纤维轻骨料混凝土抗冻性试验研究

Experimental Study on Frost Resistance Durability of Fiber Reinforced Lightweight Aggregate Concrete

利用浮石轻骨料、钢纤维、聚丙烯纤维及硅灰配制纤维轻骨料混凝土,研究在水中冻融作用及硫酸钠溶液中冻融作用下纤维轻骨料混凝土的抗冻耐久性能。研究表明,轻骨料混凝土在硫酸钠溶液中冻融损伤明显大于水冻环境;掺入两种纤维后,轻骨料混凝土的强度损失率降低,而掺有粉煤灰和硅灰的纤维轻骨料混凝土的强度损失率和质量损失率均显著降低。SEM照片显示,掺有硅灰的轻骨料混凝土界面过渡区厚度减小,水化反应生成大量凝胶产物并交织成网状结构,界面的粘结强度提高,使得掺有硅灰的纤维轻骨料混凝土具有均匀致密的显微结构。

Pumice, steel fiber, polypropylene fiber and silica fume were used to prepare fiber reinforced lightweight aggregate concrete （LWAC）. Frost resistance durability of fiber reinforced LWAC is studied in 5% Na2SO4 solution and water. The results show that LWAC freezing and thawing durability deteriorates more rapidly in Na2SO4 solution than in water. The strength loss rate of LWAC decreases by steel and polypropylene fiber introduction. As fly ash and silica fume are filled, the strength loss rate and mass loss rate of fiber reinforced LWAC reduces obviously. SEM shows that the thickness is reduced and hydrate gel forms dense net structure in interfacial transition zone （ITZ）. Bond strength around the ITZ increases. So fiber reinforced LWAC has uniform and compact microstructure when fly ash and silica fume are used.