钢纤维增强水泥砂浆弯曲强度的尺寸效应

摘要

Based on the Bazant's size effect law, the specimen size on flexural strength of cement mortar, randomly distributed steel fiber reinforced cement paste and aligned steel fiber reinforced cement paste which is combined with three-point bending test of notched beams is investigated. The results show that it strongly demonstrated the size effect on the flexural strength for cement mortar and randomly distributed steel fiber reinforced cement paste but the changes in specimen sizes has little influence on aligned steel fiber reinforced cement paste which flexural strength is stable at a rela-tively smooth level, it shows that the aligned distribution of steel fiber can improve the ductility of material while the char-acteristics of brittle fracture is not obvious. A calculation formula to predict the flexural strength of aligned steel fiber rein-forced cement paste is established by the regression curves. Quantitative analysis on the influence of steel fiber distribution on brittleness is studied.%基于Bazant尺度律理论，结合预制缺口梁的三点弯曲试验，研究了水泥砂浆、乱向钢纤维增强水泥砂浆以及定向钢纤维增强水泥砂浆弯曲强度的尺寸效应。研究结果表明，水泥砂浆和乱向钢纤维增强水泥砂浆的弯曲强度具有尺寸效应，而定向钢纤维增强水泥浆受试件尺寸的影响程度不明显，其弯曲强度稳定在一条相对平稳的水平线上。可以认为，钢纤维的定向分布提高了材料的延性，其脆性断裂特征不明显。由回归曲线建立了用以预测定向钢纤维增强水泥砂浆弯曲强度的尺度律计算式，并通过脆性数定量分析了钢纤维分布形式对材料脆性的影响。