Cutback Asphalt and Emulsified Asphalt
Table of Contents
What Are Cutback Asphalt and Emulsified Asphalt?
Cutback asphalt and emulsified asphalt are used for a number of applications during road construction. In preparing these products, asphalt cement is mixed with either a petroleum diluent to produce cutback asphalt or with emulsifiers, water, and sometimes petroleum diluent to produce emulsified asphalt. Once the liquefied asphalt cement is applied during road construction, the diluent petroleum solvent (in the case of asphalt cutbacks) and water (in the case of asphalt emulsions) evaporates leaving the cured residual asphalt cement. The application of asphalt causes emissions of volatile organic compounds (VOC) through the evaporation process described above and contributes to the creation of ground-level ozone and particulate matter, which are major components of smog.
The majority of asphalt used in Canada is the emulsified asphalt type. Based on a study conducted for Environment Canada in 2010, 301 kilotonnes (kt) of liquefied asphalt were used in Canada in 2009, 85 percent of which was emulsified asphalt while 15 percent was cutback asphalt. The total VOC emissions associated with this usage are estimated to be 8.8 kt (5.2 kt for cutback asphalt and 3.6 kt for emulsified asphalt). While cutback asphalt represented only 15 per cent of asphalt use in Canada in 2009, it was responsible for 59 per cent of the VOC emissions associated with the use of asphalt. The same study estimated that VOC emissions from asphalt could reach 10.8 kt in 2020 without an environmental framework to guide the use of asphalt in Canada.
A consultation session on possible control measures to establish VOC concentration limits from asphalt products was held in March 2012. A Discussion Document on the Possible Control Measures on Volatile Organic Compounds (VOC) Concentration Limits in Cutback Asphalt and Emulsified Asphalt that outlines the background information and discusses potential approaches was developed.
Proposed Code of Practice for the Reduction of VOC Emissions from the Use of Cutback and Emulsified Asphalt
After the March 2012 consultation regarding the discussion paper, a Code of Practice was deemed as an efficient and cost-effective tool to achieve up to 5 000 tonnes of VOC reductions annually while minimizing the burden on the road construction industry.
On April 4, 2014, Environment Canada published a draft Code of Practice for the Reduction of VOC Emissions from the Use of Cutback and Emulsified Asphalt. Stakeholders were invited to comment on this draft Code during a public consultation period which ended June 6, 2014. Comments received during this consultation period will be considered in finalizing the Code.
How Can I Stay Informed?
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Questions and inquiries can be directed to Environment Canada at:
Telephone: 888-391-3426 or 819-938-4483
Fax: 888-391-3695 or 819-938-4480
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