| Raveling is one of typical damages in porous asphalt pavement,which is induced by the fatigue fracture in asphalt mortar or the damage of bitumen-coarse aggregate interface.Meanwhile,because the air void ratio of porous asphalt pavement is usually more than 20%,both asphalt mortar and bitumen-coarse aggregate interface are easy to be damaged by aging and moisture under environment conditioning.However,aging and moisture induced damage were seldom considered in existed researches for fatigue life of asphalt mortar,and the stability of bitumencoarse aggregate interface coupling aging and moisture was rarely studied in recent papers.Therefore,based on muti-scale laboratory tests and numerical simulation,the effects of aging and moisture induced damage on anti-raveling property of porous asphalt pavement were investigated in this paper sponsored by the Postgraduate Research & Practice Innovation Program of Jiangsu Province（KYCX170138）.Asphalt mortar is easy to be damaged by aging and moisture firstly,then after asphalt mortar fractured,aging and moisture induced damage will propagate to the bitumen-coarse aggregate interface.In terms of mortar fatigue fracture induced raveling,linear amplitude sweep test was adopted to investigate the fatigue life of asphalt mortar in full strain region after different aging or moisture conditioning durations,based on the viscoelastic continuum damage model.Meanwhile,the strain regions of high fatigue life（SHF）and low fatigue life（SLF）for asphalt mortar after different aging or moisture conditioning durations were studied.Results show that the SHF of aged asphalt mortar is shrunken,specifically,the SHF of asphalt mortar after 40 h PAV aging is（0%,3.12%）,wihle the SLF of it is（3.12%,3.98%）.Moreover,the SLF of moisture damaged asphalt mortar is expanded,specifically,the SLF of asphalt mortar after 20 d water bath is（0%,5.51%）.Both SHF and SLF of asphalt mortar can be affected by aging or moisture induced damage,so the maximum shear strain region（MSSR）of asphalt mortar in aged or moisture damaged porous asphalt mixture was investigated in this paper.First,the effects of aging and moisture induced damage on viscoelastic property of asphalt mortar were studied,and the Generalized Maxwell Model with Aging Elements or Moisture Elements were established.Meanwhile,CT scanner and Reverse Engineering Method were adopted to rebuild the 3D meso structure of porous asphalt mixture.Furthermore,the inflated tire-pavement finite element model was established by ABAQUS to analyse the effects of tire pressure and vehicle load on the stress distribution in tire-pavement interface.Finally,the meso numerical model of porous asphalt mixture was enstanblished,and both MSSR and fatigue life of asphalt mortar were calculated.Results show that aging（PAV aging duration≤40h）will improve the fatigue life of asphalt mortar under the same vehicle load,while the fatigue life of moisture conditioned asphalt mortar will decrease.Specifically,the fatigue life of asphalt mortar after 40 h PAV aging is 69 times as many as that of fresh asphalt mortar under same load condition.Meanwhile,the fatigue life of asphalt mortar after 20 d water bath decreased 85.3%.As for bitumen-coarse aggregate interface damage induced raveling,photoelectric colorimetry and pull-out test were adopted to measure the adhesion of bitumen binder and the strength of bitumen-coarse aggregate interface.Results show that both aging and moisture induced damage had negative effects on the stability of bitumen-coarse aggregate interface.After same water bath duration,the adhesion of bitumen binder and the strength of bitumencoarse aggregate interface decreased 16.0% and 58.3% respectively in the first 20 h PAV aging.Meanwhile,the first 5d water bath for asphalt mortar had obvious effects on adhesion reduction of bitumen（-47.7%）,and the stability of bitumen-coarse aggregate interface would reduce obviously in the first 10 d water bath（-48.4%）.According to the fatigue life of asphalt mortar and the stability of bitumen-coarse aggregate interface,the type of aging and moisture induced raveling in porous asphalt pavement were analysed.Results show that the stability decrease of interface between aged bitumen and coarse aggregate（adhesive failure）will lead to the aging induced raveling in porous asphalt mixture,and both the mortar fatigue life reduction and stability decrease of interface strength between bitumen and coarse aggregate（cohesive failure and adhesive failure）will lead to the moisture induced raveling in porous asphalt mixture. |
