Cold Winter and Early Asphalt Pavement Cracking Observed in Ontario

摘要

In portions of Southeastern Ontario, the standard asphalt cement grade is PG 58-28, which is bumped to PG 64-28 for heavier or slower moving traffic. When properly designed and constructed, agencies expect 15 to 20 years of good service from their new or rehabilitated pavements before further remedial action is required. Recently, however, some pavements have exhibited premature cracking after 2 to 3 years; occasionally after as little as 6 months. The 2014 winter was considered to be very cold in Ontario with the temperature often dropping to -25°C or even lower. Some agencies believe that the premature cracking was mainly due to the very cold winter. However, it was observed that this cracking occurred mainly in pavements where PG 64-28 asphalt cement was used. This focused the attention of the road agencies on the quality of asphalt cement used in Ontario. This paper describes three municipal roads that incorporated PG 64-28 asphalt cement and exhibited very early cracking. It presents some of the laboratory and field test data collected, comments on methods of asphalt cement modification, and presents an example of updated specification requirements.