Viscosity Modifying admixtures or VMAs are the admixtures used to change the properties such as viscosity, workability, cohesiveness etc. of fresh concrete. A handy chemical admixture for the concrete producer
Accelerating admixtures can be used to increase either the rate of stiffening or setting of the concrete or the rate of hardening and early strength gain to allow earlier formwork striking and demoulding. Most accelerators achieve one rather than both of these functions.
Hardening accelerators are most effective at low temperature. Accelerators can be used with superplasticisers where early age strength is required, especially at lower temperatures.
It is an admixture that causes the development of a system of microscopic air bubbles in cement paste during mixing, usually to increase its resistance to freezing and thawing and to improve workability.
Air Entrained Concrete is used to achieve homogeneously dispersed air bubbles increasing the freeze-thaw resistance.
