Which of the following represents the nominal size (mm) of a modular brick?
Try it first: pick an option, then read the explanation.
Correct answer: C. 200 × 100 × 100
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Understanding Nominal vs. Standard Size
In brick masonry, it's crucial to distinguish between the actual size of a brick and the space it occupies in a wall.
- Standard Size: This is the actual manufactured size of the brick (190 mm × 90 mm × 90 mm).
- Nominal Size: This is the standard size plus the thickness of one mortar joint (typically 10 mm). The nominal size is used for all masonry calculations as it represents the total space a brick takes up in a wall.
Detailed Analysis of the Options
C. 200 × 100 × 100
This is the correct answer. The nominal size is calculated by adding the mortar thickness (10 mm) to each dimension of the standard brick size.
Length: 190 mm + 10 mm = 200 mm
Width: 90 mm + 10 mm = 100 mm
Height: 90 mm + 10 mm = 100 mm
Thus, the nominal size is 200 mm × 100 mm × 100 mm.
A, B, and D
These options are incorrect as they do not represent the standard nominal dimensions derived from a standard modular brick and a 10 mm mortar joint.
Summary: Brick Size Definitions
| Type of Size | Dimensions (mm) | Description |
|---|---|---|
| Standard Size | 190 × 90 × 90 | Actual manufactured size of the brick. |
| Nominal Size | 200 × 100 × 100 | Size including one mortar joint; used for calculations. |
Study Tips
- Nominal = Standard + Mortar: This is the key formula to remember.
- Memorize Both Sizes: For exams, you must know both the standard size (190x90x90 mm) and the nominal size (200x100x100 mm).
- Check the Units: Pay attention to whether the question asks for cm (20x10x10) or mm (200x100x100).
- Why Nominal?: The nominal size makes calculations easy. For example, it tells you that 5 nominal bricks laid end-to-end will perfectly span 1 metre (5 x 200 mm = 1000 mm).