纳米高岭土改性砂浆抗酸雨侵蚀试验研究

Experimental study on acid resistance of nano-kaolinite modified cement mortar

为了研究纳米高岭土对砂浆抗酸雨腐蚀性能的影响,配置pH值为1.5的硫酸硝酸混合溶液以模拟酸雨环境,研究了模拟酸雨环境下包含不同纳米高岭土掺量(0,1%,3%,5%)的砂浆试件的物理力学性质.利用场发射扫描电镜分析了酸性介质侵蚀过程中砂浆材料微观结构的变化规律,探讨了纳米高岭土对砂浆抗酸雨腐蚀性能的改善机理.试验结果表明:纳米高岭土能够改善砂浆的微观结构,提高砂浆基体密实性,掺入水泥质量1%的纳米高岭土砂浆试件抗压强度提高了21%;同时,还能有效阻碍H+和SO2-4进入砂浆基体内部,减弱了H+引起的溶蚀破坏以及SO2-4引起的膨胀破坏,显著提高砂浆抗酸雨腐蚀能力.酸雨腐蚀60 d后,掺入水泥质量1%的纳米高岭土砂浆试件表面溶蚀现象减弱,强度损失率较普通砂浆试件降低27.23%.

The effects of nano-kaolinite clay on the acid resistance of the ordinary cement mortar are investigated.To simulate the acid deposit condition,the acid solutions with a pH level of 1 .5 are prepared by the mixture of sulfate and nitric acid in the laboratory.The physical and mechanical properties of the cement mortar with four different amounts of nano-kaolinite clay additives （0,1%, 3% and 5%）are studied.The scanning electron microscopy （SEM）is used to analyze the micro-structure evolution of cement mortar during the acid corrosion,and the improvement mechanism of the nano-kaolinite clay for the acid resistance of the cement mortar is discussed.The experimental re-sults show that nano-kaolinite clay leads to a denser microstructure in the mortar matrix.The com-pressive strength of the modified cement mortar with 1% nano-kaolinite clay is increased by 2 1%. And the addition of nano-kaolinite clay can effectively impede the penetration of H＋and SO2-4 into the cement mortar matrix,weaken the corrosion damage caused by H＋and the expanding erosion by SO2-4 ,and therefore improve the acid resistance of the cement mortar significantly.After 60 d expo-sure,the surface erosion of the modified cement mortar with 1% nano-kaolinite clay weakens,and compared with the ordinary cement mortar,the strength degradation ratio decreases by 27 .23%.