Cement is one of the most significant construction materials that form the basis of almost every building, from small houses to high-rise buildings and business centers. In Nepal's infrastructure sector, two of the most popular types of cements are OPC (Ordinary Portland Cement) and PPC (Portland Pozzolana Cement).
Understanding the distinction between OPC and PPC cement can help you make the best decision when building, especially when choosing the best material for the strength, affordability, and longevity of your project.
In this blog, we will discuss the difference between OPC and PPC cement based on various factors like composition, strength, use, environmental impact, and many more.
Ordinary Portland Cement (OPC) is one of the most commonly used types of cement, known for its early strength and fast-setting properties. It is manufactured by grinding the clinker along with gypsum in a standard ratio and is marketed in Nepal in three grades, i.e., OPC 33, OPC 43, and OPC 53, out of which OPC 53 finds extensive application in structural construction.
This cement is produced by controlled burning of limestone, clay, and other substances in kilns at around 1400–1500°C to get clinker, which is ground to a fine powder with gypsum.
The two most commonly used OPC brands in Nepal are Shivam Cement (OPC 43 Grade) and Udaypur Cement (OPC 43 Grade), both widely trusted for their quality and performance in residential and commercial structural projects.
Portland Pozzolana Cement (PPC) is a blended cement into which pozzolanic material like fly ash, volcanic ash, or calcined clay is added. They will react with the calcium hydroxide produced by OPC during hydration and form other cementitious materials that contribute to durability and reduce porosity of the concrete.
PPC is manufactured by mixing 15–35% pozzolanic materials with OPC clinker and gypsum. The eco-friendly mix makes it more sustainable as it reduces the carbon footprint and utilizes industrial waste like fly ash.
The two most commonly used PPC brands in Nepal are Arghakhanchi Cement (PPC) and Jagadamba Cement (PPC), both favored for general construction work because of their affordability and reliable performance.
Although both PPC and OPC cement have extensive uses in Nepal's construction industry, there are several differences concerning their composition, performance, workability, environmental suitability, and application.
Here’s a detailed difference between OPC and PPC cement:
OPC (Ordinary Portland Cement) is produced through the grinding of clinker and gypsum in the ratio of about 95:5. OPC doesn't contain any pozzolanic material and relies totally on clinker as the main reacting component. This gives OPC the high early strength but contributes to higher production carbon emissions.
PPC (Portland Pozzolana Cement) is manufactured by blending 65–85% clinker and 15–35% pozzolanic material such as fly ash, volcanic ash, or calcined clay along with gypsum. The inclusion of pozzolans enhances the durability and long-term strength of PPC and also ensures it is eco-friendly.
OPC 43 grade cement is extensively used in large-scale infrastructure projects like bridges, flyovers, commercial buildings, high-rises, and precast structures due to its early strength gain. It is particularly well-suited for structural elements such as columns, beams, slabs, and foundations where high load-bearing capacity is required.
PPC (Portland Pozzolana Cement) is commonly used in residential construction for non-structural applications such as plastering, masonry, and flooring work. Its slower setting time and smooth finish make it ideal for architectural finishes and long-duration concrete pours, especially under hot weather conditions.
OPC has a faster setting time, usually starting to set within 30 minutes and achieving the final set in about 280 minutes. This rapid setting advantage is highly sought after for time-schedule-based construction activities.
PPC has a longer setting time than OPC, with more extended placement and finishing time. This feature is particularly beneficial during hot weather or large pours of construction when extended working time is required.
OPC gains early high-intensity strength within 7 days and is used when turnaround is quick or stripping of formwork is required early.
PPC gains strength cumulatively, whereas its 28-day and long-term strengths can be equal to or even superior to those of OPC. Hence, PPC is more suitable for buildings with extended periods of duration where early strength is not the primary demand.
OPC is less resistant to sulfate attack, chloride penetration, and severe environments. It is more prone to chemical attack, especially in marine or brackish surroundings, unless it is treated with oil or other protective methods.
PPC is more resistant due to the pozzolanic reaction that decreases permeability and increases resistance to chemicals. It is well adapted to function in harsh environments and is best employed in foundations, coastal development, and sewerage systems.
OPC hardens quickly and is more water-seeking in blending, and therefore, is less workable when it is newest or in dry weather. It requires faster consumption, which isn't easy with larger applications.
PPC possesses improved workability due to finer particle size and pozzolanic characteristics. It can better retain moisture, reduce the potential for shrinkage cracks, and is simpler to spread and finish, especially in plaster and masonry applications.
OPC is slightly coarser in texture compared to PPC. This coarser nature allows it to set faster, which is beneficial for rapid construction. However, it may result in a less refined surface finish if not applied with care.
PPC is finer due to the inclusion of pozzolanic materials like fly ash or calcined clay. The increased fineness provides a larger surface area for hydration, leading to better strength development. It also improves compaction and finish, making it ideal for plastering and surface works.
OPC has a bigger environmental footprint as it contains higher clinker content and an energy-consuming manufacturing process. It is one of the primary sources of CO₂ emissions.
PPC is greener in use, utilizing industrial waste like fly ash that lowers the utilization of clinker and carbon emissions. This choice is better for green and sustainable building techniques in Nepal.
OPC releases more heat of hydration, which can lead to thermal cracking, especially in high-volume concreting and also in hot weather. It is not as suitable for large structural pours.
PPC produces less heat of hydration and minimizes thermal cracks. This makes it more suitable for Nepal's hot and hilly conditions, where low heat generation guarantees long-term structural stability.
Both PPC and OPC cement have their advantages, and the choice of which one to use depends on the nature of the construction, budget, and environmental exposure of your project.
If you are building a high-rise structure, an RCC slab, or a bridge, OPC could be a better choice since it develops its early strength. However, if the work of your project is plastering, walling, or exposure to water, PPC is a more convenient and durable option.
PPC is better in Nepal's climatic conditions and composite soils, with higher resistance to water penetration and sulfate attack. Due to the cost-effectiveness, sustainability, and all-around versatility of PPC, it is becoming the go-to option for most of Nepal's residential projects.
Yes, OPC can be used for plastering, but PPC is generally preferred because of its better workability and smoother finish.
Yes, PPC is suitable for foundations, especially in areas with sulfate-rich soil or moisture, as it offers superior chemical resistance and durability.
OPC is better for large-scale structural projects that require high early strength, such as bridges, flyovers, and high-rise buildings.
It’s technically possible to use both in the same project, but they should not be mixed in the same concrete batch; use them for different components as advised by your engineer.
PPC contains pozzolanic materials that react with calcium hydroxide to form additional binding compounds, making the structure denser and more resistant to water and chemicals.
PPC is usually the best choice for general house construction in Nepal due to its cost-effectiveness, smooth finish, better durability, and suitability for local weather conditions.
The cost of OPC 43 grade in Nepal ranges from Rs 750 to Rs to-900 per bag of 50 kg, whereas the cost of PPC cement ranges from Rs 650 to Rs 800 per bag of 50 kg.
