Which of the following statements is incorrect for compressive strength of cement mortars?
- AOrdinary Portland Cement: Required Strength at 72 hours is not less than 16 MPa
- BPortland Slag Cement: Required Strength at 72 hours is not less than 16 MPa
- CPortland Pozzolana cement (Fly ash based): Required Strength at 72 hours is not less than 16 MPa
- DRapid hardening Portland cement: Required Strength at 72 hours is not less than 16 MPaCorrect
Solution
Concept
Compressive strength of cements
Step-by-step solution
1. OPC, PSC and PPC: minimum 16 MPa at 72 h. 2. Rapid hardening Portland cement needs a higher strength, 27 MPa at 72 h.
Explanation
Rapid hardening cement gains strength faster, so its requirement is higher than 16 MPa.
Why the other options are wrong
A, B and C are correct statements.
Shortcut
RHPC: 27 MPa at 3 days.
Correct answer: D) Rapid hardening Portland cement: Required Strength at 72 hours is not less than 16 MPa