不同纤维对再生骨料透水混凝土性能的影响与评价

Influence and Evaluation Analysis of Different Fibers on the Performance of Recycled Aggregate Pervious Concrete

再生骨料透水混凝土可以缓解日益严峻的城市内涝、热岛效应、噪音效应等问题,但其强度不高,为填补短板,开展了纤维改性再生骨料透水混凝土的研究.依照规范,在基准配合比(水胶比为0.3、不掺纤维)基础上,设计制备了掺入短切玄武岩纤维、短切碳纤维、聚丙烯纤维等3种纤维不同掺量情形,共计16组配合比,分别测定其抗压强度、劈拉强度、孔隙率及透水系数等指标.结果表明,掺入纤维有效提高了再生骨料透水混凝土的抗压强度、劈拉强度和拉压比,且对劈拉强度的改性优于抗压强度.基于Image法分析了再生骨料透水混凝土平面孔隙率、孔数、平均等效孔径等指标对其强度与透水性能的影响及其规律关系;同时,采用灰色理论结合熵权法对纤维改性再生骨料透水混凝土进行了综合评价,结果显示聚丙烯纤维掺量为0.3%时,综合评价指标最高,为84.6%,此时再生骨料透水混凝土的整体性能最佳.

Recycled aggregate pervious concrete can alleviate the increasingly serious problems such as urban waterlogging,heat island effect and noise effect,but its basic performance,especially its strength is not high.In order to fill in the shortboard,the research of fiber modified recycled aggregate pervious concrete was carried out.According to the specification,on the basis of the standard mix ratio(water-binder ratio 0.3,without fiber),three kinds of fibers including chopped basalt fibers,chopped carbon fibers and polypropylene fibers were designed and prepared which were included in 16 groups mix ratios.The compressive strength,splitting tensile strength,porosity and permeability coefficient were measured respectively.The results show that the compressive strength,splitting tensile strength and tension-compression ratio of recycled aggregate pervious concrete are effectively improved by adding fiber,and the modification of splitting tensile strength is better than that of compressive strength.Based on the method of Image,the effects of plane porosity,number of holes and average equivalent pore diameter of recycled aggregate pervious concrete on its strength and permeability are analyzed.At the same time,the Grey Theory and entropy method are used to comprehensively evaluate the fiber modified recycled aggregate pervious concrete.The results show that when the content of polypropylene fiber is 0.3%,the comprehensive evaluation index is the highest,which is84.6%,and the comprehensive performance of recycled aggregate pervious concrete is the best.