Glossary
Characterization of cement-based materials by infrared spectroscopy

Carbonation; Carbonation

Over time, the hydrates formed from the reaction of cement and water, in particular portlandite crystals (Ca(OH)₂), naturally carbonate on contact with atmospheric carbon dioxide dissolved in capillary water according to the carbonation reaction: Ca(OH)₂ + CO₂ ⇒ CaCO₃ + H₂O.

Under ambient conditions of temperature and relative humidity, carbonation is governed by the transport of atmospheric CO₂ within capillary water. It begins at the extreme surface of the concrete and progresses towards the core of the material. Note that hydrated calcium silicates (C-S-H) also carbonate, but more slowly than portlandite.

Clinker; Clinker

Granules resulting from the high-temperature firing of a mixture of clay and limestone. Portland clinker is mainly composed of alite (∼ C3S), belite (∼ C2S),...