Investigation of engineering properties and filtration characteristics of porous asphalt concrete containing activated carbon
2019
Hu, Xiaodi | Dai, Kang | Pan-Pan,
Permeable asphalt pavement (PAP) provides a promising method for controlling the pavement runoff, which is known as non-point source pollution. Since porous asphalt concrete (PAC) serves as an important part of PAP structure, this paper aims to study the feasibility of using activated carbon in porous asphalt mixture for improving the filtration effectiveness of pavement runoff. The effect of activated carbon on the optimum asphalt content, engineering properties and filtration characteristics of PAC were investigated by a series of laboratory tests. Abrasion loss and binder drainage tests results show that activated carbon increases the optimum asphalt content of porous asphalt mixture due to its high absorptivity and surface area. PAC strength is affected by softening effect of high asphalt content and stiffness effect of activated carbon. In addition, PAC sample with activated carbon that entirely substitutes for the mineral filler is superior in moisture stability and filtration effectiveness compared to the control sample without activated carbon. Activated carbon can modify the absorptivity of asphalt film and therefore improves the pollution removal rate for PAC. Moreover, acidic compound residues on the surface of activated carbon would infiltrate into runoff solution and slightly decreases the runoff pH value. Furthermore, the effect of thickness and air void content on pollutant removal rate of PAC sample shows different trends. PAC layer with a thickness of 6 cm and an air void content of 18% is recommended for permeable asphalt pavement to obtain the optimum filtration effectiveness of pavement runoff.
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