Investigation of Permeability Persistence of Porous Asphalt Concrete under Coupled Conditions of Clogging and Cleaning

Porous asphalt concrete (PAC) has excellent performance in managing rainwater, improving groundwater quality, mitigating the heat island effect, and reducing traffic noise. However, PAC often becomes clogged with soil, sand, and other clogging materials, which attenuates its permeability performance. This paper investigated the anticlogging performance of PAC. Firstly, a clogging test of PAC was carried out, and the clogging material was aeolian sand. Then the PAC specimens were cleaned by manual brushing, vacuum pump suction, and high-pressure water cleaning after each clogging. The permeability coefficients (kR) after clogging and cleaning were measured by a variable head seepage device. Next, the influence of porosity, nominal maximum grain size and cleaning method on the permeability performance of PAC under cyclic clogging–cleaning were investigated in terms of the change law of the permeability coefficient. The effect of different clogging materials on the PAC's permeability performance also was investigated. The influence of PAC gradation parameters on the permeability performance of PAC pavement was investigated using statistical methods. The results showed that with the increase of loading times, the permeability coefficient's values after clogging and cleaning first decreased rapidly and then stabilized gradually. The larger the porosity and nominal maximum grain size, the better was the PAC's anti-clogging performance and the better was its effect on the permeability coefficient's recovery. The residual rate of permeability coefficient (γ) of PAC specimens with different porosities and nominal maximum grain sizes differed significantly. The value of γ was large for large-porosity and nominal maximum grain size PAC specimens after each cycle. The order of ranking of the cleaning effect from best to worst was high-pressure water cleaning, vacuum pump suction, and manual brushing. The order of ranking of the clogging effect was sandy soil mixture, aeolian sand, and silty soil. Among the PAC gradation parameters, the effect of porosity on PAC's anticlogging performance was greater than that of nominal maximum grain size.