Preparing a Concrete Substrate for a Floor Coating
Nearly every failed resin floor we are asked to inspect failed at preparation, not at product choice. This is the sequence we follow and the tests worth insisting on before anyone quotes you.
Where this works
- New build slabs due to receive a resin system
- Existing warehouse floors with previous coatings
- Slabs with laitance, curing compound or power float polish
- Floors with active cracks and failing joints
- Damp or ground bearing slabs with no damp proof membrane
How we install it
- 1Test before you plan
Hygrometer readings in several locations, pull off tests, and a check for curing compound with a water drop. Three tests, an hour of work, and they decide the entire specification.
- 2Remove laitance mechanically
Shot blasting for open areas, diamond grinding at edges and in confined spaces. Acid etching is not preparation and we do not use it, because it leaves salts and an inconsistent profile.
- 3Repair the concrete honestly
Spalled arrises, joint edges and pop outs are cut out and rebuilt with resin mortar. Cracks are stitched across their line and filled. Nothing is left to be bridged by the coating.
- 4Detail the joints
Movement joints are carried up through the new finish, never coated over. Saw cut joints in a slab that has finished shrinking are filled with a semi rigid filler and the coating runs across.
Common pitfalls we prevent
Frequently asked
How new can concrete be before coating?+
Twenty eight days as a minimum, and longer for thick slabs poured in cold weather. What matters more than the calendar is the hygrometer reading, which should be below 75 percent relative humidity or the system must be moisture tolerant.
Is shot blasting or grinding better?+
Shot blasting is faster and gives a more uniform profile over open areas. Grinding is used at edges, in confined spaces and where a specific flatness is needed. Most jobs use both.
Can you coat over an existing resin floor?+
Sometimes. If it is well bonded and compatible, it is abraded and overcoated after adhesion testing. If it is delaminating, it has to come off, and paying to remove it properly is cheaper than doing the job twice.
What is a pull off test and do I need one?+
A dolly is bonded to the slab and pulled until the concrete or coating fails, giving a tensile strength figure. On any significant industrial floor, yes, insist on it. It is the only objective evidence the slab can carry the system.
What if the slab has no damp proof membrane?+
Either apply a surface damp proof membrane primer or specify polyurethane concrete, which tolerates moisture vapour. Coating a ground bearing slab with no strategy for rising moisture will fail.
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