Acoustic deterioration of porous asphalt pavement induced by the clogging and deformation

Polymer-modified friction course, a prevalent porous asphalt pavement in Hong Kong, serves as an effective low-noise pavement. However, the local subtropical climate characterized by high temperatures and heavy rainfall accelerates void reduction in porous asphalt roads. Previous studies have primarily investigated how void clogging affects pavement’s hydraulic permeability but paid insufficient attention to the influence on acoustic performance. Furthermore, existing research on void reduction has mainly focused on clogging while neglecting the compaction effect caused by traffic loads. This study aims to investigate and compare the acoustic deterioration characteristics in porous asphalt pavement induced by clogging and deformation. Impedance tube tests revealed that clogging changed the sound absorption coefficient spectrum of porous asphalt from a single peak to a dual peak pattern within 0–1,600 Hz, while rutting-induced deformation transformed a multi-peak pattern into a single peak spectrum across 0–6,400 Hz. Rubber ball free fall impact tests further demonstrated that clogging significantly increases airborne noise emissions, particularly in medium-to-high frequencies (500–8,000 Hz), with a pronounced increase at ∼2,500 Hz. Clogging caused the porous asphalt specimen to evolve from a homogeneous acoustic medium to a stratified system with depth-dependent impedance. By contrast, rutting produced an overall structural compaction of the porous asphalt mixture, degrading its noise reduction ability, especially notably at high frequencies (>2,000 Hz). These findings provide critical insights into the acoustic deterioration of porous asphalt pavements, offering a foundation for more durable low-noise pavement design.