How to Harden Recycled Asphalt [Solved]

Last updated on July 24, 2022

Asphalt milling hardens over time. However, there are various ways to speed up the process. Read some of the examples below!

Asphalt millings are a recycled material that is turned into gravel-like aggregate. They’re then spread on road surfaces and compacted.

Recycled asphalt is a cost-effective and eco-friendly way to repave a road or a driveway. It’s also a preferred material because it’s budget-friendly and doesn’t need much maintenance.

Additionally, this material is durable and can withstand even worse weather conditions such as heavy rain, ice, or snow. Hardening the asphalt is a great way to make it last longer. While it can harden over time, speeding up the process gives you a better value for the cost.

But how do you harden recycled asphalt? The answer depends on the type of asphalt you use for your project. A steam roller is best if you use a cold mix of asphalt millings. However, that’s not the only way. Scroll down to know more!

Table of Contents

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Hardening Asphalt Millings vs. Regular Asphalt (Hot Mix vs. Cold Mix)

Hardening Asphalt Millings

Hot mix asphalt is usually hardened by compacting the asphalt with a roller machine. Recycled asphalt millings, also known as cold mix asphalt, must first be heated before being compressed to ensure it hardens properly. That is why a steam roller is commonly used for compacting and hardening asphalt millings. 

A regular asphalt layer is made by mixing heated bitumen or tar with aggregate. The mixture is applied to the road, pavement, driveway, or parking lot using a paving machine. What follows is hardening using a standard roller machine. 

Asphalt millings are also known as crushed asphalt or recycled asphalt. They are created by grinding up a deteriorated asphalt surface. Asphalt millings or cold mixes are typically used to pave driveways, parking lots, and private roads. 

A steam roller must be used to harden asphalt millings. The heat from the steam will melt the bitumen in the asphalt to allow for firmer bonding. The hardening process usually takes 24 hours. 

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How Long Does It Take for Asphalt Millings to Harden on Its Own?

How Long Does It Take for Asphalt Millings to Harden on Its Own

It is important to note that asphalt millings can harden on their own over time without using any special equipment. It may take weeks and months, and the process depends on the weather. Hardening of asphalt millings may be faster in the summer due to the high intensity of sunlight. 

Hardening and sealing recycled asphalt will significantly prolong its service life.

If you’ve been wondering how to harden recycled asphalt, you now know a few available options. If you want your asphalt milling pavement to harden on its own, be sure to do the installation in the summer. Otherwise, using a steam roller to set the recycled asphalt would be best. 

For proper hardening of recycled asphalt, experts recommend using a steam roller once the cold mix of asphalt has been spread on the surface. The heat from the equipment will heat the bitumen in the asphalt to ensure proper bonding and hardening. In just 24 hours, you will have a hardened recycled asphalt driveway. 

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Binder Materials

Binder Materials

Coal-tar binders often bind asphalt (the aggregate) to create a bitumen mixture. Different grade aggregates (such as cement or sand) may also be added to the mixture. However, recycled asphalt is different in this regard.

RAP binders (recycled asphalt pavers) must differ because the millings have aged binders. This is usually the same hardened bituminous binder. Its properties and the presence of virgin aggregates influence the choice of the right binder material for recycled asphalt.

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How Is Recycled Asphalt Hardened?

How Is Recycled Asphalt Hardened?

A steam roller is typically used to harden cold mix asphalt. As the name suggests, a steam roller produces steam and has a roller for compacting the asphalt millings. Once the asphalt millings have been spread onto the surface to a suitable thickness, the steam roller is used to harden the surface. 

A steam roller uses super-heated steam to melt the tar in the asphalt millings. The molten tar in the asphalt millings will bind together and harden more effectively when the roller passes over the surface. On average, it takes just 24 hours for the recycled asphalt to harden compared to the 30 days it takes regular asphalt to harden. 

One of the main benefits of paving a driveway with asphalt millings is the speed of installation. In just one or two days, your driveway will be ready. Secondly, this is a cheaper and eco-friendly option for paving driveways and private roads. 

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Using a Steamroller

Using a Steamroller

A steam roller is a type of heavy equipment used in road construction. The equipment has a drum instead of rear wheels and two smooth wheels in front. The drum is hot and heavy, making it the perfect equipment for compacting recycled asphalt surfaces. 

After the asphalt millings have been spread onto the surface, the steam roller is driven slowly over the asphalt millings to apply high pressure per square foot of the mix. The heat and weight of the drum of the steam roller will ensure the asphalt millings are hardened effectively. 

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Spraying Diesel on Recycled Asphalt

Spraying Diesel on Recycled Asphalt

The primary binding agent in asphalt is bitumen or tar, a crude oil by-product. When diesel fuel is sprayed onto a recycled asphalt road, driveway, or parking lot, it acts as a solvent. While the asphalt milling driveway can be easier to compact after spraying with diesel, its strength will reduce. 

It is a mistake to spray diesel on recycled asphalt as diesel is a solvent that will dissolve the binder in the asphalt. Other compounds that should be removed from asphalt surfaces include grease and engine oil. If you want to spray diesel to kill weeds on the asphalt driveway, only use a small quantity. 

If you have a DIY recycled asphalt driveway that is not as smooth as you would like, diesel may seem the obvious choice. However, the best option is to use a steam roller. Many local contractors have steam rollers usually hired out to interested parties. 

Steamrollers combine the intense heat and weight of the equipment to flatten and compact surfaces made of asphalt millings. Instead of experimenting with diesel to achieve a smoother finish, consider renting a steam roller. To get superior results, however, consider hiring a licensed contractor to pave your driveway with asphalt millings.

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