In 1918, Abrams discovered the ratio of weight of water to the weight of cement (the water-cement ratio) influences desirable qualities of concrete. This concept is referred to as Abram’s Law.
Supplementary cementitious material, such as fly ash, slag, silica fume, and natural pozzolans, have been used as admixtures in recent years to alter properties of portland cement concrete.
Hydration requires .22 kg to .25 kg of water per 1 kg of cement.
Excess water causes the development of capillary voids in concrete, which increases porosity and permeability, thus reducing strength.
Low W-C ratios increases resistance to weathering, provides a good bond between successive layers of concrete and steel reinforcement, and limits volume change due to temperature or moisture.
Air-Entrained Concrete – includes an air-entraining agent, an admixture, which is used to increase the concrete’s resistance to freezing and thawing.
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