| With the increase of service life and the improvement of the driving safety and comfort requirements of asphalt pavement,Jiangsu province has been conducting research and promotion of drainage and noise reduction asphalt pavement in highway maintenance projects since 2014.But there are still key issues such as air void design,interlayer bonding design,selection of aggregate types and construction technology research.For this reason,this paper firstly clarified the applicability of drainage and noise reduction asphalt pavement in Jiangsu expressway maintenance and the problems it faces based on the current status of Jiangsu expressway road conditions and future maintenance requirements.Based on this,the paper studied the mix design of drainage noise reduction pavement and basic performance,such as high temperature performance and crack resistance.In addition,the drainage and noise reduction asphalt pavement was further optimized from the selection of raw materials,the design of the air void ratio,and the determination of the interlayer combination.At the same time,combined with the test section,the construction technology of drainage and noise reduction asphalt was investigated and the adding technology of additives,the rolling technology,as well as construction quality control standards were determined.Finally,based on field maintenance project,the performances of the drainage and noise reduction asphalt pavement were tracked.According to the results,the use of high-viscosity modified asphalt and increasing the thickness of the asphalt film(more than 12.5μm)can improve the anti-stripping performance of the drainage asphalt mixture;in addition,the addition of polyester fiber(addition amount: 0.15% wt),basalt fiber(addition amount: 0.2～0.4%wt),the use of quicklime or slaked lime as filler,etc.,can further reduce the raveling potential and improve the anti-scattering performance of the drainage asphalt mixture.For drainage asphalt mixtures,basalt should be used as the corase aggregate.When diabase is used,half of the mineral powder should be replaced by cement.Limestone has poor abrasion resistance and is not suitable as aggregate for drainage pavement.Taking PAC-13 as an example,the high-temperature performance and anti-cracking performance of the drainage asphalt mixture and SMA-13 are compared and analyzed.The results show that the drainage asphalt mixture has the comparative dynamic stability and indirect tensile strength as SMA-13.In order to ensure the good bonding performance of the drainage pavement and the original pavement,the shear test and the pull test were used to analyze the three types of bonding layer designs: synchronous chip seal,rubber asphalt chip seal and SBS modified emulsified asphalt.In the scheme,considering the bonding strength between layers and the sensitivity to environment(temperature),the rubber asphalt chip seal has the best interlayer bonding performance.In addition,after milling the old pavement,the roughness of the road surface is improved,and the interlayer bonding performance of the drainage asphalt pavement can be improved.The mixing process of "aggregate + fiber dry mix 15 S,then asphalt + HVA,mix asphalt and HVA for 15 S,then put mineral powder,and mix 35 S after the mineral powder is put in",which solves the problem of high viscosity after HVA is melted by high temperature.Combined with the field test section of the drainage pavement,it is found that the scattering performance of the drainage asphalt mixture shows an obvious decay trend with the increase of the road age.The longer the road age,the greater the scattering loss,and the high temperature stability continues to increase with the increase of the road age.In the case of medium temperature,the indirect tensile strength of the mixture increases with the increase of road age,the fracture energy remains stable,and the toughness is still good.In addition,as the road age increases,the water seepage performance of the wheel track zone gradually decreases. |
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