Asphalt is one of the most common and most popular materials in the world. Widely used for the construction of pavements and roads, asphalt is all around us, and has been for some time. However, while in the past asphalt has represented one of the least environmentally-friendly construction materials out there, being made as it was from crude oil products, things have changed a lot. We now have access to a variety of different techniques for producing asphalt and have learned to use much more eco-friendly materials in its production.
Today, there are a number of reasons why you should consider asphalt as one of the most environmentally-friendly materials out there.
1. Energy Conservation
One of the key environmental advantages of asphalt is that it requires less energy to produce than other pavement materials. One study, published in 2005, found that the energy cost of producing an asphalt pavement was on average 20% lower than other common materials. Not only this, but the physical properties of asphalt as a material mean that vehicles travelling over it also require less energy. In fact, beyond the production of asphalt, and the way in which it is then used as a construction material, there are other, more indirect, ways that asphalt is more environmentally-friendly than the alternatives.
For example, all construction materials are susceptible to erosion and degradation over time. At some point or another, most of us have had to deal with congestion on the highway, caused by lanes of traffic being closed in order for repairs and maintenance of the road surface to be carried out. These repairs cause quite a considerable environmental impact, once you factor in the various ways in which it requires energy.
Slowing down traffic means having vehicles idling on the road for prolonged periods of time. This means that the emissions of these vehicles are released slowly and in a relatively concentrated area, exacerbating their negative impact. Then of course there are the environmental costs of producing the materials in order to carry out the repairs, transporting them to the site, and undertaking the repairs themselves. The longer it takes to complete these repairs, the more environmental damage will arise due to emissions.
Asphalt is much easier and faster to repair than other paving and road surface materials. This means that, in addition to its lower emissions during production, it continues to exact a much lower environmental cost over time. Because of this, asphalt is a popular material to use in home driveways amongst the most environmentally conscious consumers. Check out SaveOnPaving.com for more detail on why asphalt is preferred for driveways specifically.
The concept of recycling is one of the most powerful and important when it comes to the environment. Anything that can be reused or repurposed can save us the costs, financial and ecological, of producing new materials. There are, to state the obvious, a lot of roads and pavements across the United States. As we mentioned earlier, all these roads and pavements require periodic maintenance and repairs. If we have to produce or use our stockpiles of new materials each time we do this, the environmental costs rapidly add up.
Simple logistical concerns make it impractical to transport and use very small amounts of material. This means that, in some cases, essential repairs which only require a small amount of material end up producing the same costs as a much larger job. In the case of asphalt, however, the industry in the United States claims to recycle some 95 million tons of the material every year. This is in addition to a further 100 million tons of product which are reclaimed every year. These numbers add up to make the asphalt industry the number one recycler in the United States.
As well as the ability to reuse and reclaim asphalt itself, it is also increasingly being made from recycled materials. In the early days of asphalt, it was produced from crude oil products and other ingredients which were decidedly not environmentally friendly. However, it is now mostly produced from other materials which are repurposed and recycled. In particular, rubber from old car tires, glass, and roofing shingles are regularly melted down and used to produce new asphalt.
When it is constructed and installed properly, asphalt has a very impressive level of durability. Road surfaces made from asphalt, which are laid down in the most effective way possible, will keep the road itself protected permanently. Over time, there will be some damage to the asphalt arising from general wear, tear, and erosion. When it does need to be fixed or replaced, it is only the top layer that needs to be removed. This allows for repairs to be carried out overnight, minimizing the disruption to traffic, and limiting the amount of excess emissions resulting from the reduced flow of traffic.
Any asphalt which is removed as part of the repair process can then be repurposed. Reclaiming and recycling old asphalt in order to produce new material is a straightforward process, and the resulting asphalt, while made from old and worn material, has just as much strength and integrity as the new material which replaces it on the road.It is very rare that an asphalt surface will need to be completely removed and replaced. On the rare occasions where this is required, the surface can be replaced with recycled materials, greatly reducing the environmental costs of the process.
A similar situation applies to pavements. When asphalt isn’t used, it is generally concrete that pavements are made from. Concrete is a more difficult material to work with. While durable and strong, concrete cannot practically be repaired, requiring a complete replacement instead. This means that just about any damage to a concrete pavement will necessitate a replacement, requiring much more material than would be needed to repair a layer of asphalt.
Through a process called rubblization, damaged or worn concrete can be used as the basis for a new asphalt road. This can reduce the environmental costs of repairing a surface considerably. First of all, it will eliminate the need to have trucks hauling old material away and bringing new materials to the site. The repairs will require less materials, needing only enough asphalt for the rubblization process, and saving a considerable amount of concrete. Replacing a concrete surface with an asphalt one also means a reduced need for repair and maintenance works in the future, giving an ongoing environmental benefit.
