9 minute read
Why asphalt is the superior choice
Why asphalt pavement is the superior choice
by James Careless
When it comes to driver safety, all-weather durability, ease of maintenance, life cycle expenditures, and environmental impact, asphalt pavement has been proven to be the best alternative for Ontario’s roadways. This is why 95 per cent of provincial roads are paved with asphalt. Few materials have stood the test of time like asphalt. The first recorded asphalt road was paved in 625 BCE in Babylon. The Greeks and Romans subsequently used asphalt for many applications. The word itself comes from the Greek “asphaltos” which means “secure” in English. ››
Innovative, cost-effective speciality mixes are being developed that demonstrate excellent performance, resist rutting, and can be produced and applied at lower temperatures. (McAsphalt)
Warm mix asphalt technology allows asphalt pavement mixes to be produced at lower temperatures, producing a more durable mix because a lower production heat results in less initial aging of the asphalt cement. The mix remains workable for a longer period of time and compacts well at lower operating temperatures. WMA cools more slowly, extending the time window that it can be placed before becoming unworkable. Lower emissions also make WMA better not only for the environment, but for the people who work with it.
Warm mix asphalt extends the paving season and makes night paving more feasible.
Thanks to ongoing innovations in material mixes, production techniques, and application methods, asphalt remains the best pavement option in the 21st century. Asphalt pavement delivers a wide range of benefits to clients and users including improved safety, all-weather durability, reduced maintenance impact, economical life cycle investments, and reduced environmental impact.
SAFE DUE TO PROVEN ALL-WEATHER DURABILITY
Every road in Ontario is subject to extreme weather conditions. To maximize driver safety through reliable traction and skid resistance, road pavements must consistently retain their strength, the quality and consistency of their composition, and their ability to support traffic loads during heatwaves and -40 degree cold snaps alike.
The blend of high-quality aggregate, asphalt binders, and Reclaimed Asphalt Pavement contained in both hot mix asphalt (HMA) and warm mix asphalt (WMA) — built upon solid subsurface bases — provide this level of driver safety year in and year out. In addition, new porous asphalt mixes have been designed to disperse surface water, which reduces blinding spray and helps to decrease the risk of aquaplaning. ››
Speed of construction and maintenance is an important benefit of asphalt pavement. New membranes to protect the bridge deck and a new wearing surface may be applied in a single night and the road opened to traffic for morning rush hour. (McAsphalt)
The invention of long-lasting asphalt-based perpetual pavement has taken this level of safe, reliable pavement to the next level. “A well-designed perpetual pavement allows for a roadway structure to last 50 years and more while only requiring the surface course to be removed and replaced every 15 to 20 years,” says Fernando Magisano, Senior Technical Advisor at Canadian Asphalt Industries Inc.
ECONOMICAL, EASY TO MAINTAIN WITH MINIMAL TRAFFIC DISRUPTION
When it comes to selecting a road building option that is affordable for both construction and maintenance, asphalt pavement has been proven to be the most economical choice. “Asphalt pavements have much lower initial construction expenses and have proven lower Life Cycle Assessment investments,” explains Magisano. “Asphalt pavements can also be constructed quickly, which reduces traffic delays for the end user,” adds Amma Wakefield, Canadian and Research Engineer with the Asphalt Institute. This is because asphalt pavement cools quickly and doesn’t require a curing time period to harden quickly. Because of asphalt’s ability to be applied quickly without any compromise to quality or durability, selecting asphalt for roadways and highways makes it possible for maintenance repairs and resurfacing projects to be completed in hours, not days. At a time when traffic congestion is a major issue for Ontario’s cities, this is welcome news for governments and the public who vote for them. “For major highways and arterial roads, many resurfacing projects can be completed at night when traffic is minimal, allowing for zero disruption for the daily commute,” Magisano says. “People just see another section of smooth, quiet and safe asphalt pavement on their way back and forth to work the next day.” “The quicker that construction, repairs or resurfacing activities can be completed, the better for everyone,” observes Ambaiowei. “Fortunately asphalt offers a blend of strategies to ensure minimal disruption to traffic,
Asphalt pavement is quiet, durable, economical, easy to maintain and repair, and 100 per cent recyclable.
each with considerations given to the existing surface distress and underlying pavement problems.”
