Concrete Grinding and Crack Repair in Tampa

Surface profile, in numbers

Coatings bond to texture, and there is a standard way to describe that texture. The International Concrete Repair Institute’s guideline 310.2R sets out ten concrete surface profiles. CSP 1 is nearly flat, and CSP 10 has peaks more than a quarter inch high. Installers compare a prepared floor against molded replica chips that show each level.

Coating data sheets name the profile they need. One polyaspartic sheet asks for CSP 2 to 3, but never rougher than the coating is thick, because a profile taller than the film will poke through it. One flake system asks for CSP 3 or more. A planetary diamond grinder typically produces around CSP 2, and a light shot blast around CSP 3, so the coating chosen decides which machine does the prep.

Why grinding instead of acid etching

Acid etching with diluted muriatic acid was once the standard garage prep. It produces roughly a CSP 1 profile, at the thin end of the scale. It also can’t remove curing compounds, sealers or oil, all of which stop a coating from bonding. The data sheets for today’s high-solids systems call for mechanical prep instead: diamond grinding, shot blasting or scarifying. Grinding also takes the weak top skin, called laitance, off the slab.

Grinding concrete releases crystalline silica dust. OSHA’s table for walk-behind floor grinders calls for either water fed to the cutting surface or a dust collector with a filter of at least 99% efficiency. Indoors, it adds a HEPA vacuum between passes. Heavy oil stains are handled separately, often with an enzyme degreaser that may take more than one application.

Cracks, joints and spalls

Spalls, pits and small cracks are filled and ground flush so the coating goes on over a flat surface. Joints need more thought. One manufacturer’s guide says isolation and expansion joints must be honored, meaning kept open and sealed with a flexible joint material after coating. Saw-cut contraction joints may be filled and coated over, but a coating can crack there if the slab keeps moving. Cracks that are still moving, and shrinkage cracks, may show through any rigid coating.

When a crack isn’t a coating problem

Hillsborough, Pasco and Hernando counties are known as “Sinkhole Alley.” Florida’s Office of Insurance Regulation found that two-thirds of the sinkhole damage reported statewide from 2006 to 2010 came from those three counties. Most garage cracks are ordinary shrinkage, not ground movement. But if a crack in a garage in Land O’ Lakes or Wesley Chapel is widening, has one side lower than the other, or matches new cracks in the walls, have it evaluated before anyone coats over it. Filling a moving crack only hides it.

Once the slab is sound, the prepared surface goes straight to the base coat, before dust or moisture can settle back in.

What sets the schedule? The profile the chosen coating requires, how many old sealers or oil stains have to come off, the number and type of cracks and joints, and whether a crack needs to be evaluated before it is filled.

Common questions