粘土对聚羧酸减水剂吸附性能的机理研究

发布时间：2018-07-16 12:06

【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。
[Abstract]:With the application of polycarboxylic acid water reducing agent in practical engineering , it is found that the mud in concrete aggregate can adsorb polycarboxylic acid water reducing agent , which results in poor concrete working performance , which is mainly characterized by the decrease of concrete fluidity , excessive slump loss , strength and durability .

The effect of clay mineral on the performance of polycarboxylic acid water reducing agent was studied by experiments . The results showed that montmorillonite had the greatest influence on the dispersibility of polycarboxylic acid water reducing agent . When the content of clay was more than 4 % , the net slurry fluidity after 1h was 0 ;
The adsorption capacity of montmorillonite to polycarboxylic acid water reducing agent is the strongest , the adsorption capacity of montmorillonite is 2.5 times that of cement particles , and the adsorption of kaolin to polycarboxylic acid water reducing agent is the weakest ;
the adsorption capacity of the clay mineral to the polycarboxylic acid water reducing agent increases with the concentration of the polycarboxylic acid water reducing agent , and finally reaches the saturated adsorption capacity ;
The saturated adsorption capacity of montmorillonite to polycarboxylic acid water reducing agent was 12.76mg / g and 11.11mg / g , 7.69 mg / g and 7.69 mg / g , respectively .
The Freundlich adsorption model calculates the adsorption strength and adsorption capacity of the clay to the polycarboxylic acid water reducing agent , and the adsorption strength decreases with the increase of the temperature , but the adsorption capacity gradually increases as the temperature increases ;
The adsorption rate of various clay minerals on polycarboxylic acid water reducing agent was calculated by Lagergren ' s adsorption model , and the adsorption rate was decreased with increasing temperature .

The adsorption mechanism of clay to polycarboxylic acid water reducing agent was studied from electrostatic interaction and chelating effect of metal cation and polycarboxylic acid water reducing agent .
The adsorption form of clay to polycarboxylic acid water reducing agent was studied by means of infrared spectrum and XRD . The results showed that the adsorbed polycarboxylic acid water reducing agent molecules entered into the clay structure ;
In view of the clay in Wuhan area , the adsorption mechanism of polycarboxylic acid water reducing agent was studied by using clay , and the measures to improve the fluidity of slurry body were put forward .
【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.042.2

【参考文献】