Concrete Admixtures are ingredients of chemicals that added to concrete when mixing concrete,in the purpose of improve concrete performance and workability,normally the adding rate is not more than 5% of cement in weight.
According to functions of concrete admixtures there are 4 types of admixtures.
Type 1:Improve the flowability of concrete and workability,e.g.water reducing admixture,air entraining admixture and pumping aid admixture.
Type 2:Adjust the concrete setting time,hardening properties,e.g.set retarding admixture,hardening accelerating admixture and flash setting admixtures.
Type 3:Improve the concrete durability,e.g.water proofing admixture and anti-corrosion admixture.
Type 4:improve other performance and properties:gas forming admixture,expanding admixture,coloring admixture.
There are following concrete admixtures according to admixtures names:
1.Water reducing admixture,According to chemical ingredients,there are lignosulfonate based water reducing admixture,naphthalene sulfonate formaldehyde based water reducing admixture,and polycarboxylate based water reducing admixtures.
2.Accelarating admixture/early Strength admixture .Trethanolamine(TEA),Calcium formate,sodium nitrite,sodium nitrate,urea,chromates,sodium sulfate,calcium sulfate etc.are used to formulate hardening accelerating admixture.
3.Set retarding admixture.Sodium gluconate,sugar etc.are often used to make set retarding admixtures.
4.Air entraining admixture.
5.Superplasticizer,There are naphthalene based superplasticizer and polycarboxylate based superplasticizer.
6.Corrosion inhibiting admixture,normally there are Darex Corrosion Inhibitor(DCI) and Migrating Corrosion Inhibitor(MCI)
7. Expanding Admixture
8.Coloring admixture,
9.Pumping aid