氯盐环境对PVA纤维增强水泥基复合材料抗冻性的影响

Influence of Chloride Environment on Frost Resistance of PVA Fiber Reinforced Engineered Cementitious Composite

在氯盐环境和淡水环境中进行聚乙烯醇纤维增强水泥基复合材料(polyvinyl alcohol fiber reinforced engineered cementitious composite,PVA-ECC)快速冻融试验,研究了氯盐环境对试件外观形貌、质量损失率、相对动弹性模量和耐久性指数的影响。结果表明:氯盐环境中,PVA-ECC试件质量在冻融循环初期呈增大趋势,在冻融循环后期因表层严重剥落,导致质量下降,质量损失率显著增大,整个冻融循环过程中试件的耐久性指数较小,相对动弹性模量明显下降;淡水环境中PVA-ECC试件经历冻融循环后基本保持原有形状和尺寸,质量损失率变化幅度较小,相对动弹性模量下降趋势平缓,耐久性指数较大。与淡水环境相比,氯盐环境中PVA-ECC试件的抗冻性显著下降,表明氯盐环境对PVA-ECC抗冻性有重要影响。

The frost resistance of polyvinyl alcohol fiber reinforced engineered cementitious composite （PVA-ECC） in chloride and freshwater environments was investigated via an accelerated freeze-thaw test. Influence of chloride environment on the appearance morphology, mass loss ratio, relative dynamic elastic modulus （Erd） and durability indices was analyzed. The results show that the mass of specimen in chloride environment increases during first freeze-thaw cycles, but the mass and Era both decrease, the mass loss rate increases during later freeze-thaw cycles because the surface layer of specimen flakes away seriously. The durability indices of specimen in chloride environment are less during whole freeze-thaw cycles. However, the original shape and size unchange, the mass loss rate changes slightly, Era decreases and the durability indices are more for the specimen in freshwater environment during the freeze-thaw cycles. The frost resistance of specimen can decrease readily in chloride environment rather than in freshwater environ- ment, illustrating that the chloride environment has a significant effect on the frost resistance of PVA-ECC.