Research On Composition Design And Application Of Permeable Asphalt Concrete

In the process of urbanization in our country,due to the extensive use of non-permeable paving materials,the urban ecosystem has suffered great damage,and many areas are facing various "water" problems.In order to realize the sustainable development of the city and build an environment-friendly society,China has put forward the construction theory of "The Sponge City".During the construction of "The Sponge City",permeable asphalt materials have been widely used due to good water permeability and safety.Therefore,based on the "The Sponge City”construction demonstration project in Tongzhou District of Beijing,this paper has studied on the composition design and application of Permeable Asphalt Concrete(PAC).First of all,referring to the technical requirements of PAC raw materials in the existing specifications at home and abroad,and combining with China's climate,environment and traffic characteristics,the technical indicators and requirements of PAC raw materials suitable for China are put forward.Through indoor tests,the raw materials used in this project are tested,and the results show that the selected materials meet the requirements.Secondly,using orthogonal test and regression analysis,a mathematical regression model between PAC voidage and the passing rate of each main sieve pore was established when the nominal maximum particle size was 16mm,and the key sieve pore of PAC-16 was determined to be 2.36mm.The improved Japanese gradation design method is adopted to design the mix proportion of PAC-13 and PAC-16.When the target void ratio is 20%,the pass rates of PAC-13 and PAC-16 key sieve holes are determined to be 12.1%and 14.3%respectively by test.Taking 0.3%the binder drainage test and 15%the cantabro test as control standards to determine the optimal asphalt dosage range,the empirical formula calculates the optimal asphalt dosage of PAC-13 and PAC-16 to be 4.67%and 4.69%respectively;Finally,test pieces are prepared according to the determined gradation and the optimum asphalt content to test the performance of PAC.The test results show that all indexes of PAC meet the specification requirement.Finally,three-dimensional models of permeable asphalt pavement structure in the supported project are established by using finite element software.The mechanical response of the I-type structure combination under static and dynamic loads,and the variation law of various mechanical indexes are analyzed,and the bearing capacity of the pavement structure is checked.The results show that all mechanical indexes meet the specification requirements.In addition,this paper also studied the mechanical response of permeable asphalt pavement structure at the transition section of road-bridge under moving load,and analyzed the variation law of various mechanical indexes of pavement structure at the transition section of road-bridge and the influence degree when the speed,load and concrete grade of wedge-shaped slab are different.The results show that load has the greatest influence on mechanical index of road-bridge transition section pavement structure,followed by speed and the influence degree of concrete grade of wedge-shaped slab is the lowest.