4.2.4.1 Chemical Admixture

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4.2.4.1 Chemical Admixture
4.2.4 Concrete Admixture

• Introduction
• Water-Reducing Admixture
• Hardening Accelerator
• Air Entraining Admixture
• Set Retarding Admixture
• Flash Setting Admixture
• Expanding Admixture
• Frost-resistance Admixture

4.2.4.2 Mineral Admixture
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Air Entraining Admixture

• Definition
• Mechanism
• Performance
• Improving durability
• Improving workability
• Decreasing concrete strength
• Application
• Common air entraining admixture

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Air Entraining Admixture
Definition

• It refers to the concrete admixture that is added
  bubbles with
• large quantities
• separate
• independent
• tiny
• even

Definition
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Air Entraining Admixture
Mechanism

• It is the hydrophobic apparent active substance
• Reduce the surface tension
• Cause the oriented adsorption in the bubble
  surface
• Change the air in the course of mixing into
  separate, tiny and even bubbles

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Performance
Air Entraining Admixture
Improving durability
Improving workability
Decreasing concrete strength

• Air entraining admixture can improve durability
  and plasticity, but it reduces strength.

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How Properties Improved

• Air entraining admixtures
• Change the pore structure, improve durability
• Increase lubricate of aggregates, improve
  plasticity
• Increase air content, reduce strength

Fig4.2.2 Sketch map of improve durablity
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Air Entraining Admixture
Application

• This type of admixture should always be used in
  freezing and thawing deterioration.
• It reduces the strength unnecessarily in
  structural concrete.

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Common Air Entraining Admixture
Air Entraining Admixture

• Rosin soap and rosin pyrolytic polymer and so on
• the amount 0.005-0.012
• introducing D0.05-1.25mm air bladder
• making concrete air content to 2-6

Common Air Entraining Admixture