Asphalt As A Paving Choice: The Pros And The Cons
Commercial cleaning services deal with asphalt regularly as this surface material is one of the two most popular paving choices in widespread use today. Parking lots, parking garages, and walkways are usually made of concrete or asphalt.
If you choose asphalt, the form of asphalt and its compatibility with maintenance and commercial cleaning services, such as power washing, help determine the long-term cost. Other factors to keep in mind are its intended use, its durability, the initial installation cost, aesthetics, and its impact on the environment.
There are Several Forms of Asphalt Available
When choosing asphalt, there are many options. Each type has its own attributes and applications, although all are basically asphalt.
- Hot Mix Asphalt Concrete: It is produced at around 320° F resulting in a less viscous product with less moisture content. This allows it to be a relatively tough, durable material that can be used in high traffic areas such as roadways and airport landing strips.
- Warm Asphalt Mix: Certain additives are used to reduce the heat necessary for producing the final material. This process requires less fossil fuel to produce and creates fewer fumes, making it more environmentally friendly.
- Cold Mix Asphalt Concrete: Soapy water is used to emulsify the asphalt before mixing in the aggregate. This eliminates any need for high temperatures. It also reduces the toughness and durability, so that it is useful only in low traffic areas and for patching of hot-mix applications.
- Glassphalt: In this form, a percentage of the aggregate has been replaced by recycled glass crushed to size. It allows bottles and other forms of glass products to be recycled. It also has a higher surface roughness that provides extra skid protection. While being a source of slightly higher wear on tires, the added safety adequately offsets this consideration.
- Since the 1970’s, glassphalt has been used and tested for roadways and landing strips, to name a few. More studies are needed to establish its best use and application. It is not widely commercialized but has proven to be a valid alternative for some applications at least.
- Rubberized Asphalt Concrete: Similar in concept to glasphalt, it uses a proportion of crumb rubber to replace part of the aggregate. This rubber comes from grinding up recycled tires otherwise headed for the landfill. It is now enjoying high popularity. In the last decade, a number of states and federal agencies have run tests on its durability and its viability for reducing road noise. It has proven to lower noise in a range from 7 to 12 decibels. Recycled Asphalt: Old asphalt rubble can be broken down and reused after some preliminary treatment.
Asphalt Exists in Porous and Non-Porous Forms
1. Porous Asphalt
This version is made up of particles adhering together, yet with sufficient spaces between the particles to allow passage of moisture through and into the soil beneath. This is made possible by screening out the smaller particles in the aggregate. A special substrate incorporates filtering layers and a more permeable substrate to allow water to pass through.
Pros:
- Can last as long as the non-porous version
- Reduces runoff by up to 80%, or so
- Replenishes groundwater
- Reduces necessity of having catch basins and runoff channels (saves money and space)
- Reduces flood dangers
- Requires no different tools and machinery to handle
- Provides superior icy weather traction over non-porous asphalt
- Can be used in areas not meeting stormwater retention guidelines
- Cooler in hot weather than non-porous
- Used on runways and highways, it can reduce hydroplaning
Cons:
- Pre-filtering recommended for runoff coming from food, oil, and other chemical runoff sources to prevent clogging and contamination of the substrate
- Higher initial expense because of specific substrate preparation requirements
- Tires can cause raveling – meaning aggregate is rubbed loose from the surfaces, resulting in road damage and potholes, which makes it less desirable for highways, large landing strips, and high traffic areas
- Extra care in cleaning is required to prevent clogging
- Incorrect cleaning with the wrong chemicals can reduce the life of both non-porous and porous, but especially the porous
2. Non-porous Asphalt
This version is constructed of fine and larger sized aggregate material, which resists the passage of moisture.
Pros:
- Allows efficient runoff and drying time
- Competitive price compared to other materials
- Spot repairing easier and cheaper compared to concrete
- All forms tend to last decades
- Somewhat self-healing, especially where hot weather can re-melt the surface
- Can be used easily in combination with other paving materials
- Dark color hides spills and stains
- Better lasting than concrete in icy and freezing wet environments
- Can undergo pressure, distortion, and flexing without immediately cracking
Cons:
- Repeated high impacts cause a failure sooner than in pre-stressed concrete
- Very susceptible to dissolution under exposure to oils, fats, petrochemicals, and incorrect cleaning solvents
- Susceptible to some environmental pollution during installation and use through evaporation and washing away of petrochemical-based constituents during weathering
- Must be frequently treated with a seal coat to prevent early failure
Asphalt Choice Impacts Cleaning and Maintenance Costs
Care must be exercised during pressure washing as incorrect detergents and solvents should not be allowed to attack the asphalt sensitive to them. For most outdoor paving, pressure cleaning and pressure washing is a primary choice.
With any type of asphalt including glassphalt, extra care is needed to assure the correct techniques to protect it; plus, insufficient cleaning may be destructive.
Debris, waste, contaminants, and pollutants must be removed quickly to avoid damaging the surface.
Further Considerations
The drainage pattern, including proper sloping (or not) of the surface, must be correct for the specific material chosen. The substrate, which may differ from one pavement type to another, is actually the major part of the paving job and contributes toward the long-term function, stability, appearance, and life of the pavement. Don’t forget to factor in the possibility that different surfaces may end up being used in conjunction with each other.
Protect your investment. Before installation, consult a cleaning and maintenance pro. A reputable commercial cleaning services company can advise you about what to include and what to avoid so that you will encounter the least number of problems with the care and maintenance of your asphalt pavement.
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