Dynamic Strength Analysis of Bitumen Binders for Asphalt Concrete Mixtures in Terms of the Fracture Incubation Time Criterion

摘要

The operating conditions of current highways require the development and implementation of new testing standards for pavement materials with regard to dynamic impact. Pavement materials have a complex hierarchical structure exhibiting a self-consistent response to load at different scale levels. The corresponding parameters of the phenomenological models used for macroscopic objects essentially depend on lower-scale processes, and this relationship determines the behavior and strength of the material under both static and dynamic loading. This paper reports dynamic test results for some bitumen binders and asphalt concrete, and provides their analysis on the basis of the incubation time criterion. The tests were conducted using a split Hopkinson pressure bar on materials previously exposed to room or negative (-10 degrees C) temperature. Experimental data showed that the structural-temporal approach based on the concept of the incubation time of fracture can be a good tool for analyzing and predicting the dynamic strength effects of pavement materials. Since the fracture incubation time characterizes the duration of macrofracture preparation processes at different scale levels, control over this parameter through the structural features of the material can provide the desired material response to dynamic load. The proposed structural-temporal parameters can be incorporated into new standards developed with the idea of a differential choice of materials depending on the expected highway operating conditions.