适用于高海拔地区的防冻泵送剂制备及性能研究

Preparation and performance of antifreeze pumping agent for high altitude areas

高海拔地区年平均气温低,日温差大,气候恶劣,为提高泵送混凝土的应用性能,通过在减水剂中添加防冻、引气、缓凝和早强组分制备应用于高海拔地区的液体防冻泵送剂。采用五因素四水平正交试验设计确定各组分的最佳掺量并进行试验验证。采用方差分析(analysis of variance,ANOVA)法对防冻泵送剂的低温储存稳定性、混凝土的坍落度和坍落度经时损失值、R-7、R 28及R-7+28技术性能指标进行研究。采用扫描电子显微镜(scanning electron microscope,SEM)表征防冻泵送剂对混凝土微结构的影响。结果表明:聚羧酸减水剂、葡萄糖酸钠、十二烷基苯磺酸钠、硝酸钙和甲醇的质量分数分别为25%、0.3%、0.5%、11%和9%时,其低温抗冻性、初始坍落度、坍落度经时损失及低温抗压强度较优;掺加防冻泵送剂的受检混凝土早期即可形成相互连接、紧密堆积的C-S-H凝胶,且混凝土内部孔隙被填满,微结构致密。

In order to improve the application performance of pumping concrete,the liquid antifreeze pumping agent was prepared by adding antifreeze,air entraining,retarding and early strength components into water reducing agent..The optimal concentration of each component was determined by 5-factor 4-level orthogonal test design.Analysis of variance(ANOVA)was used to study the low temperature storage stability of antifreeze pumping agent,the slump of concrete,the slump loss value and the technical performance indexes of R-7,R 28 and R-7+28.The effect of antifreeze pumping agent on concrete microstructure was discussed by scanning electron microscope(SEM).The results show that when the mass fraction of polycarboxylate superplasticizer,sodium gluconate,twelve alkylbenzene sulfonate,calcium nitrate and methanol were 25%,0.3%,0.5%,11% and 9% respectively,their low temperature frost resistance,initial slump,loss of time slump and low temperature compressive strength were better.The C-S-H gel was connected and packed early in the tested concrete with antifreeze pumping agent.And the internal pores of concrete was filled and the microstructure was compact.