OPC vs PPC: How to Make the Right Choice

• OPC: Ordinary Portland Cement
• It is the most commonly used cement in the world mostly because it is available in abundance and the cost associated with it is comparatively low cost.
• OPC cement is produced simply by grinding limestone and secondary materials into a powder.
• However, manufacturers now a days don’t even manufacture OPC. They have switched on to PPC cement as an alternative.

• PPC: Portland Pozzolana Cement
• 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.
• Nowadays, it is being used as a replacement to OPC as it is known to fulfill green building criteria and hence helps in sustainable development.

In the manufacturing of ordinary Portland cement, the followings raw materials are used,

• Calcareous material containing lime and alumina such as limestone or chalk.
• Argillaceous material containing silica and alumina such as shale or clay.
• Gypsum: If you want to know in detail then read, Raw Materials Used For Manufacturing of Cement.

In the manufacturing of Portland Pozzolana Cement, the followings raw materials are used,

• OPC cement or OPC clinker.
• Pozzolanic material such as fly ash and calcined clay.
• Gypsum

Also Read: Pozzolanic or Mineral Admixtures! Eco-Friendly and Inexpensive Cementing Material

• According to ‘A.M. Neville’ (Author of Properties of Concrete), all the raw materials are mixed in a certain proportion according to their composition and purity. After that, they are burnt in the kiln at a temperature of 1450 °C to form clinkers which are later grinded to required fineness to obtain this cement. There are two methods of manufacturing of cement:

(a) Wet Process of cement manufacturing,

(b) Dry Process of cement manufacturing.

If you want to know in detail that how cement is made then read, Manufacturing Process of Ordinary Portland Cement (OPC).

• PPC is manufactured by blending a mixture of Ordinary Portland cement clinker and Pozzolana materials (such as fly ash, calcine clay) or OPC and fine pozzolana material.
•  According to the ‘IS 1489 (Part-1): 1991’ (Portland pozzolana cement specification, part 1- fly ash based) and ‘IS 1489 (Part-2): 1991’ (Portland-pozzolana cement Specification, Part 2-calcined clay based) the proportions of pozzolana should not be less than 10 % and not more than 25 % by mass of PPC. But according to the latest revision, it is 15 to 35%.

• The IS mark on the OPC cement bag is painted in black and standard specification number is printed near to that. From that number you can identify the type of cement and its grade. For the OPC standard specification number is:

(a) IS 269: 2013 for OPC 33 grade

(b) IS 8112: 2013for OPC 43 grade

(c) IS 12269: 2013 for OPC 53 grade

• The IS mark on the PPC cement bag is painted in red and standard specification number is also given near to that. This standard specification number for PPC is:

(a) IS 1489 (Part-1): 1991 for fly ash based PPC

(b) IS 1489 (Part-2): 1991 for calcined clay based PPC

Also Read: Things to Keep in Mind Before Purchasing Cement

• OPC is admirably suitable for use in general concrete construction when there is no exposure to sulfates in the soil or groundwater.
• Ordinary Portland cement is easy to handle as compared to PPC because PPC is finer than OPC.
• Curing period of OPC is less than PPC. Therefore, curing cost reduces, hence recommended where curing cost are restricted.
• OPC is the prime material to produce many kinds of special cements like,

(a) Rapid hardening Portland cement

(b) Low heat Portland cement

(c) Portland slag cement

(d) Portland Pozzolana cement etc.

• Portland pozzolana cement is a green material, hence eco friendly and helpful in achieving green rating.
• PPC is the best choice for mass concreting because of low heat of hydration. It is also good and better suited for plaster and masonry.
• It has higher fineness; hence it has better cohesion with aggregates and makes denser concrete matrix. Therefore, it has lower permeability thus, resulting into high durability and sustainability.
• PPC improves workability of concrete consequently it can be easily pumped.
• It gives good surface finish.
• It provides resistance against the attack of various chemicals, alkalis, sulphates, chlorides etc.
• It is less costly as compared to OPC because costlier cement clinkers are replaced by cheaper pozzolana material.
• 1 bag of PPC (50 kg) gives more volume of mortar than OPC bag as the pozzolanic material is finer and it has  lower density.

• The major disadvantages of OPC is, it emits large amount of CO2. This is harmful for environment.
• Ordinary Portland cement cannot be used for mass concreting as it has high heat of hydration as compared to PPC that causes shrinkage cracks in the structure.
• Higher grade like grade 53 is also not recommended for plastering as it is known to develop shrinkage cracks due to its high strength and high heat of hydration.
• Its resistance to aggressive chemicals, alkalis, sulphates, chlorides is lower than PPC; hence it can be said that OPC is less durable than PPC.
• It produces less cohesive concrete than compared to PPC; hence concrete pumping becomes a little difficult or else admixtures needs to be used to increase its workability.
• OPC is costlier than PPC.

