The characterisation of the conservation status of concrete can be done by verifying the carbonation depth of the material by applying a chemical indicator of phenolphthalein in holes or probes previously performed on the surface of the material.

Carbonation is a common mechanism of deterioration in reinforced concrete and is a result of the reaction of calcium hydroxide with carbon dioxide from the air, forming calcium carbonate and water.

This process is accompanied by a reduction in the alkalinity of concrete that, when it crosses the thickness of the coating concrete, and in the presence of water and oxygen, causes corrosion of the reinforcements, accelerating the degradation of the concrete and steel and reducing the durability of reinforced concrete.

Ultimately, this test makes it possible to determine the depth and extent of concrete zones requiring repair.