| Porous asphalt is a type of open-graded asphalt pavement with stone-on-stone and porous skeleton,used to improve friction,minimize hydroplaning,reduce splash and spray,improve visibility,and lower pavement noise levels.Because of the composing characteristic of porous asphalt with high percents of coarse aggregate and low percents of fine aggregate,strong skeleton can not be forming which resulting in the situation that the strength of porous asphalt mixture is mainly decided by the cohesion of the asphalt binder.Therefore,asphalt property with high viscosity is needed,the prominent feature of which can improve the stability of porous asphalt mixture and reduce the permanent deformation at high temperature.The profound research on the properties of porous asphalt mixture contaning the high viscosity additive is singnificant for the application of it in practical projects.On the basis of preparation of the TPS modified bitumen,the properties of TPS modified bitumens are studied including the penetration,softening point and ductility. The viscosities of TPS modified bitumens with the change of TPS percentages are also investigated which resulting in obvious effect of TPS additive on the viscosity increase of the modified bitumens.Dynamic Shear Rheometer is chosen to conduct the researches on the complex modulus,rutting factor and shear resistance properties of TPS modified bitumens and the results indicate that with the increase of the TPS percentages,the complex modulus and rutting factor are increased,the shear resistance properties is enhanced,where the properties of SBS modified bitumen is between the 8%and 12%TPS modified bitumens by comparing with all the TPS modified bitumens.With the consideration that the porous asphalt pavement is used as the surface layer,properties of porous asphalt mixture containing TPS additive are investigated stressing on the high temperature and creep property,anti-cracking property at low temperature,moisture susceptibility and aging property.The rutting test at high temperature and uniaxial static creep test are employed to study the property of porous asphalt mixture which show that prominent improvement of the stability and reduction of deformation can be obtained by adding the TPS additive,and conclusion is drawed that the resistance property to permanent deformation of porous asphalt mixture containing 16%TPS additive is better than SBS modified asphalt mixture.The three-point bending and bending creep test are conducted to find the relationship between the property of porous asphalt and TPS additive percentage,and results indicated that with the increase of TPS additive,the flexural-tension strength and strain are increased,the bending creep rate is also increased.Marshall retained stability uinder the condition of long-time immersion and indirect tesile strength ratio under several freeze-thaw cycles are developed to evaluate the moisture susceptibility of porous asphalt mixture containing TPS additive,which reveals that the resistance propertity to water damage is enhanced by using the TPS additive and performance of porous asphalt mixture containing 16%TPS additive can be close to SBS modified asphalt mixture.The indirect tesile strengths of porous asphalt mixture before and after short term and long term oven aging are tested to compare the mechanical property affected by the aging condition,which lead to no enhancement of aging property with high TPS additive contents,whereas the mixtures behave a decrease trend on the aging characteristic with the increase of TPS additive.At last,supported by the test section for the application of porous asphalt mixture containing TPS additive in practical projects,the quality control and construction technology of such porous asphalt mixture during mixing,preparation and paving are studied and discussed.Results including the road drainage and noise reduction function are obtained from the test section and some conclusions are presented. |
