Category: Driveway Paving

How Asphalt Paving Works

Paving Companies Summerville SC is a great way to save time and money on road repairs. Unlike concrete, which requires long periods of time to cure and can be disrupted by traffic delays, asphalt can be paved overnight. Asphalt is made by combining aggregates (such as crushed stone, gravel, and sand) with bitumen, a black petroleum byproduct that holds the aggregate together. Different asphalt mixtures are created to match the specific needs of each project.

Asphalt paving must be compacted well in order to withstand the weight of vehicles and the stress that is applied over time. A poorly compacted surface can be prone to moisture damage, cracking and rutting. Great asphalt contractors understand the importance of proper compaction and work hard to ensure that the process is done correctly and efficiently.

The quality of the asphalt mix directly affects the compaction process. The aggregate in the mix should be angular to resist early wearing and have different sizes of gradations for optimal compaction. The aggregate should be coated with an asphalt binder to bind the individual particles together, which in turn increases the interparticle friction and reduces the air-void content in the finished pavement.

Once the asphalt mixture has been poured, it needs to be compacted while it is still hot. This can be accomplished by a special machine called a roller that applies large amounts of pressure to the asphalt. The roller moves in a specific pattern to create shear stress that compresses the asphalt and helps achieve high compaction.

There are a number of factors that influence the ability of an asphalt mix to be compacted, including the temperature of the mix as it comes out from under the paver screed and the thickness of the layer being placed. Environmental conditions such as wind velocity also impact the rate at which an HMA mix cools.

The type of equipment and rollers used in the compaction process is important as well. Static steel wheeled rollers, vibratory rollers and pneumatic tire rollers all have their own benefits and limitations. A good contractor will use a combination of these machines to ensure that the final pavement is as compact and strong as possible.

Asphalt is a mixture of aggregates (crushed stone, gravel, and/or sand), binder, and filler that’s used for roads, parking lots, and driveways. High-quality aggregates are carefully screened and tested to ensure that the finished product meets certain specifications. The mixture is also heated to a high temperature, which helps it bond and set. The most common type of asphalt is called hot mix.

Before any asphalt can be laid, the sub base layer must be properly undercut. This is done by digging down two to three feet under the existing surface and replacing soft clay or soil with a more durable aggregate material. 

Once the sub base is undercut and repaired it’s time to add the binder layer. The binder is large aggregate mixed with oil and it’s the foundation that all asphalt surfaces are built upon. Once the binder is applied, a smooth and jet black finish can be created.

In addition to traditional asphalt, can use a cold mix asphalt (CMA). This is made by grinding recycled pavement and mixing it with an additive that lowers the melting point of the bitumen. This results in a more sustainable, environmentally friendly material. This alternative to hot asphalt also requires less energy during the paving process and produces significantly fewer fumes. This makes CMA an ideal option for projects with strict environmental guidelines.

In order for an asphalt pavement to withstand the forces of traffic and temperature fluctuations, it needs to be built strong. This is where a good paving contractor pays off. The base course of a pavement is essential because it’s the load-bearing layer and the structure that distributes the stress of vehicle traffic over the entire foundation layer. It also needs to be resistant to cracking, rutting and fatigue. A reputable paving contractor will use the best quality materials to construct this layer.

This is typically a mixture of emulsified or cutback asphalt and unheated mineral aggregate prepared in a central mixing plant and spread and compacted using conventional paving equipment while at or near ambient temperature. The mixture is often spread over a base course and placed in a layer up to 4.5 inches deep.

Ideally, the binder will be a highly durable material that will resist deformation caused by heavy loads on the base course, yet be soft enough to promote good compaction. It should also be of high workability, meaning it will be easy to place and compact and should provide a smooth surface for traffic. It is also important that the binder be able to bind the aggregate together.

Researchers at TFHRC are investigating new ways to look at the performance of asphalt binders. Previously, all testing of asphalt binders focused on engineering properties like stiffness. However, these tests don’t give a full picture of what the binder is made up of.

One concern is that many of the binders used in asphalt paving are being produced with recycled oil base (REOB). These binders may pass standardized engineering tests, but they perform miserably in Hamburg physical rut testing and have a low stiffness at low temperatures, which is an issue for highways and other long-distance road construction.

Once the old surface is removed and any soft areas of the base are repaired, it’s time to lay the asphalt. It is important to make sure the asphalt surface is smooth and even for safe driving. This step involves grading the transition from old to new surfaces as well as testing the water drainage and compaction. This is done using a variety of small to large machinery like bobcats, forklifts and front loaders.

Before laying the asphalt, contractors must first make sure the mixture is at the right temperature. This is done by reading the temperature with a fast-reacting thermal probe or a depth thermometer. The asphalt must be hot enough to work with but not too hot to burn the workers or damage the equipment.

The base layer of the asphalt is made from a mix of aggregate rock material and binder. Aggregate materials may be recycled or reused, which helps reduce the environmental impact of the paving project. The aggregates are blended with a binding agent, most commonly bitumen. The bitumen binds the aggregates together and also provides the structure of the finished asphalt. Today, some companies are also developing more sustainable binders, including those that use recycled materials or waste byproducts.

Once the binder layer has been applied and compacted, the asphalt paver is ready to be rolled out. To ensure the proper thickness of the asphalt, the paver is fitted with a screed unit that determines the profile of the HMA being placed. The screed controls the amount of asphalt being extruded, allowing for the correct mat thickness and initial compaction. The asphalt is then spread evenly across the area and rolled over with rollers to achieve a smooth finish.

In asphalt paving, curing is the process by which the asphalt hardens and is ready for traffic use. The curing process requires time and environmental conditions to be just right for the asphalt to achieve its full strength and durability. There are several factors that can affect the curing time, including the weather and temperature.

The evaporation of water from the surface of the asphalt is the primary factor in determining how long it takes for the asphalt to cure. Humidity is another important consideration as high humidity slows evaporation and makes it take longer for the asphalt to dry. Similarly, extremely cold temperatures make it harder for the asphalt to evaporate and cause it to take longer to cure.

It is also important to have good drainage on the project site. Any standing water can damage the asphalt and prevent it from fully curing. In addition, it is necessary to ensure that the asphalt is not exposed to any chemicals, such as salt or de-icing products, until it is completely cured.

If a contractor uses a curing compound, it is important to follow the directions carefully to ensure that the compound performs correctly. If the compound is applied too soon, it will interfere with the evaporation of water from the asphalt and lead to poor performance. The curing compound may also interfere with the ability of the asphalt to oxidize and release excess oils.

Asphalt can be cured in various ways, including with hot mix, warm mix, and cold mix asphalt. In addition, newer technologies, such as recycled asphalt resurfacing (RAS), allow pavements to be constructed without any heating at all. Despite the differences, all asphalt needs to be cured properly before it can be used.