Evaluating the Cracking Performance of Asphalt Mixes Using Four-point Beam Fatigue and Semicircular Beam Testing

Abstract

This paper studies the relationship between fracture resistance and fatigue performance of conventional asphalt mixtures, asphalt mixtures with reclaimed asphalt pavement (RAP), and rubberized asphalt mixtures. The four-point beam (4PB) test has been widely used to assess the fatigue performance of asphalt pavements; however, long testing time and difficulty of specimen preparation are the major drawbacks of this test which limit it from being applied as a routine mix design and quality control/quality assurance (QC/QA) method. The semi-circular beam (SCB) test has been developed to serve as a simple and fast surrogate test for QC/QA or even mix design method of asphalt pavement for routine projects. SCB measures the fracture resistance of asphalt mixes at intermediate temperatures. In this study, fracture parameters, including fracture energy, flexibility index, stiffness, fracture toughness, and strength were obtained from the SCB test. The correlation between fracture parameters from the SCB test and the fatigue behavior as measured by the 4PB test has been explored. The simple linear regression results indicated that the stiffness and fracture toughness from the SCB test have good correlations with the initial stiffness from 4PB tests. It was also shown that the fracture toughness from the SCB test correlates moderately well with the strain at 1-million fatigue cycles normalized by the stiffness, both from the 4PB test.