Betonas

Betonas, or concrete, is a composite construction material formed by mixing cement, aggregates, and water. The cement paste binds the aggregates during hydration to form a hard, stone-like mass. Commonly used cement is Portland cement, although other binders exist. Aggregates include fine material (sand) and coarse material (gravel or crushed stone). Admixtures may be added to modify workability, setting time, or durability, and supplementary cementitious materials such as fly ash, slag, or silica fume can improve performance.

Concrete varies in properties and forms. Normal-weight concrete uses standard aggregates; lightweight concrete uses lightweight aggregates; reinforced concrete incorporates steel reinforcement to carry tensile stresses; prestressed concrete introduces prestressing tendons. High-performance and self-compacting concretes are also common.

The strength and durability depend on mix proportions, the water-cement ratio, curing conditions, and exposure environment. Compressive strength is classified in many systems (for example C20/25 up to C90/105). Typical curing at ambient temperatures develops most strength over 28 days.

Manufacture involves batching ingredients, mixing, placing, compacting, and curing. Quality is assessed via tests such as slump for workability and cylinder or cube compression tests for strength. Reinforcement, formwork, and joints influence behavior under load.

Applications span buildings, bridges, pavements, foundations, and precast elements. Environmental considerations include the CO2 footprint of cement production and the use of recycled aggregates or supplementary cementitious materials to reduce emissions.