search
arrow-left Previous
Next arrow-right
Q: Addition of pozzolana to ordinary Portland cement causes
  • A. decrease in early strength
  • B. reduction in chemical action with sulphates
  • C. increase in shrinkage
  • D. All option are correct
Correct Answer: Option D - Pozzolana are silicate–based materials that react with the calcium, hydroxide generated by hydrating cement to form additional cementitious materials. Calcium hydroxide (lime) accounts for upto 25% of the hydrated Portland cement, and lime does not contribute to the concretes strength. Pozzolona combine with the lime to produce additional calcium, silicate hydrate, the material responsible for holding concrete together, by consuming the excess lime. Thus overall strength is increased but gain of strength is slow and early strength is decreased. Pozzolana increases the resistance against the chemicals also.
D. Pozzolana are silicate–based materials that react with the calcium, hydroxide generated by hydrating cement to form additional cementitious materials. Calcium hydroxide (lime) accounts for upto 25% of the hydrated Portland cement, and lime does not contribute to the concretes strength. Pozzolona combine with the lime to produce additional calcium, silicate hydrate, the material responsible for holding concrete together, by consuming the excess lime. Thus overall strength is increased but gain of strength is slow and early strength is decreased. Pozzolana increases the resistance against the chemicals also.

Explanations:

Pozzolana are silicate–based materials that react with the calcium, hydroxide generated by hydrating cement to form additional cementitious materials. Calcium hydroxide (lime) accounts for upto 25% of the hydrated Portland cement, and lime does not contribute to the concretes strength. Pozzolona combine with the lime to produce additional calcium, silicate hydrate, the material responsible for holding concrete together, by consuming the excess lime. Thus overall strength is increased but gain of strength is slow and early strength is decreased. Pozzolana increases the resistance against the chemicals also.