Anticarbonation

What is carbonation? Carbonation means chemical conversion to a carbonate; It is referred to “the process of chemical weathering by which minerals containing soda, lime, potash and other basic oxides are changed to carbonates by the action of carbon dioxide and water”. T

he process is represented by the reaction below,

CO2 + H2O ——> H2CO3 H2CO3 + CaO ——> CaCO3 + H2O

As represented by the above chemical reaction, carbon dioxide with water forms carbonic acid. This carbonic acid subsequently reacts with alkaline material such as lime to form calcium carbonate.

Effects of Carbonation on concrete structure:

The action of atmospheric carbon dioxide on lime mortars and cement concretes has been known for centuries. Roman plasters used air-hardened lime, which gained strength due to the reaction of carbon dioxide with calcium hydroxide formed an interlocked mass of calcium carbonate.

But, traditionally concrete is reinforced with steel to increase tensile strength. Concrete protects steel from corrosion by forming a “passive layer” because of very high alkalinity induced by cement and other minerals. 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.

Preventing Carbonation -Carbonil: Anti Carbonation coatings 

Under CarboNil series, following products are offered.