Discussion
Characteristic strength of M20 concrete is 20 MPa. What is the number of cubes having 28 days compressive strength greater than 20 Mpa out of 100 cubes made with the concrete?
Answer: B
About 95 of the 100 cubes will exceed 20 MPa.
IS 456 defines the characteristic strength as the strength below which not more than 5 percent of test results are expected to fall. So for M20 concrete, 5 cubes in 100 may fall below 20 MPa and about 95 should exceed it.
50 cubes would correspond to the mean strength, and 100 would mean no failures at all, which the statistical definition does not promise. 80 implies a 20 percent failure rate.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development