粘土对聚羧酸减水剂吸附性能的机理研究

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1、ADissertationSubmittedinPartialFulfillmentoftheRequirementsfortheDegreeofMasterinEngineering（MechanismResearchofclayontheadsorptionperformanceofploycarboxylatesuperplasticizer）MasterCandidate：HeZhenglianMajor：CivilEngineeringSupervisor：A.P.GuoshengLiaoWuha

2、nUniversityofScienceandTechnologyWuhan,Hubei430065,P.R.ChinaMay,2015摘要随着聚羧酸减水剂在实际工程的大量应用，发现混凝土骨料中的泥会吸附聚羧酸减水剂，导致混凝土工作性能变差，主要表现为混凝土流动性下降、坍落度损失过快、强度和耐久性降低。本研究主要选取蒙脱土、伊利土和高岭土三种粘土矿物，通过实验分析粘土矿物对聚羧酸减水剂性能的影响，研究表明蒙脱土对聚羧酸减水剂分散性影响最大，当粘土掺量大于4%时，1h后的净浆流动度为0；蒙脱土对聚羧酸减水剂吸

3、附最强，其吸附量是水泥颗粒的2.5倍，高岭土对聚羧酸减水剂吸附最弱；粘土矿物对聚羧酸减水剂的吸附量随聚羧酸减水剂的浓度增加而增加，最后达到饱和吸附量；通过Langmuir等温吸附模型计算出蒙脱土对聚羧酸减水剂的饱和吸附量为12.76mg/g，伊利土的饱和吸附量为11.11mg/g，高岭土的饱和吸附量为7.69mg/g；Freundlich吸附模型计算粘土对聚羧酸减水剂的吸附强度和吸附能力，且吸附强度随着温度的升高而降低，但是吸附能力随着温度的升高逐渐增大；Lagergren吸附模型计算各类粘土矿物对聚羧酸减

4、水剂的吸附速率，随着温度的升高吸附速率降低，说明升温不利于粘土聚羧酸减水剂的吸附。从静电作用和金属阳离子与聚羧酸减水剂的螯合作用出发，研究粘土对聚羧酸减水剂的吸附机理；利用红外光谱和XRD等微观测试手段，研究粘土对聚羧酸减水剂的吸附形式，研究表明被吸附的聚羧酸减水剂分子进入到了粘土结构内部；针对武汉地区粘土，利用粘土对聚羧酸减水剂的吸附机理，提出复配抗泥剂改善浆体流动性的措施。关键词：聚羧酸减水剂；分散性；粘土矿物；吸附；模型；温度IAbstractHaveappearedmudintheaggregate

5、absorbingtheploycarboxylatesuperplasticizerwiththeapplicationofploycarboxylatesuperplasticizerintheactualengineering,whichlowerconcreteperformanceseriously,mainshowinglessliquidityconcrete,slumplosstoofast,strengthanddurabilityreduceobviously.Thisstudychoo

6、semontmorillonite,illiteandkaolinitethreekindsofclaymineralsandthroughtheexperimentanalyzedtheeffectonploycarboxylatesuperplasticizerofdifferentclayminerals,researchshowsmontmorillonitehasthegreatesteffectinthedispersivityofploycarboxylatesuperplasticizer,

7、theflowabilityiszeroafter1hwhenclaycontentismorethan4%;montmorillonitehasthestrongestadsorptioncapacityofploycarboxylatesuperplasticizers,whichadsorptionpropertiesismorethan2.5timesthanthecementparticleadsorption,theadsorptionofkaoliniteisweakest.Clayadsor

8、ptionincreaseswithconcentrationofploycarboxylatesuperplasticizer,andgetsaturatedadsorptionfinally;Simulatingtheadsorptionmodelforploycarboxylatesuperplasticizerthroughrelevantexperimentaldata,theresultsshowth