Cementi

Cementi are hydraulic binders used in construction to bind materials such as aggregates and water. The term is often associated with cement powders that set and harden to form a solid mass, and the most widely used form is Portland cement. Cement powders are typically mixed with water to produce paste that binds sand and gravel into concrete, or with lime to form mortars.

Manufacture involves shaping raw materials into a cementitious product. The main ingredients are limestone and clay or other siliceous materials, which are quarried, ground, and blended to create a raw mix. This mix is calcined in a kiln at high temperature to form clinker, which is then cooled and ground with a small amount of gypsum to produce cement powder. Some cement formulations also incorporate supplementary cementitious materials to modify performance or reduce environmental impact.

Types and standards vary by region. Ordinary Portland cement is the standard type in many markets, while other variants include rapid-hardening, sulfate-resistant, and blended cements that incorporate fly ash, slag, or natural pozzolans. Regional standards, such as EN 197-1 in Europe or ASTM C150 in the United States, classify cement types and specify composition, performance, and testing requirements.

Uses and properties center on strength, workability, and durability. Cement is mixed with water and aggregates to produce concrete, or with lime for mortars. Its setting behavior and long-term strength development depend on chemical composition, curing conditions, and admixtures. Portland cement typically gains substantial strength within days and continues to cure over weeks.

Environmental considerations are prominent in modern production. Cement manufacture is energy-intensive and emits CO2 from calcination and fuel use. Mitigation strategies include clinker optimization, alternative fuels, incorporation of supplementary cementitious materials, and development of low-carbon cements and carbon capture technologies.