PPC Vs OPC Cement: What is the Difference?

Portland cement is the most common type of cement widely used around the world as a basic ingredient of concrete, mortar, stucco and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19^th century by Joseph Aspdin and usually originates from limestone.

Raw materials for the manufacture of Portland cement are found in nearly all countries. Portland cement is produced by heating limestone and clay minerals in a kiln to form clicker, grinding the clinker and adding 2 to 3% of gypsum. There are several types of Portland cement available today. The most common are:

• Ordinary Portland Cement (OPC)
• Portland Pozzolana Cement (PPC)

What Is PPC (Portland Pozzolana Cement)?

Portland Pozzolana cement is a kind of Blended Cement which is produced by either inter-grinding of OPC clicker along gypsum and pozzolanic materials in certain proportions or grinding the OPC clinker, gypsum and pozzolanic materials separately and thoroughly blending them in certain proportions.  Fly ash is a very fine material produced as a residue precipitated electro-statically or mechanically from the exhaust gases of coal-fired thermal power station.

The pozzolanic materials are usually added within a range of 15% to 35% by cement weight. Pozzolanic materials include:

• Volcanic ash
• Calcined clay
• Fly ash
• Silica fumes  

In North America for example, 15-35% fly ash is mixed and grounded together with 65-75% Portland clicker and 3-6% gypsum to make the best PPC cement.

Pozzolana is a natural or synthetic materials containing silica in reactive form. They generally react with calcium hydroxide generated by hydrating cement to form additional cementitious materials. Pozzolana needs to be in a finely divided state so that silica can be combined with calcium hydroxide (liberated by the hydrating Portland cement) in the presence of water and form calcium silicates with cement properties.  If enough moisture is available for continued pozzolanic action, the long term strength of Portland pozzolana cement beyond 90 days is higher than ordinary Portland cement.

Uses of Portland Pozzolana Cement

• Largely used in making quality building materials
• It is used in hydraulic structures, marine structures, construction near seashores, dam construction etc.
• Used for mass concreting works, masonry mortars and plastering.
• Used for the construction of sewers and sewage disposal works
• Used for construction of thick foundations and bridge piers etc.

What You Need To Know About PPC Cement

• PPC is a variation of OPC which includes a mixture of pozzolanic material which is known to increase the strength of concrete. The raw materials used for manufacturing of PPC is OPC, gypsum, pozzolanic material such as fly ash, rice husk ash, volcanic tuffs and pumicites, clay and shale etc.
• Best choice for mass concreting, plastering and masonry.
• PPC is highly resistant to sulphate attacks hence its prime use is in construction of dams, foundations, building near the sea shore, reservoirs, marine construction etc.
• There is no specific grade of PPC cement is available.
• It has higher resistance against alkalis, sulfates, chlorides etc.
• It has a slow hydration process and thus generates less heat than OPC.
• Setting time of PPC is higher than OPC. Its initial setting time is 30 minutes and the final setting time is 600 minutes.  Its slower setting time helps to get better finishing.
• PPC is less costly than OPC, which makes it a better option for your residential constructions.
• PPC is favorable in aggressive weather.
• PPC has a higher strength than OPC over a long period of time.
• PPC has finiteness of 300sqm/kg. It has higher fineness than OPC; therefore it has lower permeability resulting in higher durability.

What Is OPC (Ordinary Portland Cement)?

Ordinary Portland Cement is made primarily by grinding a mixture of stone and other raw materials like gypsum, calcareous and argillaceous materials such as limestone or chalk and from aluminum oxide, silica oxide, ferric oxide and magnesium oxide found as clay or shale.  These ingredients when heated at high temperatures form a rock-like substance that is ground into the fine powder that we commonly think of as cement. OPC is commonly used in general concrete construction when there is no exposure to sulphates in the soil or groundwater. OPC is available in three types of grades such as OPC 33 Grade, OPC 43 Grade and OPC 53 Grade.

OPC can be used for the following applications:

• General Civil Engineering construction work
• Asbestos products such as sheets and pipes
• Non-structural works such as plastering, flooring etc
• Pre-cast items such as blocks, tiles, pipes etc
• RCC works, preferably where grade of concrete is up to M-30

What You Need To Know About OPC Cement

• OPC is produced simply by grinding limestone and secondary materials to a powder. The main raw materials used for manufacturing OPC is calcareous material, argillaceous material and gypsum.
• OPC is the most commonly used cement in construction. It is suitable where fast construction is required but not suitable for mass concreting due to its high heat of hydration.
• OPC is available in three grades, 33 Grade, 43 Grade and 53 Grade.
• It has lower resistance against alkalis, sulphates, chlorides, carbonates etc.
• Generates more heat than PPC in hydration reaction which makes it less suitable for mass casting.
• Setting time of OPC is lower than PPC. Its initial setting time is 30 minutes and final setting time is 280 minutes. Its faster setting time helps faster construction.
• OPC cement is more costly than PPC.
• OPC is not favorable in aggressive weather.
• Initial strength is higher than PPC.
• OPC has finiteness of 225 sqm/kg. It has lower fineness than PPC; therefore it has higher permeability resulting in lower durability.

Difference Between PPC  And OPC Cement In Tabular Form

Advantages Of PPC (Portland Pozzolana Cement)

• PPC is eco-friendly and made of natural materials and industrial recycled waste.
• PPC has very low initial strength and they become stronger with curing time.
• PPC is economical and costs lower than other materials.
• A 50 kg bag of the Portland pozzolana cement gives more volume of mortar than ordinary Portland cement as the fly ash is finer and of lower density.
• High durability compared to OPC
• After curing PPC achieves the strength equivalent to grade 33 ordinary Portland cement.
• It does not alter the properties of cement.
• PPC is highly resistant to aggressive chemicals such as sulphate or chloride attack.
• Being a very fine cement, it is best for mass concreting, plastering and masonry

Advantages Of  OPC (Ordinary Portland Cement)

• Higher initial strength compared to PPC
• Shorter curing period and as a result low curing costs.
• OPC has shorter setting time compared to PPC.
• It has great resistance to cracking and shrinkage but less resistant to chemical attacks.