Fineness of cement has a great effect on the rate of hydration and hence the rate of gain of strength.
Fineness of cement increases the rate of evolution of heat.
Finer cement offers a great surface area for hydration and hence faster the development of strength.
Increase in fineness of cement also increases the drying shrinkage of concrete and hence creates cracks in structures.
Excessive fineness requirement increases cost of grinding.
Excessive fine cement requires more water for hydration, resulting reduced strength and durability.
Fineness of cement affects properties like gypsum requirement, workability of fresh concrete & long term behavior of structure.