Pozzolanic admixture

Best pozzolans in optimum proportions mixed with Portland cement improves many qualities of concrete such as

1. Lower the heat of hydration and thermal shrinkage
2. Increase the water tightness
3. Reduce the alkali-aggregate reaction
4. Improves resistance to attack by sulphate soils and sea water
5. Improve extensibility
6. Lower susceptibility to dissolution and leaching
7. Improve werkability
8. Lower costs

Pzzolanic materials are-

• Clay and shales
• opaline shales 
• Diatomaceous earth
• Volcanic tuffs and pumicites

Artificial pzzolans are-

• Fly ash
• Surkhi