Research On Anti-cracking Material And Structure Optimization For Drainage Asphalt Pavement

On the basis of disease surveied in the drainage asphalt pavement of airport expressway,aiming at the transverse crack disease caused by rainwater infiltration due to shrinkagecracking of semi-rigid base when uneven settlement was happened in subgrade, someresearches which includes optimal porosity and anti-cracking material gradation in thedrainage layer, anti-cracking technology of graded interlayer, drainage asphalt pavementasphalt layer, structural optimization and optimum thickness of asphalt layer crackperformance were worked.Firstly, according to the structure characteristics of drainage asphalt mixture for largevoids, continuation as a whole, squeezing between stone and stone, and existing cohesionbetween gravels, mixture ratio design method of orthogonal test based on viscoelasticgranular model was provided. Based on the viscoelastic granular pavement load model andthe granular shear failure mechanism, it is concluded that the same kind of stone shearmodulus calculation formula which can be easy for the quantification of shear resistanceperformance of drainage asphalt pavement. the optimal range of anti-cracking gradation fordrainage asphalt mixture is obtained through optimization of shear resistance performance,the key control points in the drainage asphalt mixture ratio design is that controlling thesynthesis gradation key sieve2.36mm pass rate under the premise,9.5~16mm and4.75~9.5mm the proportion need to control focally, at the same time, in order to improve theanti-cracking performance, controlling9.5mm sieve through rates is range of50%to70%, isput forward.Secondly, According to analyze the factors such as the traffic load, traffic volume,temperature stress, asphalt pavement fatigue cracking, the anti-cracking proper thickness ofasphalt pavement except for the drainage layer is confirmed.Finally, through simulating constants C and N of formula of Paris material, andstatistical analysis for results, numerical relationship of C and N in the asphalt mixture isdeduced, and according to the derivation of the statistical relation with N randomization, theC probability distribution can be calculated, and make the crack fatigue life prediction forasphalt pavement structure based on principle of probability, which analyzes the crack propagation fatigue reliability under the conditions of specified reliability.Results show thatno matter what value n(n≠2) take, fatigue life of pavement structural combination1(OGFC-13;AC-20;ATB-30;Lime-Fly Ash Concrete) is superior to combination2（OGCF-13;AC-13;AC-25;Lime-Fly Ash Concrete), which is mainly due to the asphalt layerof combination1(OGFC-13;AC-20;ATB-30;Lime-Fly Ash Concrete) much thicker, andusing the asphalt stabilized macadam(ATB-30) with flexible base as the lower layer in whichgravel of large size can stop or slow down the reflection crack of semi-rigid base.