What is the meaning of the designation ‘M30’ concrete suggested for a reinforced cement concrete work?
Try it first: pick an option, then read the explanation.
Correct answer: C. Characteristic compressive strength of a 150 mm cube at 28 days is 30 N/mm²
Meaning of the Concrete Grade ‘M30’
In the designation ‘M30’: the letter M stands for Mix, and the number 30 is the characteristic compressive strength in N/mm², measured on a 150 mm cube at 28 days.
Common traps:
• The cube size is 150 mm (not 100 mm)
• The curing age is 28 days (not 365 days)
• The strength is 30 N/mm² (not 300 N/mm²)
• The cube size is 150 mm (not 100 mm)
• The curing age is 28 days (not 365 days)
• The strength is 30 N/mm² (not 300 N/mm²)
M30 means characteristic compressive strength of a 150 mm cube at 28 days is 30 N/mm² — option C.
Key takeaway
M = Mix; the number = fck in N/mm²; measured on 150 mm cubes at 28 days. Straightforward once you know the system.