Use of poker chip ductility for practical measurements of cracking in asphalt binders

Abstract: Asphalt binder properties play a critical role in cracking resistance of asphalt pavements. Today, the properties of asphalt binders available can vary widely from a significant increase in the use of modifiers, additives, and recycled materials. Test methods included in current specifications do not adequately characterize the cracking resistance of asphalt binders. Several studies have been performed since the 1960s by testing asphalt binders in thin films, also known as poker chip geometry, to represent the stress state experienced by them in the field and have led to the development of the poker chip test. The poker chip test is identified as a simple method to make practical measurements of cracking resistance of asphalt binders. This study summarizes the laboratory studies and field-validation performed to identify the poker chip ductility as an effective and highly repeatable parameter to characterize the cracking resistance of asphalt binders. The study includes on the impact of laboratory testing conditions such as temperature, loading rate, and mode of loading, on tensile properties of asphalt binders to evaluate the use of poker chip ductility for routine testing. This is further supported through the ability of poker chip ductility distinguish asphalt binders by modifier type and content, laboratory and field aging, different crude sources, and recycled materials.