Simulation of Asphalt Concrete (AC) Pavement Temperatures for use with FWD

Abstract

ABSTRACT A simulation model to be used primarily for falling weight deflectometer (FWD) testing has been developed to calculate temperatures of asphalt concrete (AC) layers. Input to the model is a series of measured temperatures at the surface of AC layer. The measuring series need to be started in the morning, before the sun has strongly heated up the AC layers. A start-up procedure is proposed to follow, if the measuring series lacks the early morning data. By means of a finite difference approximation of the heat transfer equation, the temperatures below the AC surface are calculated. Parameter values were adapted using data for 8 days during the period June 20 to June 27, 2001 from 3 different locations in Sweden. Two other locations in Sweden were used for validation. For the measuring data, the proposed model gives essentially better results than the commonly used BELLS method, as well as the improved version BELLS3 and a method recently proposed by researchers at the Michigan State University. Comparisons with measured temperatures, show that the proposed method calculates the temperature distribution of the AC layers with good accuracy. This includes cloudy as well as sunny days. The method also accurately handles the change between cloudy and sunny weather during the day.