Asphalt mixtures' properties indicative of tire/pavement noise

There are many factors that influence tire/pavement noise such as road friction, acoustic absorption, pavement material type as well as pavement texture. Highway noise is addressed through several models such as Traffic Noise Model (TNM) developed by the Federal Highway Administration (FHWA). The TNM computer program is capable of predicting highway noise to differentiate between asphalt and Portland cement concrete pavements. However, it does not take into account the specific asphalt mixture pavement type.;The objective of this research study was to recommend laboratory test procedures to identify pavement materials properties that are indicative of tire/pavement noise dampening characteristics in the field.;Test parameters from two laboratory test procedures were examined in depth for potential dampening properties. The first test was the Dynamic Complex Modulus test (AASHTO TP 62-03), which provides valuable information about the viscoelastic properties of asphalt mixtures. Of specific interest was the phase angle parameter, which is indicative of the viscous behavior of the material. Over 215 asphalt mixtures were analyzed, constituting conventional dense graded and modified gap and open graded mixtures. The phase angle was determined to be a good potential laboratory parameter to distinguish the asphalt mixture's tire/pavement noise characteristics in the field. Furthermore, phase angle test parameter master curves and predictive equations were developed.;The second test was aimed at evaluating the dampening properties of pavement materials using a nondestructive ultrasonic pulse velocity technique. The Ultrasonic Pulse Time (UPT) was measured and the Effective Flow Resistivity for the various asphalt mixtures was calculated. In addition, a mathematical model to predict the UPT based on the asphalt mixture volumetric properties was developed. The UPT experimental program encompassed 18 mixtures including several field cores obtained from national and international pavement sections. Correlations between predicted and laboratory measured dampening properties were good to excellent. The model and test data collected in this research will be a potential enhancement to the wider use of different pavement types into the TNM.;In addition, field noise measurements were obtained to validate the noise characteristics in the laboratory using the recommended test parameters. Correlations between both the phase angle and UPT test parameters with field measurements were good.;Since the FHWA TNM does not incorporate specific properties of asphalt pavement materials in tire/pavement noise estimations, recommendations on how to incorporate such input properties based on test parameters analyzed in this study were provided.