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Asphalt Resurfacing 101: Slurry Seal vs. Microsurfacing

Slurry seal was invented in Germany in the early 1930s as a new technique to cost-effectively maintain roadways. In the late 1960s, German scientists began experimenting with conventional slurry seal to help with the wheel ruts on the autobahns. By introducing different polymers, emulsifiers and better aggregate, microsurfacing was born.

Autobahn

The following chart is a comparison of these two closely-related products:

  Slurry Seal Microsurfacing
Product Description A cold-mix paving treatment containing specially graded aggregate, asphalt emulsion, water and other additives. A cold-mix expansion of slurry seal with a higher polymer and asphalt residual content, better quality aggregate and fast-setting chemicals.
Application Method Specialized, self-mixing equipment with applicating spreader box. Specialized continuous feed or flow equipment similar to slurry seal with adjustable augured spreader box.
Cure Time for Traffic 24 hours Under 1 hour
Life Span Improvement** 5-7 years 7-10 years
Cost $$ $$$

**Life span improvements are based off pavements that are regularly maintained and depend on the condition of the pavement prior to the method used. Other factors that contribute to a treatment’s life span are asphalt mix type, asphalt thickness, construction quality, and traffic loads.

Slurry Seal

Slurry seal helps replace the fines in the existing surface that have raveled out over time. It also fills minor cracks and adds a new skid resistant driving surface. When applied, slurry seal will have a brownish color due to its ingredients. It is quite malleable at first which makes it easy for spreading it into tight corners of parking lots and other not-so-wide-open surface areas. After it is smoothed out, slurry seal is left to cure for at least 24 hours before being made available for traffic. It is a recommended treatment for everything from residential driveways to public roads, highways, parking lots, airport runways, and even golf cart paths.

Microsurfacing

Microsurfacing will also correct moderate to severe raveling by sealing and filling voids in the existing surface. However, the addition of better quality aggregate, emulsifiers and fast-setting chemicals makes for a more durable skid resistant surface that’s traffic-ready in less than 1 hour. When applied, it also has a dark brown color but quickly blackens as the water is chemically ejected during the curing process. Because of the fast cure time and type of equipment used, microsurfacing is typically recommended for roadways, airport runways and open parking lots (void of landscape islands, covered awnings, etc.) where the equipment has room to stop and start without crossing over previously applied material.

Both resurfacing treatments have their rightful place in preventive asphalt maintenance. Which solution is best for your surface is dependent on its current condition. Let one of our professional estimators help you determine which is right for you!

PS: Advancements continue to be made in the effectiveness of slurry seal mixes. Look for more information on polymer-modified slurry seal in a future post.

Let us help you determine which asphalt resurfacing solution is right for your parking lot. Contact ACE for a free assessment today.

ACE Asphalt is a full service asphalt maintenance, repair, and paving company with offices in Phoenix, Tucson, and Flagstaff, Arizona, Las Vegas, Nevada, Albuquerque, New Mexico, and Dallas,Texas. Ace serves the parking lot repair, maintenance, and paving needs of property managers, building owners, and contractors.

Comments
(7) responses to "Asphalt Resurfacing 101: Slurry Seal vs. Microsurfacing"
Dave Thompson says: 17-Aug-2015 01:40 PM
I did not know there were different ways of resurfacing asphalt. Even though microsurfacing costs more it lasts a few years longer than a slurry seal. I guess it just depends on how bad the surface is that you are redoing, and what you need it to do.
Lori Andrews says: 22-Jun-2017 04:36 PM
If slurry seal is described as TypeII, is the formula of Emulsion and Aggregate always the same or can a city change the formula. I ask because our street has a lot of loose aggregate and it has been over 8 months since it was resurfaced. Is that normal or could the mixture alteration compromise the performance?
Ron Erickson says: 26-Jun-2017 10:01 PM
Hi Lori,

Slurry seals come in many types (example: Type II, Type III) as well as many oil formulations that can be utilized with each slurry type. It is not necessarily the governing body that determines the specific formulation as they can vary from company to company, yet still meet formulation specifications set by the municipality.

What you are noticing is likely due to that fact that slurry seals cure slowly, typically within 60-90 days from application. During this period, it is common to see the newly placed surface scuff, ravel (minor loss of aggregate) and even tear due to hard turning or scrubbing of tires. These areas typically become less noticeable with time and the fact that traffic generally re-compacts the scuffs and tears. Most of the raveled (loose) aggregate can be swept up after the surface cures and you should not see this process continue to occur in significant amounts. However, warm temps can cause the surface to soften and you may see that continue in lesser amounts until the next cold cycle.
Jonathan says: 07-Aug-2017 10:40 AM
I've never heard of closing a slurry road for 24 hours. Isn't this misleading? Are you talking about slow set emulsion? REAS?
Haq Samo says: 17-Aug-2017 02:09 PM
Dear Sir/madam, One of my Bridge Rehab projects (Bridge over North Saskatchewan River carrying Anthony Henday Drive Edmonton Alberta Canada), a warranty inspection was completed and moderate segregation of the ACP along the wheel paths in both lanes at various locations was identified. I am wondering if there is specific/suitable slurry patch product available for segregation repairs. Please let me know. Thanks and I will appreciate your time and help.
Jon Baggett says: 24-Aug-2017 11:39 AM
Good morning, Haq. Since we do not specialize in bridge repairs in Canada, I suggest contacting a local material supplier and/or service provider to seek specific recommendations for your repair needs.
Jon Baggett says: 24-Aug-2017 11:46 AM
Hi Jonathan, thanks for your question. Ace specializes in parking lot maintenance, repair, and paving and this post is written from that perspective. Our recommendations for parking lots may differ from what is required on roadways.
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