In this article, we will go over the process of asphalt recycling and its dynamics. A mixture of filler, binder, and aggregates make the paving solution we know of as asphalt. Manufacturers use mineral materials such as slags, gravel, sand, crushed rock, or other recycled materials to process aggregates.
Manufacturers then have to use binders to unite the aggregates together and form a combined mixture. The most common binder in asphalt production is bitumen. For recycling asphalt, one has to mix asphalt millings or chunks, along with some additives and water in a reclaimer.
There are two methods of recycling asphalt. To learn more about the process, along with other details, read on below.
How is Asphalt Made?
You will find asphalt just about everywhere you go on a daily basis. From roads and parking lots to playgrounds and sidewalks, asphalt is the most common material in construction projects. In fact, even the coating on your roofs, carriages, and pipes is asphalt-based.
To explain it in simple words, asphalt is the aggregate material binding the gravel and crushed stone that make up our hard surfaces. Technically speaking, we can classify asphalt mixture as a bitumen-class hydrocarbon. You will typically find it in dark-brown or close to black color. Geologically, bitumen refers to petroleum’s naturally-recurring deposits, either semi-solid or solid form.
The process of asphalt manufacturing consists of several steps:
- Distillation- manufacturers heat crude oil rapidly for the initial distillation. After heating it, they transfer the crude oil to a distillation container from where they can extract the lighter-weight and volatile components. We call these fractions whose removal includes a series of cooling and condensing mechanisms. The distillation process leaves a heavy deposit we call “topped” crude that makes asphalt.
- Cutting back- Manufacturers then require a volatile substance for blending asphalt. This volatile substance has to create a more malleable product than chaste asphalt at a lower temperature.
- Emulsifying- emulsification creates an easier product to combine with aggregate. During emulsification, experts grind the asphalt into globules that must be smaller than five microns. After mixing it with water, they add the emulsifying agent to reduce asphalt and water’s potential to separate. Some of the most common emulsifying, asphalt-producing agents include vegetable oils, soap, silicates, and clay.
- Pulverizing- manufacturers may crush hardened asphalt to reduce its powdered form. After pulverization, the asphalt passes through multiple sieves to obtain uniform-sized granules.
How is Asphalt Recycled
Asphalt recycling has become widely popular, mainly because it is a greener approach and also because it is super cost-friendly. Recycled asphalt does not refer to any compromise on quality by any means or its potential durability.
Milling is the first requirement to initiate the recycling process. In asphalt milling, experts remove the top layer of asphalt from a surface, such as a driveway or a parking lot, but do not penetrate all the way to the sub-base.
Once they finish milling the asphalt, they take it to an asphalt plant for screening and sizing again. Only after completing these steps is recycled asphalt ready for new pavements or other projects. This asphalt is one of the better materials for pavements and similar hard surfaces in comparison to newer material.
Asphalt has the potential to undergo recycling numerous times without compromising on quality and durability.
The Process
There is more than one method for recycling asphalt, including full-depth recycling or hot or cold recycling. The full-depth process includes revamping worn out pavements for rebuilding and reusing. The typical, stepwise process of recycling this material is as follows:
- Mixing millings or asphalt chunks in a reclaimer or recycler and adding additives and water in it.
- For the hot recycling process, experts tumble and heat the mixture for approximately twenty minutes before they can use it. Cold recycling is different in this regard because it not only avoids heat but also saves energy in the process.
- The asphalt cement contains glue to hold the pavement together. If it is able to retain that adhesive in recycling, then it is useful as a binding agent too.
- The recycling process also aims to conserve fine mineral particles. These are a natural resource that manufacturers generate when producing material for asphalt pavement.
Benefits of Recycling Asphalt
Economic Benefits
Recycling may be an elaborate process, but its benefits far outweigh that factor. The process of asphalt is largely beneficial for local governments because it saves money that would go into new materials for paving roads.
Additionally, not only is the recycling process greener and environmentally friendly, but it also creates new business opportunities.
Taxpayers save so much money from asphalt recycling while contractors save by reducing transportation costs, materials, and energy. The best part of it all? You can rest assured of the consistent value of your asphalt even if you recycle it multiple times.
The estimates from National Asphalt Paving Association tell us that taxpayers in the U.S alone save more than 1.8 billion in a year from recycling asphalt. Even homeowners benefit because purchasing recycled asphalt is cheaper than the new material. Nevertheless, the quality and durability of recycled materials remain consistent and service individuals just as well.
Environmental Benefits
The repeated process of asphalt creation increases pollution by a large degree. What could be better than recycling what is otherwise a toxic material? It would prevent toxin production, preserving the environment.
Recycling old asphalt means you can reduce the amount of new oil you will need for your construction projects. Reducing dependence on a finite resource like oil is great news for the planet. This way, you can feel confident about making an effort for the environment.
