Improved Asphalt Concrete Mix
In late 2008, a study carried out by the Quality Assurance Section of Engineering Services identified that hot mix asphalt concrete mixes tested for the City of Edmonton were showing moderate to severe aggregate stripping (moisture susceptibility). As a result of these findings, samples were obtained and tested from all asphalt suppliers providing hot mix asphalt concrete mixes to the City over the first two months of the 2009 construction season.
The results of the 2009 testing, to date, indicate that hot mix asphalt concrete mixes being supplied to City projects have moisture susceptibility issues and are showing aggregate stripping, which can impact the performance and service life of the road.
As a result, the City is requesting a minimum of 0.3% of an anti-stripping additive be used in all hot mix asphalt concrete mixes supplied for City construction projects (including developer contributed assets). Effective September 1, 2009, all infrastructure constructed by developers with the expectation to be transferred to City inventory must include the 0.3% anti-stripping additive to hot mix asphalt mixes for current and ongoing projects.
As of August 17, 2009, the City began ensuring these measures are addressed through the 2009 Capital Construction Program. It is expected that contractors will specifically address this issue in all 2010 mix designs submitted to the City of Edmonton. All new hot mix asphalt concrete mix designs for materials supplied to the City or used on City projects will be evaluated according to AASHTO T 283, "Resistance of Compacted Bituminous Mixture to Moisture Induced Damage," using 150mm or 100mm diameter specimens compacted utilizing gyratory or marshall apparatus. The minimum acceptance value shall be 75% for specimens subjected to the freeze-thaw conditioning.
For more information:
Transportation Operations
15th Floor, Century Place
9803 102A Avenue
Edmonton, Alberta
T5J 3A3
| Telephone | 780-496-3095 |
|---|---|
| transportationoperations@edmonton.ca |
