Urea — Urea is commonly found in fertilizers. In its pure form it is less damaging than most other salts. Most deicers containing urea are not pure and can be damaging to stone, terrazzo and masonry.
The above salts are in a solid crystalline form. There are liquid deicers available containing ethylene glycol and potassium acetate but liquids are usually impractical to apply at schools and other public buildings.
Which salts are safe for stone, terrazzo and masonry flooring? Thanks to our many icy roads, a salt known as calcium magnesium acetate was developed. Not only is this type of deicer more environmentally friendly, but it is also biodegradable, noncorrosive and less damaging to stone, terrazzo and masonry surfaces. The downside you might guess is the expense. But what will that new floor cost?
SAFE FOR CONCRETE DEICERS
The biggest concern with deicers is the corrosion of rebar in concrete. For this reason many deicers are claiming to be safe for concrete. This is true as far as causing less corrosion. Your concern, however, is not necessarily corrosion but salt crystallization. Make sure to check the ingredients of these so-called safer deicers by requesting Material Safety Data Sheets (MSDS) or consulting with a stone expert.
As I travel in areas where deicers are used, I see thousands of schools and government buildings, as well as public building with damage to stone, terrazzo and masonry flooring. If the damage is caught in time a restoration company may be able to repair the damage, but if these harmful salts continue to be used, you'll be replacing the flooring in a very short time.
About the author: Fred Hueston is a worldwide expert on stone installation, failures, fabrication and restoration. He is the founder of the National Training Center for Stone & Masonry Trades (ntc-stone.com) and Stone University (stoneuniversity.org). He can be reached at Fhueston@aol.com.