Asphalt Thickened Edge Detail: Enhancing Durability and Functionality

The asphalt thickened edge detail is an innovative approach to enhance the durability and functionality of asphalt surfaces. Developed as a solution to address the challenges associated with edge deterioration in asphalt pavements, this technique focuses on strengthening the outermost edges of the asphalt layer. Additionally, this approach not only enhances the durability of the pavement but also improves it’s functionality by providing better resistance to heavy traffic loads, weathering, and environmental factors.

What Happens if Asphalt Is Too Thick?

If asphalt is too thick, it can negatively impact it’s durability and functionality. Over time, traffic on the surface can cause depressions, especially in areas with frequent use. These depressions can disrupt the smoothness and evenness of the pavement, compromising it’s durability.

This can create a bumpy and uncomfortable driving experience, as well as increase the risk of accidents and vehicle damage. An uneven surface can cause vehicles to swerve or lose control, posing a safety hazard to both drivers and pedestrians.

Furthermore, excessive thickness can also increase the cost of the project. Asphalt is typically priced by the ton, so applying more material than necessary will result in higher expenses. This can prolong the construction process and incur additional labor costs.

To ensure the durability and functionality of an asphalt pavement, it’s essential to adhere to the recommended thickness guidelines and properly compact the material. This will enhance the longevity of the surface and provide a smoother, safer, and more cost-effective solution for residential driveways and various other applications.

In addition to it’s cost-effectiveness, a thin asphalt overlay offers many benefits such as improved ride quality, enhanced skid resistance, and increased pavement life. However, determining the minimum thickness for such an overlay can be challenging. Factors like traffic loading, existing pavement condition, and climate conditions must be considered to ensure adequate performance and durability. This article explores the various factors influencing the thickness of a thin asphalt overlay and how it can be optimized for different scenarios.

How Thin Can an Asphalt Overlay Be?

Asphalt overlays are often used as a cost-effective solution for rehabilitating deteriorated pavements. A thin asphalt overlay, as the top layer of the pavement, is typically a dense graded mixture with a small nominal maximum aggregate size (NMAS). This type of overlay is placed at a thickness of less than 1½ inches, utilizing conventional asphalt production and placement techniques.

The primary purpose of a thin asphalt overlay is to enhance the durability and functionality of the pavement. By resurfacing the existing pavement with a thin layer of asphalt, it provides a smooth driving surface with improved skid resistance. This not only increases the overall safety for road users, but it also reduces the occurrence of roughness and potholes.

The key to achieving this lies in the selection of appropriate materials and application techniques. The mixture should possess adequate stability and flexibility to resist cracking and rutting, while also maintaining good workability during placement operations.

Prior to overlay construction, any underlying distresses, such as potholes or cracks, should be identified and repaired to ensure a stable base for the overlay. Additionally, proper surface preparation, including cleaning and applying a tack coat, helps promote bonding between the existing pavement and the overlay.

Although it’s placed at a thickness of less than 1½ inches, it can provide a smooth driving surface with improved skid resistance. However, it’s crucial to address any underlying pavement distresses and ensure proper surface preparation to ensure a successful overlay installation.

The thickness of asphalt over concrete is a crucial factor in ensuring the stability and integrity of the pavement. Bonded concrete overlays of asphalt (BCOA) pavements have been found to be effective when they’re between 3 to 6 inches thick. This range is particularly important for thin concrete overlays, as it allows for a strong bond between the asphalt and the concrete, enabling the pavement to function as a single, unified structure.

How Thick Should Asphalt Be Over Concrete?

When it comes to the thickness of asphalt over concrete, bonded concrete overlays of asphalt (BCOA) pavements are typically constructed to be between 3 to 6 inches thick. This range is considered ideal to ensure the durability and functionality of the pavement structure. The bond between the asphalt and the concrete plays a crucial role in achieving a harmonious integration, especially for very thin concrete overlays.

The thickness of the asphalt layer is carefully determined based on several factors. One such factor is the anticipated traffic load and volume. Pavements subject to heavy traffic or high volumes will generally require a greater thickness of asphalt to withstand the stresses imposed on the structure. Additionally, considerations such as climate, soil conditions, and the desired design life of the pavement must also be taken into account.

