The cement is manufacture by burning and crushing. The cement is made by various ingredients like lime, silica, Alumina, iron oxide, magnesia, sulphur trioxide, soda and Potash, Gypsum (or calcium sulphate). There are some types of cement are as following.
- Rapid hardening cement
- Low heat cement
- pozzolana Portland cement
- Sulphate resisting cement
- Blast furnace slag cement
- White cement
- Oil well cement
- Hydrophobic cement
Question: Name any four types of cement and state their uses.
Some types of cements are explain bellow with their application and properties.
Rapid hardening cement
The Rapid hardening cement which set quickly but does not develop strength quickly.
This cement is high percentage of C3S (Tricalcium Silicate) and low percentage of C2S (Dicalcium Silicate) content.
Rapid hardening cement should not be used in mass concreting because this cement gives out more heat of hydration at a time.
Excessive heat affect strength and durability of structure and also expansion crack, cavity formation.
Application or use of rapid hardening cement-
- Rapid hardening cement is used to formwork needs to be remove early.
- It is useful in manufacturing pre-fabricated and precast concrete products like poles sleepers frames etc.
- Trenie method of concreting in underwater construction works.
- Also useful in repairs of roads.
- Rapid hardening cement used in cold weather concreting.
Properties of rapid hardening cement
Maximum fineness of cement should be 5% by IS sieving method and specific surface not less than 3250 sq. Cm/gram by Blaine air permeability apparatus.
10mm for un-aierated cement and 5m for aerated cement by le-chateliar apparatus.
Initial setting time should be 30 minutes minimum and final setting time should be 600 minutes maximum.
1 day compressive strength 16 MPa and 3 days compressive strength is 27 MPa.
Low heat cement
Low heat cement hardens slowly. Low heat cement consists C2S proportion is higher and C3S and C3a proportion is lower.
This cement evolution of less heat in the exothermic hydration reaction. Low heat cement will gain strength slowly.
BIS specifies the heat evolution rates for low heat cement are following-
- 7 days- not more than 65 calories per gram.
- 28 days- not more than 75 calories per gram.
Application of low heat cement
- Low heat cement is used in mass concreting such as dams, nuclear, power plant, sea walls, and breakwaters.
- It is also used for construction of chimney of factory.
- Used for construction of machine Foundation.
- It’s used for crack resistant structure and sulphate resistant structure.
Properties of low heat cement
- Fineness- 5 – 10 percent or 3200 CM square/gram.
- Soundness- Soundness not more than 10 mm
- Setting time- initial setting time 30 -60 minute, final setting time 600 minute
- Compressive strength- for,
3 days- 10 MPa
7 days- 16 MPa
28 days -35 MPa
Blast furnace slag cement
Slag from a blast furnace is actually a waste product.
- Blast furnace slag cement mainly used in Marine construction.
- It is used in Mass concreting.
- Also used for sea walls and break waters.
- All construction work when OPC is used.
- Fineness- 2250 cm2 per gram
- Soundness- 10mm
- Setting time- initial setting time should be 30 minute minimum final setting time should be 600 minute maximum
- Compressive strength- for,
3 days – 18 MPa
7 days – 22 MPa
28 days – 33 MPa
- White cement is used in decoration works like false ceiling.
- It is used in high class filing works so that the joints are not visible.
- Also its used for internal plaster work and finishing work.
- White cement is also used for waterproofing work.
- Degree of whiteness percent as per IS code 70% minimum, 88% and above maximum Hunter’s scale 91% and more.
- Fineness – 2500 cm sq/gram
- Setting time – initial setting time 30 minuts, Final setting time 600 minut
- Compressive strength for,
3 days 14.4 MPa minimum and 45 MPa maximum
7 days 19.8 MPa minimum and 55 MPa maximum
28 days 29.7 MPa minimum and 67 MPa maximum
Some important points on topic types of cement listed below.
- Mass concreting work like bridge Dam etc.
- RHC IS Code 8041-1990