Cementitious

Cementitious is an adjective used in construction and materials science to describe any material that can act as a cement, binding particles together to form a solid mass. In practice, cementitious materials harden and gain strength through a chemical reaction with water (hydration) or, in some cases, through carbonation of binders in the presence of air. The term encompasses a broad range of binders used in concrete, mortar, plaster, and composites.

Two broad categories are hydraulic cementitious materials and non-hydraulic (or lime-based) binders. Hydraulic binders set and harden under water and provide strength even in damp conditions. Portland cement, hydraulic lime, fly ash, slag cement, metakaolin, silica fume, and calcium sulfoaluminate cements are common examples. Non-hydraulic binders rely on carbonation or drying to harden; lime putty and lime mortars are traditional non-hydraulic cementitious systems.

Common applications include concrete, mortars, grouts, screeds, and plaster. Key properties include binding strength, durability, workability, curing rate, shrinkage, and heat of hydration. The use of supplementary cementitious materials (SCMs) like fly ash or slag can modify performance and reduce clinker content, improving sustainability.

Standards and nomenclature vary by region; examples include ASTM C150 for Portland cement and EN 197-1 for cement types in Europe. The term cementitious is widely used in specifications and product descriptions to denote materials that form a cementitious matrix when mixed with water and, optionally, aggregates.