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不同成型方法对沥青混合料路用性能和细观结构的影响

Influence of Different Forming Methods on Road Performance and Meso-structure of Asphalt Mixture

  • 摘要: 为研究不同成型方法对沥青混合料路用性能和空隙结构的影响,采用马歇尔击实仪和旋转压实仪制作了AC-16(粗集料最大公称粒径为16 mm碎石的中粒式沥青混凝土,级配连续)、SUP-16(粗集料最大公称粒径为16 mm碎石的中粒式沥青混凝土,连续级配但有禁区)和PAC-13(粗集料最大公称粒径为13 mm碎石的沥青混凝土,开级配)的沥青混合料试件。以动稳定度、抗弯拉强度和冻融劈裂强度比等作为评价指标,对比分析不同成型方法对其路用性能的影响。同时,采用断面扫描和空隙图像识别(PCAS)进行试件断面的图像处理,分析2种压实条件下不同混合料类型的空隙率、空隙数量和空隙分析维数等结构参数的变化规律。结果表明,采用旋转压实成型方法获得的沥青混合料的路用性能较好,同时,旋转压实成型方法获得的混合料试件断面的空隙参数均小于马歇尔击实成型方法,表明旋转压实能够有效改善沥青混合料内部空隙的结构分布,使沥青混合料试件成型的均匀性更好,路用性能更强。因此,旋转压实试件的路用性能比击实成型试件的路用性能好。

     

    Abstract: In order to study the effects of different forming methods on road performance and void structure of asphalt mixtures, the specimens of AC-16(Medium grained asphalt concrete with coarse aggregate of maximum nominal particle size 16 mm crushed stone, with continuous gradation), SUP-16(Medium grained asphalt concrete with coarse aggregate of maximum nominal particle size of 16 mm crushed stone, continuously graded but with prohibited areas) and PAC-13(Asphalt concrete with a maximum nominal particle size of 13 mm crushed stone in coarse aggregate, open graded) were fabricated by using Marshall compaction and gyratory compaction instruments. The dynamic stability, flexural tensile strength and freeze-thaw splitting strength ratio were used as evaluation indexes to compare and analyze the effects of different forming methods on their road performance. Meanwhile, section scanning and void image recognition(PCAS) were used for image processing of specimen sections, the change laws of structural parameters such as void ratio, void number and void analysis dimension of different mix types under two compaction conditions were analyzed. The results showed that the asphalt mixes obtained by gyratory compaction molding method had better road properties. At the same time, the void parameters in the cross-section of the specimens obtained by gyratory compaction were smaller than those of Marshall compaction, which indicated that gyratory compaction can effectively improve the structural distribution of the internal voids in asphalt mixture, resulting in better uniformity of the specimens and better road performance. Therefore, the road performance of the rotary compaction specimen was better than that of the compaction specimen.

     

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