The pebbles of Knowledge must be Bonded together by the Cement of Experience
– R. G. LeTourneau; Inventor of earthmoving machinery
Why did he use the word cement though? The answer is simple, cement is the primary material used as a binder in buildings and other mega projects. Cement binds things strongly and it is the reason why the word “cement” has become synonyms with “bind”.
But is cement really the best binding material? For buildings – Yes but then again it depends on what type of cement you are using and for what type of building. There are various types of cement but the most common ones are OPC and PPC cement.
They are the most common types of cement after all. You can find their use from constructions like Roads and Dams to marine structures and plastering. A lot of you may be wondering what difference is there between OPC and PPC cement. Don’t worry you are not the only one as many people are unaware of this. We are here to clarify this for you. Now let’s move on to see the difference between OPC and PPC cement – the Two most common types of Cement Found in Nepal!
Difference between OPC and PPC cement
Before we move on to know the difference between OPC and PPC cement, we first have to know what they mean. OPC and PPC cement are both Portland cement and these are the most common types of cement used around the world.
While they seem similar -which they are in more ways than one, there are some differences as well. The following are the 10 major differences between OPC and PPC cement.
1. Full Forms of OPC and PPC
You should have already guessed by now that OPC and PPC are not the real names of these types of cement rather they are the abbreviation. Their full forms are:
Full form of OPC – OPC stands for Ordinary Portland Cement
Full form of PPC – PPC stands for Portland Pozzolana Cement
2. Raw materials
Raw materials are basic materials that get processed into a product. The raw materials used for OPC and PPC cement are not the same, despite how similar the finished product looks.
- Raw materials used for OPC – Limestone, raw argillaceous, calcareous materials, gypsum
- Raw materials used for PPC – 30% Pozzolana to Ordinary Portland Cement Clinkers
Pozzolana is formed from volcanic materials. It is made from silica that has somewhere around 80% clay in it.
Durability means the ability to withstand damage. As you may have guessed, both OPC and PPC cement have different durabilities.
- The durability of OPC – It is less durable when compared to PPC cement. You can crumble it rather easily if it is not used as concrete.
- The durability of PPC – This is slightly more durable when compared to OPC. The motto of PPC is, after all, to enhance the durability of OPC cement.
4. Initial Strength
If you did not know, the strength of the cement changes over time. Initial strength is the strength that cement has during the first few months after it sets.
- The initial strength of OPC – This type of cement is strong during the first few months after it sets but it degrades over time.
- The initial strength of PPC – This type of cement is not as strong as the OPC cement during the first few months but over time the strength increases and gets significantly stronger than the later one.
Cement are graded based on their comprehensive strength. It is basically the amount of pressure that a millimeter cube of cement can handle/Mega-pascal of pressure after 28 days of curing.
- Different grades for OPC – OPC 44, OPC 43, OPC 53
- Different grades for PPC – There are no grades in PPC. Its strength is similar to OPC 33 grade cement. That being said, PPC cement is graded by the types of Pozollonic materials such as Fly ash, Volcanic tuff, and Rice Husk Ash.
6. Heat of Hydration
The heat of hydration refers to the amount of heat produced while the cement absorbs water. Since it is a chemical reaction, subtle heat is produced. The heat is far too little to be noticeable for us but it is still high enough for scientists to track change its effect.
- The heat of Hydration for OPC – The heat production is more during the process of rehydration so it is not useful for mass casting.
- The heat of Hydration for PPC – Since PPC has a slow hydration process it produces lower heat of hydration.
This is a thing that a lot of us don’t know about. Unless you have gone in person to buy cement or have worked on a construction project, you may not know that different cement products cost differently.
- Cost of OPC – This cost is slightly higher when compared to PPC cement
- Cost of PPC – The cost is a bit less when compared to OPC cement which makes it an economic choice.
8. Firmness and permeability
Permeability is the property that allows liquids or gasses to pass through it. The higher the permeability, the lower the firmness. As you may have guessed, there is a difference between the levels of permeability and firmness between OPC and PPC cement.
- Permeability and Firmness of OPC – OPC has a firmness of 225 meter square per kilogram
- Permeability and Firmness of OPC – PPC has a firmness of 300 meters square per kilogram
9. Workability of Concrete
Since we have talked about all of the differences so far, it should not be a shock to you that PPC and OPC have different workability with concrete. This means that both of these types of cement have a difference in how easy is it to work when mixed with the concrete.
- Workability of Concrete of OPC – You can get a good workable concrete with OPC but it is harder to make it work.
- Workability of Concrete of PPC – You can get good workable concrete easily with PPC
10. Curing Period
The curing period is the time taken to maintain satisfactory moisture content and temperature in freshly cast concrete for a definite period of time immediately following placement.
- Curing Period of OPC – The normal minimum period for curing is above 7 days and it is 10 days when the weather is extreme.
- Curing Period of PPC – The normal minimum period for curing is above 10 days and it is 14 days when the weather is extreme.
So these are common differences between OPC and PPC cement. For those who find paragraphs hard to understand don’t worry we got it simplified for you. Following is a table showing the mentioned difference between OPC and PPC cement.
|Ordinary Portland Cement
|Portland Pozzolana Cement
|Limestone, raw argillaceous, calcareous materials, gypsum
|30% Pozzolana to Ordinary Portland Cement Clinkers
|Slightly less Durable
|Slightly more Durable
|Strong during the initial phase but gets weaker later on
|Slightly weaker during the initial phase but gets stronger later on
|OPC 44, OPC 43, OPV 53
|Graded by Pozollonic Materials like Fly ash, Volcanic tuff, Rice Husk Ash, etc.
|Heat of Hydration
|Higher Heat during the phase of Hydration
|Lower Heat during the phase of Hydration
|Slightly Higher Cost
|Slightly Lower Cost
|Firmness and Permeability
|225 Meter square per Kilogram
|300 Meter square per Kilogram
|Workability of Concrete
|Hard to work but still can make good concrete
|Easy to work with Concrete
|Minimum curing Period of 7 Days during Normal Days
Minimum curing Period of 10 Days in Harsh Weather
|Minimum curing Period of 10 Days during Normal Days
Minimum curing Period of 14 Days in Harsh Weather
Before We Go,
Cement is a binding used in projects that last a long time. It is a binding agent, holding small parts together and making the construction rigid. Different types of cement are available for different projects but in Nepal, the most common ones are OPC and PPC.
While they look and feel the same, they are two completely different products. While this is being said, if you use a bad one the construction will fail. So be sure to use the ones from trusted brands like Shivam, Agni, and Sarbattoam which rank among the best brands of Nepal. If you would like to know the top 10 cement brands in Nepal, we have linked our article related to them below.
For now, we shall be taking our leave. And as always thank you for reading till the end. If you have any suggestions for us, do leave them down in the comments below.