When having your parking lot, driveway, or roadway paved in asphalt, there are a few things to consider. Generally this consideration is done by us at O'Brien Paving, then we give our clients the best recommendations for there specific project.
1.) The first thing to consider is the quality of the base; It needs to be strong, well graded, and allow for water flow. More detail is located in the Solid Foundation section.
2.) The second thing to consider is the grade of asphalt. Grade refers to the mix percentages of asphalt to aggregate, or even the types of aggregate used. Asphalt grades range from a pure asphalt and sand mix, to asphalt stone and sand, to asphalt and just stone. There are also other materials which can be mixed in with asphalt to produce desired properties, for instance recycled roofing shingles. The basic nomenclature for hot asphalt are the letters "HL" followed by a number, and then sometimes an additional adjective or identifier. ie. "HL3A or HL3FINE" is a hot asphalt mix with 3/8's of an inch stone as well as sand to create a smoother finished surface. "HL4" is an asphalt mix with 1/2 inch stone.
3.) Thickness and number of layers of the asphalt; While the thickness and the number of layers varies depending on the application. For a standard driveway or light duty parking lot, a single layer of 50mm or 2 inches after compression provides a sturdy surface suitable for light to medium weight vehicles with a long life expectancy. For heavier traffic parking lots, often two layers are used, a base layer ranging from 1.5-3 inches as well as a top layer of between 1-2 inches. Often a larger stone asphalt HL4-HL8 will be used on the base layer for greater strength.
Rest assured that O'Brien Paving Inc. will always recommend and provided the best and most cost effective solution for your project.
Why asphalt is used to pave driveways, parking lots, and roads.
Asphalt also known as "asphalt cement" and "bitumen" is actually only one ingredient in the material used for paving. At ambient temperatures it forms a relatively dense solid substance but at the same time it remains flexible. This is because it is actually a highly viscous liquid, sometimes referred to as a semi-solid at ambient temperatures. This is also why asphalt is has to be heated to more than 150 degrees Celsius before it can be mixed and paved with.
When asphalt is used to pave with it is actually used like a glue, binding aggregate together. The combination is really what makes a great paving product. With the strength, solidity, and low cost of the aggregate, plus the flexibility and cohesion of the asphalt, you get a surface which can last for many years and withstand almost anything nature will throw at it. Which is important when in a climate with four seasons.
As an added bonus, because of its flexibility asphalt can be used in smaller quantities per square foot than cement concrete, meaning it is significantly cheaper to use.