Question

The characteristic strength of concrete is defined as that compressive strength below which not more than

• A. 10% of results fail
• B. 5% of results fail
• C. 2% of results fail
• D. None of these

Answer 1

The correct option is B 5% of results fail

Characteristic Strength $f_{ck}$ - It is that strength below which not more than 5% of test results are expected to fail.


$f_{ck}=f_m-1.65\sigma$