Fracture testing for the evaluation of asphalt pavement joints

Abstract

Asphalt joints are inevitable parts of every pavement. Although much attention is dedicated to the construction of such joints, reliable tools for assessing the mechanical properties of joints for design and performance assessment are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing pavement as in the case of large patches for pavement repair. This paper intends to evaluate different new or modified static fracture testing methods for ranking existing joint construction techniques. Some of these testing methods, such as indirect tensile test, direct tensile test and 4-point bending test are familiar in the field of asphalt pavement characterisation, but have scarcely been used for assessing the quality of joints so far. These three test types were adopted and evaluated for joints and the test results were analysed with finite element (FE) software ABAQUS. Different joints for testing were prepared in the laboratory using a special specimen construction procedure. The results suggest that joints with inclined interfaces seem to show more promising behaviour than vertical joints. It was confirmed that starting compaction from the hot side of the joint generally produces better results than compaction starting from the cold side of the joint. Pre-heating of the joint surface and using a bond sealant appears to provide the best results.

Keywords:

• cold asphalt pavement joints
• asphalt joint laboratory production
• IDT joint evaluation
• DTT joint evaluation
• 4PB joint evaluation
• joints FE analysis

The authors would like to thank Kenneth Olsson (District manager at Skanska, Stockholm) for sharing his valuable experimental knowledge, providing asphalt and also for specifying a part of the Skanska laboratory for the compaction of the slabs. The authors would also like to express their gratitude to solid mechanics laboratory manager Martin Öberg at KTH Royal Institute of Technology for manufacturing the fixtures required for the tests and also for his collaboration on running the DTT. Finally, the authors would like to appreciate Dr Alvaro Guarin and Dr Denis Jelagin for their help in obtaining the CT images presented in this paper.