So, you have a patio and you are wondering if you can use recycled asphalt as the base? You have read online that some people have started using asphalt millings for paver base, and you want to know more? Well, do not worry, we have the answers for you.
In the past few years, asphalt has become an alternative to concrete. It is a material used in road construction repairs. Similar to concrete, asphalt has a life span that runs its own course.
So, because it has a life span, the question is what to do with old asphalt? And what exactly is asphalt milling?
What is asphalt milling?
Let’s start from the beginning. Asphalt milling is the result of grinding old and worn out asphalt, allowing it to take on a shape similar to traditional gravel. So, in a way, it is something between gravel and asphalt.
The difference is unlike gravel, recycled asphalt millings will bind together when compacted down. That makes it a great alternative to gravel roads, parking lots, and more.
One of the big questions people ask is whether asphalt millings wash away? Do not worry, asphalt does wash, but not as bad in lighter rains. Yes, heavy downpour, running downhill, it can wash. But that is why you put a crown to get the rain off to the sides.
Benefits of asphalt millings
Because we are talking about asphalt millings for paver base, you are naturally wondering why you should use them? Why not use gravel instead? Well, here are some of the asphalt milling benefits.
- Low price – it is incredibly affordable compared to other materials. Because it is asphalt crushed into a new form, they can cost quite cheap because the process of preparing and transporting involves a far fewer investment of resources like time, money, and labor
- Environmental benefits – old asphalt that has reached the end of its service is usually discarded in landfills. But asphalt millings can reuse and recycle asphalt, giving it new life. We are living in the era of sustainable materials and more and more people are looking for ways to reduce their carbon footprint. Asphalt millings are one way to do it
- Low maintenance – Once it is placed, asphalt milling can reduce the amount of dust, dirt, and mud that appear on your property. Asphalt milling is also resistant to the ravages of weather and time, and it will grow stronger and harder over the years. There is no need to worry about things like refinishing or resurfacing
- Great aesthetics – We know people love gravel because of its aesthetics. Well, now you get the same beautiful look for a lower price. Asphalt milling can mimic the appearance of crushed gravel or crushed stone. And still, get the appearance of a polished asphalt as well
- Great in weather – One of the best aspects of this material is its ability to stand up to harsh weather conditions. It produces less dust and less mud, and the snow has a tendency to melt faster on asphalt millings compared to gravel. Ice has a difficult time forming, resulting in a safer walking path
Disadvantages of gravel
We talked about the benefits of asphalt millings, now let’s talk about some of the disadvantages of gravel.
- Potential for displacement – Plowing, driving, or crossing a gravel path can displace individual pieces away from their initial location
- Sand and dirt can leave a muddy path
- Lack of solid surface – At the end of the day, gravel is a collection of rocks that are not close to the same size. It is nearly impossible to obtain a solid surface even with compacting
- Snow and ice can stick to gravel and snow will form between the pieces of gravel
How is it collected?
So, how do professionals collect asphalt millings? When replacing an asphalt road, the typical practice is to use a milling machine to grind up the old asphalt and then vacuum up the milled asphalt material. That leftover material serves as a base for the new asphalt.
But now that asphalt millings are collected, it is time to decide what to do with them. It can easily be recycled.
The most common method for recycling is re-mixing the millings back into the crushed asphalt mixture for a cost-effective aggregate. But it can also be used as a base for asphalt paving if you want to buy it.
How to Install Asphalt Millings?
So, now that we know the benefits and how it is collected, let’s talk about how to install asphalt millings for paver base.
- Start by evaluating the existing subgrade. Drive a vehicle over the driveway. For the test, always use the largest vehicle that will use the driveway. Look for tire ruts or lateral movement under the wheel loads. If weak subgrade material is found, just remove it and replace
- Now look at the asphalt millings. Determine if it has a lot of fine material or if the material is coarse. If you have coarse material, use an added emulsion percent of 2.5% to 3%. If you have fine material, use an added emulsion percent of 3% to 3.5%. An emulsion is an additive that helps bind the mix. Make sure to select one for a cold mixture of asphalt
- Screen the millings and see if there are pieces larger than two inches. Crush them in size to make the material pass through the two-inch screen opening
- Add the emulsion to the screened millings in the pug mill. Mix the ingredients until you get homogenous material
- Transport the mixture to the driveway location
- Dump it into a spreader or asphalt paver. Spread it using an asphalt paver or spreader and place at least 3.5 inches of the mix over a soil subgrade. If there are rocks under the recycled material, you can use less of it, depending on the size of the vehicles
- Compact the milling using a 25-ton pneumatic-tired roller then a 12-ton or larger double drum vibratory steel-wheeled roller. Make sure to add water to the steel drums to avoid any material sticking to the roller
- Place a chip seal mix over the pavement mat or a 1.25-inch layer of new asphalt surface course. This will seal the surface of the recycled asphalt pavement
Tips for installing
Here are some bonus tips for installing recycled asphalt millings for the paver base.
- Make sure the driveway can withstand extra cars. Check the current condition by driving a car over the asphalt milling driveway
- Inspect it for coarseness and use emulsifiers to thicken the millings
- Do not forget the spreader or asphalt paver to distribute the material evenly