Structural Behaviour And Construction Measures Of Asphalt Treated Permeable Base Asphlt Pavement

Asphalt treated base is more and more widly used in the roadconstruction in our country. According to the air voids, it can be divided intotwo kinds of different types——dense-graded and open-graded. Open gradeasphalt treated permeable base（ATPB）provide sufficient permeabilitytodrain pavement structures of intruding water, thus preventing the waterdamage. At the same time reflective cracks of the asphalt pavement is alsodelayed, and the service life of the ATPB asphalt pavement is also increased.However, the study on pavement structure behavior of the asphalt treatedpermeable base asphale pavement is little.Firstly, the values of pavement mechanical response are calculated bythe software of Bisar, which is based on the elastic layer system theory. Theeffects of layer thickness and modulus on the mechanical response are alsodiscussed. And two kinds of different asphalt treated permeable basepavement structure are obtained in this paper.1、Two layers asphalt concrete ATPB asphalt pavement：Upper asphalt concrete4⁶cm+Lower middle graded asphalt concrete6¹0cm+ATPB8¹0cm （modulus greater than600MPa）+Cement stabilizedmacadam base30⁴0cm+Lime-ash soil subbase20cm.2、Three layers asphalt concrete ATPB asphalt pavement:Upper asphalt concrete4cm+Lower middle graded asphalt concrete4⁶cm+Lower coarse graded asphalt concrete6⁸cm+ATPB8¹0cm（modulus greater than600MPa）+Cement stabilized macadam base25⁴0cm+Lime-ash soil subbase20cm.Secondly, compared with the semi-rigid base asphalt pavement, thepavement performance of asphalt treated permeable base is discussed.Reference to the related background, the paper determines the structural behavior equation of asphalt treated permeable base and semi-rigid baseasphalt pavement.1、Equation of semi-rigid base asphalt pavement:PCI=PCI₀{1-exp[-（9.95/y）⁽0.95}。2、Equation of two layers asphalt concrete asphalt treated permeablebase asphalt pavement:PCI=PCI₀{1-exp[-（11.13/y）^0.98}。3、Equation of three layers asphalt concrete asphalt treated permeablebase asphalt pavement:PCI=PCI₀{1-exp[-（11.64/y）^1.12}。Based on this, I analyze and predict the size of pavement conditionindex （PCI） of asphalt treated permeable base asphalt pavement andsemi-rigid base asphalt pavement during the30years’ estimate time. Takethe Yichang-Zhangjiajie expressway as an example, life-cycle cost analysisis used to evaluate the over-all-long-term economic efficiency between thethree different kinds of pavement structure. Pavement construction cost,maintenance cost, road user cost and pavement residual value is competedby the way of present value method. The results show that:1、when middle-high maintenance standard is utilized, the economicbenefit of two layers asphalt concrete asphalt treated permeable base is thebest, three layers asphalt concrete asphalt treated permeable base grassrootsnext, semi-rigid base asphalt pavement economy is the worst.（1） Compared with the semi-rigid base and three layers asphaltconcrete ATPB asphalt pavement,3%-5%and2%-3%of the cost is savedwhen PCI=70. （2） Compared with the semi-rigid base and three layers asphaltconcrete ATPB asphalt pavement,2%-4%and1%-2%of the cost is savedwhen PCI=60.2、when low maintenance standard is utilized, the economic benefit ofthree layers asphalt concrete asphalt treated permeable base is the best, twolayers asphalt concrete asphalt treated permeable base grassroots next,semi-rigid base asphalt pavement economy is the worst. Compared with thetwo layers asphalt concrete ATPB asphalt pavement and semi-rigid baseasphalt pavement,1%-2%and2%-4%of the cost is saved.In a word, the economy of the ATPB asphalt pavement is better thansemi-rigid base asphalt pavement. Finally, the corresponding constructionoptimization measures are proposed in view of segregation of ATPB. Andthis paper summarizes the design types of the ATPB subsurface drainagesystems.