The Basin's Dirtiest Jobs - Chip Seal Road Workers - July 2011

Before the emulsion has been applied

By: M. Michelle Spencer


    One of the not so glorious parts of being a road worker is taking care of the chip seal projects that occur every spring all over the western United States. The Uinta Basin is no exception to this rule.

    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 or enrichment.

    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. It reduces emissions of volatile organic compounds (VOCs) due to the lower solvent content.

    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.

    Although chip seal is an effective low cost way to repair road, it has some drawbacks. For instance it is not any fun when you happen to get some of the nasty, sticky emulsion on you or you vehicle. It does help with the wear and tear on our roads however and for that we salute the men and women who are willing to sit out there under the scorching sun and make our roads a nicer place to drive.

Applying the Emulsion is the not so clean part of the process

After the emulsion has been applied