Engineering Materials·MCQ explained

What is the thickness of one and half brick wall made up of standard modular brick?

Try it first: pick an option, then read the explanation.

Correct answer: B. 30 cm
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Understanding Brick Wall Thickness

The thickness of a brick wall is determined by the way the bricks are laid. It is based on the dimensions of a standard modular brick and the mortar joints between them. For calculation purposes, we use the "nominal" size of a brick.

  • Standard Brick Size: 19 cm × 9 cm × 9 cm
  • Standard Mortar Joint: 1 cm
  • Nominal Brick Size: 20 cm × 10 cm × 10 cm

Detailed Analysis of the Options

B. 30 cm

This is the correct answer. A "one and a half brick wall" is constructed with a thickness equal to the length of one brick plus the width of one brick, separated by one vertical mortar joint.
Calculation: (Length of one brick) + (Width of one brick) + (Mortar Joint)
Using nominal sizes for simplicity: 20 cm (one brick thick) + 10 cm (half brick thick) = 30 cm.
Using actual sizes: 19 cm (length) + 9 cm (width) + 1 cm (mortar) = 29 cm, which is nominally referred to as 30 cm.

A. 20 cm

This is incorrect. A thickness of 20 cm represents a "one-brick wall," which is equal to the nominal length of a single brick.

C. 40 cm

This is incorrect. A thickness of 40 cm would represent a "two-brick wall" (20 cm + 20 cm).

D. 50 cm

This is incorrect. A thickness of 50 cm would represent a "two and a half brick wall" (20 cm + 20 cm + 10 cm).

Summary: Standard Brick Wall Thicknesses

Wall TypeNominal ThicknessComposition
Half Brick Wall10 cmWidth of one brick
One Brick Wall20 cmLength of one brick
One and a Half Brick Wall30 cmOne brick length + One brick width
Two Brick Wall40 cmTwo brick lengths

Study Tips

  • Memorize the Basics: Know that a half-brick wall is 10 cm and a one-brick wall is 20 cm.
  • Build from the Basics: Understand that thicker walls are simple combinations of these basic units. A 1.5 brick wall is just a 1-brick section plus a half-brick section (20 cm + 10 cm = 30 cm).
  • Nominal is Key: Always use the nominal dimensions (20x10x10 cm) for these calculations, as they already account for the mortar joint.
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