Study On The Moisture Susceptibility Of Porous Asphalt Mixture

Porous asphalt pavement has many outstanding advantages like high safety,good skid resistance,low noise,water mist suppression,and glare reducing.It is easy to cause moisture damage because of its special large void structure.It is great practical significant to study on the moisture susceptibility of porous asphalt mixture.This article analyzes the moisture damage characteristics of porous asphalt mixture theoretically,and optimizes the methods for evaluating moisture susceptibility of porous asphalt mixture.The preparation and properties of high viscosity asphalt are studied,and the preparation methods and selection requirements of high viscosity asphalt are put forward.The mix design parameters and procedure of the asphalt mixture are optimized,and the gradation range of PAC-16 porous asphalt mixture is put forward.The moisture susceptibility of PAC-16 porous asphalt mixture is studied by using different kinds and proportion of fiber reinforcements and anti-stripping agents replacing mineral powder.(1)The characteristics and mechanism of porous asphalt mixture moisture susceptibility are studied from the structure,material composition,water ways.The methods for evaluating moisture susceptibility of porous asphalt mixture are selected by using the scoring method.The results show that the gradation and the performance of asphalt have a great influence on the moisture susceptibility of the porous asphalt mixture.The weight ratio of accuracy,convenience and economy of the moisture susceptibility evaluation methods is 5: 3: 2,and the freeze-thaw splitting test,the flooding scatter test and the immersion tread test are the better evaluation methods of the moisture susceptibility of porous asphalt mixture.(2)In this paper,the modification method and properties of 70 # matrix asphalt and SBS modified asphalt(I-D)are studied by changing the content of HVA high viscosity additive.The results show that the HVA additive improve the performance of the original asphalt obviously,and the high viscosity modified asphalt of SBS modified asphalt with 8% HVA modifier is better performance to meet the requirements.(3)The effects of fiber type and content on the moisture susceptibility of porous asphalt mixture are studied.The moisture susceptibility of porous asphalt mixture by adding lignin fiber,polyacrylonitrile fiber and polyester fiber is improved.The fiber type polyacrylonitrile fiber and the content of 0.1% is recommended.At the same time,the effects of mixed slaked lime,quicklime and P·O 42.5R cement on the moisture susceptibility of porous asphalt mixture are studied.The results show that the effect of improving the moisture susceptibility of porous asphalt mixture is as follows: slaked lime > quicklime> cement.Mixed with 2% of the slaked lime has a good ability to resist moisture damage.(4)In this paper,the mixing process and the rolling process of the porous asphalt mixture are optimized,and the keys of construction technology of PAC-16 ultra-thin drainage bonded wearing course is put forward.