Investigation on sound absorption coefficients of porous asphalt concrete under different clogging conditions

Porous asphalt concrete (PAC) generates significant less noise during the loading of vehicles compared to conventional pavements. However, it might be clogged during lifespan, which results in a reduced noise reduction function. To evaluate the noise reduction function of PAC during service, the change in sound absorption coefficients of PAC under different clogging conditions was investigated by the means of laboratory tests. The standing wave tube method was used in this paper, with considering the changes in void ratios, clogging materials, and cleaning methods. The attenuation parameters of PAC sound absorption coefficients under continuous clogging and cyclic clogging-cleaning conditions were investigated. Based on this, the prediction model of the sound absorption coefficient under two clogging states was proposed. The results showed that aeolian sand had the most negative impact on the noise reduction function, with a 56 % decrease in the sound absorption coefficient after clogging. The sound absorption coefficient of the PAC remained between 0.3 and 0.4 after completely clogged. The sound absorption coefficient of the PAC can be partially even fully restored after cyclic clogging cleaning. High-pressure water washing is the most effective approach, recovering up to 80 % of the original value before clogging. Therefore, regular cleaning and maintenance of the PAC during its survice life is necessary. Predictive modeling of the sound absorption coefficient was highly correlated with measured values, allowing accurate prediction of changes after clogging and cleaning.