Chemical additives are the ingredients in concrete other than Portland cement, water, and aggregate that are added to the mix immediately before or during mixing. Manufacturer’s use admixtures primarily to reduce the cost of concrete construction; to modify the properties of hardened concrete; to ensure the quality of concrete during mixing, transporting, placing, and curing; and to overcome certain emergencies during concrete operations.
Air-entraining admixtures cause small stable bubbles of air to form uniformly through a concrete mix. The bubbles are mostly below 1 mm diameter with a high proportion below 0.3 mm. The benefits of entraining air in the concrete include increased resistance to freeze-thaw degradation, increased cohesion (resulting in less bleed and segregation) and improved compaction in low-workability mixes.
Super plasticisers are also known as high-range water reducers (HRWR). Super plasticisers reduce water content by 12 to 30 percent and can be added to concrete with a low-to-normal slump and water-cement ratio to make high-slump flowing concrete. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction.
Controls the amount of air in the concrete mix to increase the concrete durability.
Facilitates the process of forming foam during the mixing of concrete, which enables it to add strength to individual bubbles.