Selected Answers

From Scott Sammons of Independent contractor at large on January 14, 2019:
When confronted by a situation where we had strong ...read more When confronted by a situation where we had strong oil residue and steam cleaning failed to allow an adequate adhesion to existing concrete, one of my employers resorted to bushing down (Chipping hammer with bush bit for small areas, I have used a rotomill on bigger surfaces) the surface and using as Ardex product to form a cap over the concrete that we then coated. Five years in it still looks very good despite extreme weather exposure. There are many products available to meet the need, and the surface prep required will vary depending on end needs and product chosen. It should go without saying that acid etching is no help for oil or paint contamination.

From Warren Brand of Chicago Corrosion Group on January 11, 2019:
Two options. First, remove the oil. There are ma ...read more Two options. First, remove the oil. There are many ways to do this, depending on how deep the oil has penetrated, and how large the stains are. Within the option of removing the oil, there are two ways to go. First, using various chemicals, treatments, hot water, steam, etc., to coax the oil from the concrete. Second, chip out the bad concrete until you get clean, oil-free margins. The only other alternative is to look into various exotic coating systems and primers. Some purport to be able to adhere to "lightly" contaminated concrete. I've seen demonstrations of these products, but have not done any in-depth evaluation. Going this route, I would, of course, recommend pull tests.

From Erik Andreassen of CPS on January 10, 2019:
Speak to the coating suppliers and seek their prof ...read more Speak to the coating suppliers and seek their professional knowledge, for both the surface preparation and their recommended coating system for the type of storage items you have.They will base their proposal on the type of stored material. They should also offer a warranty on their specified system, providing the correct surface preparation has been carried out according to the product data sheet.

From Larry Muzia of Exceletech Coating & Applications, LLC on January 7, 2019:
Wash with an emulsifier and very hot water to incl ...read more Wash with an emulsifier and very hot water to include scrubbing, then shop vac while still wet and prime using a primer that will properly cure on damp concrete. Be advised that if the oil is deeply penetrated into the concrete, it may through capillary action return to the top; therefore, my advice is to prime as soon as concrete is no longer visibly wet. I would also perform the water break test to insure water will penetrate into the concrete and not bead up and sit on the surface. There are several primers on the market which will cure on damp concrete...not wet but damp.