改性聚酯纤维对混凝土早期开裂与收缩的影响

1)空军工程大学航空工程学院,陕西西安 710038; 2)武警部队研究院工程设计研究所,北京 100020

建筑材料; 改性聚酯纤维; 混凝土; 早期收缩; 早期开裂; 抗折强度

Effect of modified polyester fiber on early crack and shrinkage of concrete
WU Haoxiang1, WU Yonggen1, and LI Wenzhe2

1)Faculty of Aeronautical Engineering, Airforce Engineering University, Xi'an 710038, Shaanxi Province, P.R.China2)Institute of Engineering Design, People's Armed Police Academy, Beijing 100020, P.R.China

construction material; modified polyester fiber; concrete; early shrinkage; early crack; flexural strength

DOI: 10.3724/SP.J.1249.2020.02173

备注

为探究改性聚酯纤维对混凝土早期开裂和收缩的影响,以纤维掺量为变量,采用平面薄板和非接触法收缩测定仪对改性聚酯纤维混凝土的早期开裂和收缩进行测试分析.结果表明,改性聚酯纤维对混凝土的早期收缩和开裂均有明显的改善作用.随着纤维掺量的增加,裂缝面积和早期收缩呈现先减小后增大的趋势.当纤维掺量为1.2 kg/m3时,纤维对混凝土早期开裂和收缩性能的改善均达到最好的效果,与未掺纤维的对比试样相比,裂缝面积可降低86.4%,早期收缩率可降低68.7%.试验结果表明,纤维的掺入对混凝土的早期抗折强度影响不大,相较于对照试样而言,纤维混凝土的7 d抗折强度增长率均在6%以下.通过裂缝面积、早期收缩和早期抗折强度的对比分析,发现改性聚酯纤维对混凝土抗裂性能的增强主要是由于纤维的掺入减小了混凝土的早期收缩.

To investigate the effect of modified polyester fiber on the early crack and shrinkage of concrete, taking the fiber content in fiber reinforced concrete as a variable, the early shrinkage and crack of modified polyester fiber concrete are measured and analyzed by flat sheet and non-contact shrinkage tester. Results show that the modified polyester fiber can significantly improve the early shrinkage and crack of concrete. With the increase of fiber content, crack area and early shrinkage decrease first and then increase. When the fiber content is 1.2 kg/m3, the fiber improves the early crack and shrinkage to the best extent, with the crack area reduced by 86.4% and the early shrinkage rate reduced by 68.7% compared with those of contrast sample without fiber. The test shows that the fiber has little effect on the early flexural strength of concrete, and the 7 d flexural strength increase rate of fiber reinforced concrete is below 6% compared with that of contrast sample. The comparative analysis of crack area, early shrinkage and early flexural strength show that the improvement of the crack resistance of concrete by modified polyester fiber is mainly due to the reduction of early shrinkage of concrete.

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