A concrete additive is a material other than water, aggregates and hydraulic cement used in mixing to modify one or more of the properties of the mixture during the plastic stage. Concrete additives enhance the workability of concrete by increasing or decreasing water content without altering its consistency. They also delay the time it takes for concrete to set and increase strength, such as compressive, tensile and flexural strength.

There are a number of different types of cement additives for strength, such as accelerators, air entrainers, retardants and abrasion control agents. Accelerators help to speed up the rate of hydration in the early stages of cement synthesis, thus shortening the setting times and improving the concrete’s strength development at these early ages. Traditionally, calcium chloride has been used as the main accelerating additive.

Other organic chemical accelerators are also available to replace the more traditional corrosive accelerators. These include alkanolamines such as triethanolamine (TEA) and triisopropanolamine (TIPA), which are added in the grinding process. However, they are not very effective compared to Ca(NO3)2.

Air entrainers are used to introduce microscopic air bubbles into the concrete mix to improve its performance. They can reduce segregation and water bleeding, and can prevent the concrete from cracking in cold environments. They can also increase the cohesion force in the concrete, which helps to reduce curling of the concrete during placement.