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Published on: July 12, 2024
Emissions of tar-containing binders: a laboratory study
Martin Hugener1, Lukas Emmenegger, Peter Mattrel
1Laboratory for Road Engineering/Sealing Components, EMPA, Swiss Federal Laboratories for Materials Testing and Research, Duebendorf, Switzerland. martin.hugener@empa.ch
Summary
Hot recycling of tar-containing pavements is controversial due to unknown hazardous emissions. Research shows polycyclic aromatic hydrocarbons (PAHs) emissions correlate with vapor pressure, but standard assessments may be inappropriate.
Area of Science:
- Environmental Science
- Occupational Health
- Materials Science
Background:
- Hot recycling of tar-containing pavements in Switzerland faces controversy.
- Concerns exist regarding hazardous compound emissions, particularly polycyclic aromatic hydrocarbons (PAHs), and worker health risks.
Purpose of the Study:
- To investigate the emission behavior of tar-containing materials during hot recycling.
- To identify and quantify key parameters influencing PAH emissions.
Main Methods:
- Mixtures of tar and bitumen with varying PAH content were heated in an open reactor flask.
- Emissions were analyzed at different temperatures to quantify PAH levels.
Main Results:
- A linear correlation between PAH concentration in fumes and binder was observed only for binder mixtures exceeding 5000 ppm PAH.
- PAH emissions correlated with vapor pressure, but Naphthalene and 3-ring PAHs showed partial depletion in vapor.
- This suggests a slower increase in emissions for these compounds compared to 4-6-ring PAHs with rising temperature.
Conclusions:
- The standard EPA-PAHs assessment may be inadequate for evaluating health hazards in hot recycling of tar-containing materials.
- Further research is needed to refine emission assessment methods for these materials.
