Admixtures are materials added to the concrete mix, other than cement, water, and aggregate, to enhance or modify the properties of concrete in the fresh and hardened states. These can include accelerators, retarders, water reducers, air entraining agents, and superplasticizers, among others. Each type of admixture serves a specific function by altering the chemical and physical interactions within the concrete mix. For instance, superplasticizers increase the flowability of concrete without requiring additional water, thus maintaining strength.