Estimating the Healing Characteristic of Asphalt Binder Using the LASH Test

Abstract

Understanding of the healing behavior of asphalt binder is critical for fatigue modeling of asphalt paving materials. Binder-healing characterization based on the traditional time sweep test is time-consuming. The purpose of this study was to compare the damage-healing behavior of various neat and modified asphalt binders with the newly developed linear amplitude sweep healing (LASH) procedure, followed by verification on a simplified LASH (S-LASH) procedure to alternatively estimate binder-healing characteristics with reasonable testing efficiency. Thirteen neat and modified asphalt binders (17 sample conditions) were selected and respectively analyzed with standard LASH and S-LASH. Standard LASH showed that the healing performance of neat binders with the same penetration grade generally aligns with increasing damage. For the neat binders with different penetration grades, softer binders have better healing capacity. The negative aging effect on binder healing was demonstrated. Meanwhile, the healing master curve (HMC) was effective in comparing binder-healing characteristics under prefailure conditions. The healing rate (HR) for the tested binders basically varied from 0.1 to 0.2. Finally, mean absolute error (MAE) analysis of HMC and HR between standard LASH and S-LASH indicated 50% Sf (damage intensity at failure) with a 900-s rest period to be a critical LASH testing condition to derive reliable healing HMC and HR values. S-LASH is also recommended to estimate binder healing characteristic with significantly reduced testing time.