外掺植物纤维对冻融作用下植被混凝土抗剪强度的影响

目的]研究外掺2种植物纤维对冻融作用下植被混凝土抗剪强度的影响,为植被混凝土生态防护技术在高寒地区的应用提供科学依据。方法]参考相关标准(GB/T50082-2009)中的慢冻法,采用2因素3水平全面交叉试验开展研究。结果]未掺植物纤维的植被混凝土,冻融后黏聚力显著减小,内摩擦角变化不明显。掺入植物纤维可使经受5次冻融循环作用后植被混凝土的内摩擦角平均增加5°左右,并且随植物纤维掺量的增加,内摩擦角变化无明显规律,黏聚力则呈先增加后减小的趋势。表明纤维加筋对黏聚力的贡献存在临界掺量。棕纤维掺量对黏聚力的影响比黄麻纤维掺量更为敏感。结论]外掺植物纤维可有效改善植被混凝土抵抗冻融破坏的能力,棕纤维和黄麻纤维的建议掺入比为0.6%和0.6%,具备推广应用前景。

Effect of Additive Plant Fiber on Shearing Strength of Vegetation-compatible Concrete Under Freezing-thawing Cycles

Objective] The effect of mixing two plant fiber into vegetation-compatible concrete on its shearing strength under the condition of freezing and thawing was studied, aimed to provide a scientific basis for the application of vegetation-compatible concrete based ecological protection technology in the alpine region. Methods] According to slow freezing method in relevant test standards(GB/T50082-2009), 2 factors and 3 levels of comprehensive cross test was conducted. Results] For the fiber unincorporated vegetation-compatible concrete, the frozen-thawed cohesion value of vegetation-compatible concrete was reduced remarkably as compared with that without freeze-thaw cycle, whereas no obvious change of internal friction angle value was observed. After 5 frozen-thawed cycles, the fiber addition made the internal friction angle value of vegetation-compatible concrete increased by an average of about 5°. The internal friction angle variation was not significant with the increase of fiber addition. However, cohesion firstly increased and then decreased with increasing fiber content, which implied that the contribution of fiber reinforcement to cohesion has a critical content. Palm fiber was proved more effective on cohesion than hemp fiber did as their content varied. Conclusion] Fiber can improve the ability of vegetation-compatible concrete to against freezing and thawing. The reasonable proportion of palm and hemp fiber was 0.6% and 0.6%.Fiber added vegetation-compatible concrete with the above testified materials and proportion is applicable and has the market prospection.