## OPC vs PPC: How to Make the Right Choice

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Cement is a binding material which plays an important role in making concrete and mortar.

OPC and PPC cement are most widely used. Now a days PPC is used as a replacement to OPC. So, the most confusing thing is how to make the correct choice. There is no need to blindly follow the trend. Knowing their properties, recommended uses, cost benefits, etc. will give you a better idea about which cement should be used and where it should be used.

Courtesy - 123rf

### (Pozzolanic Portland Cement)

#### 01. General

OPC: Ordinary Portland Cement

01. It is the most common cement used in the world mostly because of the abundance and low cost to produce it.

02. OPC is produced simply by grinding limestone and secondary materials to a powder.

03. However manufacturers now a day don’t even manufacture OPC and have switched to PPC.

PPC: Pozzolanic Portland Cement

01. Portland Pozzolana Cement (PPC) is a variation of OPC which includes a mixture of a pozzolanic material which is known to increase the strength of concrete and reduce the amount of OPC used.

02. Now a day It is being used as a replacement to OPC as it is known to fulfill green building criteria and hence helps in sustainable development.

#### 02. Identification On Site

The IS mark on this cement bag is BLACK in color. The IS mark on this cement bag is RED in color.

#### 03. Raw Material

01. Calcareous (material containing lime).

02. Argillaceous (material containing silica and alumina).

03. Gypsum.

All these materials are mixed in a fixed proportion, are heated in kilns and to form clinkers which are than grinded to required fineness to obtain this cement.

01. OPC cement.

02. Gypsum.

03. Pozzolanic material.

All these materials are both mixed and grinded together or separately grinded and then mixed to obtain the cement.

01. Its setting time is less than PPC so it is recommended in projects where props are to be removed early.

02. It is easy to handle as compared to PPC.

03. Its initial strength is higher than PPC.

04. Its curing period is less than PPC. Hence curing cost reduces, hence recommended where curing cost are prohibitive.

01. It is the best choice for mass concreting, plaster and masonry.

02. It can be used at any and every place.

03. It has high durability, means the structure will last longer.

04. It is resistant to attack against various chemicals.

05. It has higher fineness, hence has lower permeability and as a result it has high durability.

06. It is a green material, hence ecofriendly and helpful in achieving green rating.

07. It produces more cohesive concrete which can be easily pumped.

08. It is less costly as compared to OPC.

01. It cannot be used for mass concreting as it has high heat of hydration as compared to PPC.

02. Higher grade like grade 53 is not recommended to be used for plastering as it is known to develop shrinkage cracks due to its high strength.

03. Very few manufacturers are known to produce 33 grade of cement.

04. It is less durable when compared to PPC.

05. Its resistance to aggressive chemicals is lower than PPC.

06. It is known to emit CO2 which is harmful to the environment.

07. It produces comparatively less cohesive concrete than PPC; hence concrete pumping becomes a little difficult.

08. It is costlier than PPC.

01. Its setting time is more than OPC.

02. It is difficult to handle due to its high fineness.

03. Its Initial strength is lower than OPC. Hence props cannot be removed early.

04. Its curing period is a little higher than OPC.

#### 06. Uses and Recommendations

01. Use of OPC is highly recommended where fast pace of construction is required.

02. It cannot be used for mass concreting as it has high heat of hydration.

03. Higher grade like grade 53 is not recommended to be used for plastering as it is known to develop shrinkage cracks due to its high strength.

04. It’s also not required to use it in masonry as mortar strength in initial period is not that critical.

It can be used in all type of construction work Example:

01. RCC (Reinforced Cement Concrete) work in residential and commercial work.

02. Plaster and masonry, where high strength is not so important.

03. Marine Works

04. In mass concrete work e.g. Dams, huge foundation.

05. Commercial and industrial complexes.

06. Road, Runway Bridge and flyover,etc.

07. Also recommended for all non-structural concreting like wall mortar.

*Adding various admixtures in concrete mix may help in achieving quick setting time. Limitation of higher setting time can be overcome by using proper admixtures.

The different grades of OPC cement available in India are:

*Note that the ultimate strength depends on the Mix Design and not on the cement strength alone.

No specific grades of this cement are available like OPC.

