Contamination, degreasing, and a clean slab

A perfect profile on a greasy slab is still a failure

For a bond, the concrete has to be free of contaminants as well as properly profiled. Areas that sat unsealed for a long time are the most likely to be contaminated, and the most common offenders are fats, oils, and grease. Other chemicals that have leached into the slab cause the same problem. The quick field check is the water drop test: put a drop of water on the concrete, and if it beads up instead of soaking in, there is a good chance of contamination.

Degreasing, in order

1. 01
   Prepare first, degrease second

   Mechanical preparation draws contaminants to the surface, so degreasing is performed AFTER preparation is complete. Doing it in the other order wastes the work.

2. 02
   Use an aggressive profile method

   Shot blasting or scarifying are the preferred preparation methods on a contaminated slab, because they ensure an aggressive profile.

3. 03
   Mix the degreaser to concentration

   Simple Green at 4 ounces per gallon for light contamination, 8 ounces per gallon for heavy contamination.

4. 04
   Apply and dwell

   Apply to the substrate with a mop and let it sit 3 to 10 minutes. Do not let the solution dry on the floor.

5. 05
   Scrub

   A Clarke machine with a stiff nylon bristle brush.

6. 06
   Rinse and extract

   Shop vacuum or auto scrubber. Repeat the whole cycle as many times as needed until the substrate is sufficiently degreased.

7. 07
   Dry with air, never heat

   Fans assist drying. Do NOT use heaters — heat draws more contaminants to the surface and undoes the work.