are ingredients, other than Portland cement,
that are added to the concrete mixture just
during mixing. The types of admixtures used are air entraining,
water reducing, retarding, accelerating and superplasticizer
admixtures. Air entraining admixtures entrain or suspend, and
small air bubbles throughout the concrete. Entrained air makes the
concrete more resistant to damage caused by freezing and thawing, and
scaling caused by deicers. It also increases concrete workability, and
reduces bleeding and segregation. Water reducing strength increasing
admixtures reduce the water needed to produce concrete at a
required slump, reduce the ratio of water to cement, reduce the total
of water and cement needed, and increase the slump. When the water to
cement ratio is reduced, concrete strength
increases. Water reducing
admixtures can cause an increase in drying shrinkage, and, if the water
to cement ratio is maintained while water is lost, a decrease in
concrete compressive strength.
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.