POSITIVE ENVIRONMENTAL IMPACT
Asphalt pavement provides many positive environmental benefits to the clients who choose it, the motorists who use it, and the geographic areas that its roadways run through. Fuel economy is a key benefit of asphalt pavement, specifically the fuel consumed by cars and trucks on the roads today. The long-lasting smoothness of asphalt-paved roads reduces the amount of fuel vehicles have to consume driving from Point A to Point B. Less fuel burned means less pollution in the air, and less energy spent on producing more fuel. The facts support this conclusion. According to the U.S. Federal Highway Administration (FHWA), the rougher (unevenness, ruts, cracks, and other surface deformations) the road, the more resistance cars and trucks have to overcome when driving on it. This is because rough roads put more strain on a vehicle’s suspension system and drive train components, while deforming tire sidewalls. “The working of these vehicle components converts mechanical energy into heat that is then dissipated into the air, requiring greater work by the engine than would be necessary to propel it along a flat surface,” the FHWA web page ‘Vehicle Fuel Consumption and Pavement Characteristics’ explains. In 2007, Applied Research Associates (ARA) reviewed an Ontario Ministry of Transportation database containing over 35 years’ worth of biannual pavement condition surveys to see how asphalt pavement fared against other options in retaining this fuel-saving smoothness. ARA found that Ontario’s asphalt pavements are much smoother initially and remain smoother over their lifetime than other options. Asphalt pavements are quiet pavements. The smoothness of asphalt pavements helps to reduce tire-pavement noise by five decibels says a 2013 Virginia Department of Transportation study. While five decibels may not seem that much, a three decibel reduction is the same as a 50 per cent reduction in the sound level and six decibels is a 75 per cent reduction in sound level (inverse square law). The result: “In many countries other materials are now banned from use in road surfaces in densely populated or noise sensitive areas, with asphalt recognised as the only successful noise reducing surfacing material,” says the European website www.asphaltadvantages.com. Asphalt pavements do not leach into water or groundwater. As a result, asphalt is commonly used to seal potable water reservoirs and fish farming ponds. “Asphalt has been used in these applications for more than half a century,” www.asphaltadvantages.com says. “As an inert material, it is resistant to the action of most acids, alkalies, and salts.” ››
High quality, high performance RAP pavement. (County of Brant)
The use of RAP in pavements is considered a sustainable approach to road building that leads to cost-effective spending on infrastructure while preserving resources of virgin materials and diverting large amounts of solid waste from landfills. Reducing asphalt consumption and using locally available recycled materials also limits greenhouse gas emissions.
100% RECYCLABLE
When an asphalt road needs repaving, the old asphalt surface is removed. But this material isn’t sent to a landfill; instead, it becomes RAP (Reclaimed Asphalt Pavement). “RAP can be milled from an old road or pavement structure, brought to a yard, re-crushed in a solid ‘black rock’ state, and then added back at the asphalt plant,” says Donn Bernal, Principal at Corfinium Solutions Inc. “It can be mixed at the plant at percentages of up to 50 per cent or more (with the proper technologies and mix design) of the new asphalt mix and then brought back to the paving project and paved back to a ‘new’ state for another 20 years or more of design life.”
What this means is that “asphalt pavements are 100 per cent recyclable,” Magisano says. “This is why asphalt pavements are the most recycled product in North America,” notes Wakefield. In fact, more asphalt pavement is recycled on this continent than anything else, including aluminum, paper or plastic. This makes using asphalt to pave roads an environmentally sustainable practice, and one that matches the needs of our times. “As our times strive for us to achieve net zero in many things we do, I look at asphalt and whether that is possible with this material. The quick answer is yes!” Bernal says. “And now research and trials are being completed to add recycled plastics to asphalt (without giving up performance) and we have a material that helps to move people while being sustainable. Then add the fact that the technology has advanced to allow us to produce asphalt at a lower temperature (where a 10˚C drop in temperature yields an exponential drop in emissions), and we have ourselves a material that gets us closer to net zero.”
THE BEST OPTION
There are few products in this world that are durable, economical, easy to maintain and repair, and 100 per cent recyclable. Asphalt pavement is one of them, which is why it is the overwhelming choice for roads not just in Ontario, but around the world.
James Careless is an Ottawa-based freelance writer with credits in the National Post, Toronto Star, and AI’s Asphalt magazine.
