Although they’re not quite as common as some of their counterpoint materials, chip seal roads can be found around the world, from Dallas, Texas to London, UK. In the United States, this material tends to be used in lesser populated areas to support low traffic volumes. Meanwhile, New Zealand and Australia apply chip seal in both rural and metropolitan areas.
In this post, we’ll shed some light on the exact process used to build chip seal roads. We’ll also cover some of the advantages of the material as well as its drawbacks.
Ready? Then let’s hit the road!
Chip seal roads are formed by pouring a mixture of bitumen, asphalt or hot tar over an existing road, then adding fine aggregate into the base. Once the aggregate is spread evenly throughout the pavement, heavy rubber tyred rollers are used to pulverize it into the mixture, forming a paved road.
That’s the installation process in a nutshell, though there are several potential variations that can be applied in order to optimize a chip seal road. For instance, a common extra step installers can take is to seal the pavement with a top layer (also known as a fog seal).
Chip seal roads can be further optimized by the addition of polymer-modified bitumen and emulsion binders. These go a long way in helping the pavement retain its aggregate while avoiding crack reflection. More modern methods use a combination of water, liquid asphalt and surfactant (also known as asphalt emulsion) in place of asphalt in order to improve stone retention while reducing installation costs.
Proper post-installation follow-up is crucial to a chip seal road’s health. These roads typically require two days to cure, during which time traffic must be maintained at reduce speeds. Once cured, several sweepings are needed in order to remove loose gravel from the surface.
Chip Seal Road Advantages
Cost: Generally speaking, chip seal roads can be installed at 20-25% the cost of conventional asphalt.
Anti-glare: Chip seal roads do not cause glare in wet weather conditions or nighttime driving.
Skid-resistance: Thanks to its unique composition, a chip seal road offers a skid-resistant surface in both wet and dry conditions.
Non-porous: Chip seal roads prevent water from penetrating the structure of the pavement. When properly sealed, the non-porous material can minimize the effects of wear and tear.
Chip Seal Road Drawbacks
Roadway Noise: Chip seal roads provide a less uniform surface than asphalt or concrete surfaces, which leads to increased roadway noise. This increased volume tends to vary based on traveling speed, vehicle density and tire tread design.
Installation Quality is Critical: The quality of a chip seal road can vary greatly depending on how much care was taken during its installation process. Depending on climate and traffic volume, additional steps might be necessary in order to optimize the pavement throughout its lifespan. It’s also important that post-installation followup (allowing the surface to cure and sweeping loose gravel afterwards) be tended to with extreme care.