Concrete Mixtures 12

Air Entraining Admixtures


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Bubbles that form during the concrete mixing process are kept steadied and small by air entraining admixtures. The admixture forms a tough soapy film over the bubbles that keeps them from joining together and keeps out water. The mixing process spreads the bubbles throughout the concrete. The resistance of hardened concrete to freezing and thawing in moist conditions is improved by entrained air. Pressure on expanding and freezing water forces it out of the concrete capillaries and pores. It enters the entrained air spaces without expanding inside the concrete and cracking it. When the water thaws it returns to the capillaries and pores. Deicers used for ice and snow removal cause surface scaling of non entrained concrete. Deicer hydraulic and osmotic pressures are greater than the pressures exerted by the water in the concrete. Entrained air spaces relieves these pressures and prevents scaling.




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  Concrete Mixtures Links

1.The Materials In Concrete.
2.Concrete Aggregates - Concrete Slump.
3.Concrete Placement - Vibration - Hydration.
4.Types of Portland Cement - Concrete Moisture & Cracking.
5.Watertight Concrete - Supplementary Cementing Materials.
6.Supplementary Cementing Materials.
7.Chemicals That Damage Concrete.
8.Concrete Aggregate Properties.
9.Angular & Smooth Aggregate Properties.
10.Admixtures.
11.Admixtures Continued.
12.Air Entraining Admixtures.
13.Air Entraining Admixtures Continued.
14.Conditions Affecting Concrete Air Volume.
15.Superplasticizers & Other Admixtures.
16.Ordering & Mixing Concrete.
17.Concrete Mixing - Subgrade Preparation.
18.Subbase Preparation - Concrete Placement.
19.Concrete Consolidation.
20.Concrete Finishing.
21.Concrete Curing.
22.Hot Weather Concreting.
23.Cold Weather Concreting.
24.Concrete Slump Test.

                                                     
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