膨胀剂中过量SO_4^(2-)对混凝土性能影响

Effect of Overdose SO_4^(2-) of Expansive Agent on Concrete Property

本文采用化学方法对掺膨胀剂水泥石28d可溶出SO42-进行了化学分析,测试了掺不同膨胀剂混凝土的强度,采用NEL法测试了掺不同膨胀剂混凝土试件冻融循环前、后的氯离子扩散系数,试验结果表明:随着膨胀剂水泥石试样28d可溶出SO42-的增多,混凝土强度呈递增趋势,且掺膨胀剂的混凝土强度都高于空白混凝土,混凝土氯离子扩散系数呈降低趋势;冻融循环后,掺28d可溶出SO42-最少的膨胀剂的混凝土氯离子扩散系数最小,可溶出SO42-较多的膨胀剂的混凝土氯离子扩散系数最大,未掺膨胀剂混凝土居中,可见膨胀剂中过量SO42-的存在,对掺膨胀剂混凝土强度、抗渗性是有利的,对掺膨胀剂混凝土抗冻性是不利的。

This paper studies the 28 days dissolved SO42-of the cement paste with expansive agent by chemical method and tests strength of the concrete with different expansive agent, tests the Cl-diffusion coefficient of the concrete with different expansive agent before and after freezing and thawing cycle by NEL method.The experimental result shows that with the increasing of the 28 days amount of dissolved SO42-, their strength increases gradually, the strength of concrete with expansive agent is higher than the strength of concrete without expansive agent, and the Cl-diffusion coefficient decreases gradually .After freezing and thawing cycle, the Cl-diffusion coefficient of the expansive agent concrete with the least 28 days amount of dissolved SO42-is lowest, the Cl-coefficient of diffusion of the expansive agent concrete with the most 28 days amount of dissolved SO42-is highest, the Cl-diffusion coefficient of the concrete without expansive agent is placed in the middle.It can be seen that the overmuch dissolved SO42-from expansive agent is propitious to the strength and impermeability of concrete and is not propitious to the frost resistance of concrete.