PPC or PORTLAND POZZOLANA CEMENT

Pozzolana is a volcanic powder found near Vesuvius in Italy.

A pozzolanic material is essentially a siliceous or aluminous material with no cementitious properties. But it has the property that when it combines with lime to form a stable pozzolana compound, it has definite cementitious properties.


In the presence of water pozzolana reacts with calcium hydroxide, which is liberated in the hydrogen process at normal temperature to produce cementitious process compounds.

By adding additional pozzolana such as fly ash calcium hydroxide cover in calcium silica hydrated gel

Ca(OH)2 + pozzolana + water -> csh (gel)

CSH is responsible for most of the engineering properties of the gel cement paste and it occupies half of the volume of the paste phase. it’s a microstructure

When the CSH gel dries in that area, pores will form and there will be a loss of strength. This can be reduced by maintaining proper hydration.

artificial pozzolanas: fly ash, silica fume, rice bran, blast furnace slag.

Natural Pozzolana: Burnt clay, pumicete, diatomaceous earth.

The ball bearing effect and particle packing effect can be reduced in concrete by converting pozzolana to a cement material.

Pozzolanic materials commonly used for the manufacture of Portland cement are calcinated clay (lS: 1489 part 2 1991) or fly ash (IS: 1489 part 1 of 1991).

Composition and Formulation of Pozzolana Portland Cement (PPC):

  • Pozzolana Portland cement is manufactured by grinding Portland cement clinker and pozzolana (typically 10 to 30% fly ash by mass of PPC) or by mixing and finely grinding Portland cement and fine pozzolana. According to the latest revision the ratio of pozzolana to clinker by weight can range from 15 to 35%, previously it was 10 to 15%.
  • Addition of fly ash content to the permissible limits increases long-term strength, durability and minimizes volume changes
  • Carbon dioxide emissions can be reduced by adding fly ash to cement concrete
  • Maintain low tri-calcium aluminate content in PPC which is good against sulfate attack
  • Average compressive strength of mortar cube (face area 50 cm.)2) composed of 1:3 by mass and (p/4) +3% (combined mass of cement and sand)
  1. 22 MPa in 7 days (Min)
  2. 33 MPa in 28 days (Min)

{where p is the % of water required to make a paste of standard consistency}.

  • Initial setting time = 30 minutes (minimum)
  • Last setting time = 600 minutes (max).
  • The drying shrinkage should not exceed 0.15%
  • The beauty should not be less than 300 square meters2/Kilogram
  • Initial strength of PPC is less but final strength is equal to 28 days strength of OPC
  • PPC has a lower rate of development of strength than OPC

1.1 Advantages of PPC:

  • it enhances functionality
  • It can reduce the permeability
  • reduces water evaporation
  • Honey combing will reduce
  • Improves harmony which means less separation
  • Increases the elastic modulus of concrete
  • low heat of hydration
  • Gives good surface finishing
  • recession can be mitigated
  • PPC is used in pre-stressed and post-tensioned concrete
  • Provides greater resistance to aggressive weather
  • It can reduce shrinkage, creep and bleeding
  • Global warming can be reduced by using PPC
  • Reduces leaching in concrete
  • Used in tall buildings that provide over 100 years of life
  • Used in Mass Concreting
  • Reduces PPC Sulfate Attacks
  • It is specially used in marine and hydraulic structure
  • The cost of construction should be reduced by using PPC
  • used in concrete pavement
  • Used in Pre Cast Pipes and Blocks
  • Used in harsh environments such as tunnel linings
  • In hardened concrete it can reduce carbonation.

1.2 Disadvantages of PPC:

  • Reduction in alkalinity lowers resistance to corrosion of steel reinforcement
  • The curing period for PPC is short, which may lead to the possibility of unhydrated cement concrete
  • Due to more fineness proper operation should be done
  • Initial power gain is low
  • When setting time is shorter for PPC than for OPC

Description

BIS Specification

PPC Grade

,As per IS 1489:1991, Part-I ,

chemical requirements
loss on ignition (%) 5.0 Max
Insoluble Residue (%) x,+4.0 (100-X) / 100
Sulfuric Anhydride (%) 3.0 Max
Magnesia (%) 6.0 max
Chloride Content (%) 1.0 max
physical requirements
beauty (m2/Kilogram) 300 minutes
Perseverance
Le-Chatelier (mm) 10 Max
Autoclave (%) 0.8 Max
setting time (min)
Initial 30 minutes
The last 600 Max
Compressive Strength (Mpa)
3 days (72 .)+ 1 h) 16 minutes
7 days (168 .),2 hours) 22 minutes
28 days (672 .)+4h) 33 minutes
Dry Shrinkage (%) 0.15 Max

Where x The declared percentage of fly ash in Portland Pozzolana cement is

Article written by:

Praveen Babu


Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.