玄武岩-聚乙烯醇纤维对再生混凝土抗冻性能的影响

Influence of Basalt-Polyvinyl Alcohol Fiber on Frost Resistance of Recycled Concrete

为了推广再生混凝土在高海拔和北方寒冷地区的应用,对单掺、混掺不同体积掺量玄武岩纤维和聚乙烯醇纤维的再生混凝土进行质量损失率、相对动弹性模量、抗压强度损失率3项抗冻性能指标的探究,并用SEM对200次冻融循环后混掺纤维再生混凝土进行细观作用机理分析,最后结合响应面法对混掺纤维掺量进行优选。结果显示:外掺纤维能够提高再生混凝土的抗冻性能,而混掺纤维效果优于单掺纤维;2种纤维在试件内部呈网状分布,协同受力,与基体互相约束,很大程度限制了裂缝的扩展和数量;纤维优化结果显示当聚乙烯醇纤维与玄武岩体积掺量分别为0.170%和0.246%时,再生混凝土的抗冻性能最优。研究成果对玄武岩-聚乙烯醇纤维再生混凝土纤维掺量设计具有一定的借鉴意义。

To enhance the utilization of recycled aggregate concrete( RAC) in high-altitude and cold regions of northern China,we investigated three anti-freezing performance indicators,namely,mass loss rate(MLR),relative dynamic elastic modulus(RDEM),and compressive strength loss rate(CSLR) of RAC reinforced with single and combined basalt fiber(BF) and polyvinyl alcohol fiber(PVAF).Scanning electron microscopy(SEM) was employed to analyze the meso-mechanical behavior of the mixed-fiber recycled concrete following 200 freeze-thaw cycles.Subsequently,the optimal mixed fiber content was determined using the response surface method.Findings indicate that fiber additives enhance the frost resistance of recycled concrete,with the combined fiber exhibiting superior performance compared to single fiber.Both BF and PVAF are intricately interwoven within the specimen's network,synergistically reinforcing the structure while mitigating crack formation.Optimization analysis reveals that the optimal volume content of PVAF and BF is 0.170% and 0.246%,respectively,yielding the highest frost resistance in recycled concrete.These results offer valuable insights for the design of basalt-polyvinyl alcohol fiber content in recycled concrete applications.