What is the chemical reaction called when Portland cement is mixed with water?

The chemical reaction that occurs when Portland cement is mixed with water is known as hydration. During this process, the cement particles react with water to form various compounds that contribute to the setting and hardening of the cement. Hydration is crucial because it transforms the slurry of cement and water into a solid mass with strength and durability, which is essential in construction applications.

The products of hydration help develop the structure and integrity of concrete, binding aggregates together and allowing it to achieve its intended performance characteristics. This process is exothermic, releasing heat as it progresses, which is important to the proper curing of concrete.

The other options pertain to different chemical processes that do not directly relate to the behavior of cement and water. Air-entrainment, for instance, is a method used to improve the workability and durability of concrete but does not describe the fundamental reaction between cement and water. Polymerization refers to the reaction of monomers to form polymers, which is relevant in plastics and other materials but not in cement chemistry. Oxidation involves the reaction of substances with oxygen, which is not what occurs when mixing cement with water.