钢纤维改善轻骨料混凝土耐冻融性能研究

Freezing and thawing durability of lightweight aggregate concrete improved by steelfiber

通过掺入高效减水剂、引气剂、粉煤灰及钢纤维等配制两种强度等级(LC30、LC35)的浮石轻骨料混凝土。对比盐溶液(5%Na2SO4)和水中冻融循环试验发现:轻骨料混凝土在盐溶液中的冻融劣化程度大于水中。掺入钢纤维后,轻骨料混凝土抵抗冻融破坏能力提高。SEM研究表明,界面过渡区的水化产物有钙矾石、氢氧化钙和水化硅酸钙凝胶。随着盐溶液的侵蚀以及冻融循环次数的增加,水化产物的显微结构由密实逐渐变得疏松,钢纤维与水泥浆体的黏结力也逐渐减弱。

Pumice lightweight aggregate concrete （LWAC） of LC30, LC35 are compounded with superplasticizer, air-entraining agent, fly ash and steel fiber.Comparing freeze-thaw test of LWAC in salt solution （5% Na2SO4） and in water, the degree of LWAC durability deterioration shows freezing-thawing in salt solution〉freezing-thawing in water.The frost resistance durability of LWAC is improved by mixing steel fiber.The large volume fraction has tendency of good frost resistance of LWAC.SEM shows that hydrate structure in Interfacial Transition Zone （ITZ） becomes loose gradually with the increasing cycle of freeze-thaw and corrosion. Steel fiber has weaker cementing bond with paste.