为了在橡胶改性沥青的基础上继续提高废旧橡胶的利用率,同时解决橡胶改性沥青黏度大、易离析的问题,将易溶于沥青基体的活化橡胶与硫化橡胶共同掺入基质沥青进行改性,制备高掺量活-硫共混橡胶(activated-vulcanized compound rubber,AVCR)改性沥青.通过改性沥青聚合物离析试验、沥青动态剪切试验和沥青低温弯曲蠕变试验,测试AVCR改性沥青的技术性能,通过高温车辙、三轴压缩、低温小梁弯曲和冻融劈裂试验,对比AVCR改性沥青混合料相对于硫化橡胶(vulcanized rubber,VR)改性沥青混合料和SBS改性沥青混合料在路用性能方面的优势,利用扫描电子显微镜(scanning electron microscope,SEM)观察并分析AVCR改性沥青的微观机理.结果表明:相比于VR改性沥青和SBS改性沥青,AVCR改性沥青的失效温度分别提高了15.1℃和20.5℃,蠕变劲度模量分别降低了76 MPa和89 MPa,高低温性能均有明显提升;AVCR改性沥青混合料相比其他2种改性沥青混合料,高温性能和抗水损坏性能优良,低温抗裂性能突出,其最大弯拉应变分别比SBS和VR改性沥青混合料高出29.4%和10.8%;AVCR改性沥青微观呈现"海岛结构",其中活化橡胶、硫化橡胶和沥青均匀融合,整体性好,同时具有一定的抗变形能力.研究结果可为AVCR改性沥青混合料在路面工程中的应用提供参考.
Study on road performance and underlying mechanism of activated-vulcanized compound rubber modified asphalt mixture
To further improve the utilization rate of waste rubber on the basis of rubber modified asphalt and solve the problems of large viscosity and easy segregation of rubber modified asphalt,activated rubber and vulcanized rubber,easily dissolved in asphalt,were mixed into asphalt for modification.The modified asphalt of activated-vulcanized compound rubber(AVCR)with high content was prepared.The technical performance of AVCR modified asphalt was tested by modified asphalt polymer segregation test,asphalt dynamic shear test and asphalt low-temperature bending creep test,respectively,while scanning electron microscope(SEM)was used to observe and analyze its microscopic mechanism.Through high temperature rutting,triaxial compression,low tempera-ture trabecular bending,and freeze-thaw splitting tests,the advantages of AVCR modified asphalt mixture over vulcanized rubber(VR)modified asphalt mixture and SBS modified asphalt mixture in terms of road performance were compared.The results show that the failure temperature is increased by 15.1℃ and 20.5℃ respectively compared with VR and SBS modified asphalt,the creep stiffness modulus is reduced by 76 MPa and 89 MPa.High and low temperature performance has been significantly improved.AVCR modified asphalt mixture has excellent high temperature and water damage resistance,and the low temperature crack resis-tance is the most outstanding.The maximum bending tensile strain is 29.4%and 10.8%higher than that of SBS and VR modified asphalt mixture,respectively.AVCR modified asphalt microscopically presents an"island structure",in which the activated rubber,VR modified asphalt and substrate asphalt are uniformly fused with good integrity and certain deformation resistance.The findings can provide reference for the application of AVCR modified asphalt mixture in pavement engineering.
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