Which of the following materials is known to react with lime and water to enhance concrete properties?

The correct choice, pozzolans, plays a significant role in enhancing the properties of concrete through its chemical reaction with lime and water. When pozzolans, which include materials such as volcanic ash or certain types of natural or artificial siliceous materials, are combined with lime in the presence of water, they undergo a reaction that produces additional calcium silicate hydrate (C-S-H). This substance is crucial in the formation of concrete, as it contributes to strength, durability, and impermeability.

The key aspect that makes pozzolans beneficial is their ability to improve the long-term performance of concrete by enhancing its strength and reducing permeability, which contributes to better resistance against environmental factors. This process also helps in reducing the overall aluminum content in concrete, further improving its durability.

While cement is a vital component of concrete and aggregates are necessary for its structural integrity, they do not react with lime in the same way that pozzolans do to create additional binding compounds. Fly ash, while also beneficial for concrete properties and acting similarly to pozzolans, is specifically a type of pozzolan and is thus not the best answer to the question as it is a subset of the broader category.