带预制裂缝的PVA-ECC抗(盐)冻性能及机理

Frozen resistance of PVA-ECC with initial crack and its mechanism

为了研究寒冷地区带缝工作的聚乙烯醇纤维增强水泥基复合材料(PVA-ECC)的抗(盐)冻性能,采用快冻法研究带有2种不同预制裂缝高度的PVA-ECC分别在淡水和氯盐中的抗冻性能;分析对比不同预制裂缝高度、粉煤灰掺量和冻融循环次数对PVA-ECC抗冻性能的影响;并对各个因素的影响机理进行了分析。研究结果表明:PVA-ECC在氯盐环境中的抗冻性能较差,表层剥落严重;粉煤灰掺量对PVA-ECC抗冻性能影响较大,粉煤灰掺量越高,PVA-ECC抗冻性越差;水冻时,125次冻融循环之前缝高对质量损失影响较大,缝高越大,质量损失率越大,125次冻融循环后,缝高对质量损失的影响不明显;无论是盐冻还是水冻,整个冻融循环过程中,缝高越大,动弹性模量降低得越多,抗冻性越差。

In order to study the （salt） frozen resistance with initial crack of polyvinyl aicohol-engmeerea cementitious composites （PVA-ECC）, the antifreeze performance of PVA-ECC with two kinds of different initial crack were studied by rapid freeze-thawing experiment in fresh water environment and chlorine salt environment respectively. The influence of different crack height, fly ash content and freeze- thaw cycle times on the frozen resistance of PVA-ECC were analyzed and compared, and the influence mechanism of the factors were analyzed. The results show that the antifreeze performance of PVA-ECC is poorer in chlorine salt environment and surface spalling is serious. Fly ash content has a great influence on the antifreeze performance of PVA-ECC. The higher the fly ash content is, the worse the antifreeze performance of PVA-ECC is. Before 125 times freeze-thaw cycle, effect of crack height on the mass loss is great in fresh water environment. The longer the crack, the mass loss rate is greater. After 125 times freeze-thaw cycle, effect of crack height on the mass loss is not obvious. During the entire freeze-thaw cycle process, whether in fresh water environment or in chlorine salt environment, the longer the crack, the dynamic elastic modulus reduces more and the frost resistance is poorer. 2 tabs, 11 figs, 20 refs.