Abstract
Highways traffic noise is a major issue all over the world. It is annoying to the residents who live nearby major transportation corridors. Noise pollution adversely affects the quality of their life. It also causes sleep disturbance and anxiety. Some of the noise abatement techniques such as noise barrier walls are costly and not effective all the times. Reducing the tire-pavement noise at the source is viable alternative to cut down the noise level. This study examined the use of impedance tube to measure the acoustic absorption of asphalt mixtures in the laboratory. The effect of various parameters on the acoustic absorption was investigated including aggregate gradation, aggregate type, binder type, percent air voids, and sample thickness. In addition, factors that could affect the acoustical performance of asphalt mixtures after pavement construction was also investigated including air void structure, surface texture, temperature, and surface conditions. Percent air voids and layer thickness were found to have a significant influence on the acoustic absorption of asphalt mixtures. An analytical model was proposed to estimate the acoustic absorption coefficient of asphalt mixtures during the design stage. A good correlation was found between predicted and measured absorption coefficients in the laboratory. In addition, a double-layer system of asphalt mixtures was found to be effective in providing improved acoustical performance that overcomes the issues associated with the use of open graded friction course as a wearing surface.
Keywords: Acoustic absorption, impedance tube, PFC, and double layer.