Carbonation Testing

Carbonation Testing Lab in Delhi

Advance Inspection & Testing Lab is one of the best Carbonation Testing Lab in Delhi

Carbonation of the concrete, caused by carbon dioxide and sulphur dioxide in the atmosphere to cause gradual neutralisation of the alkalinity from the surface inwards, a process known as carbonation. It also has the effect of reducing the pH. Cement paste normally has a pH of about 13, which provides a protective layer (passive coating) to the steel reinforcement against corrosion. This alkalinity causes the formation of a passive oxide layer around the steel reinforcement. Concrete will react with atmospheric carbon dioxide. 

The Carbonation testing is most commonly carried out by spraying the phenolphthalein indicator on freshly exposed surfaces of concrete broken from the structure or on split cores.

Carbonation depth is assessed using a solution of phenolphthalein indicator that appears pink in contact with alkaline concrete with pH values in excess of 9 and colourless at lower levels of pH.

Hence there may be corrosion in the zone ahead of the front defined by the indicator. In general, the change in pH occurs in this zone which is only a few millimeters ahead, and the phenolphthalein method provides a good indication of the location of the depassivation front.