Question

Normally, the tensile strength of concrete is about ______ of its compressive strength.

• A. \(10\) to \(12\%\)
• B. \(15\) to \(20\%\)
• C. \(20\) to \(25\%\)
• D. \(25\) to \(30\%\)

Hint:

Concrete strength relationship: \[ \boxed{ f_t \approx 0.10\text{ to }0.12\,f_c } \] where \(f_t\) is tensile strength and \(f_c\) is compressive strength.

Answer 1

The Correct Option is A

Step 1: recall the general compression versus tension behaviour of concrete.
Concrete gains most of its strength from the crushing resistance of its aggregate and cement matrix in compression, but it has almost no reinforcement of its own to resist tension, so its tensile capacity is only a small fraction of its compressive capacity.
Step 2: put a rough number to that fraction.
For normal concrete, the commonly used approximate figure taught in design practice is that the tensile strength works out to only around $10\%$ to $12\%$ of the compressive strength, which is why concrete is never relied upon alone to resist tension in a design.
Step 3: match this figure to the options.
This matches the smallest of the given ranges rather than the higher ones.
\[ \boxed{10\% \text{ to } 12\% \text{ (option A)}} \]