We have been carrying on about the Pavement Preservation & Recycling Alliance (PPRA) Treatment Toolbox, a free, online resource for your pavement preservation planning in several newsletter articles and we regret nothing. Pavement preservation is an essential part of any strategy to make the most of street maintenance funding and all agencies should explore the toolbox. Have a look at the Treatment Resource Center for some background on slurry seal.
Pavements in good condition don’t stay in good condition by themselves and the best way to extend their service lives is regular maintenance and preservation techniques that can add years of good performance for a fraction of the cost of mill and overlay. The key is to use the right technology for the right road at the right time.
For pavements still in good condition, slurry seal can be used alone or in conjunction with other treatments to extend the pavement life by 5-7 years and restore some of the skid resistance of the original asphalt overlay, all at a discount to milling and overlay that will be prematurely necessary otherwise. It is a surface treatment designed to restrict moisture intrusion, protecting the structure from further oxidation and raveling, and restoring a uniform black appearance.
What is it? Well, to be fair, it is one of the least elegant pavement processes, but that is misleading. Slurry seal is a mixture of asphalt emulsion (sometimes polymer-modified), mineral aggregate, water, and additives. It is precisely proportioned, mixed onsite in a special truck-mounted rig, and uniformly spread over a properly prepared surface at a single stone thickness. As a homogenous mat with good bonding properties, it adheres firmly to the prepared surface. It can be applied rather quickly, allowing traffic soon after the emulsion “breaks,” causing only reasonable disruption to the traveling public.
Slurry seal is often used after the surface has been crack sealed (see our January 2021 e-newsletter article), but it can also be used in combination with one or more chip seal layers. As with other surface treatments, mix design, surface preparation, and proper application are critical to a successful deployment, so have a look at some of the details in PPRA’s Treatment Resource Center.
The Delaware T2/LTAP Center’s Municipal Engineering Circuit Rider is intended to provide technical assistance and training to local agencies and so if you have pavement management questions or other transportation issues, contact Matt Carter at matheu@udel.edu or (302) 831-7236.
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