What Is PCC Cement?
PCC Cement is manufactured by grinding the OPC clinker with 10 to 25 percent of the pozzolanic material. As per the recent standards of manufacturing, it is about 35%. Pozzolana materials may be natural or artificial that have silica in them in a reactive form. PPC Cement also contains OPC clinker and gypsum along with pozzolanic materials.
These pozzolanic materials include volcanic ash, calcined clay or silica fumes, and fly ash which makes around 15% to 35% of cement weight. Flyash is primarily used in PPC cement.
Portland Pozzolana Cement is becoming a popular type of cement used in building construction. PPC is made from pozzolanic material. Pozzolanic material history extended up to roman time.
PCC Full Form
The PCC Cement full form is Portland Pozzolana Cement
PCC Cement Grade
It has 33 Grade Cement
PPC Cement strength is considered to be equivalent to that of OPC 33 grade cement. Therefore, it has grade strength of is 330 kg per sq cm.
In many areas of world, the PPC is graded similarly to OPC depending upon their compressive strength, at 28 days. As per India Standard, the PPC is considered equivalent to 33 grade OPC, strength-wise, although some brand of PPC is as good as even 53 grade OPC.
Many cement brands recommended using BIS for grading PPC just like grading OPC. They also suggested using a higher amount of fly ash content from 25% to 35%. Recently, the United Kingdom has increased the fly ash content in PPC in BIS from 10-25% to 15-35%.
Manufacturing of Portland Pozzolana Cement
A Pozzolanic ingredient in PPC essential includes the siliceous or aluminous material. Which itself does not possess any cementitious properties, which will, in finely divided form and in the presence of water, react with calcium hydroxide liberated in the hydration process which is performed at normal temperature to form compounds Possessing cement properties.
In the Manufacturing of Portland Pozzolana cement, the main ingredients are calcined clay, or fly ash is a waste material, generated in the thermal power station when powdered coal is used as a fuel. This material is then collected in electrostatic precipitators. In the United Kingdom, it is known as pulverized fuel ash.
The material produced may also be called calcium silicates produce considerable quantities of calcium hydroxide, which is by and large a useless material from the point of view of strength or durability. It is just a waste material that could be converted into a cementitious product; it considerably improves the quality of concrete. The pozzolanic action is shown below:
Calcium hydroxide + Pozzolana + water —> C – S – H (gel)
When PCC is used in concrete produce lesser heat of hydration and offer greater resistance to the attack of aggressive waters than ordinary Portland cement.
Moreover, it reduces the leaching of calcium hydroxide when used in hydraulic structures. Such types of low heat-producing properties of cement are mainly useful in marine and hydraulic construction and other mass concrete constructions.
PPC can be used where OPC is utilized. However, it is fact that addition of Pozzolana does not contribute to the strength at early ages. The strength property of PPC almost similar to that ordinary Portland cement in general.
It can be said that this fear is not justified. In case, if portland pozzolana cement is manufactured by using the right type of reactive pozzolanic material, the Portland pozzolanic cement will not be in any way inferior to ordinary Portland cement except for the rate of development of strength up to 7 days.
It will affect to OPC only when inferior pozzolanic materials used, which are not of the reactive type and which do not satisfy the specifications limit for pozzolanic materials, are used the cement would be of doubtful quality.
Read More: What Is Cement And History Of Cement
PPC Cement Properties
- Initial setting time = 30 min (minimum)
- Final setting time = 600 min (maximum).
- At 3 days 13MPa (minimum)
- At 7 days 22 MPa (minimum)
- At 28 days 33 MPa (minimum)
- Drying shrinkage should not be more than 0.15%
- Fineness should not be less than 300 m2/kg
- The early strength of PPC is less but the final strength is equal to the 28 days strength of OPC
- PPC has a lower strength development rate than OPC
Investigation Result on PPC
All the Awe advantages of PPC are mainly due to the slow conversion of calcium hydroxide in hydrated cement paste into the cementitious products. In one investigation, 20 percent calcium
Hydroxide in one-year-old OPC paste was found to be only 8.4 percent calcium hydroxide in a and leaching also a certain reduction in calcium hydroxide may have taken place. After considering the effect the calcium hydroxide should have been 14%.
