By: Nelly Ewurabena Ayiku
Introduction
Asphalt is a crucial building material used for constructing roads, driveways, and parking lots across the globe (Hidalgo, Moreno-Navaro, Tauste and Rubio-Gamez, 2020). However, experts have raised concerns over the climate change and environmental implications associated with asphalt production (Hidalgo, Moreno-Navaro, Tauste and Rubio-Gamez, 2020) With that in mind, this article provides an in-depth look at how manufacturing asphalt contributes to greenhouse gas emissions, the effects of extracting and transporting raw materials, and potential sustainable solutions.
The Manufacturing Process
The manufacturing process of asphalt requires aggregating materials like crushed stone and sand mixed with an asphalt cement binder to be heated to high temperatures around 300°F (Mrugała and Chomicz-Kowalska, 2017). This produces a durable and adaptable final product able to withstand heavy loads and traffic. However, heating the ingredients necessitates immense energy supplied mainly through the burning of fossil fuels like coal and natural gas (Mrugała and Chomicz-Kowalska, 2017). The combustion of these hydrocarbon fuels emits substantial volumes of carbon dioxide and other greenhouse gases, greatly enabling climate change and furthermore, acquiring raw materials like mining for aggregates and refining crude oil for binder has large environmental footprints (Mrugała and Chomicz-Kowalska, 2017).
Greenhouse Gas Emissions
When it comes to greenhouse gas emissions, experts approximate the asphalt industry directly accounts for nearly 5% of total global carbon emissions annually (Ma, Sha, Lin, Huang and Wang, 2016). The high temperatures mandated during the manufacturing process result in enormous outputs of carbon dioxide and other toxins from extensive fossil fuel combustion (Ma, Sha, Lin, Huang and Wang, 2016). Continuing such rates could severely hinder climate change mitigation attempts occurring in other sectors. Lastly, the overall lifecycle emissions including ingredient procurement, transport, paving roads, and disposal contributes up to 8% of carbon outputs around the world (Gruber and Hofko, 2023).
Raw Material Extraction and Transportation
With regards to the material extraction and transportation of asphalt, along with direct production emissions, the extraction and transportation this raw material also promotes environmental damage (Khater, Luo, Abdelsalam, Ma and Ghazy, 2021). Broadly speaking, aggregate mining with heavy machinery tears up landscapes, destroys flora and fauna habitats, and scars quarry sites (Tafazzoli, 2019). Moreover, ocean freighters and long-haul trucks carrying tons of raw asphalt components like stone aggregates and binder over far distances generate immense carbon dioxide emissions from extensive fuel consumption (Vega A., Gilberto and dos Santos, 2019)
Implementing Sustainable Practices
Fortunately, the asphalt sector actively invests in sustainable technologies and processes to lower its environmental footprint. For example, reusing old asphalt by adding reclaimed asphalt pavement (RAP) into new batches cuts down on the virgin materials required, saving costs and emissions (Mantalovas and Di Mino, 2019). On the other hand, leading business in the industry are developing novel or new bio-binders from organic waste streams which could potentially replace standard synthetic binders to improve carbon efficiency (Mantalovas and Di Mino, 2019). Nonetheless, there is also the idea of switching manufacturing plants to renewable energy such as; wind and solar as reliance on electricity or electrical power using these renewable sources reduces the dependence on fossil fuels for heating raw materials or ingredients needed in the production or transformative process of asphalt for everyday use in society. Last but not the least, undertaking a complete environmental lifecycle analysis will shed light on the opportunities for efficiency as well as improvements in the sense that, with such impactful changes, the asphalt industry can continue providing essential infrastructure materials while achieving climate change targets (Mantalovas and Di Mino, 2019).
Conclusion
On an ending note, asphalt is an integral construction material for infrastructure around the world, yet its manufacturing process exerts a heavy environmental toll through immense greenhouse gas emissions from fossil fuel usage and raw material extraction. Experts estimate the industry directly accounts for 5% of global emissions in addition to upstream and downstream impacts associated with ingredient supply chains and product lifecycles. Fortunately, promising solutions exist from reusing old asphalt to developing bio-based binders that could substantially curb emissions while still delivering essential pavement materials. However, fully transforming asphalt production requires holistic lifecycle thinking across stakeholder groups. Thus, via innovation and strong climate policies, the sector can continue providing roads and parking lots society depends on but through an environmentally-conscious and sustainable lens. Nonetheless, there remains work in quantifying total footprints and identifying optimization potential, however, strategic collaboration and investment offer realistic paths to significant emission reductions over the coming years.
References
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Vega A., D. L., Gilberto, M. A. and dos Santos, J. M. O. (2019) ‘Life Cycle Assessment of Warm Mix Asphalt with Recycled Concrete Aggregate’, IOP Conference Series: Materials Science and Engineering, 603(5), pp. 1–5. doi: 10.1088/1757-899X/603/5/052016.
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