Admixtures are substances added to concrete or mortar to enhance its properties. They can improve workability, durability, or resistance to environmental factors. Common types of admixtures include water-reducing agents, accelerators, and retarders, each serving a specific purpose in the construction process. These additives can be natural or synthetic and are used in various construction projects to achieve desired performance characteristics. For example, superplasticizers help reduce the amount of water needed, while air-entraining agents create tiny air bubbles that improve freeze-thaw resistance. Admixtures play a crucial role in modern construction techniques.