It is classified into different types depending on the type of Pozzolanic material used; The different pozzolanic materials used are:

• Fly ash
• Rice Husk ash
• Volcanic tuffs and Pumicites
• Clay & Shale

*Fly ash is the most commonly used Pozzolanic material.

#### 08. Properties

(The properties which the cement  imparts to the concrete)

##### a) Strength
Its initial strength is Higher than PPC. The long term strength of PPC is higher than that of OPC.
##### b) Durability
The durability of concrete made using OPC cement is less than that of the concrete made using PPC cement. It imparts higher durability to the concrete because it has low water permeability.
##### c) Workability
The concrete made using OPC cement has a lower workability as compared to the concrete made using PPC cement.

*Adding various admixtures in concrete mix may help in achieving the required Workability.

Concrete made using PPC cement has a higher workability.

*The Pozzolana present in the cement increases the fineness and decreases the water content in the cement. Hence it saves the cost of admixtures.

##### d) Heat of Hydration
The hydration process of this cement is faster and hence its heat of hydration is more as compared to PPC; Making it unsuitable for mass concreting. The heat of hydration of PPC is lower than thatof OPC resulting lower heat of hydration; making it ideal for mass concreting
##### e) Setting Time
01. Its initial setting time is: 30 mins.

02. Its final setting time is:   280 mins.

03. Its setting time is known to be lower than PPC. Hence, where faster work rate or faster removal of framework is required, this cement is preferred.

01. Its initial setting time is: 30 mins.

02. Its final setting time is:  600 mins.

03. PPC cement prolongs the setting time of concrete, hence helps in better finishing of concrete.

*Adding various admixtures in concrete mix may help in achieving quick setting time.

##### f) Fineness
01. Its fineness is at least 225 m²/kg.

02. It has lower fineness, hence has higher permeability and as a result it has lower durability.

01. Its fineness is at least 300 m²/Kg.

02. It has higher fineness, hence has lower permeability and as a result it has high durability and better workability.

##### g) Resistance to attack against chemicals
Resistance to attack against sulphates, alkalies, chlorides, and chemicals is lower compared to PPC

*However Special Cements are available which are resistant to various chemicals.

sulphates, alkalies, chlorides, and chemicals as compared to OPC.

*However Special Cements are available which are resistant to various chemicals.

#### 09. Curing Time

01. Requires a minimum curing period of 7 days.

02. When exposed to hot and dry weather condition the minimum curing period shall not be less than 10 days.

01. Requires a minimum curing period of 10 days.

02. When exposed to hot and dry weather condition the minimum curing period shall not be less than 14 days.

#### 10. Environmental impact

There is Major emission of CO2 in its manufacturing process. It is very environment friendly as it utilises the by products from the thermal station. Where otherwise there is a disposal problem of flyash.

#### 11. Cost

The cost per bag is around Rs. 300.

*The price may vary depending on your city.

Its cost is slightly lower than that of OPC bag.

*The price may vary depending on your city.

#### 12. Manufacturers

01. Ultratech Cement

02. Shree Cement

03. ACC

04. Ramco Cements

05. Prism Cement

06. Dalmia Cement

07. JK Laxmi Cement

08. Orient Cement

09. Birla Corp

01. Ambuja Cement

02. Ultratech Cement

03. Jaypee Cement

04. ACC

05. Prism Cement

06. Dalmia Cement

07. JK Laxmi Cement

08. Orient Cement

09. Birla Corp

#### 13. Manufacturing Process

OPC is produced simply by grinding to a powder limestone and secondary materials. to know about its manufacturing process.

##### Also Read: Manufacturing Process of OPC
It is manufactured by blending a mixture of Ordinary Portland cement and Pozzolana materials such as Flyash, slag Silica fumes etc.in proportions not less than 15 % and not more than 35 % by weight of cement. Hence it is called blended cement.

#### 14. Identification

The ISI mark on this cement bag is BLACK in color The ISI mark on this cement bag is RED in color

In the end it’s all about how long will the structure last?The ultimate strength being the same, If you can afford to keep the props for few more days, PPC is highly recommended. PPC cement is also used in all the government buildings these days, as it helps them in achieving green building ratings.

After going through the above information the user needs to make a judicial and rational choice.

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