What are pozzolans?

Pozzolans are defined as siliceous or siliceous/aluminous materials that have the ability to react with calcium hydroxide in the presence of moisture to form compounds possessing cementitious properties. When added to concrete, pozzolans can enhance the overall strength and durability of the mix by filling voids, improving workability, and reducing permeability. This reaction leads to the formation of additional cementitious compounds, which can contribute to the long-term strength and chemical resistance of concrete.

This application of pozzolans in concrete aligns with sustainable building practices, as they can be derived from natural or industrial by-products, such as volcanic ash, fly ash from power plants, or silica fume from the production of silicon metal. The use of pozzolans not only improves performance but can also reduce the carbon footprint of concrete by decreasing the amount of ordinary Portland cement needed in the mix, subsequently lowering greenhouse gas emissions associated with cement production.