Different grades of cement

Cement is a binding material and is available in different grades and types. Two main types of cement used for residential buildings are Ordinary Portland Cement and Portland Pozzolana Cement.

OPC denotes ordinary portland cement and PPC stands for Portland pozzolana cement. Portland Pozzolana Cement is fly ash based cement containing pozzolana materials as additives. Manufacturers claims PPC as a superior product compared to Ordinary Portland Cement. Nowadays getting OPC is very difficult because the market is flooded by PPC. In a recent study conducted by central road research institute, New Delhi found that PPC has no advantages over Ordinary Portland cement in strength.

Ordinary Portland cement

The name comes from Portland stone which is high quality limestone quarried from Portland in Dorset, England. William Aspdin in 1840 invented Portland cement.

While mixing water to cement several complex reaction takes place liberating large amount of heat. Initial setting time of OPC is 30-45 min and final setting time is 10-12 hours. Adding gypsum to cement will delay the setting time of cement.

Ordinary Portland cement grades

There are different grades of OPC based on 28 days strength.

OPC 33 grade cement

The compressive strength of concrete not less than 33 N/mm2. Most commonly used for Reinforced cement concrete till a few years back.

OPC 43 grade cement

Strength of concrete not less than 43 N/mm2. Recently most used for RCC. Preferred for all Government projects and pavement quality concrete. Generates more heat than OPC 33 grade cement, so curing is very important to avoid cracks.

OPC 53 grade cement

Compressive strength of concrete not less than 53 N/mm2. OPC 53 grade is not commonly used in RCC and residential structures. Used only for specialized concretes and marine applications. It is hard to get in market and need to be specially ordered.

Pozzolana Portland cement

PPC is nothing but a Portland cement blend. When additives are being added to OPC such as fly ash or volcanic ash it is generally called as Portland Pozzolan cement. Different types of Portland cement blend are

  • Portland pozzolan cement
  • Blast furnace slag Portland cement
  • Portland fly ash cement
  • Portland silica fume cement

Pozzolanic ash is volcanic ash derived from Pozzuoli, Italy. Any volcanic material additive is called as pozzolana. Portland blend cement can be desirable in special applications because it is more resistant to alkalies, chlorides ans sulfates.

Portland blend cement is more preferred in marine work because of less permeability and less prone to cracking. Unlike ordinary portland cement PPC have no grades.

OPC verses PPC

Portland pozzolana cement or Portland blend cements has no superior strength than Ordinary portland cement. More over ordinary portland cement is superior in strength than PPC because it is available in diffrent grades. For design mix we need OPC because PPC manufactures does not specify any strength. Some brands of PPC are offering more strength than desired which is undesireable for design mix. Definitely PPC offers some benefits over OPC not in strength wise.

Portland blend cements are less prone to cracking and less permeable than OPC.


Subscribe to OpenW3.com

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.