Defining the Distinction
While they may look similar to the untrained eye, Polished Concrete and “Grind and Seal” systems are fundamentally different in performance and maintenance profiles.
- Polished Concrete: A mechanical process where the concrete surface is refined with progressively finer diamond abrasives. The shine is the concrete itself.
- Grind and Seal: The concrete is ground to open the pores, and a topical sealer (epoxy, urethane, or acrylic) is applied. The shine comes from the chemical coating.
The Moisture Factor
- Breathability: Polished concrete is generally “breathable,” allowing moisture vapor to pass through without causing failure. This makes it an excellent choice for slabs with high Relative Humidity (RH).
- Topical Risk: Sealed systems create a non-permeable layer. If high moisture vapor drive exists in the slab, it can accumulate beneath the sealer, causing whitening, bubbling, or delamination.
The IFTI Verdict
Before specifying a “Grind and Seal” system for a retail or industrial project, an ASTM F2170 moisture test is non-negotiable. If moisture levels are high, you must either mitigate the moisture or switch the specification to mechanical polishing to avoid catastrophic coating failure.
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