Development and Field Experience of Performance-Based Low Permeability Asphalt Mixture Used to Overlay Bridge Decks

摘要

Asphalt mixtures on bridge decks often do not last as intended. Raveling, delamination, and potholing are more frequently observed on bridge decks as compared to their adjacent asphalt surfaces. The main cause of such differences in performance could be simply due to inability to achieve proper in-place density by being restricted to static only compaction mode and reduced temperature. Compaction temperature is limited to a certain range to avoid melting any underlying waterproofing membranes that could cause so called "slippage planes." Compaction mode and temperature restrictions could further complicate the projects when the distance between the job site and production plant is far away. This paper provides information on the development of a performance-based low permeability overlay mix to protect bridge decks against the penetration of water and de-icing chemicals. This paper also provides steps employed to develop a performance-based requirement focused on permeability and long-term fatigue behaviour under extreme repetitive stresses that would be expected from heavily loaded traffic coupled with extreme temperatures. Production and paving experience with the low permeability mix is also included, as well as more field performance of a trial section in Southern Ontario.