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Cracking and Rutting Performance Evaluation of Asphalt Mixes for Moving Towards a Balanced Mix Design - A Pilot Study

Traditionally, asphalt mix designs have been selected based on the volumetric properties of mixes without considering the actual field performance parameters such as resistance to cracking and rutting. The balanced mix design approach, which considers a matrix of volumetric properties and cracking as well as rutting performance, in the selection of asphalt mix constituents is a promising trend. Furthermore, asphalt mix design and mix acceptance are becoming more and more complex with the increasing uses of recycled materials, binder additives/modifiers, and multiple warm-mix asphalt technologies. These new trends came with compatibility problems and ultimately performance issues in terms of rutting and cracking. Thus, volumetric mix design alone is not sufficient for evaluating the potential behaviour of asphalt mixtures. Therefore, establishing and implementing reliable performance tests that can be used in asphalt mix design, selection and acceptance are important. These will assist to eliminate weak or brittle mixes for ensuring durable pavements and to model asphalt pavements for predicting the primary distresses that frequently drives the need for rehabilitation of asphalt pavements. A pilot performance-testing program has been initiated at the University of Manitoba to evaluate the asphalt mixes, which are currently in use in Manitoba, for potential field performance in terms of cracking and rutting. The results of this pilot testing program can assist in changing the Manitoba’s asphalt mix constituents for moving towards the balanced mix design.

Numerous performance tests have been developed to evaluate asphalt mixes, including the Hamburg Wheel Tracking test, the indirect tensile strength test, the semi-circular bend test, the Illinois flexibility index test (I-FIT), the disk-shaped compact tension test, and the Ideal-CT test among others. This paper aims to review the available literature on each test to assess their suitability. The paper then presents the results of the pilot testing program conducted at the University of Manitoba to assess the cracking and rutting performance of current Manitoba mixes in an effort to produce a framework for a balanced mix design. Several specimens have been collected from both laboratory and field compacted mixtures for this pilot testing program. The cracking and rutting performance are being assessed using the I-FIT test and Hamburg Wheel Tracking test, respectively. The results of these tests including the materials and design parameters that influence rutting and cracking performance, and the test limitations will be discussed. This paper will also introduce an approach for optimizing mix constituents for volumetric properties, and the cracking and rutting resistance

Author

Rizk, Mahmoud
Ghazy, Ahmed
Kibbons, Blake
Ahammed, M. Alauddin
Shalaby, Ahmed
Liske, Tara
Tran, Thanh

Session title

Testing and Modeling of Road and Embankment Materials (PS)

Organizers

Soils and Materials Standing Committee

Category

Soils & Materials

Year

2020

Format

Paper

File