Hot mix asphalt a runway choice material

As hot mix asphalt is used to construct the overwhelming majority of this province’s highways, the official motto of the Ontario Hot Mix Producers Association (OHMPA) is “Why Ontario Rides on Us.”

A slight variation of that slogan was used at the association’s recent fall conference to underscore the point hot mix asphalt is also the material of choice in the construction of airport runways and taxiways.

‘Why Ontario Lands on Us’ was the title of a presentation by Ludomir Uzarowski, principal of Golder Associates, a geotechnical firm which has been the consultant on several Canadian airport redevelopment projects.

Ninety per cent of airport runways in North America are constructed with asphalt, although in Canada the figure is between 80 to 85 per cent, he said.

“Asphalt works well in all climatic zones: hot, moderate, cold, and has wide application across Canada and North America,” said the speaker, in explaining that extensive use.

Other factors include asphalt’s proven history of long-time performance, its cost effectiveness, easy maintenance, and the fact that, in most regions, there is always an available supply of aggregates, asphalt cements, and mixes.

Airport owners, designers, consultants and builders, however, are increasingly being challenged by governance change. In the past, guidance for pavement material and technology was provided by Transport Canada. “But that has been changing with privatization (of government services).”

In the specific case of Golder Associates, it looks for input and solutions from still valid Transport Canada guidelines, provincial technology, and some of the decisions enacted by the U.S. Federal Aviation Administration, he said.

But it’s the roadbuilding industry which airports ultimately follow. New technologies, mixes, and methods employed in road building are gradually implemented in runway and taxiway construction, said Uzarowski.

In 2008 Golder Associates conducted a study for SWIFT, an annual industry airfield pavement and maintenance conference. Among the conclusions was the fact that Marshall Mix designs were predominant and few airports were utilizing material transfer vehicles (MTV). Now that Superpave PGAC (Performance Graded Asphalt Cement) and HTVs are more prevalent in road building, those systems are now being adopted by airports, he pointed out.

Similarly, airports are exploring the potential of warm mix asphalt because of the benefits it offers over hot mix asphalt such as the reduced fuel consumption needed in its manufacture, plus its suitability for late season paving, the audience was told.

“There are ongoing improvements in airside asphalt paving specifications,” said Uzarowski, citing the specifications Golder created to master the challenges of pavement work at the Churchill Falls Airport in Labrador.

Those challenges include “very difficult soil and limited quality of good quality materials in a remote location.” In a short interview after the conference, he said those specifications are now being studied by the Newfoundland and Labrador department of transportation and works for possible use in roadbuilding.