Chipseal
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Chip Seal is a pavement surface treatment. In the US, chip seals are typically used on rural roads carrying lower traffic volumes. In Australia and New Zealand, chipsealing is referred to as a "sprayed seal" and is used on a larger percentage of roads, both rural and urban. It is cheaper, but not as long lasting, than resurfacing an asphalt concrete or a Portland Cement Concrete pavement.
It can keep good pavement in good condition by sealing out water, but provides no structural strength and will only repair minor cracks. While the small stones used as surface yield a relatively even surface without the edges of patches, it also results in a very rough surface that leads to significantly louder rolling noises of automobile wheels.
Chip seals are constructed by evenly distributing a thin base of hot bitumen or asphalt onto an existing pavement and then embedding finely graded aggregate into it. The aggregate is evenly distributed over the seal spray, then rolled into a smooth pavement surface. A chip seal surfaced pavement can optionally be sealed with a top layer which is referred to as a fog seal. The introduction of Polymer Modified bitumen and emulsion binder has increased the chip seal's ability to prevent crack reflection and improve stone retention by improving the properties of the bitumen binder. Newer techniques use asphalt emulsion (a mixture of liquid asphalt, surfactant, and water) instead of asphalt. This has been shown to help reduce aggregate loss and reduce cost of installation, but can increase the occurrence of stripping.
Bitumen, as it is known everywhere else in the world, is the actual binder used in chip seal applications. It is referred to as asphalt (binder) in the US.
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[edit] Noise and vibration effects
The rough wearing surface of the chipseal generates more roadway noise at any operating speed than typical asphalt or concrete surfaces. This typically is not a major concern at very low operating speeds, moreover, chipseals are typically used on low volume rural and urban roadways. These sound intensities increase with higher vehicle speeds.[1] There is a considerable range in acoustical intensities produced depending upon the specific tire tread design and its interaction with the roadway surface type.
The rough surface causes noticeable increases in vibration and rolling resistance for bicyclists, and increased tire wear in all types of tires.
[edit] References
[edit] See also
Bituminous Surface Treatment under Pavement (material)
[edit] External links
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