Why do I see entire parking lots get a coat of sealant, but never really see streets or highways get a large coat of sealant?
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For example: [https://youtu.be/Lmd1r0P0GWE?t=192](https://youtu.be/Lmd1r0P0GWE?t=192)
In: 709
Seal coats are mostly liquid asphalt emulsion, so it does a good job of making the existing pavement smooth, uniform in color, and extends the life of the pavement by a few years. The problem is that most seal coats do not offer much grip. You can add some fine sand to the mix, but it doesn’t provide the level of skid resistance that you need to give vehicles traction when driving in wet conditions. Seal coats being all liquid also do not last very long, and depending on the amount of traffic using the street might only last a year or two before it would need to be applied again. Parking lots get the seal coat treatment because of the lower speeds and smooth, dark surface that a seal coat provides.
For streets, cities and counties can go with a slurry seal or chip seal treatment, which is asphalt emulsion, water, and small aggregate. This provides a rougher surface (increased skid resistance) and a more durable surface. These treatments can last over 5 years before they have to be reapplied. Slurry seal takes a few hours to try and can be inconvenient to the people who live or work on the street that is getting treated, so the longer life span means they won’t be inconvenienced frequently.
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