Types of concrete additives

Concrete additives are defined as materials apart from aggregate, water and cement added to concrete. Concrete additives are chemical or mineral substances that are usually added as a percentage of the weight of cement to the weight of concrete during the process of mixing concrete to change some of its properties in a desirable way. A mistake about the amount of concrete additives can cause adverse consequences in fresh or hardened concrete. The consumption of additives in concrete has been low, these additives are very diverse and are divided in a very wide range. Concrete additives, which can be used both for fresh concrete and for hardened concrete, are very important and have led to significant progress in the concrete industry, and therefore it is essential for every civil engineer to know and gain knowledge about these materials. Concrete itself is one of the most widely used materials, and now with the help of various concrete additives, it can go even further. In fact, the use of various types of concrete additives became more popular when concrete structures with different uses in different environmental conditions were established. Types of concrete additives are mineral or chemical substances that are added in the form of powder (powder) or liquid during the mixing of concrete. be. These materials drastically change the properties of concrete, so the dosage should be calculated correctly. More precisely, the amount of additives in concrete is always less than 5% of the weight of cement.

Manufacturers use additives primarily to reduce the cost of making concrete. To improve the properties of hardened concrete, to ensure the quality of concrete during mixing and significantly increase workability, easier transportation, use less cement and reduce environmental risks, placing and processing; And they use concrete additives to overcome special emergency conditions during concrete operations.

Some of the basic tasks of using concrete admixtures are: ▪️ Reduce the amount of water needed to reach the desired slump by about 5-10%. It delays the setting speed of concrete and at the same time keeps it usable. It delays the effects of hot weather. ▪️ It makes the concrete reach the desired strength sooner. ▪️ Reduces the time required for processing. ▪️ It delays the corrosion of reinforcing bars. ▪️ It helps to improve the curing of concrete.

▪️ Reduces concrete shrinkage. Reduces the alkali-silica reaction. It is used to improve pumping capacity. ▪️ Improves the connection of concrete to rebar. Strengthens the bond between the existing and new concrete. Increases impact and wear resistance. Creates colored mortar or concrete. Generally, additives are made by mixing powder with liquid. Some admixtures such as pigments, pumping aids, and expansion agents are added manually to the concrete mix because they require small amounts.

▪️ Accelerating the process of acquiring initial resistance Controlling alkaline reactions of cement with aggregates ▪️ prolonging its time Increase efficiency without changing the ratio of water to cement ▪️ Preparation of concrete with high resistance against frequent freezing and thawing ▪️ Adjust and improve concrete properties Reducing construction costs ▪️ Contributing to sustainable development