Could you please tell me what procedures to take in preparing the concrete. The concrete has several long cracks in it. What to fill it with? Is a stain or paint best to use? Can we use a floor polyurethane paint? Is polyurethane a good product for sealing the paint? Please let me know what you advise. Thank you.
- To repair the cracks may require more effort, depending on width. If they are open more than 1/8 inch and are starting to branch you may have to clean them and remove debris before sealing.
- In slab-on-grade it may be best to use a product designed for cracks which can be found at most large hardware warehouses. Look for flexible materials.
- Stains are difficult to apply uniformly because of different absorption in concrete. They may last longer, however, since they are absorbed into the concrete.
- Paints are a problem when applied over concrete that is not dry. Where moisture exists under the surface you may see bubbles and peeling later.
Oil stains and other dirt may also cause the paint to fail soon. It may be necessary to "acid wash' the concrete first to remove the surface. This too is a tricky operation that might cause more damage if done with strong acid for too long.
- At the same hardware store ask for paint that is specifically designed for concrete. They will usually be able to recommend methods of preparation and application. Some, like our local "HOME DEPOT" have free literature.
- As a rule "never try to seal external slab-on-grade". It needs to 'breath' and allow moisture in and out. The moisture will find its way out of the concrete - usually by lifting the paint/sealer off the surface.
Good luck with your project,