Building Materials MCQ Questions & Answers | Civil Engineering

Chlorite is a green-colored mineral that belongs to the clay mineral group and is commonly formed during the alteration or decomposition of other minerals.

It is primarily formed by the decomposition of minerals like Augite, Biotite, and Hornblende, which are all common minerals in igneous rocks.

Option A: Augite is a pyroxene mineral, and when it undergoes weathering, it can transform into chlorite.

Option B: Biotite is a mica mineral that can also decompose to form chlorite under certain conditions.

Option C: Hornblende, a type of amphibole mineral, can also undergo alteration to form chlorite.

Therefore, the correct answer is Option D: All of these, as chlorite can be derived from the decomposition of Augite, Biotite, and Hornblende.

Definition: Silica is a key component of brick earth that influences the strength and durability of bricks. However, its excess can negatively impact the quality of bricks.

Step 1: Understanding the role of silica:

Optimal amount: Silica in the right proportion (about 50-60%) provides strength and prevents shrinkage.

Excess silica: When silica content is too high, it prevents proper bonding between particles, leading to weak bricks.

Step 2: Evaluating the options:

Cracking and warping of bricks: Usually caused by rapid drying or improper burning, not excess silica.

Loss of cohesion: Excess silica reduces the binding property of clay, making the bricks brittle and weak.

Enhancing the impermeability of bricks: Impermeability is affected by the proportion of clay and firing temperature, not directly by excess silica.

Step 3: Since high silica content leads to poor cohesion, the correct answer is Loss of cohesion (Option B).