Recycling asphalt further saves on construction material waste, but there are leftover, residual recycled materials that end up in the landfill. Plus, the mineral particles that you recycle conserve more natural resources.
So much material that comes from other industries that would otherwise go to the landfill find a purpose too. Recycling asphalt means recycling other materials into it, such as glass, pig manure, asphalt roofing shingles, and whatnot.
Asphalt mining is already quite a destructive act for the area where it occurs. Then consider the high amount of water used for it. The wisest course of action is to use only as much of the natural resources as is necessary.
It is not only the usefulness that is a positive factor here but also that the quality of your recycled asphalt increases with the other additions. You know every other material has its own attributes, which they add to your recycled goodness.
Asphalt Surface
The quality of your asphalt pavement would also improve with recycled material. The additional mineral fillers would produce stronger resistance to cracking, and so would the organic fibers in the recycled materials.
But like every other good thing, it has some disadvantages too. Reclaimed asphalt is environmentally friendly, and you can use it for paving projects. However, when it comes down to a choice between reclaimed asphalt pavement and a new asphalt one, you have to consider some important factors.
Below is a comparison of reclaimed asphalt pavement and new asphalt.
Reclaimed Asphalt Pavement VS. New Asphalt
Reclaimed asphalt will enhance the environment you live in but will also be a far cheaper option for you. When you opt for a pavement with new asphalt, you will have to incur the costs of mining, its production, and a lot of other technical details.
Reclaimed asphalt does not demand as much labor in the process, so the actual cost of it is easier on the pockets. Furthermore, from an aesthetic point of view too if you have an advantage. Many people find the look of reclaimed asphalt similar to that surface, lending it more visual appeal.
If you wish for your pavement to be serviceable and aesthetically pleasing, then perhaps reclaimed would suit you better than new asphalt.
Reclaimed asphalt also has more permeability than virgin asphalt. It can allow water to pass through it, and if you particularly live in a wetter climate, then this would work to your advantage too.
But then there are some downsides to consider. When it comes to being superior in quality, the new asphalt does take the lead. You can never be sure of what the recycling process will do the material, especially if you allow a less reputable facility to do it for you.
If you do not find the gravelly appearance pleasing, then you will not enjoy using your reclaimed asphalt pavement. Many people prefer the dark and deep appearance of new asphalt, and if you are one of those, the reclaimed might make you want to look away.
Concrete Recycling
Much of the waste stream consists of solid waste materials, like concrete. To reduce negative impacts, policymakers came up with the idea of concrete recycling, and it has several advantages. The process of recycling this solid material reuses concrete rubble in the form of aggregates.
Recycling concrete is the next best option to recycled asphalt. It has certain properties that appeal to homeowners for their construction projects. If, for some reason, asphalt is not your first choice, you may consider using concrete in its place for your pavement and other hard surfaces.
These recycled aggregates, in turn, have a lesser crushing strength, specific gravity, impact resistance, and even more absorption value than fresh aggregates.
But what factors necessitated the act of recycling concrete? Let’s take a look at them below:
- Tons of demolitions on a daily basis. While one cannot argue against the necessity of demolishing old and failing structures, how can one justify the tons of concrete that lie in waste resultantly?
- Removing useless concrete from road pavements, buildings, structures and etc.
- Earthquakes and other natural calamities leaving behind destroyed structures and buildings.
- Waste concrete comes about as a result of cylinder testing, concrete cube, and other destructive testing methods.
Hence, like asphalt recycling, concrete recycling is a positive movement, and it has several striking benefits of its own.
Let’s take a look at those below:
Benefits of Concrete Recycling
Concrete recycling is a far better option than letting it go to a landfill or merely dumping it. Like reclaimed asphalt, recycled concrete benefits the economy and environment in multiple ways, including:
- Freeing up a lot of landfill space that debris from concrete otherwise occupies
- You will find recycled a far more cost-friendly source of aggregate than the one newly mined
- It reduces tippage and the charges of freight relatively.
- Recycling concrete reduces the demand for gravel mining and hence, conserves natural resources.
- When you have recycled gravel available at convenient distances, you will not have to spend a lot of money on haulage. We can consider this as an economic and environmental advantage because high-grade aggregate for construction projects is usually available at greater distances. To acquire that, you have to go all-out in terms of longer haulage distances and costs.
- The recycled concrete is also a high-quality aggregate and enhances the strength of your construction. This results from the meticulous process of crushing, sorting, pre-sizing, screening, and eliminating contaminants from the mixture for the final product. Hence, you can rest assured of top-most quality even if it is recycled aggregate.
Final Thoughts
Recycling asphalt is a process of milling, adding water and additives in a reclaimer for obtaining an aggregate. It has many economic and environmental benefits and is a better option for homeowners looking for cost-friendly yet serviceable and durable pavement solutions.