Question

M20 is a type of :

• A. Concrete Mix
• B. Reinforced steel bars
• C. Rolled steel section
• D. Bitumen

Hint:

Examples of concrete grades:
• M10
• M15
• M20
• M25 Higher grade number: \[ \Rightarrow \text{Higher compressive strength} \]

Answer 1

The Correct Option is A

Concept: Concrete grades are designated using the letter \(M\) followed by a number. \[ M \rightarrow \text{Mix} \] The number represents the characteristic compressive strength of concrete after 28 days, measured in: \[ \text{N/mm}^2 \] For example: \[ M20 \Rightarrow 20 \, \text{N/mm}^2 \]

Step 1: Analyze option A.
M20 is a standard grade of concrete mix used in construction. It indicates concrete having characteristic compressive strength of: \[ 20 \, \text{N/mm}^2 \] Hence, option A is correct.

Step 2: Analyze Reinforced steel bars.
Steel bars are designated differently, such as Fe415 or Fe500. Hence, option B is incorrect.

Step 3: Analyze Rolled steel section.
Rolled steel sections use designations like I-section, channel section, etc. Hence, option C is incorrect.

Step 4: Analyze Bitumen.
Bitumen grades are classified differently based on penetration or viscosity grading. Hence, option D is incorrect.

Step 5: Choose the correct option.
M20 refers to a grade of concrete mix. Therefore, the correct answer is: \[ {\text{(A) Concrete Mix}} \]