Book Description

As one measure to reduce traffic noise, designing a noise-reducing ("quiet") pavement surface has received increasing attention. For asphalt pavements, some existing asphalt mixtures have shown better noise-reducing capabilities than conventional dense-graded asphalt concrete (DGAC) pavements. To design a new asphalt mixture optimized for noise reduction, the acoustic performance of existing asphalt-surface mixtures needs to be evaluated and understood. For this purpose, a study was conducted to measure tire/pavement noise on a variety of asphalt pavements for four consecutive years. The tire/pavement noise was measured with an on-board sound-intensity (OBSI) method that was continuously improved during the study. Regression analysis was applied to determine the levels and increase rates of tire/pavement noise on four major asphalt mixtures, and the effects of mix design variables on tire/pavement noise. Results show that tire/pavement noise generally increases with pavement age on all types of asphalt pavements. For newly placed or overlaid pavements, open-graded or rubberized gap-graded mixtures exhibit lower noise levels than conventional dense-graded asphalt mixture. Open-graded asphalt mixtures can retain noise-reduction benefit for a longer period than gap-graded mixtures. Using rubberized binders in the open-graded mixtures can further reduce the noise-increase rate. Pavement surface permeability, macrotexture, and existing surface distresses may affect the tire/pavement noise level.