Driveways are made from a wide range of materials, including rock, polished stone, concrete etc......but often today, bitumen is added to stone for improved quality and performance. Bitumen can be used for roads, footpaths, residential driveways, car parks....airport runways, racing tracks, storage areas and many other facilities for the community.
Asphalt can be placed as a thin layer to act only as a surfacing on a prepared base, or, it can be placed in one or more thick layers that contribute to the strength of a road. The asphalt surface allows any applied wheel loads to be transferred to the base beneath.
When thick layers are used, the asphalt itself provides support for the wheel loads.
The surface texture is smooth and uniform, (although some asphalt designs are open-graded and course textured to reduce water spray and noise on highways). The compacted layer thickness for drives and residential streets is 25 - 40mm, increasing to 50mm + for main roads and highways.
CHOOSING THE TYPE OF ASPHALT SURFACE
Before choosing asphalt there are many factors to consider. It is very important to clearly identify the area location and purpose. Issues that must be considered, include:
• Durability.
• Environment (wet, hilly, alpine, flood prone).
• Appearance.
• Conditions of use, vehicle size and type, vehicle speed, vehicle maneuvers, exposure to chemicals and spills.
• Existing surface (gravel, rock, sand, asphalt).
• Size of job (total area, length, width, depth).
• Future maintenance.
Specialist advice about the effects of these variables on the choice of bitumen road must be sought from ASP Engineers.
ESSENTIAL GUIDELINES
The information about asphalt given below should only be used as an initial guide.
When asphalting you should consider:
• The type of edging, brick, gutters, treated pine, pavers, etc.
• The shape of the area to be asphalted.
• The size of the area to be asphalted.
• If a uniform appearance is required for a visually smooth effect.
• A hard wearing surface with long life durability.
Specifications
- Minimum 100mm road base
- Minimum 25mm asphalt
Driveways
- Minimum 150mm road base
- Minimum 25mm asphalt
Spoon drains may be required to collect run-off from drive and land
Sub-surface drainage may be required to protect the pavement
Concrete, paver or timber edging may be required on some sites
Carparks
- Minimum 150mm road base
- Minimum 25mm asphalt
- Sub-surface drainage may be required to protect the pavement
- Concrete kerbing or edging may be required on some sites
Industrial Pavements
- Minimum 200mm road base (possibly cement treated)
- Minimum 40mm asphalt
- Sub-surface drainage may be required to protect the pavement
- Concrete kerbing or edging may be required on some sites
