Investigation of Fracture Properties of California Asphalt Concrete Mixtures

California Department of Transportation (Caltrans) had recently adapted the mechanistic empirical pavement design method to replace the older Hveem method. The University of California Pavement Research Center (UCPRC) is currently developing a mechanistic empirical pavement design method CalME, Kohler et al (2006). The program will predict the performance of flexible pavement based on the engineering properties of its constituents. The major distresses that are addressed for the flexible pavement are rutting, fatigue cracking and low temperature cracking. In their effort to predict the material performance, UCPRC is conducting several performance tests on asphalt concrete mixtures that are used in California. In addition, they are developing constitutive models to predict the material performance under several loading conditions. This research will address the fracture properties of 16 California asphalt mixtures that are used in the development and calibration of CalME. UCPRC had conducted and in the process of conducting Beam Fatigue tests (BFT) on these mixtures. After communication with the researchers at UCPRC they indicated that further investigation of the fracture properties using monotonic loading (using SCB) is needed for comprehensive characterization (the attached letter of participation). The objective of this research is to investigate the fracture properties of California asphalt concrete using monotonic loading by Semi Circular Bend test. The SCB test will add valuable input to the development and calibration of CalME. The experimental factorial will include mixtures with different properties including, five open-graded types of mixtures, two rubberized hot mix asphalt - gap graded (RHMA-G) and polymer modified mixtures, and nine rubberized warm mix asphalt - gap graded (RWMA-G) mixtures. The SCB test will be conducted on all these mixtures. The fracture properties for some of these mixtures will be further investigated for the model calibration.