But, actually only 8.4% has remained in it which goes to prove that 5.6% of calcium hydroxide was converted by the pozzolanic activity.
Fig. shows the typical reduction of Ca(OH)2.
PCC Cement Advantages
Using PPC with OPC has greater advantages if proper types of reactive materials are used in manufacturing of PPC.
(a) PPC is made by replacing costly clinker with cheap waster pozzolanic material.
(b) In PPC manufacturing a soluble calcium hydroxide is converted into insoluble cementitious products which result in improvement of permeability. Hence it offers, abounds durability characteristics, particularly in hydraulic structures and marine construction.
(c) Generally, a Portland pozzolana cement consumes the calcium hydroxide and does not produce calcium hydroxide as much as that of OPC.
(d) It produce heat of hydration and that too at a low rate.
(e) PPC being finer than OPC and also due to pozzolanic action, it improves the pore size distribution and also reduces the micro cracks at the transition zone.
f) Reduction in permeability of Portland pozzolana cement offers many other & bound advantages.
(g) Fly ash used in PPC is lightweight and has less density, the bulk volume of 50 kg bag is slightly more than OPC. That’s why Portland pozzolana cement offers a larger volume of mortar than OPC.
(h) PPC strength development over a long period is comparatively more than OPC if enough moisture is available for continued pozzolanic action.
PCC Cement Disadvantages
PPC has few disadvantages as given below,
- PCC has a low rate of development of strength initially compared to OPC.
- PPC has lower the alkalinity contain which reduces the resistance to corrosion of steel reinforcement.
- But on the other hand, PPC significantly improves the permeability of concrete, increases the resistance to corrosion of reinforcement.
- The setting time is nominally longer.
PCC Cement Uses
PCC Cement can be utilized where OPC is used except where high early strength is of special requirement. As PPC use demands moisture for sustained pozzolanic activity, a little longer curing is desirable.
Use of PPC would be particularly suitable for the following situations:
- For hydraulic structures
- For mass concrete structures like a dam, bridge pier, and thick foundation
- For Marine structures
- For sewers and sewage disposal works etc
Difference Between OPC and PPC Cement
|Full Form||Ordinary Portland Cement||Portland Pozzolana Cement|
|Manufacturing||OPC Cement is a mixture of raw argillaceous, calcareous materials, limestone, and gypsum||PCC Cement is manufactured by mixing 30% of pozzolana with OPC cement clinkers.|
|Composition||OPC mixer has a large amount of Limestone powder in it.||PCC has about 80% of siliceous material in clay form.|
|Durability||The durability of OPC Cement concrete is low as compare to PCC.||Pozzolana Materials added to PPC cement increase its durability.|
|Initial Strength||Higher than PPC||Less than OPC|
|Grades||OPC cement has different grades such as OPC 33, OPC 43, OPC 53 which are available in the market.||There is no grade in PPC cement, but its strength is considered equivalent to OPC 33 grade cement.|
|Environmental Impact||OPC has a bad effect on the environment as its manufacturing produces a large amount of CO2.||PPC Cement manufacturing used waste materials of the thermal power plant such as fly ash which makes it more environmentally frinedly.|
|Heat of Hydration||Produce more heat of hydration when water added into it.||Produce less heat of hydration compared to OPC|
|Permeability and Fineness||The OPC Cement has a lower fineness which is about 225m2/kg. But higher the permeability.||PPC Cement fineness of 300m2/Kg. Therefore, It offers lower permeability with higher durability|
|Workability of Concrete||The workability of concrete made up with OPC cement is less compare to PPC||Offers higher workability than OPC|
|Curing period||As per IS 456:2000 guideline, the minimum curing required by OPC cement is 7 days.||As per IS456:2000 guideline minimum curing period for OPC cement should not be less than 10 days.|
|Resistance to chemical attacks||The resistance chlorides, sulfates chemical attack is less compare to PPC||PPC has a higher resistance to resistance chlorides, sulfates chemical attack|
|Setting time||The initial setting time of OPC is 30mins|
The final setting time of OPC is 600mins
|The initial setting time of PPC is 30mins.|
The final setting time of PPC is 600mins
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