Most people take smooth asphalt pavement surfaces for granted. Whether you're speeding across a parking lot, roadway or cruising along your favorite commercial pavement, you might not think much about what it takes to build an asphalt paving surface.
From start to finish, there's a lot that goes into how asphalt pavement is built: from excavation to final compaction. In fact, preparing the subgrade and installing a long-lasting asphalt pavement takes detailed planning, expert engineering, and skilled craftsmanship.
If you're paving a new commercial parking lot, industrial facility or roadway, here's what happens during asphalt pavement construction. Every step is important and determines how long your pavement will last.
Whether your pavement project is a commercial asphalt parking lot, industrial paved lot, roadway or private development, proper construction techniques help ensure a strong, smooth surface that will last for years to come.
Let's look at how asphalt pavement is constructed from start to finish.
The construction process matters because every layer of the pavement structure affects the overall strength of the finished surface.
Asphalt won't last long if the supporting layers underneath aren't properly installed. Using high-quality asphalt is pointless if it's laid on poorly prepared base material.
Many pavement problems can be traced back to poor construction practices and subpar site preparation or base work. Remember, you can't see the base, but your asphalt pavement drives on it!
With that said, paving contractors who take the time to build a quality pavement from the ground up will give you a much better product overall. It also saves you money on maintenance and repairs down the road.
Planning and evaluation are the first steps in building an asphalt pavement. Everything that happens on your job site will be determined by how your paving project is designed.
Soil conditions, drainage, traffic loads, elevations, and other factors are identified before excavation begins. Contractors may also take soil samples to help determine strength and stability.
Problems with drainage, unstable soils, utilities, grade concerns, or other issues are typically identified during this phase. Taking the time to work through these issues can help prevent costly mistakes and headaches down the road.
Before installing asphalt pavement, every plant, rock, animal (yes we mean gophers too!), or bit of debris that doesn't belong in the final structure needs to be removed.
Typically this means excavating the parking lot or driveway to the proper depth to make room for base material and pavement.
How much excavation is required will vary from project to project. Commercial asphalt lots and industrial pavement takes a lot more traffic than a residential driveway so they require deeper excavation and stronger base material.
The subgrade is the native soil surface that will support your pavement structure. All layers of asphalt pavement rely on the subgrade for strength and support.
Think about a house with a weak foundation. Eventually the structure is going to start developing problems.
The same can happen with asphalt if the subgrade is poorly prepared or weak in spots. Contractors identify these areas so they can be stabilized during the base construction process.
One of the reasons subgrades are prepared with a specific slope is to promote positive drainage.
Water is asphalt pavement's worst enemy. Moisture weakens the base, causes support materials to erode, and can lead to cracking and settlement.
Asphalt contractors use grading to create positive drainage. This allows water to run off of the pavement surface and away from the underlying structure.
Drainage may include catch basins, swales, storm drains, culverts, or retention systems to manage water on your property.
The base is a layer of compacted aggregate that sits between the subgrade and asphalt pavement surface.
Aggregate usually consists of crushed stone, gravel, sand, or a combination of all these materials. This layer helps distribute vehicle loads, provides stability, and allows for proper drainage through the pavement structure.
Commercial, industrial and driveways that see heavier traffic volumes require thicker and stronger base material.
Skipping this step or installing a weak base could cause premature asphalt pavement failure.
As the name suggests, compaction involves removing air from the aggregate base.
Achieving proper density ensures a stable driving surface while maximizing strength and reducing the risk of future problems.
Rollers and other specialized tools are used to achieve maximum density. Contractors may also perform density tests to ensure project specifications are being met.
There's always one more thing to think about before asphalt pavement can be installed. Prior to paving, contractors will check the base for proper grading, make sure the surface is clean, and verify that compaction specs were achieved.
At this point crews may apply a tack coat to help provide a strong bond between the base and pavement surface.
Once every aspect of the base has been double-checked, it's time to pave.
In addition to aggregate materials, asphalt is made up of asphalt cement. Asphalt cement is a petroleum product that binds the materials together.
Together they create a durable paving surface designed to stand up to traffic and Mother Nature.
Similar to asphalt cement, asphalt pavement is actually mixed at the plant.
Hot mix asphalt leaves the plant at a high temperature and begins cooling immediately as it travels to the job site, which is why timely transportation and installation are critical.
Once the asphalt truck empties, a paving machine will spread the asphalt across your pavement surface.
You might be wondering how asphalt is kept smooth during this process. Pavers are highly skilled pieces of equipment that control the thickness and width of your new pavement.
Plus, the machine does an initial pass to ensure your pavement is nice and smooth.
While there's nothing wrong with having asphalt that's slightly over thickness specifications, having asphalt that's too thin can cause problems.
Conversely, asphalt that's too thick could cost you money that you don't want to spend on your paving project.
During the design phase of your pavement, engineers take traffic volumes and weight into consideration.
If you've been wondering why asphalt is hot, you might also be curious how asphalt gets so solid.
