, Professor, Civil, Environmental and Geo-Engineering
Joseph Labuz, Professor & Department Head, Civil, Environmental and Geo-Engineering
Good fracture properties are an essential requirement for asphalt pavements built in the northern part of the US and in Canada, for which the predominant failure mode is cracking due to high thermal stresses that develop at low temperatures. Currently, there is no agreement with respect to what experimental methods and analyses approaches to use to investigate the fracture resistance of asphalt materials and the fracture performance of asphalt pavements. This report presents a comprehensive research effort in which both traditional and new experimental protocols and analyses were applied to a statistically designed set of laboratory prepared specimens, and to field samples from pavements with well-documented performance, in order to determine the best combination of experimental work and analyses to improve the low-temperature fracture resistance of asphalt pavements.
The two sets of materials were evaluated using current testing protocols, such as creep and strength for asphalt binders and mixtures, as well as newly developed testing protocols such as the disk compact tension test, single edge notched beam test, and semi circular bend test. Dilatometric measurements were performed on both asphalt binders and mixtures to determine the coefficient of thermal contraction.
Discrete fracture and damage tools were utilized to model crack initiation and propagation in pavement systems using the finite element method, and TCMODEL was used with the experimental data from the field samples to predict performance and compare it to the field performance data.