What Is PPC Cement?
Portland Pozzolana cement is an incorporated cement produced in that certain ratio by the synthesis and characterization of OPC cement from pozzolana materials. It’s also generally referred to as PPC cement.
PPC type cement is a form of Portland cement distinguished by the existence of pozzolana particles such as fly powder, volcanic ash, that is applied to OPC by 15percent to 35%. Cement is accessible in every grade. It is indeed finer and far less dense than the OPC.
The inclusion of pozzolana particles contributes to the production of cement, which uses less OPC but has greater longevity and strength. PPC grade cement does have a greater settling period as well as a lower compressive strength initially. Even so, the very same outcomes as OPC are considered to be obtained in the long term.
It is usually used for the building of marine systems, masonry mortars including hydraulic structures. These are widely found in mass concrete works such as dikes, sewer tanks, dams, respectively. In certain instances, PPC cement grade must be used in replacement of OPC.
Types of Pozzolana Materials:
Pozzolanic materials are siliceous as well as aluminous materials, having very little if any cementitious quality of their own, but also in finely separated form and even in the presence of water, respond chemically with calcium hydroxide produced at normal temperature by hydration process to form compounds possessing cementitious properties.
Siliceous or aluminum compounds in a finely separated shape react with calcium hydroxide in order to form extremely stable, cemented substances of a diverse structure containing calcium, silica, and water.
Usually, amorphous silicate reacts even quicker than that of the crystalline form. Calcium hydroxide, a water-soluble substance, is transformed through an insoluble cement either by process of pozzolanic materials.
Originally, the pozzolanic reaction occurs and therefore the processing of hydration heat as well as the formation of power is also slow. The reaction requires the absorption of Ca(OH)2 and therefore there is no output of Ca(OH)2. The reduction in Ca(OH)2 improves the toughness of cement paste by making cement paste thick and impervious.
Pozzolanic materials might be of two groups:
- Natural Pozzolanic Materials.
Natural pozzolan is a raw or calcined natural material that shows pozzolanic properties. Volcanic ash or pumicite, tuffs, shales, and opaline cherts and diatomaceous earth are examples of natural pozzolans.
- Calcined diatomaceous earth.
- Volcanic ash, Tuffs, and Pumicites.
- Opaline cherts.
- Clay and shales.
Natural pozzolans should be more grounded and calcined to enable them. Theses days, these also losing attention owing to the accessibility of more successful artificial pozzolans.
Silica Fume: That is an artificial pozzolanic product. It’s also created by the reduction of high-quality quartz using coal inside an electric arc furnace in the manufacturing of silicon or ferrosilicon alloys. Silica smoke rises as oxidized gas in the method. It melts, compresses, and gathers in fabric bags. The silica smoke so obtained has been further treated to extract impurities and also to monitor the size of the particles.
Fly ash: This is a finely separated residue from its burning of powdered coal. This is a waste material of coal-fired power plants and railway locomotives, respectively. It was the most popular artificial pozzolana material. Fly ash crystals are spherical being of the same fineness as cement. Silica is also still easily accessible for a reaction.
Pozzolanic activity of fly ash is pleasant, although it is important that this has a steady carbon content as well as a constant fineness. Its use of fly ash in concrete as a blend not just to adds technological benefit to the properties of concrete, but also leads to the prevention of environmental emissions.
Blast furnace slag: The replacement of cement with ground granulated blast furnace slag has been found to diminish the measure of water in the new concrete to acquire a similar droop. The decrease in water substance will be more with the increment of slag substance and fineness of the slag. This is because of the various designs and state of slag and cement particles. Further the water added for blending isn’t promptly lost because of the slight lower surface hydration of slag than cement.
Manufacture of Portland Pozzolana Cement:
The production process is roughly the same as ordinary Portland cement, which can be separated into four processes: crushing of raw materials, grinding of raw materials, calcination of clinkers, and grinding of cement.
- Crushing of Raw Material: Limestone and clay are the primary ingredients used in the manufacture of Portland cement. After digging, these raw material stones are dumped by trucks and sent to crushers to reduce the particle size. They are then piled up in a pre-homogenization yard waiting to be recycled.
