| 摘要: |
| 研究了2种减缩剂被水泥熟料、矿渣和粉煤灰等固体颗粒吸附的性质及其对水溶液和模拟水泥石孔隙溶液表面张力、蒸发速率的影响.结果表明：水泥熟料、矿渣和粉煤灰等固体颗粒对2种减缩剂的平均吸附率小于10%，有90%以上减缩剂溶于溶液中；2种减缩剂溶于水或模拟水泥石孔隙溶液中均能有效降低溶液的表面张力和蒸发速率.减缩剂的作用历程和机理为：溶解于水泥石孔隙溶液中的减缩剂能长期稳定地降低溶液的表面张力，从而减少因毛细孔失水所产生的收缩应力，此外还能在一定程度上降低溶液的蒸发速率，这两方面的共同作用抑制了水泥基材料的收缩. |
| 关键词: 减缩剂(SRA) 吸附量 表面张力 蒸发速率 机理 |
| DOI：10.3969/j.issn.1007 9629.2012.05.004 |
| 分类号: |
| 基金项目:国家重点基础研究发展计划（973计划）项目(2009CB623104)；高性能土木工程材料国家重点实验室开放基金资助项目(2010CEM011) |
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| Action Course and Mechanism of Shrinkage Reducing Admixture in Cement Based Materials |
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WANG Zhi1, GUO Qing chun1, JIANG Nan1, QIAN Jue shi2, DANG Yu dong2
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1.College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China;2.College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China
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| Abstract: |
| The adsorption of two shrinkage reducing admixtures(SRAs) on the surface of solid particles, such as cement clinker, slag and fly ash were investigated. Besides, the effect of SRA on surface tension and evaporation rate of water solution and simulated pore solution(SPS) were researched as well. The results indicate that the average adsorption rate of SRA on the surface of solid particles is less than 10%, so more than 90% of SRA remains in solution. The SRAs can significantly reduce the surface tension and evaporation of water solution and SPS. The action course and mechanism of SRA can be considered as the fact that the shrinkage reduction of cement based materials is resulted from the dissolution of SRA in the pore solution leading to significant reduction of surface tension of pore solution. Meanwhile, the SRA lowers the evaporation rate of the solution. These two effects may be the main causes of shrinkage reduction of cement based materials. |
| Key words: shrinkage reducing admixture(SRA) adsorption surface tension evaporation rate mechanism |
