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So Many Slurry Seals. What’s the Difference?
Slurry seal formulations have been around for a long time. Since the 1960s, in fact! And, over time slurry seals have undergone an evolution. More sophisticated formulations have proven to be better for our environment and result in longer lasting roads. According to the International Slurry Seal Association’s “Pavement Condition Index”, [slurry seals] can extend the life of roads up to 7 years or more. However, not all slurry seals are created equal. Read on to learn more about the features that define slurry seal types.
In its most basic form, conventional slurry seals consist of a mixture of emulsified asphalt and aggregate. Unlike traditional hot mix and warm mix asphalt, conventional slurry seals can be transported and applied at ambient temperatures. Conventional slurry seals retain a consistency that is similar to chocolate milk without heat. The benefits include a cleaner process (no CO2 emissions), faster set times and flexibility with weather conditions. It can be applied in hot or cold climates, day or night. Due to its cationic nature, conventional slurry seals cure quickly, so road construction crews have to work fast!
Two Types of Rubberized Slurry Seals
Cold Blended Rubberized
There are two types of cold blended rubberized slurry seals: REAS (rubberized emulsion aggregate slurry) and RPMS (rubberized polymer modified slurry). Crumb rubber is added to the mixture cold, like an aggregate, so it cannot modify the asphalt by itself. There are some caveats with this method. Once applied, rubberized slurry seals are set through a dehydration process that is similar to paint drying. It sets much more slowly than conventional seals. And, in order to make pavements appear darker, carbon black must be added to the mixture.
Terminal blend rubberized asphalt products are the best of both worlds. With terminal blends, rubber is introduced at the refinery or offsite, and is completely digested into the asphalt. The output is just like regular, unmodified asphalt. No special equipment or adjustments required. You can use the same conventional slurry seal machinery with terminal blends. Using highly modified asphalt is ideal because the color stays darker longer and retains a wider viscosity curve. Terminal blends can dip to lower temperatures without cracking and higher temperature without softening. This feature is especially useful in hot weather conditions, where softer slurry seals result in power steering marks.
Now that you understand the nuances between different types of slurry seals, in our next post, we’ll take a deeper dive into the origins and benefits of terminal rubber modified slurry seal (TRMSS) and the significance of it for our partners in California.
Stay tuned for more.