Question

Which of the following building materials is characterized by brittleness, good compressive strength and low tensile strength?

• A. Steel
• B. Bamboo
• C. Wood
• D. Brick

Hint:

Masonry rule of thumb: Bricks, stones, and unreinforced concrete love to be squeezed (high compressive strength), but hate to be pulled apart (low tensile strength). Because they cannot stretch or flex, they snap suddenly without warning (brittle failure).

Answer 1

The Correct Option is D

Concept: Materials engineering classifies materials based on their stress-strain behavior when subjected to mechanical forces:
• Ductile materials (like steel) undergo significant plastic deformation before fracturing.
• Brittle materials display negligible elastic yielding and fracture abruptly without warning when their structural capacity is exceeded.
• Ceramic and masonry products are classic examples of brittle materials that handle high compressive loads well, but fail quickly under tension.

Step 1: Analyzing the structural nature of Brick.
A structural clay brick is a hardened, unreinforced ceramic block. On a microscopic scale, its atomic structures are held together by tight ionic and covalent bonds. These rigid bonds prevent atomic planes from sliding past one another under load.
• When a brick is compressed, its internal matrix compacts efficiently, allowing it to withstand high compressive loads (often exceeding \(10\text{ to }35\text{ MPa}\)).
• However, under tensile loading, any minor micro-crack or void inside the brick acts as a severe stress concentrator. Because the material lacks ductility to deform and redistribute these stresses, tensile forces pull the crack tips apart effortlessly, causing sudden brittle failure at low tensile stresses.

Step 2: Contradicting the other material behaviors.

• Steel: Highly ductile, exhibits excellent tensile strength as well as compressive strength, and deforms noticeably before failing.
• Bamboo and Wood: Fibrous, anisotropic natural materials. Thanks to their continuous longitudinal cellulose fibers, they offer substantial tensile flexibility and strength parallel to their grain, meaning they do not behave like purely brittle masonry materials. Thus, brick perfectly fits the description of a material characterized by brittleness, high compressive strength, and low tensile strength.