Study On Cold Repair Technology Of Porous Asphalt Pavement And Its Influence On Permeability

China was late in starting the application of porous asphalt pavement for highway.Domestic researches on functional characteristics,its attenuation laws of structural strength and maintenance have just started,with less results.In the existing practice,the maintenance of porous asphalt pavement is generally carried out in accordance with the maintenance scheme of dense-graded asphalt pavement,resulting in adverse effects such as ugly appearance,poor maintenance effect,and weakened drainage capacity of the porous asphalt pavement after maintenance.Therefore,in order to increase the service life of the porous asphalt pavement and maintain its original road performance,the paper conducts related research on open-graded cold mend material of porous asphalt pavement.The optimum mix proportion of cold mend material for porous asphalt pavement is obtained through the re-amendment marshall test.The results are:the mineral powder accounts for 6%of the dry mass of aggregate,the waterborne epoxy modified emulsified asphalt accounts for 7.5%of the dry mass of aggregate,the waterborne epoxy resin accounts for 15%of the mass of waterborne epoxy modified emulsified asphalt,and the total water consumption accounts for 5%of the dry mass of aggregate.The forming stability of marshall test sample under this optimum mix proportion reach to8.43k N,which satisfy the requirements for the use of porous asphalt pavement.Rut specimens of porous asphalt pavement are made,slotted and repaired,so the actual repairing condition of porous asphalt pavement can be simulated,and the repair effect is verified.The results of the vertical pull-out test show that when the spraying dosage is 0.75L/m~2,the adhesion property of the bonding oil is the best,and the water-borne epoxy modified emulsified asphalt proposed in the paper has significantly better adhesion than the traditional method.The results of the accelerated loading abrasion test show that as the number of abrasions increase,the abrasion value of the cold mend material for porous asphalt pavement increases,and the spraying dosage of bonding oil has little effect on the abrasion value.The overall abrasion value is less than 1%,revealling that the new cold mend material is good in abrasion resistance.With the number of abrasions increase,the abrasion value of the cold mend material initially increases,then gradually decreases and finally stabilizes.When the number of abrasions is 60,000 times,the abrasion value of the cold mend material maintain more than 86%of the highest abrasion value.The penetration test results show that the rut specimens’permeability coefficient decreased with the increase of the spraying dosage of bonding oil after repaired by cold mend material.When the spraying dosage increases to 1.00L/m~2,the rut specimens’permeability coefficient decreases by more than 50%,which seriously affects the original drainage capacity of the rut specimens.And the rut specimens’permeability coefficient sprayed with water-based epoxy emulsified asphalt decrease more.Based on the test results and the actual engineering conditions of the pavement,the geometric parameters and material parameters of the Seep3D finite element model are determined,and the changes of the porous asphalt pavement’s drainage capacity after repaired by different schemes are calculated using Seep3D.The results show that when the pavement slope is constant,the drainage capacity of the drainage layer gradually decreases with the increase of the pavement width;when the pavement width is constant,the drainage capacity of the drainage layer gradually increases with the increase of the pavement slope;when the pavement width and slope are constant,the permeability coefficient of the repaired part of the road surface decreases with the increase of the spraying dosage of bonding oil,so the drainage capacity of the drainage layer decreases.According to the calculation results of drainage capacity and the formula of storm intensity,the paper gives a calculation method to determine the spraying dosage of bonding oil to provide guidance for porous asphalt maintenance projects in different areas.