Corrosion caused by chemical aggression
Moisture is required to cause aggression due to chemical attack. Dry, solid or gaseous substances do not destroy the concrete. Depending on the effect of the damage, the substances differ as widening and corrosive.
Expansion is caused by water-soluble sulfates (CaSO₄,Na₂ SO₄,MgSO₄), which react with the separated Са(OH)₂ from the cement. This results in volume increase and can cause concrete destruction.
Са(OH)₂ + Na₂SO₄ → CaSO₄.2H₂O+NaOH+H₂O
Corrosive effects are caused by acids, salts, animal fats, oils, etc. The cement stone has an alkaline character and can only be resistant to alkaline and neutral environments. Concrete is very hard to protect against the action of strong acids. A special kind of acid-resistant cement must be used, if necessary.
Environment: Chemically low aggressive.
Additional classes covered: XC1, XC2, XC3, XF1
Environment: Chemically moderate aggressive.
Additional classes covered: XC1, XC2, XC3, XC4, XS1, XF1, XD1, XD2, XA1, XM1
Environment: Chemically highly aggressive.
Additional classes covered: XC1, XC2, XC3, XC4, XS1, XS2, XS3, XF1, XF2, XD1, XD2, XD3, XA1, XA2, XA3, XM1, XM2, XM3