POZZOLANAS
Pozzolana is defined as a siliceous material that does not possess cementation property, but reacts
with lime in the presence of water at normal temperature to form compounds.
Pozzolana is added to fat lime to produce hydraulic lime. Addition of pozzolana to cement makes
product cheap, which is known as PPC. It gets strength slowly but final strength is same as that of
OPC. It possesses better impermeability compared to OPC. Addition to concrete helps in getting
dense concrete and it reacts with free lime. Hence, chances of blisters appearing latter is
eliminated. Heat of hydration is reduced, which is essential in mass concrete works.
Surkhi, blast furnace slag, fly ash, silica fame and rice husk ash are the pozzolanic materials.
