What Exactly Is Asphalt?
Many refer to all forms of blacktop paving as “asphalt,” but what is it? Asphalt is a premixed solid composite material that contractors can use to construct a wide range of surfaces, including parking lots, roads, etc. Asphalt itself contains a mix of ingredients. While formulations vary, all asphalt contains mineral aggregates, fillers and a binder. The aggregates typically include gravel, crushed rock or slags. Meanwhile, the fillers are usually sand or limestone powder.
The binder is bitumen, a byproduct of crude oil. Bitumen is the heaviest part of petroleum, so it’s easily separated from crude oil and modified for various uses during refinement. Bitumen is a crucial piece of the asphalt puzzle. Not only does it give finished surfaces their sleek black color, but it also serves as a binder to lock the aggregates and fillers together, resulting in a solid surface after compaction.
There are many types of asphalt mixes available. Changing the types of ingredients used and their ratios will affect the quality of the asphalt. Hot asphalt is the most widely used for paving projects. When laid, it has a temperature between 275 and 325 degrees Fahrenheit. Warm-mix and cold-mix asphalt are also available for paving and patching projects.
How Much Do Asphalt Overlays Cost?
An overlay is a layer of new asphalt applied to an existing foundation or structure. It’s a cost-effective way to prolong the life of paved surfaces, address drainage issues and more. When done right, overlays can last 15 to 20 years or more, making it a worthy investment. It can transform the look and overall reliability of asphalt paving at a fraction of the cost of reconstruction.
The precise costs of an asphalt overlay vary based on several factors. Beyond the square footage of the area that needs paving, the condition of the foundation and subbase, the quality of materials used and the load-bearing capacity requirements for the new surface will impact final costs. The best way to understand how much your resurfacing or overlay project will cost is to consult an experienced contractor for a thorough inspection and quote.
How Thick Does My Asphalt Need to Be?
The thickness of asphalt paving is an important detail to consider because it directly impacts load-bearing capacity and strength. Before starting a project, experienced contractors will gather as much information about the property and the pavement’s intended use as possible. Paving companies engineer surfaces based on the required weight capacity and traffic. They’ll also perform soil tests to understand the strength of the subgrade, using their findings to determine the appropriate thickness of both the aggregate subbase and the asphalt itself. All these factors will affect the strength of the final product.
Standard residential driveways are typically two to three inches thick with several inches of compacted subbase. Commercial parking lots with moderate traffic have an asphalt layer of three to four inches. Meanwhile, high-traffic roads can be as thick as 12 inches.
The right thickness for a paving project varies, and it’s important to discuss the intended use of your new pavement with your contractor to ensure it has the strength to support traffic for decades.
How Long Does an Asphalt Parking Lot or Driveway Last?
Asphalt is a resilient material that’s easy to maintain and repair. While many factors will influence the overall lifespan of a surface, you can expect 20 to 30 years of reliability. In some cases, asphalt paving can last even longer.
Proper construction is vital to longevity, but the most important element is long-term maintenance. Staying on top of preventative care and investing in services designed to protect your pavement from weathering and wear make a difference. Maintenance and timely repairs are key to optimizing lifespan.
Why Do I See Roller Marks on My Surface?
Roller marks are typically a result of the compaction process. Asphalt paving requires thorough compaction to eliminate air voids, increase density and reduce the risk of water infiltration. It’s one of the last steps of asphalt paving and is vital to producing a strong and fully capable of supporting heavy loads. Experienced contractors aim for 90 percent compaction or more.
Roller marks and streaks appear due to the equipment used. Contractors use heavy-duty rollers that help compact the material and produce a smooth finish. However, the roller drums sometimes leave marks when the asphalt is still hot and pliable. Those marks are temporary and will become less noticeable as the surface fully cures in the year after construction.
What Can I Do About Poor Parking Lot Drainage?
Proper drainage is important for asphalt surfaces of all sizes and shapes. While asphalt is a naturally water-resistant material, standing water can be problematic. If water pools on pavement, it can slowly degrade the material, infiltrate the surface and erode the soil below. Poor drainage can wreak havoc on asphalt paving and the surrounding soil.
During construction, contractors will grade the foundation and create the proper elevation when laying the asphalt. All surfaces need a subtle slope that redirects water away from the pavement and to nearby drainage infrastructure. For efficient water runoff, surfaces need a 2 percent slops. Otherwise, water won’t shed and may pool.
If your parking lot drainage is insufficient, contact a paving contractor immediately. There are many ways to improve drainage. Professionals may recommend installing concrete catch basins and curbing. Depending on your needs, resurfacing could also be a viable solution, allowing contractors to apply a new overlay with the right slope.
Is There an Environmentally Friendly Way to Resurface My Parking Lot?
Asphalt is already impressively sustainable. It’s one of the most recycled materials in the world, making it more environmentally friendly than the alternatives. For resurfacing projects, contractors take measures to support that sustainability. Asphalt milling involves removing several inches of damaged material to make room for an overlay. It’s an eco-friendly practice. After pulverizing the asphalt to a specific depth, teams collect the milled asphalt before transporting it to a recycling center. Later, it gains new life in new paving projects.
When resurfacing a surface, contractors can also incorporate recycled asphalt pavement aggregates. Eco-friendly resurfacing methods can also help earn credits towards LEED certification.
Can I Put an Asphalt Surface Over My Concrete Parking Lot?
Applying an asphalt overlay to an existing concrete surface in good condition is possible. However, there are some risks. Concrete parking lots typically have expansion joints to prevent cracking. The concrete can still move, even if a thick asphalt overlay sits above it. When it does, those joints can cause the asphalt to crack. Contractors can implement measures to reduce this risk, including applying geotextile fabric. However, it’s only a matter of time before cracks appear above the concrete’s expansion joints.