Design parameter of low-temperature performance for asphalt mixtures in cold regions

Abstract

The low-temperature performance of an asphalt mixture plays important roles in the thermal cracking mechanism of asphalt pavements in cold regions. However, the existing asphalt mixture design process does not involve a design parameter for low temperature performance as the asphalt content is determined. In this study, two types of asphalt mixtures are involved, Asphalt Concrete (AC) and Stone Mastic Asphalt (SMA), which are the most widely used materials for surface layer. The zone for low-temperature performance was defined on the basis of a survey of pavement distresses and numerical analysis. The design parameter was captured from an indirect tensile test by using Digital Image Correlation (DIC) analysis, considering the universalizability and simplification of the indirect tensile test. The selected indicators, such as tensile failure strain, validated that significant linear correlations existed between bending beam test and thermal stress restrained specimens test. Thus, the design parameter, which was defined as the tensile failure strain (εDIC), could characterize low-temperature property with asphalt content. Moreover, the critical strain of εDIC was proposed. The low-temperature design parameter (εDIC) was applied to the Marshall design method. The optimum asphalt content based on the new design method was slightly greater than that of the conventional Marshall design method. The evaluation methods used in this paper indicate that the low-temperature property of the asphalt mixture created by the new design method was better.