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Q: Select the INCORRECT statement in the case of effects of natural pozzolanas.
  • A. the heat of hydration of pozzolana is higher than that of low heat cement.
  • B. At early ages, the replacement of cement by pozzolana usually results decrease in the compressive strength.
  • C. Addition of pozzolana in cement increases workability of concrete for the same water-cement ratio.
  • D. Shrinkage and moisture movement on addition of pozzolana in cement is similar to Portland cement.
Correct Answer: Option A - Portland Pozzolana Cement (IS 1489-part-1–Ordinary Portland + 10-30% of fly ash by mass of PPC. • It is used in marine work • The heat of hydration of pozzolana is lower than low heat cement. • At early ages, the replacement of cement by pozzolana usually results decrease in the compressive strength. • Addition of pozzolana in cement increases workability of concrete for the same W/C ratio. • Shrinkage and moisture movement on addition of pozzolana in cement is similar to portland cement.
A. Portland Pozzolana Cement (IS 1489-part-1–Ordinary Portland + 10-30% of fly ash by mass of PPC. • It is used in marine work • The heat of hydration of pozzolana is lower than low heat cement. • At early ages, the replacement of cement by pozzolana usually results decrease in the compressive strength. • Addition of pozzolana in cement increases workability of concrete for the same W/C ratio. • Shrinkage and moisture movement on addition of pozzolana in cement is similar to portland cement.

Explanations:

Portland Pozzolana Cement (IS 1489-part-1–Ordinary Portland + 10-30% of fly ash by mass of PPC. • It is used in marine work • The heat of hydration of pozzolana is lower than low heat cement. • At early ages, the replacement of cement by pozzolana usually results decrease in the compressive strength. • Addition of pozzolana in cement increases workability of concrete for the same W/C ratio. • Shrinkage and moisture movement on addition of pozzolana in cement is similar to portland cement.