Determining Damage Development in Hot-Mix Asphalt with Use of Continuum Damage Mechanics and Small-Scale Accelerated Pavement Test

The modeling of asphalt concrete based on continuum damage mechanics (CDM) is an attractive and useful method of determining damage development in hot-mix asphalt (HMA). However, the CDM approach requires the calculation of the convolution integral over the loading duration and creates problems when large amounts of fatigue test data generated from accelerated pavement tests are handled. This study presents an approach to facilitating the calculation of the convolution integral for large amounts of data. Therefore, the approach can be used for pavement performance monitoring. Several asphalt concrete slabs were constructed in a laboratory with a vibratory roller compactor and instrumented with strain gauges and thermocouples. These slabs were tested under the small-scale accelerated loading device called the Model Mobile Load Simulator3. A frequency domain approach was used to analyze the continuous strain data. The constitutive equation in time domain was transformed to a frequency domain with the use of the Fourier transform technique; the pseudostrain and the complex modulus values were determined continuously during the loading. Results indicated that both the pseudostrain and the complex modulus were influenced by the combined effect of loading and temperature. A general trend of reduction of the pseudostiffness and the complex modulus because of these factors was observed in the study. Analysis results indicated that the frequency domain analysis approach was an efficient, better way to handle large amounts of data generated in long-term pavement studies and could be used to determine damage development in HMA as a result of loading.