PORTLAND POZZOLANA CEMENT- MANUFACTUREING, PROPERTIES, ADVANTAGES, DISADVANTAGES AND USES.

Portland Pozzolana Cement

Portland Pozzolana Cement is a varition of OPC cement. Pozzolana is a volcanic powder found in Italy near Vesuvius.A pozzolanic materials can be natural or artifical which contains silica and aluminous in a reactive form.

      1.Natural Pozzolana:

• Brunt clay
• Pumicite
• Diatomaceous earth

      2.Artifical Pozzolana:

• Fly ash
• Silica fumes
• Rice husk
• Blast furnace slag

Portland Pozzolana Cement is a king of blended cement which is produced by either intergrinding of OPC clinker along with gypsum and pozzolanic materials in certain proportion or grinding the OPC clinker, gypsum and pozzolanic materials separately and thoroughly blending them in certain proportions.

It may be further discussed as siliceous or siliceous and aluminous materials which in itself possesses little,or no cementitious properties but will in finely divided form and in the presence of moisture,chemically react with calcium hydroxide at ordinary temperature to form compounds possessing cement properties.It is essential that Pozzolana be finely divided state as it is only then that silica can combine with calcium hydroxide in the presence of water to form stable calcium silicates which have cement properties.

Manufacture Process of Portland Pozzolana Cement:

The primary raw materials used for manufacture are limestone (CaCO2) & clay (SiO2,AI2,O3,Fe2O3) where it is crushed into fine particles,then fed into air swept ball mill in desired proportions and mixed it before sent to silios for storing.The mixture is then pre heated upto 800-1000C where calcinations of CACO3 to CaO takes place after that pre heated mixture is sent into kiln where the mixture is heated at 1450C in rotary kiln.The modules formed from the burning process called clinker.

The clinker is cooled by a rotary cooler.This clinker is now mixed with gypsum and pozzolana materials in the required proportion and thus the Pozzolana cement is obtained.

Properties of Portland Pozzolana Cement:

• Initial setting time   = 30  min (Minimum)
• Final setting time    = 600 min (Maximum) 

Compressive Strength:

          3  Days = 13 MPa  (Minimum)

          7  Days = 22 MPa  (Minimum)

         28 Days = 33 MPa  (Minimum)

• Drying shrinkage should not be more than 0.15%
• Fineness should not be less than 300 m2/kg
• Initial strength of PPC is less than OPC but final strength is equal to OPC
• PPC has lower rate of development strength than OPC

Uses of Portland Pozzolana Cement:

• Used in marine structure
• Used in hydraulic stracture 
• Construction near sea shore,dam construction etc.
• Used in pre-stressed and post-tensioned concrete member.
• Used in masonry works
• Used in plastering work.
• Used in manufacture of precast sewage pipes.
• Used in manufacture of precast sewage pipe.

Advantages of Portland Pozzolana Cement:

• Pozzolana cement have good resistance against sulphate attack.
• It is very fine cement hence good for plastering works.
• Pozzolana consists of silica material hence it reduce cost of cement making it economical to use.
• It is eco-friendly cement manufacture from natural recycled waste.
• It reduces the carbon monoxide emission from the concrete making it environmental friendly.

Disadvantage of Portland Pozzolana Cement:

• The initial strength is less,which effect the de-shuttering of supports early.
• PPC have less setting time compare to OPC.
• Reduction in alkanity reduces the resistance to corrosion of steel reinforcement.