4. Water Quality
Impermeable road and paving surfaces can cause a number of problems. For example, when it rains, water can build up on impermeable surfaces. In some cases, this causes a slow erosion of the material, which can be exacerbated in areas that are susceptible to more acidic rainfall. Where there are cracks or other areas of minor damage to a surface, water can fill these in and lead to the growth of weeds, which can further damage the surface. There is also the possibility that, in colder weather, the water will freeze and expand. For a concrete paving slab, this can be disastrous. On the other hand, asphalt has more physical flexibility, and can therefore tolerate the effects of ice expansion much better.
However, the greatest environmental concern that arises from the use of non-porous materials is that of runoff. Runoff occurs when water falls onto a surface, then flows off it, picking up debris as it goes. For roads and pavements near to streams, rivers, and other bodies of water, this runoff can lead to an accumulation of minerals in the water. When this occurs, it can set off rampant and out-of-control growth of algae and other aquatic wildlife. This throws off the local ecosystem and can result in much of the local wildlife dying.
Asphalt is a porous surface which does not suffer from these same issues. Once an asphalt surface has been laid down, there are very few ongoing environmental costs, beyond the repair and maintenance that we have discussed. When rain falls on an asphalt surface, it will be absorbed, and ultimately will evaporate back into the atmosphere. For roads and pavements adjacent to flowing water, asphalt is by far the best material to use in order to avoid the potential for runoff and similar issues.
5. Cleaner Air
The production of many construction materials exacts a large environmental cost. These costs can be spread over a long and complex production line, or they might be focused around a specific area. In the case of asphalt, its relatively low emissions are centered around the plants that produce it. There was a time, many decades ago now, when the production of asphalt did cause the release of a significant volume of greenhouse gases. However, advances in the production techniques used mean that we can now produce asphalt largely from recycled materials and in a much less environmentally harmful way.
The production of asphalt today releases a fraction (just 3%) of the greenhouse gases that the older production methods did. This reduction has been achieved despite the fact that the United States today produces 250% as much asphalt as it once did. Encouraging asphalt use wherever possible will therefore help to contribute to this positive trend.
Where asphalt is used for either construction or repairs, it offers an environmental benefit due to the speed and ease with which it can be laid. This is a particularly important concern in congested and built-up urban environments where there is already a relatively large amount of construction and pollution. In these environments, the effects of inefficient construction, such as more gas guzzlers and high emission vehicles on the road, are amplified.
Asphalt can be laid down quickly and efficiently, minimizing the amount of time that heavy vehicles need to spend on the road, and also minimizing the amount of disruption to traffic in the local area, which helps to further reduce the amount of pollution caused.
One of the primary constituents of asphalt is bitumen. It is the bitumen, the sticky, black substance that many people associate with asphalt, which gives asphalt many of its most desirable qualities. For example, bitumen contributes to the flexibility of asphalt. This flexibility is at the heart of asphalt’s durability. The expansion of water as it freezes, which is so damaging to concrete surfaces, doesn’t affect asphalt in the same way, largely due to this increased flexibility.
During the winter months, where this freezing damage is most likely to manifest, concrete and other similar surfaces suffer from another disadvantage. Namely, that there are a number of common de-icing agents which cause structural damage through erosion. When concrete becomes damaged, it is often difficult and impractical to repair, rather than replace, the surface. On the other hand, you can salt an asphalt surface, safe in the knowledge that even if it does become damaged it is easy inexpensive to repair.
By requiring repairs less frequently and being easy to repair with a relatively small amount of material, asphalt offers considerable environmental advantages.
7. Heat Retention
The darker color of asphalt means that it absorbs heat much more effectively than lighter materials. In urban environments, lighter concrete pavements radiate much more heat into the environment, raising the temperature noticeably, but they do not absorb heat very well. By contrast, asphalt will absorb and retain heat. You can prove this to yourself by simply walking over the surface in bare foot on a sunny day. Crucially, while asphalt absorbs heat, it also retains it. This means that, while the asphalt itself might heat up considerably, it will not heat up the air around it in the way that concrete does. For many urban planners, this makes asphalt a preferable material.
Heat spikes in urban environments are correlated with spikes in pollution for a variety of reasons. Asphalt’s ability to absorb and retain heat, rather than reflecting it back into the environment, therefore only adds to its green credentials.
Asphalt is an excellent choice of material where environmental concerns are paramount. Whether you are a homeowner looking to redo your driveway and trying to decide on the best material, or you are responsible for urban planning, or you have any other reason for considering asphalt for construction, you should know that it is a material with solid green credentials.