This bond ensures that the two materials act as one cohesive structure, enhancing durability and functionality. Without a strong bond, the asphalt layer may separate from the underlying concrete, leading to premature cracking, rutting, and overall pavement deterioration.

This thickness is determined based on various factors such as traffic load, climate, soil conditions, and desired design life. Taking the necessary measures to promote a strong bond, such as thorough cleaning and the application of bonding agents, enhances the durability and functionality of the pavement.

The Process of Constructing Bonded Concrete Overlays of Asphalt (BCOA) Pavements

The process of constructing bonded concrete overlays of asphalt (BCOA) pavements involves adding a layer of concrete over the existing asphalt surface. This technique, known as asphalt thickened edge detail, provides numerous benefits such as enhanced durability and functionality.

The construction process begins by thoroughly cleaning the existing asphalt surface to remove dirt, debris, and any loose materials. Once the surface is prepared, a bonding agent is applied to ensure a strong adhesion between the asphalt and concrete layers.

Next, a concrete mixture is prepared and spread over the asphalt surface to achieve a desired thickness. The edges of the overlay are thickened to provide extra strength and resistance to cracking, hence the term “thickened edge detail”. It also helps in preventing water penetration and reducing the risk of damage caused by freeze-thaw cycles.

Once the concrete overlay is in place, it’s properly cured and allowed to harden. This process strengthens the bond between the asphalt and concrete layers, ensuring a long-lasting and durable pavement surface.

The use of asphalt thickened edge detail in the construction of bonded concrete overlays offers several advantages. It improves the overall performance and lifespan of the pavement by enhancing resistance to heavy traffic, reducing surface cracking, and minimizing maintenance requirements.

In summary, the process of constructing bonded concrete overlays of asphalt pavements through the asphalt thickened edge detail technique provides durability and functionality improvements to the pavement, making it a preferred choice for various applications.

Next, the contractor should apply a tack coat of asphalt emulsion to the concrete surface. This will help the new layer of asphalt adhere to the existing concrete and prevent any separation or cracking. Additionally, it’s crucial to ensure proper drainage to prevent water from seeping into the concrete and causing damage. By following these steps, the asphalt can bind effectively to the concrete, resulting in a durable and long-lasting pavement.

Does Asphalt Bind to Concrete?

Asphalt does have the ability to bind to concrete when certain steps are taken during the installation process. If you decide to lay asphalt over your existing concrete pavement, it’s important to ensure that the necessary preparations are made to ensure a strong bond between the asphalt and the concrete.

One key step that your asphalt contractor should take is to create a uniformly thick base if it doesn’t already exist. This is important because a consistent base will provide a stable foundation for the asphalt overlay and help minimize the risk of cracking or shifting over time. Creating a uniform base may involve filling in any low spots or removing any high spots in the existing concrete pavement.

Another important step is to thoroughly clean and mill, or grind, the concrete surface before applying the asphalt overlay. Cleaning the concrete removes any dirt, debris, or oil that could hinder the bonding process. Milling the concrete involves grinding it down to create a rough texture that allows for better adhesion between the asphalt and the concrete. This rough texture provides more surface area for the asphalt to bond to, improving the overall bond strength.

By following these steps, your asphalt contractor can help ensure that the new asphalt overlay will have a good bond to the existing concrete. This is important for enhancing the durability and functionality of the pavement. A strong bond between the asphalt and concrete will help prevent cracking, shifting, or separation between the layers, resulting in a longer lasting and more functional pavement surface.

The bond helps distribute loads more evenly across the pavement surface, reducing the risk of localized failures or surface distress. This can be especially beneficial for heavily trafficked areas or areas subject to heavy loads, such as parking lots or industrial driveways.

Creating a uniformly thick base and properly cleaning and milling the concrete surface are crucial for achieving a good bond between the asphalt and the concrete.


By providing a reinforced edge that resists cracking and crumbling, this technique ensures a longer lifespan and reduces the need for costly repairs. The enhanced functionality of the thickened edge detail also helps to improve drainage and prevent water damage, further increasing the longevity of roads.

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