Once asphalt is laid down, it needs to be compacted. Asphalt compaction involves using rollers to apply pressure to the pavement.
Think of compaction as removing any unwanted air bubbles from the asphalt.
After asphalt is compacted, it begins to cool and harden. While you can drive or park on the pavement fairly quickly after installation, asphalt continues to cure for several months.
Asphalt contractors often mention curing when discussing how long you should wait before making turns, parking heavy equipment on your new pavement, or loading it up with trailers.
Did you know quality control matters during asphalt construction?
Quality control ensures your pavement meets or exceeds project specifications. There are several things contractors may test during construction.
Here's a few examples:
Construction crews take great pride in their work which is why they follow these steps to build a quality asphalt pavement.
However, there are some things that can cause problems during construction or even after the project has been completed.
Cutting corners can lead to premature pavement failure. Not having proper drainage can cause a number of problems like cracking and potholes.
Failing to compact the asphalt properly can create bumps in your pavement and even reduce its lifespan.
Your pavement should last for many years if built correctly. How long your asphalt pavement lasts will be determined by a number of factors.
Weather plays a big role on asphalt construction as it affects the placement and compaction of the asphalt. Variables such as temperature, moisture, and wind must be considered for the asphalt to be paved correctly. Monitoring weather conditions before and during asphalt paving is key to a successful project.
For hot mix asphalt to be workable and reach proper compaction levels it must stay within a certain temperature range. If the temperatures are too cold the asphalt will cool too quickly preventing proper compaction density. Too much moisture will cause poor bonding affecting the overall quality of the pavement.
Paving contractors that take into consideration weather conditions will watch the weather leading up to the day of paving and schedule their projects when the weather is favorable. Controlling the variables of weather as much as possible can allow the pavement to have better performance, smoothness, and longevity. By paving during ideal weather conditions you can ensure that your pavement will be built to industry standards and function properly for years to come.
Flatness is probably one of the most overlooked characteristics of asphalt pavements. As joints bring together two separate passes of paving, they can become weak spots if cut and filled incorrectly. Masterfully constructed asphalt joints marry two passes of paving to create a smooth pavement surface without cracks or breaks.
Asphalt joints can be longitudinal or transverse. Longitudinal joints lay parallel to the direction of paving. Transverse joints are seen when asphalt paving starts and stops. Poorly constructed joints are susceptible to moisture intrusion which can cause pavement failure years down the road.
Contractors take extra precautions when creating asphalt joints to ensure they are aligned correctly and compacted and bonded together nicely. Close attention to asphalt joint construction increases pavement life and beauty while decreasing the chance of repairs down the road. Dense joints add strength to your asphalt pavement system.
Once asphalt construction is complete, the new pavement will go through a process of inspection, cooling, and opening to service. Final inspections are conducted to ensure that the project was completed with quality materials and up to design specifications.
A contractor will check the smoothness of the surface along with drainage, compaction, and overall quality of work prior to giving the project over to the owner. Any minor tweaks or adjustments can be made at this point if needed. After the pavement has cooled down enough, it will typically be opened up to traffic as specified by the project.
It's also a good idea for property owners to be advised on proper asphalt maintenance. Inspections, crack sealing, sealcoating, and repair can help maintain the new pavement. Asphalt construction can take weeks or just a couple days, but continuing to maintain the asphalt will help prolong its life.
If your pavement surface will be required to support heavy traffic in the form of commercial vehicles, delivery trucks, or heavy equipment, it needs to be designed differently than a standard passenger car parking lot or driving surface. Because every axle that drives over a paved surface places stress on the roadbed beneath, asphalt pavements designed to withstand heavy truck traffic need to be stronger, have thicker pavement depths, and a more supportive base.
Heavy vehicles place additional strain on the asphalt pavement and base beneath it.
Commercial vehicles place far more strain on the pavement than passenger vehicles. When asphalt pavement engineers design a new road surface, they take into consideration the amount of traffic and load the pavement will be expected to endure. The size and expected frequency of these loads will help them decide how deep to excavate, how thick the aggregate base should be, what asphalt mix to use, and how thick the pavement should be upon completion.
Asphalt pavement designed for heavy traffic can help reduce overall maintenance costs.
Anticipating traffic before a pavement is built can help ensure that it lasts. If a pavement is built with heavy traffic in mind, but ends up only seeing passenger car traffic, it's unlikely to suffer any ill effects. However, if a road built for passenger cars starts seeing frequent heavy truck traffic, it won't be equipped to handle the stress. By planning for these loads ahead of time, contractors can build asphalt pavements that stand the test of time.
Just like the materials used to build an asphalt pavement, maintenance plays a major role in how long your pavement lasts.
Here are some tips to help you get the most out of your pavement.
Improve your asphalt pavement knowledge when you contact our asphalt experts at Top Job Asphalt today. We put our knowledge to work by constructing commercial pavement you can rely on for years to come!