Low Heat Portland Cement (LHPC) is Portland cement with lower lower content of rapidly hydrating compounds, Tri-Calcium Silicate (C3S) and Tri-Calcium Aluminate (C3A). The process of hydration is slow and the consequent rate of heat generation is also low.
It is manufactured from the ingredients of specially selected cement clinker, gypsum and ground granulated blast furnace slag, which result in significantly lower heat generation during the process of hydration than in a typical Portland cement.
Properties of Low Heat Cement
- As per the Indian Standard Specification the heat of hydration of low-heat Portland cement shall be as follows:
7 days — not more than 65 calories per gm.
28 days — not more than 75 calories per gm.
- The specific surface of low heat cement as found out by air-permeability method is not less than 3200 sq. cm/gm.
- The 7 days strength of low heat cement is not less than 16 MPa in contrast to 22 MPa in the case of ordinary Portland cement.
- A minimum curing period of 7 days or longer, depending on the exposure classification
- Setting time:
Initial setting time —> Min. 40min
Final setting time —> Max. 12 hrs
- Soundness is same as that of ordinary Portland cement.
Uses of Low Heat Cement
- It is used in hot weather regions.
- For mass concreting works such as gravity dam and thick retaining wall where
reduced heat liberation is important.
- Due to its superior resistance to both sulphate and chloride salt attack, LH cement may also be used in aggressive sulphate-rich environments or where increased resistance to salt attack is required.
- Since it good sulphate resistant, It can be used in marine constructions/Coastal areas.
Disadvantages of Low Heat Cement
- Initial strength gained by using LHPC is lower than that of OPC concrete, but the final strength is same as that of OPC.
- This cement cannot be used in the cold weather conditions.
- It is not very suitable for Ordinary structures because the use of cement will delayed time of drying.
- It will also need more curing.
- Cost of the cement is higher than that of Ordinary cement.
Because of slower rate of strength gain, adequate precautions should be taken in their use such as with regard to removal of formwork, etc.