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
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.
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.
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.
22.Hot Weather Concreting.
23.Cold Weather Concreting.
24.Concrete Slump Test.