Curing Compounds

ASTM 309 is the specification that most people are familiar with. To meet ASTM 309 you must form a film and retain 95% of the moisture for 72 hours. It also states that you have 350 g/l or less of VOC, Volatile Organic Compound. It is broken down into two types, Type 1 and Type 2. Type 1 means the cure is clear. Type 2 is going to be white. Both also have two classes. The classes are A & B. Class A can use anything to form the film and much of the time it is wax. Class B uses a hydrocarbon resin, these can be an acrylic or a dissipating resin. Type 2 is mostly used in highway construction. If you are familiar with the terms think of white pigmented curing compound. The VOC restrictions on the ASTM 309 specifications prevent solvents from being effectively used. When you see ASTM 309 in your specifications, think of water based cures or cure and sealers.

ASTM 1315 is another curing specification. It has no restrictions on solvents in products that meet this specification. Its restriction are that it must be at least 25% acrylic resins, must retain 98% of the moisture for 72 hours and form a film of 2 mils based on 200 sf per gallon. It has four classes, Class A, B, C, D. Class A is non-yellowing, Class B is slight yellowing, Class C is moderate yellowing and Class D is unrated. Class D is seldom seen. Think of Class A is the most expensive and what would look best on decorative concrete work and Class D as the least desirable.

I have tried to make this as short and simple as possible without being too confusing. I had the help of a manufacturers rep for this one, because he is much more well versed in all of these specs. Thanks Tim. :)