Mix Design Factors to Reduce Noise in Hot-Mix Asphalt

Abstract

Noise generated from high-trafficked roadways is a significant source of noise pollution in urban environments. As population centers continue to expand, so too does the demand for quiet, serviceable pavements. Traffic noise is derived from two basic sources: standard vehicle engine operation and tire–road interaction. Reduction of the former has been a goal of automobile manufacturers since the introduction of automobiles nearly a century ago, but little focused research has been applied to the latter, especially in the United States. Research to determine the mix design factors that significantly influence noise generation in asphalt pavements is almost nonexistent. This study investigates the mix design and construction factors that influence noise generation in dense-graded hot-mix asphalt by means of noise prediction models. Laser profiling systems are used to measure pavement surface texture parameters. Models that predict noise generation as a function of these surface texture parameters are used to demonstrate the sensitivity of noise generation to commonly encountered mix design and construction variables for hot-mix asphalt. After various mixtures produced in the laboratory were characterized and various field sections were profiled, statistical analysis was conducted to determine the effect of mix variables on texture and estimated noise. Results indicate that reduction in noise at the tire–pavement interface can be achieved by considering specific mix design parameters, including gradation, asphalt content, and nominal maximum aggregate size. The percentage of air voids in the mixture (compaction effort) was also found to significantly influence tire–road noise emission.