Research On The Water Stability Of Porous As Phalt Mixture With High Viscosity Asphalt

Modified asphalt is widely studied and used in the domestic and abroad as familiar pavement material.Among them,high viscosity asphalt is largely applied to porous asphalt pavement,because it has good work of adhesion with aggregate,and it could improve the mechanical properties of asphalt mixture.Therefore,based on the study to the interfacial adhesion between the modified asphalt with HVA and the aggregate,this paper analysis comprehensive about the influence to the water stability of the porous asphalt mixture from the incorporation of the HVA high viscosity modifier.First of all,this paper use the technique of heating shear to manufacture the high viscosity asphalt with HVA,and research on the relationship between the dosage of HVA modifier(0%,5%,10% 15% 20%)and the basic properties of the modified asphalt.And then test the 60℃ dynamic viscosity of the modified asphalt with different HVA dosage.Besides,make further analysis of the relationship between the rheological properties of high temperature and fatigue characteristic of asphalt and dosage of HVA through the DSR test.The results of the study shows that as the dosage of HVA increases,the penetration of the modified asphalt reduces,the softening point increases,and the ductility at 15℃ reduces.If the dosage of HVA is higher,the 60℃ dynamic viscosity of the modified asphalt increases obviously,and the rheological properties of high temperature improves,the fatigue characteristic of the modified asphalt reduces.Secondly,this paper evaluate the conventional water stability of porous asphalt mixture by the Marshall flooding test,separation test and the freeze-thaw splitting test,and then analysis the influence of the dosage of HVA and the kind of mineral aggregate to the water stability of the porous asphalt mixture.To simulate the environment of combined action with water,temperature and inter-space water pressure,take on the Marshall flooding test with pressure,and compare with the conventional Marshall flooding test.At last,take on the freeze-thaw test for several times and use the CT images to analysis the damage by water of specimens from inside point of view.It will be seen form the results of the test that improving the dosage of HVA within the appropriate scope does good to improving the water stability of porous asphalt mixture.It has the same regular under the action of inter-space water pressure.The dosage of HVA should not be too high,it has ideal effect of improving the water stability of porous asphalt mixture using the dosage of 15%.It will be seen from the result of the CT scanning test that after 15 times of freeze-thaw circulation,the inter-space of both specimen increases.The position where initial air void is high,the change of air void is obvious.Improving the dosage of HVA does good to reducing the freeze-thaw damage inside the mixture.Then,this paper tests the adhesive of the interface between the modified asphalt with different HVA dosage and aggregate using the drawing test,and researches the damage form of the interface under different temperature,and studies the adhesive difference between limestone,basalt,granite and the same kind of asphalt.Except that,form the view of surface morphology,this paper use the test of BET to determine the SSA of the mineral aggregate.At last,this paper use the test of SEM to observe the surface characteristics of mineral aggregate,for corroboration of SSA.The results shows that the adhesive interface damage appears at the low temperature of 0℃ and the adhesiveness interface damage appears at the normal temperature of 20℃ in the drawing test.The dosage of HVA is higher,the adhesion between the modified asphalt and the aggregate is better,and the adhesiveness of the modified asphalt is better,too.The adhesion between limestone,basalt,granite and the same kind of asphalt get down in turn.It could be known for the test of BET that the SSA of the limestone is 1.18 times of the SSA of the basalt,and is 1.44 times of the SSA of the granite.The observations of the SEM test shows that the surface of limestone is very rough,the surface of basalt is not that rough,and the surface of granite is smooth and dense.It could be known that the surface of mineral aggregate is more rough,the SSA is higher,the adhesion between mineral aggregate and asphalt is better.At last,we could know that if the adhesion of the interface between the asphalt and the aggregate is stronger,the water stability of the porous asphalt mixture is better by the associated analysis of the adhesion of the interface between the HVA asphalt and the aggregate and the water stability of the porous asphalt mixture with HVA.By the means of blending the high viscosity modifier of HVA in the reasonable range,we could improve the adhesiveness and the high temperature stability of the asphalt,and the adhesion between the asphalt and the aggregate is improved,too.Therefore,the water stability of the porous asphalt mixture will become better.