Asphalt Paving Charleston is an economical and sustainable choice for roads, driveways and parking areas. Regular maintenance can prevent or minimize damage caused by weather and traffic.

Hot mix asphalt (HMA) is the most common type of asphalt. It contains aggregates of varying sizes, an asphalt binder and filler. The HMA mixture is heated to high temperatures.

Asphalt is a mixture of aggregates (crushed stone or sand), binder, and fillers that are used for road construction. The aggregates provide strength and stability to the pavement, while the binder, typically made of bitumen, acts as a glue, binding the aggregates together. The fillers, often fine aggregate or dust, help to fill any voids in the mixture and ensure a smooth surface.

The process of creating asphalt begins at an asphalt plant, where the ingredients are heated and mixed to create a consistent mixture. The material is then transported to the construction site in specialized trucks and applied using paving equipment. Asphalt can be used to create a wide variety of surface types, from roadways and parking lots to golf courses and driveways.

There are three main types of asphalt: dense graded, open graded, and permeable. Dense graded asphalt has a very consistent range of aggregate sizes, with few or no gaps between the particles. This allows for a strong and durable pavement, suitable for general use. Open graded asphalt, on the other hand, has a more uniform aggregate size with large gaps between the particles. This creates a porous asphalt that can help drain water and reduce noise.

In addition to proper installation and maintenance, the longevity of an asphalt surface depends on its drainage system. A proper drainage system can help prevent puddles and potholes from forming on the surface, while ensuring that water runs off the pavement into a ditch or stormwater sewer system.

Drying

Asphalt paving requires two steps: drying and curing. Drying is when the moisture in the asphalt mixture evaporates and leaves a firm surface that can support traffic loads. Curing is a longer process that chemically hardens the asphalt over time. Asphalt that isn’t fully cured can develop cracks and other damage over time.

To ensure an efficient and successful asphalt paving project, contractors must carefully plan out the weather conditions. Opting for sunny and breezy conditions can help to speed up the drying process because the warm, dry air allows for faster evaporation.

Proper traffic management is also crucial to the success of a new asphalt installation. This includes implementing detours, establishing barricades, and using signage to direct traffic away from the area. This will minimize congestion and ensure that both pedestrians and vehicles can avoid the newly installed asphalt and protect it from harm until it is fully cured.

While asphalt can be used as soon as it’s dry enough to walk on, a general rule of thumb is that it must be completely cured before driving on it. This typically takes 48-72 hours after application. Pedestrians can use the new pavement right away since they have lower weights than vehicles. However, they should be careful to avoid sharp turns or sudden stops, which can scuff the surface of the new asphalt. Taking these precautions will help to maintain the quality and durability of your new asphalt for years to come.

Mixing

The mixing process involves measuring and proportioning aggregate, mineral powders, and asphalt. It is typically done in an asphalt plant, ensuring consistency and quality. Some plants also incorporate a percentage of recycled materials for sustainability, cost savings, and performance benefits. Additives are also added to the mix, including polymers to increase crack resistance and modifiers to improve performance in extreme weather conditions.

Aggregates like gravel, rock, and sand are sourced from quarries or mines. They are dried and heated to high temperatures, then mixed together to achieve a uniform blend. The mixture is then combined with an asphalt binder. The type of binder used depends on the final product desired. For a durable surface, the mixture is then rolled and compacted.

After the mixing process, the asphalt is loaded into specialized insulated trucks and transported to the construction site. It is kept at a high temperature during transportation to ensure it remains workable when it is laid.

The mix is tested during the production and transporting processes to ensure it meets quality standards. Samples of the asphalt are taken and tested for various properties, including gradation, stability, and binding agent content. Any deviations from the specified criteria are quickly corrected to maintain consistent quality throughout the paving process. This enables the construction crew to lay the pavement with confidence knowing they are using a high-quality, uniform asphalt mixture.

Compaction

When the asphalt mixture is ready it’s dumped from the hopper of an asphalt paver into the roadway and compacted with a series of rollers. This process is important to ensure proper density and durability of the road surface. The paving operation should be well-disciplined to avoid damaging the new pavement while it’s being rolled and compacted. Effective traffic management is also crucial during this time to prevent premature vehicles from driving on the asphalt.

The base course is one of the most important structural layers in an asphalt road. It helps reduce rutting by spreading traffic and environmental loading evenly throughout the road surface. This requires a balance of stability and durability, which can be achieved through adequate stone-on-stone contact and stiff or modified binders.

Historically, all asphalt testing measured engineering properties such as stiffness. However, TFHRC researchers are planning a new way to look at asphalt binders: they will test for the presence of residual oil in the asphalt (REOB). This is an extremely important property because it impacts how stable the binder is at low temperatures and how resistant it is to fatigue. Ideally, REOB will be measured during the manufacturing process, before the asphalt is mixed with aggregate. Until this technology becomes available, it’s important to use asphalt mixtures with low REOB levels, especially for winter construction. This can be accomplished by using a “cold mix” of asphalt, which does not require heating the aggregate, or by adding soft materials such as recycled swine manure to the asphalt mixture, which decreases its high temperature grade.

Laying

Once all the preparation and mixing are complete the asphalt mix is poured on to the surface. The hot mixture is poured from a dump truck and spread evenly by an asphalt paver, and then compacted with rollers multiple times to ensure a dense, smooth finish that you’re familiar with seeing on roadways and parking lots. The asphalt is allowed to cool and cure before being opened up for traffic, but during this time effective traffic management is crucial to prevent any damage.

Prior to laying asphalt, the existing surface must be removed using heavy machinery like jackhammers and bulldozers. The ground is then graded and sloped correctly for proper drainage, preventing water buildup that can lead to pavement deterioration over time. This step is important, as poor drainage can lead to cracking and sinking of the new asphalt.

After the sub-base layer is laid, it’s time for the binder course to be added. This is the second layer of the asphalt structure and consists of coarse, larger aggregate material mixed with oil to provide strength and stability. The proper composition of this layer helps to reduce rutting by spreading traffic and environmental loading across the base and underlying layers evenly. This layer is also tested with a Marshall Test and a cohesiometer to ensure it’s up to the task. Once the base is in place, proof rolling is conducted to check for weak spots that may need additional material added or compacted.