JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year BUILDING MATERIALS, CONSTRUCTION AND PLANNING Previous Question Paper (August/September - 2022 - R16)

Earthen bricks are composed of specific proportions of ingredients that determine their structural integrity and durability. The primary constituents are:

• Silica (Sand): Constitutes 50-60% of the composition. It preserves the shape of the brick, prevents cracking, and ensures durability. Excess silica makes bricks brittle.
• Alumina (Clay): Constitutes 20-30%. It provides plasticity, allowing the brick to be molded. Excess alumina causes the brick to shrink and warp during drying.
• Lime: Present in small quantities (up to 5%). It acts as a flux during burning and prevents shrinkage. Excess lime causes the brick to melt and lose shape.
• Iron Oxide: Present in small quantities (5-6%). It provides the characteristic red color and acts as a flux.
• Magnesia: Present in small quantities, it influences the color (often yellow) and reduces shrinkage.

The manufacturing of bricks involves the following sequential stages:

1. Preparation of Clay: This includes weathering (exposing clay to the atmosphere), blending (mixing ingredients), and tempering (adding water to achieve desired plasticity).
2. Molding: The prepared clay is pressed into molds to achieve the required shape. This can be done via hand molding or machine molding.
3. Drying: Molded bricks are dried in the sun or in artificial dryers to remove moisture, preventing cracking during the subsequent firing process.
4. Burning: This is the final and most critical stage, performed in clamps or kilns. The bricks are heated to temperatures between 900°C and 1200°C, causing chemical fusion of the particles to achieve strength and hardness.

A stone is a naturally occurring, hard, solid, non-metallic mineral matter found in the earth's crust, extracted from rock quarries. It is a fundamental building material used for foundations, walls, and decorative purposes.

Merits of Stone Masonry: Superior strength, fire resistance, and aesthetic appeal. Demerits: High cost, heavy weight, and requirement for skilled labor for dressing.

Merits of Brick Masonry: Economical, uniform size, easy to transport, and requires less skilled labor. