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Question:
Published on: 30 June, 2022

What is an air entraining agents? Give some examples. What is efflorescence in concrete structure?

Answer:

Air entraining concrete is made by mixing a small quantity of air entraining agent or by using air entraining cement. These air entraining agents incorporate millions of non-coalescing air bubbles, which will act as flexible ball bearing and will modify the properties of plastic concrete regarding workability, segregation, bleeding and finishing quality of concrete. It also modifies the properties of hardened concrete regarding its resistance to frost action and permeability.

The following types of air entraining agents are used for making air entrained concrete:

  1. Natural woods resins.
  2. Animal and vegetable fats and oils, such as tallow, olive oil and their fatty acids such as stearic and oleic acids.

 

Efflorescence:- Efflorescence is caused when soluble salts and other water dispersible materials come to the surface of concrete and mortars. Its induced by low temp. moist conditions, condensation, rain, dew and water added to the surface of fresh concrete to assist troweling.

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