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.