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Why are admixtures used?

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Why are admixtures used?

asked Jun 30, 2015 in Concrete Technology by mfby2k  

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Admixtures are used to give special properties of fresh or hardened concrete. Admixtures may enhance the durability, workability or strength characteristics of a given concrete mixture. Admixtures are used to overcome difficult construction situations, such as hot or cold weather placements, pumping requirements, early strength requirements, or very low <strong>water-cement ratio specifications.Why admixtures are used in Concrete?.
Over decades, attempts have been made to obtain concrete with certain desired characteristics such as high compressive strength, high workability, and high performance and durability parameters to meet the requirement of complexity of modern structures.
The properties commonly modified are the heat of hydration, accelerate or retard setting time, workability, water reduction, dispersion and air-entrainment, impermeability and durability factors.
Major reasons for the use of admixtures are:

  1. To reduce the cost of concrete construction.
  2. To achieve certain properties in concrete more effectively than by other means.
  3. To maintain the quality of concrete during the stages of   mixing, transporting, placing, and curing in adverse weather conditions.
  4. To overcome certain emergencies during concreting operations.
answered Aug 27, 2015 by fawad  

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