Properly designed and constructed new asphalt pavements should provide good service for about 20 years they need major rehabilitation. The life of pavement that went through major rehabilitation should be about 15 years. In Zone 3 in Southeastern Ontario the standard asphalt cement grade is PG 58-28. It is typically bumped to PG 64-28 for heavier or slow moving traffic. The asphalt mixes incorporating these asphalt cement grades should be able to withstand the winter temperature down to – 28°C.
The 2014 winter was considered to be very cold in Ontario with the temperature often dropping to -25°C or even lower. There was premature pavement cracking observed recently on number of roads in Southwestern Ontario. Some agencies believe that this was mainly due to the very cold winter. Properly designed and constructed pavements exhibited cracking after 2 to 3 years, and sometimes even 6 months. It has also been 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. Extensive field and laboratory investigation was carried out. This paper describes three municipal roads that incorporated PG 64-28 asphalt cement and exhibited very early cracking. It presents some of the test results. It comments on methods of asphalt cement modification and present and example of updated specification requirements.
