The Basics of Slurry Surfacing with Asphalt Emulsions

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What is slurry surfacing?

Slurry surfacing is a thin dense-graded cold mixed overlay. Slurry seals are thin layers rich in asphalt used for residential streets, airports and in some countries for sidewalks and parking lots. Micro surfacing is a premium product based on specially selected aggregates and polymer modified asphalt emulsion. Micro surfacing is designed to be applied in thicker lifts for high trafficked areas.

How is a slurry seal or micro surfacing applied?

Normally, aggregate, emulsion, water and filler such as cement are mixed in a mobile mix paver and the mixture which has a slurry like consistency is allowed to fall into a ‘spreader box’ which distributes it over the road surface to a predetermined thickness. Slurry surfacings may also be hand applied. The slurry cures rapidly (typically under 1 hour for micro surfacing and under 4 hours for slurry seal) and traffic can be allowed on it.

What type of asphalt emulsion is suitable?

Cationic slow-setting emulsions are used. They are selected on the basis of a laboratory mix design process, which involves tests on the compatibility of the aggregate and the emulsion, and on the durability of the cured seals.

Where can I go for further information?

The International Slurry Surfacing Association provides detailed advice on the design and application of slurry surfacings. Their web address is slurry.org.

Where else can I learn more about slurry surfacings using asphalt emulsions?

You can order AEMA’s Basic Asphalt Emulsion CD-Rom right here on this website – just click here.