The Complete Process for Asphalt Pavement Installation

Asphalt installation may look straightforward, but this complex process requires the right aggregate size, asphalt temperature, rolling techniques, and more for safe, stable results. If you don’t install asphalt properly, it can suffer from premature damage, creating a hazardous environment for vehicles and pedestrians. Proper asphalt pavement installation ensures optimal durability, longevity, and aesthetics.

Preparation Phase

Properly preparing the site of your future parking lot is one of the most important things you can do to ensure success. If it’s already a paved area, you must remove the current pavement or concrete and dispose of all debris. If the area’s unpaved, you can skip this step and begin grading and sloping the lot to ensure proper drainage and a flat paving surface.

If you don’t prepare for drainage, your asphalt will degrade from the bottom up as water seeps beneath the surface and wreaks havoc on your pavement. A professional paving company equipped with laser-based technology can handle your grading correctly so water runs off the pavement and away from your lot.

Sub-Base and Base Course

The sub-base and base course beneath your asphalt provides essential strength and stability. Without these layers, your asphalt will sink, crack, and fall apart. The sub-base comes first, acting as a frost barrier in cold climates and a stable surface for all subsequent installations on top. The sub-base usually comprises crushed rocks, concrete, or recycled asphalt. You must roll and compact this material to form a secure foundation for your asphalt.

Some projects require a base course, an additional layer made up of aggregate and typically four to six inches thick. The base course sits between the sub-base and the pavement. The choice of material and thickness for this layer varies based on the project requirements. After installing, rolling, and compacting the base materials, it’s essential to test the sub-base and base course for flexing ability under the weight of a loaded truck.

Asphalt Mix Design

Mix design involves selecting and preparing the appropriate asphalt product for your project. The asphalt mix contains aggregates and binders in a carefully determined proportion.

Aggregates are the primary pavement materials; asphalt is usually crushed stone, gravel, or sand. Your particular asphalt mix design will determine these aggregates’ minimum and maximum particle sizes. The lift thickness for the asphalt should be three to four times the aggregate size.

The asphalt binder holds the aggregate together. There are plenty of binder products, including modified binders with additives such as polymers, to enhance performance. Climate and traffic load play a significant role in determining which binder is best for your project.

Paving Process

Once the sub-base is in place, you can proceed with the paving process. This includes the following:

• Apply a binder: An aggregate and oil binder sits atop the sub-base to help the asphalt adhere better. The binder typically needs 24 to 48 hours to cure.
• Install the surface course: The surface course, or wear course, is the top layer of pavement that makes contact with the vehicles driving on the road. Hot mix asphalt must be above 185 degrees Fahrenheit to spread and compact properly. Asphalt is usually delivered between 275 and 300 degrees and installed when ambient and ground temperatures are 50 degrees or above.
• Place butt joints and transitions: Place butt joints and transitions anywhere the parking lot makes contact with a roadway or another lot. Transitional areas must be completely smooth.
• Compaction: Once the asphalt and transitions are in place, a roller truck will compact the surface, ensuring the entire lot is smooth and solid.

Compaction Techniques

Compaction is one of the final steps in the paving process and is incredibly important. When appropriately compacted, hot mix asphalt will lose about 25% of its total thickness. You achieve this by driving rollers over the asphalt at temperatures between 240 and 290 degrees. The pavement will require several passes with a roller or rollers, ideally utilizing cross-rolling patterns to achieve a smooth surface.

The initial roller is a double drum vibratory roller. The vibration of the roller helps increase the density of the pavement. Many paving companies then arrange a train of subsequent rollers following directly behind this initial piece of equipment. The next compaction phase utilizes intermediate rollers, such as a pneumatic tire roller. The final compaction occurs with a static steel roller that removes any marks left by the previous rollers.

Compaction must take place immediately after paving so the asphalt is still hot. The roller should follow the paver by no more than 300 feet. The final compaction must happen while the asphalt is at least 175 degrees.

Curing and Quality Control

Allow the asphalt to dry for 48 to 72 hours before permitting traffic on the pavement. After about 30 days of curing, you can seal the asphalt. This process helps protect the fresh asphalt and extend its life span. It can take up to a year for the asphalt to cure completely.

It’s important to continually inspect the asphalt throughout the paving process to ensure proper strength, stability, and compaction. If raveling, cracks, or other issues are apparent at any point, you should immediately address them so they don’t compromise the entire project.

When it’s time to seal the lot, you can have your paving company perform another thorough inspection of the pavement to ensure no signs of trouble. You shouldn’t see potholes, cracks, or other damage.

Professional Guidance

Proper pavement installation requires keen attention to detail through every phase, from grading the lot and selecting the asphalt mix to practicing proper rolling techniques. Consult an experienced paving company to ensure your next project is successful. Our U.S. Pave team can help you with all your paving needs.

Roads construction site. by Troy Mortier is licensed with Unsplash License