Scaling refers to local flaking or peeling of the near-surface portion of concrete. Scaling is small localized patches that debond from the surface, typically brought on by freeze thaw cycle. There are three categories of scaling grading the degree of deterioration:
Light scaling – Scaling that doesn’t expose the coarse aggregate.
Medium Scaling – Scaling that involves loss of the surface mortar to 5-10mm in depth and exposure of the coarse aggregate.
Severe Scaling – Loss of surface mortar to 5-10mm and loss of mortar surrounding aggregate from 10-20mm. Some causes for scaling might be: Insufficient air entrainment or non-air entrained mix, improperly cured concrete, exposure to deicing chemicals, mix does not provide 0.45 Water/Cement ratio and air entrainment not in 4-8% range, finishing takes place while bleed water still on surface, concrete placed during inopportune weather conditions, heat/cold/rain etc. Below are some ways to reduce the likelihood of such problems:
-Order proper concrete mix design for environment, interior/exterior
-Proper curing, 7 days in order to ensure surface develops proper durability properties to resist scaling
-Avoid deicing chemicals as much as possible. Not at all during first year and sparingly afterwards.
-If deicing chemicals will be used, be sure they don’t contain chemicals which actually attach chemical structure of concrete surface. A.k.a. calcium, sodium chloride, ammonium sulfate, magnesium, and ammonium nitrate
-Avoid placing concrete within 30 days of impending freeze thaw cycle
-Use concrete sealers which reduce surface moisture absorption and chemical penetration.
-Utilize wet curing methods in hot/dry weather, fog spray between finishing operations