In India, cement quality is determined by a set of parameters specified by the Bureau of Indian Standards (BIS) for cement companies. Consumers should ensure that they purchase cement that meets the relevant BIS standards for their construction needs. These parameters include:
- Fineness:The fineness of cement is determined by measuring the specific surface area of the cement. BIS specifies that the specific surface area of cement should not be less than 2250 cm²/gm for OPC and 3000 cm²/gm for PPC.
- Compressive Strength: The compressive strength is a measure of its ability to resist compressive loads. BIS specifies that the minimum compressive strength of 53-grade OPC should be 53 MPa after 28 days of curing.
- Setting Time: The setting time of cement is the time taken by cement to harden and attain strength. BIS specifies that the initial setting time of OPC should not be less than 30 minutes and the final setting time should not be more than 600 minutes.
- Soundness:This refers to the ability of cement to retain its volume after setting. BIS specifies that the maximum expansion of cement after 24 hours of immersion in water should not be more than 10 mm.
- Chemical composition: The chemical composition determines cements properties and behaviour. BIS specifies the maximum limits for various chemical components of cement such as silica, alumina, iron oxide, and magnesia.
- Heat of Hydration:This refers to the heat released during the chemical reaction between cement and water. BIS specifies the maximum limit for the heat of hydration of cement to prevent excessive heat generation.