Today’s tip starts with the story of my neighbors complaining about the recent chip seal on a nearby roadway. They didn’t know to call it a chip seal, but they did know to post photos on the Nextdoor app of partially coated rocks they’d dug out of their tire treads and blame them for chipped paint on their cars.
When performing a chip seal, the pavement preservation contractor has to monitor weather and temperature closely to get the timing right and ensure the chips seat properly—even in tropical Florida.
The emulsion itself needs to be sprayed at 180°F (or higher) so it leaves the spray bar nozzles in a smooth, fan-shaped pattern.
Once the emulsion is down, the aggregate needs to be rolled within two minutes of being spread. The chips are placed almost immediately, and the roller follows closely behind to knead them into position before the emulsion begins to set and lock them into place. (Depending on lane width and those all-important weather conditions, this may mean you need more than two rollers on the job.)
The ideal machine for this work is a pneumatic-tired roller, traveling at about 3 mph to gently knead the chips into the emulsion. As a former Asphalt Institute engineer told me back in 1998: “Push them into their fat, dumb, happy places.” Whatever it takes to achieve proper embedment.
To complete the seal, you’ll broom the new surface—but timing matters here, too. Wait until approximately 85% of the moisture in the emulsion has evaporated, and make sure the roller has completed at least three passes over the chips before sweeping.
That final brooming removes loose aggregate and helps confirm the emulsion has developed a strong bond with the stone before opening the roadway to traffic—and before the public starts calling the city to complain about loose rocks damaging their paint.
Topics like this are covered in PreservationPro, the supplement you’ll find in The Asphalt Pro three times each year.
Watch for the digital edition sneak peek coming this week. Subscribe for free here and share it with members of your team who could benefit from the information.
Get tips like this delivered to your inbox each week when you subscribe to Toolbox Tips.