PPC type cement is a type of Portland cement that differs from OPC by including 15–35% of pozzolana particles, such as fly ash and volcanic ash. Portland pozzolana cement is PPC cement full form. Indeed, it is much less dense and finer than the OPC.
Pozzolana particles are used in the manufacturing of cement, which requires less OPC but has greater durability and strength. However, PPC-grade cement initially has a smaller compressive strength and a longer settling time. It is typically employed in constructing hydraulic structures, masonry mortars, and marine systems. These are frequently found in large-scale concrete construction projects, such as dams, dikes, and sewer tanks.
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See also: Non-trade cement: Meaning, applications, benefits and drawbacks
PPC cement: Types
Pozzolanic materials can be divided into two categories:
Natural pozzolanic materials
Raw or calcined natural materials exhibiting pozzolanic properties are called natural pozzolan. Natural pozzolans include diatomaceous earth, opaline cherts, tuffs, shales, and volcanic ash or pumice.
Natural pozzolans need to be more calcined and grounded. These days, these are also getting less attention because more successful artificial pozzolanic materials are readily available.
Synthetic pozzolans
- Silica Fume is a synthetic pozzolanic substance. It is also produced when high-quality quartz is reduced with coal in an electric arc furnace to make silicon or ferrosilicon alloys. In the method, silica smoke rises as oxidised gas. It melts, condenses, and collects in bags made of fabric. The silica smoke thus obtained has undergone additional processing to remove impurities and keep track of the particle size.
- Fly ash is a finely divided byproduct of burning powdered coal. It is, respectively, waste from coal-fired power plants and railroad locomotives. It is the most widely used synthetic pozzolana component. Fly ash crystals are circular shaped and have a cement-like fineness. Additionally, silica is still readily available for a reaction. Fly ash has a pleasant pozzolanic activity but must maintain constant refinement and carbon content. In addition to enhancing the technological benefits of concrete’s properties, using fly ash as a blend also prevents environmental emissions.
- Blast furnace slag: It has been discovered that substituting ground, granulated blast furnace slag for cement causes the new concrete’s water content to decrease and acquire a similar droop. The increase in slag substance and fineness will cause a greater decrease in water content. It is due to the different shapes and states of the cement and slag particles. Additionally, the water incorporated for blending isn’t lost immediately, thanks to slag’s slightly lower surface hydration than cement.
PPC cement: Making of Portland pozzolana cement
The four steps of the production process: crushing of raw components, grinding of raw resources, calcination of clinkers, and pounding of cement—are similar to those of regular Portland cement.
- Crushing of raw materials: Clay and limestone are the two main components of Portland cement. Trucks dump these raw materials stones after digging; then, they are taken to crushers to make smaller particles. After that, they are stacked up in a yard before homogenisation while awaiting recycling.
- Raw material grinding: To further reduce the particle size, the fine-particle raw materials are fed into the raw mill in the required amount. After being deposited in silos, the material is thoroughly mixed and homogenised.
- Calcination: Clinker is calcined by subjecting it to a high-temperature process in a cement rotary oven. Clinker is a group of spherical, grey particles resulting from numerous chemical reactions. These hot clinkers can be cooled to a standard temperature in the cement cooler.
- Cement grinding: After being frozen, the clinker is properly mixed with pozzolanic components and gypsum before being transported to the cement mill for grinding. Typically, cement is manufactured in cement silos, where it is also packaged and processed.
PPC cement: Properties
- PPC cement needs to cure for a longer time, and the temperature at which it cures does affect how strong it becomes. The toughening process is slow whenever the temperature is low. Despite steam curing or humid heat treatment, the hardening is intensified, making the cement less than ideal for winter construction.
- The PPC cement has a lower initial strength but higher final strength. That’s also because the calcium hydroxide produced a sizable amount of hydrated calcium silicate and effective silica in the pozzolanic substance’s ability to react with each other.
- Since the mixture’s content is porous and its particles are fine, PPC cement has a high water demand. The amount and form of the mix affect how much water is needed for a normal consistency.
- The initial setting time for Portland pozzolana cement is at least 30 minutes, and the actual set time is no more than 10 hours.
- Due to the wide range and quantity of mixed materials, PPC cement has low hydration and hydration levels.
- In environments with carbonic acid and acidic water, PPC cement has a greater sulphate threshold.
PPC cement: Advantages
- It is an environmentally friendly cement because the raw materials used in its production are made from recyclable, renewable waste.
- Since it is a very fine cement, it is excellent for plastering.
- Pozzolano is inexpensive because it contains silica, which also lowers the price of cement, making it more cost-effective.
- Pozzolana cement is used to build dams, coastal structures, buildings along the seashore, and other structures because of its high resistance to sulphate attacks.
- PPC is applied to concrete that has been pre and post-stressed.
FAQs
OPC or PPC, which is preferable?
Due to PPC's slower rate of heat and hydration, PPC has an advantage over OPC. Therefore, PPC is more resistant to cracks and shrinkage and has good workability.
What is the purpose of PPC cement?
PPC is a specially blended cement that can be used for general construction projects and is particularly well suited for use in harsh environmental conditions. It can be used to build hydraulic structures, marine structures, large-scale concrete structures like dams, dykes, retaining wall foundations, and sewage pipes.
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