Service Description
Concrete protects steel from corrosion by forming a “passive layer” because of very
high alkalinity induced by cement and other minerals.12 But many concrete structures
are exposed to atmospheric carbon dioxide emitted from various sources. In presence
of moisture / water and as described in the above reaction, atmospheric carbon dioxide
diffuses slowly through the concrete and the process of carbonation is initiated. Due to
this process, the pH of concrete slowly turns acidic and destroys the passive layer
protecting the reinforcing steel bars. Once the passive layer is destroyed, rusting of
steel bars begins.
Carbonation is a slow process but is detrimental to concrete structures as life
expectancy of concrete structures is between 50 –100 years.