concrete carbonation
concrete carbonation
(OP)
Can Anyne explain carbonationto me when dealing with concrete?
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RE: concrete carbonation
Carbonation weakens the surface of concrete and is characterized by a pH in the range of about 8.5 to 9.5. This is lower than typical concrete pH of 11+ (after curing...even higher when fresh).
Check for carbonation by taking a freshly broken piece of concrete (do not use a sawcut piece or drilled piece), coat with phenolphthalien and watch for areas around the carbonation to turn purple which the actual carbonation layer will remain colorless. It usually shows as a distinct layer about 1/8 to 1/4-inch thick at the surface.
RE: concrete carbonation
Therefore when checking the depth of carbonation you are also looking to see how much protection is still being given to any reinforcement wihtin the concrete. It is possible to calculate the rate that carbonation is forming and relate this to life-span of the structure. The rate at which carbonation forms is related to the quality of the concrete, not just strength but also porosity, cement type etc...
It is a very smle tool in assessing structural concrete.
RE: concrete carbonation
I've seen a number of fixes used to prevent or correct the surface carbonization of a floor slab. One was to apply a high solids sealer right after finishing of the slab to prevent the CO and CO2 from getting to the concrete surface.
Another was to scrub the carbonized surface of the hardened surface to remove the soft, loose powdered layer, then apply a liquid hardener like Lapidolith to the floor surface.