| Because of its large air voids characteristics, permeable asphalt mixture has the functions of good anti-sliding, drainage, noise reduction, etc. It can effectively alleviate the waterlogging, vehicle noise, heat island effect of big cities which frequently occur in recent years, thus received extensive attention. This paper mainly studied the purification characteristics to road erosion water of permeable asphalt mixture. The purpose is to obtain the pollutants adsorption rate and application method of different types permeable pavement materials, structure and water purification material.This paper selected rainfall intensity, air voids of mixture, two-layer structure as the factors which may influence the water purification effect of OGFC pavement. On this basis, the different types of OGFC-13, OGFC-20mixture and two-layer OGFC mixture are designed, and the pavement performance of them are evaluated. Research shows that the air voids have regular effect to Marshall stability, water-stability, permeability coefficient and blindly increase the porosity only for the functional effect is not accepted. Two-layer OGFC pavement is more stable than single structure, two-layer OGFC permeable performance slightly better than the upper, the shear performance of unbonded two-layer OGFC is better than that of bonded two-layer OGFC.In order to realize road erosion water purification effect evaluation of permeable asphalt mixture, this paper designed the water purification test system which could simulate natural rainfall process. The test system conclude vertical rainfall equipment which can control the rainfall intensity and period, special mould which can contain different types of asphalt mixture and water purification material, clean rainwater collecting device. In addition, combined with the test system and the characteristics of rainfall, the water purification method including runoff pollution water sample preparation, rainfall process simulation, pollutant concentration determination and data processing four parts is put forward.The method takes pollutants purification rate as evaluation index, and the calculating formula is given.This paper have studied the influence of water purification factors to pollutants(SS,COD) adsorption rate on the use of designed water purification test system and evaluation method. The water purification factors include rainfall intensity, air voids, thickness, etc. Data show that, under differentair voids, thickness, rainfall intensity, OGFC pavement has obvious purification effect to SS and COD, which the adsorption rates were more than50%. The adsorption rate increases with the increase of thickness and air voids, and decreases with rainfall intensity. The influence degree of rainfall intensity, air voids, thickness to pollutants adsorption decrease. The purification effect of two-layer OGFC is better than that of its any single layer, but only slightly better than the single layer.The quartz sand, volcano rock, ceramsite, activated carbon were selected as the water purification material and the water purification effect of each of them was evaluated. The water purification material could be used as aggregate of asphalt mixture, purification layer applied to roadside or filled in the diversion pipe for application. Research shows that, pollutants(SS,COD) adsorption rate sequence of separate purification materials:activated carbon> quartz sand> volcano rock> OGFC specimen> ceramsite. The application method of purification material used as aggregate is not obvious for runoff pollution control. Roadside purification layer can effectively improve the adsorption rate of SS pollutants. Activated carbon and quartz sand are better filling material used as roadside purification layer. The application of filling in the diversion pipe is relatively effective of removing runoff pollutants. |
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