苯丙乳液改性水泥砂浆的抗氯离子渗透性

Chloride Diffusivity of Styrene-Acrylate Latex Modified Mortars

在保持相同水灰比的条件下 ,通过改变丙烯酸丁酯、苯乙烯、丙烯酸三元共聚物乳液中丙烯酸丁酯与苯乙烯的质量比 ,研究了聚合物柔性与改性砂浆抗氯离子渗透性之间的关系 .结果发现 ,丙烯酸丁酯与苯乙烯的质量比由 60∶40提高到 90∶1 0时 ,改性砂浆的氯离子扩散系数由 6.3 4× 1 0 - 1 1 m2 /s降低到 2 .2 9× 1 0 - 1 1 m2 /s.计算了试样脱模后在室温养护过程中的失重率和真空水饱和后的吸水率 ,结果发现 ,丙烯酸丁酯与苯乙烯质量比为 80∶2 0和 90∶1 0的试样 ,其失重率和吸水率非常接近 ,而丙烯酸丁酯与苯乙烯质量比为50∶50、60∶40和 70∶3 0的试样 ,其吸水率大于失重率 。

By using styrene acrylate latexes with different styrene/acrylate ratio and under equal cement/water ratio the chloride diffusivity of the latex modified mortars were studied. The test results show that the constitute of latex has great influence on the chloride diffusivity of the latex modified mortars. The chloride diffusion coefficient decreases from 6.34×10 -11 m 2/s to 2.29×10 -11 m 2/s when the mass ratio of styrene/acrylate of the latex increases from 60∶40 to 90∶10. The calculations of the mass loss of the specimen during air curing and the mass increase after vacuum water saturation show that the mass loss and the mass increase of the specimens modified with latexes with styrene/acrylate ratio between 80∶20 and 90∶10 are almost same, while the other specimens show greater mass increase than mass loss. These results indicate that the latex with higher acrylate content can better prevent the crack formation of the cement mortars.