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

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.