Types and Properties of Cement and their Uses

There are 16 different types of Cement. They are as follows:

1. Ordinary Portland Cement (OPC): The ingredients are mixed in the proportion of about two parts of calcareous materials to one part of argillaceous materials and then crushes and ground in ball mills. This mixture is burnt at about 1500-degree Celsius and cooled where gypsum is added to it and grounded again to the requisite fineness.

Properties of OPC Cement:

1. Fineness – 225 sq. metre/kg
2. Soundness – 2.5mm
3. Normal Consistency – 25%
4. Initial Setting Time – 30 minutes
5. Final Setting Time – 600 minutes
6. Specific Gravity – 3.12 Mg/cubic. metre
7. Bulk Density – 830 to1650 330 kg/cubic. metre
8. Compressive Strength is 16 N/sq.mm & 22 N/sq.mm for 3 & 7 days respectively
9. Loss of Ignition

 

Uses: This type of cement is used for general Construction Purposes where special properties are not required such as reinforced concrete buildings, bridges, pavements and can be used at normal soil conditions. This Cement type mostly used in Concrete Masonry Units.

2. Portland Pozzolana Cement (PPC): It is manufactured by grinding Portland Cement Clinker and Pozzolana (usually fly ash or burnt clay, shale which has no cementing value). Pozzolana, when combines with lime produce stable lime-pozzolana compound, has cementitious properties.

The hardening of PPC consists in Hydration of Portland Cement Clinker compounds and then in the interaction of the pozzolana with Calcium Hydroxide released during Hardening of clinker.

Note:

• With the above effect PPC acquires greater Water Resisting Property than OPC.
• Initial Setting Time of OPC is faster than PPC. So, OPC is recommended in projects where properties are to be removed early.
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Properties of PPC Cement:

• Fineness should not be less than 300 sq. metre/kg
• Initial Setting Time – 30 minutes
• Final Setting Time – 600 minutes
• Drying Shrinkage should not be more than 0.15%
• Compressive Strength should be as follows:

                         72 + or – 1 hour not less than 16 N/sq.mm

                         168 + or – 2 hour not less than 22 N/sq.mm

                         672 + or – 4 hour not less than 33 N/sq.mm

Uses: PPC Cement has low heat evolution & used in places of mass concrete such as dams and also in places of high temperature.

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