剑麻纤维砂浆抗渗防裂性能试验

Experiments on Cracking Impermeability of Sisal Fiber Mortar

为研究普通水泥砂浆掺入剑麻纤维后抗渗防裂性能,用平板法进行早期收缩裂缝试验,并取相同配合比进行抗渗性能试验。研究不同长度、不同体积掺量的剑麻纤维对砂浆早期收缩性能和抗渗性能的影响,并开展剑麻纤维影响抗渗性能和早期抗裂性能的相关性研究。试验结果表明,0.05%体积掺量、长度6 mm的剑麻纤维抗渗防裂效果均为最佳,裂缝降低系数为98.81%,最大渗水压力提高78.8%。剑麻纤维水泥砂浆抗渗性能与抗裂性能两种耐久性能具有正相关性,即抗裂性能越高,抗渗性能越好。因为剑麻纤维均匀地分布在水泥砂浆基体之中,它可以阻碍集料的分层和离析,保证水泥基材料早期的泌水性,抑制水泥基材料的干缩从而阻止沉降裂纹的产生,且能约束基体变形并阻碍基体的错位运动。

Early shrinkage-crack test based on the slab approach were completed to study the impermeability and the anti-cracking properties of the ordinary cement mortar adding sisal fibers, and the cement mortar with sisal fibers＇ impermeability test was carried out in the same mixture ratio. The sisal fiber＇s different lengths and volume contents were discussed to figure out the influence of the mortar＇ s initial shrinkage and impermeability properties , then the correlation study between the sisal fiber＇ s impermeability and anti-cracking properties was conducted. Tests＇ results showed that the impermeability and anti-cracking properties of the cement mortar gained the optimum, when the fracture reduction coefficient reached at 98.81% and the maximum of the seepage pressure was increased to 78.8% when sisal fibers was added at 0.05% volume content and 6 mm long. It indicated that the correlation between impermeability and crack-resistance performances of the cement mortar with sisal fibers was positive, in other words, the anti-cracking property was increased to higher, the impermeability was more excellent, the sisal fiber could weaken aggregates＇ stratification and segregation on account of the fiber being got even distribution in the cement-mortar matrix, and ensure cement-based material＇s bleeding at early stage. Moreover, the sisal fiber restrained shaping settlement-cracks in related structures through restricting the dry shrinkage of the cement-based material, and constrained the matrix＇ s deformation and dislocation movement.