Improved performance grading of asphalt cement and hot mix asphalt in Ontario, Canada

Abstract

Ontario municipal government agencies have recently been afflicted by significant premature pavement cracking. In response, stricter specifications were developed and implemented for acceptance on contracts. All but a few proven additives are banned in order to provide a cleaner product and the asphalt is graded after extraction and recovery from the loose mix. A set of highly sensitive rheological and failure properties are used to effectivel y control hard to detect constituents (e.g., reclaimed asphalt, oils, waxes, other unknowns). This paper discusses the background t o the specification, the development of acceptance criteria, potential moisture susceptibility issues to be monitored, and early implementation experience.

Enhanced Acceptance Specification of Asphalt Binder to Drive Sustainability in the Paving Industry

“…Binders were extracted using dichloromethylene (DCM) solvent [8,9]. All solutions were twice fed through a high-speed centrifuge (Ploog Engineering, Crown Point, IN, USA) to remove the fines.…”

“…It is essential that the most accurate acceptance specification tests are conducted on carefully extracted and recovered binder, as it best reflects what is actually placed in the contract [7][8][9][10]. The presence of reclaimed asphalt pavement (RAP) in the mix, as well as associated overheating of the virgin asphalt binder during production, are factors that can have a detrimental impact on long-term performance of the pavement.…”

“…Several Ontario municipalities have recently switched to testing of the extracted and recovered asphalt binder according to the extended bending beam rheometer (EBBR) and double-edge-notched tension (DENT) tests with promising results [7][8][9][10]. To illustrate, Figure 1a provides representative 2020 photographs for pavement on three blocks of Princess Street and King Street in downtown Kingston, Ontario, constructed before the switch.…”