Calcium hidroxide (Ca(OH)2)

Calcium hydroxide is obtained by the hydration of calcium oxide.

CaO + H2O → Ca(OH)2

It is an inorganic compound in the form of a white powder, and is widely used in mortars and plasters, providing plasticity, water retention, and adhesion for high-quality surface finishes. Its recarbonation with atmospheric CO₂ allows walls to breathe and release moisture, preventing common building pathologies. In calcium silicate brick production, it activates the pozzolanic reaction with silica and clay, yielding units with high mechanical and thermal performance. Regarded as the oldest cementitious binder in construction history, it remains a versatile and durable mineral material.