There are two categories of admixtures which are mineral admixtures and chemical admixtures. With regards to natural admixtures, their production is not scientifically advanced, however, they enable green construction and serve as viable alternatives. Examples are: Fly ash; Silica fume; Ground granulated blast furnace slag; Rice husk ash, etc.
Chemical Admixtures
In modern-day constructions, it has become a norm to use chemical admixtures in concrete mixing. This is because chemical admixtures have an essential part in the making of sustainable concrete with better mechanical properties and the durability of concrete for a lifetime. They are used in concrete for purposes such as boosting their durability, flow nature, resistance to frost and deicing salts, sulphate resistance, moulding features, pump ability amongst others.
There are numerous varieties of chemical admixtures that can be used and each of them serves its unique purposes. The following are the most popularly used chemical admixtures:
Superplasticizer Accelerator: This is used for the reduction of the water requirement by 15% to 20% without having any effect on the workability resulting in increased strength and dense concrete.
Accelerator: To speed up the hardening process and reduce the formation time of concrete by removing the forms early, hence, it is preferably used in concrete in cold weather. Examples are triethenolamine, calcium formate, silica fume, calcium chloride, finely divided silica gel etc.
Retarder: Used to lessen the formation time by decreasing the rate of cement hydration, hence, it is preferably used in high temperature concreting places.
Examples are calcium sulphate or gypsum, starch, cellulose products, common sugar, salts of acids
Water Reducing Admixture: To achieve workability (slump) in the ratio of low-water cement to a certain strength and thus save cement. It will also increase the durability of concrete, proper bonding between concrete and steel, prevent cracking, segregation, honeycombing, bleeding etc. Examples are calcium, sodium and ammonium lignosulphonates.
Air Entraining Admixture: This Introduces small air bubbles into the concrete mix which will act as rollers enhancing the workability of the concrete by making it very effective in freeze-thaw cycles as they ease the effect on the increasing water in the concert mix in a cold climate. When introduced, they enhance the workability of concrete, reduce segregation and bleeding, reduce the unit weight and modulus of elasticity of concrete, increase the chemical resistance of concrete and reduce cement or sand or water content in concrete etc. Examples are vinsol resin, darex, teepol, cheecol etc.
Other types of admixtures are: Pozzolanic Admixtures; Damp-proofing Admixtures; Gas forming Admixtures; Air detraining Admixtures; Alkali Aggregate Expansion Inhibiting Admixtures; Anti-washout Admixtures; Grouting Admixtures; Corrosion Inhibiting Admixtures; Bonding Admixtures; Fungicidal, Germicidal, Insecticidal Admixtures; Coloring Admixtures
Whichever type of admixtures needed for your construction works, you can trust Morven Industrial to supply you with the best of products which are from the renowned manufacturers in the industry. Call us today to get started with your order.