Mineral Admixtures

Mineral admixtures (e.g. fly ash, silica fume, volcanic ash, etc.) are used in formulating concrete. Mineral admixtures impart beneficial properties to fresh and hardened concrete. For example, fly ash tends to improve the workability of fresh concrete; it improves long term compressive strength of hardened concrete. The term pozzolanic reactivity is typically associated with mineral admixtures. The operating chemistry is the reaction of reactive silica component of the mineral admixture with calcium hydroxide in the hydrated cement to form calcium silicate hydrate.

Volcanic ash – Mt. St. Helen

Fly ash