• PPC is difficult to handle due to its high fineness.
• Its initial strength is lower than OPC. Hence props cannot be removed early.
• Curing period of PPC is a little higher than compared to OPC.

• OPC is highly recommended where fast pace of construction is required.
• Ordinary Portland cement can be used in all general concrete construction where there is no exposure to sulfates in the soil or groundwater, and at places where you want fast removal of formwork.

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

• RCC (Reinforced Cement Concrete) work in residential and commercial work.
• Plaster and masonry, where high strength is not so important.
• Marine works
• In mass concrete work e.g. dams, huge foundation.
• Commercial and industrial complexes.
• Road, runway, bridge and flyover etc.
• Also recommended for all non-structural concreting like wall mortar
• Adding various admixtures in concrete mix can 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:

01. OPC 33 Grade

02. OPC 43 Grade

03. OPC 53 Grade

• Note that the ultimate strength depends on the concrete mix design and not on the cement strength alone.

• No specific grades of cement are  available in this type as available in OPC.
• It is classified into different types depending upon the type of Pozzolanic material used; the different pozzolanic materials used are:

01. Fly ash

02. Calcine clay

03. Rice Husk ash

04. Volcanic tuffs and Pumicites

05. Clay & Shale

• Fly ash is the most commonly Pozzolanic material used.

• Initial strength of ordinary cement is higher than PPC but the ultimate strength is same.

• Initial strength of Portland Pozzolana cement is lower than OPC but the ultimate strength is same.

As per the research result of ‘Lathiif Amhudo, Rasyiid et al.’ (2018) (Published in Civil Engineering Journal), comparison of compressive strength of concrete with OPC and PPC is given below. The below image clarifies the fact that the initial strength of OPC is higher than the PPC although ultimate strength of both is the same.

• The durability of concrete made using OPC is less than the concrete made using PPC.

• It imparts higher durability to the concrete because it has low water permeability.

• The concrete made using OPC has a lower workability as compared to the concrete made using PPC because it is coarser than PPC.
• Adding various admixtures like air entraining admixtures in concrete mix may help in achieving the required workability of concrete.

• Concrete made using PPC cement has a higher workability because it is finer than OPC.
• The Pozzolana present in the cement increases the fineness and decreases the water content in the cement. Hence it saves the cost of admixtures.

• According to ‘M.S.Shetty’ (Author of Concrete Technology Theory and Practice), the hydration process of ordinary Portland 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 that of OPC resulting lower heat of hydration; making it ideal for mass concreting.

As per IS 12269: 2013,the setting time of cement are as follows:

• Its initial setting time is: 30 mins (Min.)
• Its final setting time is: 600 mins. (Max.)

As Per IS 1489 (Part-1): 1991, the setting time of PPC cement are as follows:

• Its final setting time is: 600 mins. (Max.)
• Its initial setting time is: 30 mins (Min.)

Also Read: Test to Determine the Setting Time of Cement

• Its fineness is at least 225 m²/kg.
• It has lower fineness than PPC, hence has higher permeability and as a result it has lower durability than PPC.

• Its fineness is at least 300 m²/Kg.
• It has higher fineness than OPC, hence has lower permeability and as a result it has high durability and better workability than OPC.

• Resistance to attack against sulphates, alkalis, chlorides, and chemicals is lower compared to PPC.

• More resistance capacity against the attack of sulphates, alkalis, chlorides, and chemicals as compared to OPC.

• As per ‘IS 456: 2000’ (Plain and Reinforced Concrete – Code of Practice), minimum curing period of OPC is 7 days and when exposed to hot and dry weather condition, the minimum curing period shall not be less than 10 days.

• As per ‘IS 456: 2000’ (Plain and Reinforced Concrete – Code of Practice), minimum curing period of any blended cement (like PPC) is at least 10 days and when exposed to hot and dry weather condition the minimum curing period shall not be less than 14 days.

Also Read: Curing of Concrete: Things to Keep in Mind While Curing

• There is major adverse effect of OPC, as it emits large amount of CO2 during its manufacturing process.

• Portland pozzolana cement is environment friendly as it utilizes the byproducts such as fly ash from the thermal station. Where there is a disposal problem of byproducts like fly ash, this cement makes better utilization of fly ash. It also emits less amount of CO2 as compared to OPC.

• The cost of ordinary Portland cement per bag is higher than PPC.

• The cost of Portland Pozzolana cement is slightly lower than that of OPC bag.

• Ultratech Cement
• Shree Cement
• ACC
• Ramco Cements
• Prism Cement
• Dalmia Cement
• JK Laxmi Cement
• Orient Cement
• Birla Corp

• Ambuja Cement
• Ultratech Cement
• Jaypee Cement
• ACC
• Prism Cement
• Dalmia Cement
• JK Laxmi Cement
• Orient Cement
• Birla Corp