Sunday, August 4, 2013

Concrete Chemical Resistance

Concrete Chemical Resistance
Concrete Chemical Resistance
Concrete can be attacked by contaminants in water, soil or gases (e.g. air). Hazards also occur in service (i.e. in tanks, industrial floors etc.).
·     Surface and ground water, harmful soil contaminants, air pollutants and vegetable and animal substances can attack the concrete chemically.
·     Chemical attack can be divided into two types:
-       Solvent attack: caused by the action of soft water, acids, salts, bases ,oils and greases etc
-       Swelling attack: caused mainly by the action of water soluble sulphates
Measures
·     Concrete structure as impermeable as possible, i.e. low porosity
·     Low water/cement ratio aim for < 0.45
·     Increase the concrete cover by 10 mm minimum
 Concrete only has adequate resistance against very weak acids.
Medium strength acids degrade the concrete.

Therefore extra protection of the concrete with a coating must always be specified for moderate to highly aggressive acid attack.

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