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Concrete is a material commonly used in construction. It is composed of cement, aggregate, water and special chemicals known as admixtures.


Usually, Portland cement is used to make concrete. Portland cement contains calcium silicates.


Admixtures change the properties of the concrete. Different admixtures are used depending on the requirements:

  • Accelerators make the concrete harden faster.
  • Pigments change the colour of the concrete.
  • Bonding agents create a good bond when adding new concrete to old.

Reinforced concrete

Concrete is very strong in compression, but weak in tension. To make it a more useful construction material, steel bars (rebar) are often installed in fresh concrete, to increase the tensile strength.