Development of a binder fracture test to determine fracture energy properties

Abstract

Based on knowledge and findings that existing binder tests may not accurately predict cracking performance at intermediate temperatures, this study embarked in the development a new binder fracture energy test to fill this void. Nonlinear 3-D finite element analysis (FEA) was used to identify and optimise an appropriate specimen geometry to allow for accurate determination of true stress and strain on the fracture plane, thereby ensuring accurate determination of fracture energy. Various binders were tested at multiple temperatures and loading rates using prototype specimens in order to evaluate the feasibility and validity of different specimen geometries. The researchers used nonlinear FEA results to establish a data interpretation system and develop a set of diagrams to simplify calculation procedures. After extensive observation of test results, the researchers concluded that the new fracture energy test and data interpretation system suitably measure unmodified and modified binder fracture energy density. The test results reveal that binder fracture energy is a fundamental property of binder and that characteristic of the true stress-true strain relationship is a good indicator of the presence and relative content of modifiers.

Keywords:

• fracture energy test
• finite element analysis
• large deformation
• true stress
• true strain
• modified asphalt binder
• hybrid binder