Vibration of self consolidating concrete

SCC can be used for casting heavily reinforced sections, places where there can be no access to vibrators for compaction and in complex shapes of formwork which may otherwise be impossible to cast, giving a far superior surface than conventional concrete.The relatively high cost of material used in such concrete continues to hinder its widespread use in various segments of the construction industry, including commercial construction, however the productivity economics take over in achieving favorable performance benefits and works out to be economical in pre-cast industry.When normal mixes of concrete become to fluid, they segregate; large aggregates settle to the bottom of a placement and water and cement paste move to the top.SCC mix designs must maintain a tight balance; they must be fluid without a concrete mix which has a low yield stress, high deformability, good segregation resistance (prevents separation of particles in the mix), and moderate viscosity (necessary to ensure uniform suspension of solid particles during transportation, placement (without external compaction), and thereafter until the concrete sets).In everyday terms, when poured, SCC is an extremely fluid mix with the following distinctive practical features – it flows very easily within and around the formwork, can flow through obstructions and around corners ("passing ability"), is close to self-leveling (although not actually self-levelling), does not require vibration or tamping after pouring, and follows the shape and surface texture of a mold (or form) very closely once set.However it is laborious and takes time to remove by vibration, and improper or inadequate vibration can lead to undetected problems later.

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That's why SCC mixes allow for denser reinforcement, optimized concrete sections and shapes, and greater freedom of design while producing superior surface finishes and textures.SCC concrete is usually defined as having a spread of 18 to 30 inches wide, making it possible to place concrete under difficult conditions.The viscosity, as visually observed by the rate at which concrete spreads, is an important characteristic of plastic SCC and can be controlled when designing the mix to suit the type of application being constructed.It has been demonstrated that a total fine aggregate content ("fines", usually sand) of about 50% of total aggregate is appropriate in an SCC mix.SCC Concrete, also known as self consolidating concrete and self compacting concrete is a highly flowable, non-segregating concrete that spreads into place, fills formwork, and surrounds even the most congested reinforcement, without the use of any mechanical vibration.

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