An additive is a substance other than Portland cement, aggregate, and water that is in the form of powder (powder) or liquid (watery), as one of the constituents of concrete and to improve the properties of concrete, a little before mixing, during mixing, or before Pouring is added to it. In other words, additives are components of concrete other than hydraulic cement, water, aggregates and fibers, which are added to concrete to modify and improve the properties of concrete and fresh and hardened mortar. Concrete additives are divided into two groups of chemical and mineral additives.

Chemical additives are obtained from the processing, combination or mixing of organic and mineral materials in a chemical process and are added to the mixture in the form of powder or liquid and in small quantities, usually up to 5% of the weight of cement materials during the construction and mixing or just before pouring concrete. be.

Mineral additives, which are either found naturally or are industrial byproducts, are divided into three categories: neutral materials, pozzolans, and cementitious materials, and to improve and modify the properties of cement mixtures, they are generally used in amounts greater than 5% of cement weight and in They are added to the concrete during mixing.