The compressive strength of PPC as per BIS code at present is equivalent to that of 33 grade OPC. It is essential that Pozzolana be in a finely divided state as it is only then that silica can combine with calcium hydroxide (liberated by the hydrating Portland Cement) in the presence of water to form stable calcium silicates which have cement properties.

The compressive strength of PPC as per BIS code at present is equivalent to that of 33 grade OPC. It is essential that Pozzolana be in a finely divided state as it is only then that silica can combine with calcium hydroxide (liberated by the hydrating Portland Cement) in the presence of water to form stable calcium silicates which have cement properties.