Presentation on theme: "CUPGA 2008 Western Canada Perspective on State – of - the Canadian Technology Challenges and Solutions John Berti, P. Eng."— Presentation transcript:
CUPGA 2008 Western Canada Perspective on State – of - the Canadian Technology Challenges and Solutions John Berti, P. Eng.
Western Canada (WCAN) Conservative approach to the adoption of the Superpave system wrt to asphalt binder specifications and mixture design and analysis system –Marshall method is still the preferred system of choice including traditional pen/viscosity graded binders Dense fine graded mixtures are most widely specified –Minimal percentages of RAP are allowed in most mixes Very little use of SMA’s for high performance pavements
Superpave Performance Grade Binders “Straight run” asphalts –WCAN Continues to Use Penetration grades (based on CGSB Pen-Viscosity system) –PG grades are never or rarely specified Small amounts of PG58-31
Superpave Performance Grade Binders Modified Asphalts – (PG = modified) –Almost all modified demand uses PG specs –Approx. 7 different grades (from PG76-28 to PG58-37) –more commonly used in high service applications (traffic intersections and slow / high truck volume applications, new construction) –Alberta biggest user, Sask/Man lowest –No “PG plus” specs but AASHTO M320 Table 2 is occasionally specified –Alternative bids with life cycle cost adjusts sometimes used (ie 150/200A or PG 58-34)
Superpave Performance Grade Binders Usage of PG grades has been increasing slightly –Approx 6% of paving asphalts in Western Canada are specified using PG specifications –P3’s are a big factor – contractors making the decision
Superpave Performance Grade Binders Issues & Challenges –Concerns about allowing lower performing grades –Concerns about available grade selection Future changes –No switching to PG for straight runs in near term –BC – increased use of PG 70-22
Superpave Mixes Used occasionally in BC (Vancouver area) (improved rut resistance) but minimal usage in other WCAN provinces In the past many Alberta highway projects used Superpave mix specifications but usage today has dropped Overall estimate less than 10% of Western Canada mixes are using Superpave mix specifications.
Superpave Mixes Issues & Challenges –High aggregate costs and greater pit depletion –AB - Concerns about poorer performance especially with coarser mixes No big changes expected in the near term
Stone Mastic Asphalts City of Edmonton has had extensive experience and use as a regular part of their program. Usage is expected to increase slightly. Other jurisdictions (Alberta and BC) have done some SMA trials or projects and others (Sask/Man.) have not.
Stone Mastic Asphalts Issues & Challenges –Edm - Availability of zero grind (mineral filler) –High Quality aggregates expensive to import, mix design, AC drain down, getting good lay down Future changes –Other than Edm. usage of SMA is expected to stay about the same –Edm. using cement to replace zero grind –Edm. looking at smaller max. size aggregate
Other Activities Warm mix –Many jurisdictions are doing warm mix trials and a number of different technologies have been used Rubber Crumb –Used extensively throughout Alberta over last 5 years but a number of agency’s have expressed performance concerns –Usage in Alberta in future is questionable –Trials have been done in BC and Sask as well. Other emerging technologies over the last 5 years include: –Ultra thin lift overlays, foamed asphalt stabilized base course, recycled asphalt shingles