Chemical concrete admixtures are material in the form of powder or fluids that are added to concrete to give it certain characteristics not obtainable with plain concrete mixes. In normal use, admixture dosages are less than 5% by mass of cement and are added to the the concrete at the time of batching/mixing. The most common types of concrete admixtures are:
1. Accelerators speed up the hydration (hardening) of the concrete.
2. Retarders slow the hydration (hardening) of the concrete, and are used in large or difficult pours where partial setting before the pour is complete is undesirable.
|Colored Concrete: Pigment Applied|
5. Pigments can be used to change the color of concrete, for aesthetics. Mainly they are ferrous oxides.
6. Superplasticizers (high-range water-reducing admixtures)are a class of plasticizers which have fewer deleterious effects when use to significantly increase workability. Alternatively; plasicizers can be used to reduce the water content of a concrete (and have been called water reducer due to this application) while maintaining workability. This improves its strength and durability characteristics.
7. Corrosion inhibitors are used to minimize the corrosion of steel and steel bars in concrete.
|Corrosion inhibitors protect steel against corrosion by promoting a chemical reaction on the surface of the steel rebars. They interrupt the electrolytic current to produce a sharp reduction of corrosion|
8. Bonding agent are used to create a bond between old and new concrete. Pumping aids improve pumpability, thicken the paste and reduce dewatering of the paste.
Thus, chemical admixture is one ingredient creating concrete that provide the differentiation of concrete types.