are feasible.②The TG / DSC curves of air-dried red clay show that ISS can significantly reduce the weak adsorbed water of the red clay, from 0.58 percent to 0.42 percent down, lower by 28%; strong adsorbed water also can be reduced from 0.57 percent to 0.45 percent, lower by 21%.③The interlayer water of halloysite is reduced after adding ISS.④At high step of infrared spectra there are three typical absorption bands, 3700cm^-1, 3650cm^-1 and 3620cm^-1, whose transmission intensity decrease one by one. The characteristics of red clay spectroscopy show it is not well-crystalline kaolinite, similar to halloysite. Adding ISS, the internal OH and OH in the structure surface has not changed. The rate of absorption peak of adsorbed water and Si-0 bond decrease, that is to say adsorbed water in the red clay reduce, but ISS can not completely replace the strong adsorbed water of red clay surface.⑤According to the formula for calculating the thickness of weak adsorbed water before and after adding ISS. In the status of liquid limit, the thickness of weak adsorbed water film of red clay is 112.97nm, after treatment with ISS, the thickness of weak adsorbed water film of red clay can be reduced to76.74nm, 20% decline.Through the above analysis, the mechanism of ISS-reinforece red clay can be described as following:①The hydrophilic-group of ISS can combine with red clay particle, but the hydrophobic-group outward from the surface of clay particles to form a reservoir to protect the red clay. In this way, the adsorbed water of red clay surface can be forced out by hydrophobic-group.②ISS can reduce the surface tension of solution. When ISS occupy the location of red clay surface, moisten the surface of particle, decrease the surface tension of adsorbed water, in the role of hydrophobic, the surface adsorbed water will be replaced.③The adsorbed water and exchangeable cation of red clay can be replaced and form free water after adding ISS. That make the thickness of adsorbed water film thin and density of red clay increase, also make the physical and mechanical properties improved. This organic red clay has the property of hydrocarbons of hydrophobic on the surface, is often water resistant property.④ISS can make the solution high ion concentrations, and exchange the exchangeable cation and polar water molecules on the surface. The result of exchange is to enable the exchangeable cation and polarity water molecules separate from the red clay particle, thereby reducing the Zeta potential of red clay, make the thickness of adsorbed water thin. At the same time, ISS can increase the concentration of electrolyte solution, in the role of penetration, the adsorbed water diffuse to solution, the electric double layer and adsorbed water thinning. Although ISS and replace the exchangeable cation and polar water molecules of the surface of red clay, make the electric double layer thin, make the thickness of adsorbed water reduce, but ISS can not change the structure of electric double layer. Zeta potential of red clay still exists.更多还原