- Raw Material Grinding: The fine particle size raw materials are fed to the raw mill in the desired proportion for further reduction of the particle size, then deposited in silos, and the process of mixing and homogenization of the material is completed.
- Calcination of Clinker: Cement raw food is sent to a cement rotary oven to be calcined at a high temperature. After many chemical reactions, some spherical grey particles, which we call clinker, are produced. These hot clinkers can be cooled to a regular temperature in the cement cooler.
- Cement Grinding: Upon freezing, the clinker is combined in an adequate amount with pozzolanic materials as well as gypsum before being sent to the cement mill for actual grinding. Cement material is normally processed in cement silos and packaged as well as processed in the factory.
Properties of Portland Pozzolana Cement:
- PPC cement has to be cured for a lot longer, as well as the curing temperature does have a major impact on the development of its strength. Whenever the temperature is low, the hardening process is sluggish. Although steam curing or humid heat treatment is being used, the hardening is intensified so that the cement isn’t really ideal for winter building.
- The initial strength of the PPC cement is smaller, however the final strength is high. That’s also owing to the effective silica in the pozzolanic substance reacting with the calcium hydroxide in order to create a significant volume of hydrated calcium silicate.
- The water demand for PPC cement is strong since the mixture content is porous and the fine particles are fine. The water demand of normal consistency differs with the form and quantity of the mixture.
- Portland pozzolana cement has a reasonably long fixed period, the initial set time takes at least half an hour, and the actual set time requires at most 10 hours.
- The drying contraction of Portland pozzolana cement does not reach 0.15 percent.
- The fineness of pozzolana cement must not be much less than 300 m2/kg.
- PPC cement has a strong compressive strength and can cross 13 MPa in 3 days, 22 MPa in 7 days and 33 MPa in 28 days.
- The hydration and hydration levels of PPC cement are low, which is due to the variety and quantity of mixed materials.
- PPC cement has a high tolerance to sulfate in acidic water and carbonic acid environments.
Uses of Portland Pozzolana Cement:
- Portland pozzolana cement is ideal for underground, water, or wet concrete works, in particular for projects that require impermeability, resistance to freshwater, and sulfate corrosion, including such hydraulic systems, marine structures, dam building, offshore construction, waste disposal, respectively.
- Owing to its weak resistance to frost, Portland pozzolana cement isn’t really ideal for low-temperature buildings and for the climate prone to freezing periods and alternating drying and wetting.
- Such as ordinary Portland cement, PPC cement too is suitable for general engineering including mass-concrete engineering. Owing to its wide dry shrinkage, it is not ideal for dry areas.
- CCP cement has low early strength, and therefore it is best suited for general engineering that would not need high early strength.
- PPC cement is essential as a strong surface finishes for decoration including artistic structures.
Advantages of Portland Pozzolana Cement:
- It is an eco-friendly cement because the ingredients used in the manufacturing are manufactured from renewable recycled waste.
- It is very fine cement, therefore very good when used for plastering.
- Pozzolano comprises of silica material that makes it inexpensive and thus reduces the cost of cement making it economical to use.
- Pozzolana cement has a very high resistance to sulfate attacks and is thus used during hydraulic structures, coastal structures, building along the seashore, dam construction, etc.
- PPC used during pre-stressed and post-stressed concrete members.
- It eliminates carbon monoxide emissions from concrete, allowing it environmentally safe.
- Since the pozzolano materials are quite fine, the holes between the reinforcement and the aggregate can be filled, decreasing the shrinkage, minimizing the formation of honeycombs, and reducing leakage, which in turn increases the strength and toughness of the concrete.
Disadvantages of Portland Pozzolana Cement:
- The initial power acquired is smaller, which has an early effect on the deshuttering of supports.
- Since it includes more fine content, it is impossible to hand over concrete.
- As compared to the OPC setting time, the PPC setting time is lower.
- Reduction of alkalinity decreases susceptibility to corrosion of steel reinforcement.
- If the strength of this concrete steadily increases, the healing process is very important. Any flaw in this may cause issues with longevity.