Question

The target mean strength $f_{cm}$ for concrete mix design obtained from the characteristic strength $f_{ck}$ and standard deviation $\sigma$ as defined in IS 456-2000 is

• A. $f_{ck}+1.35\sigma$
• B. $f_{ck}+1.45\sigma$
• C. $f_{ck}+1.55\sigma$
• D. $f_{ck}+1.65\sigma$

Answer 1

The correct option is D $f_{ck}+1.65\sigma$

Target mean strength $=f_{ck}+1.65\sigma$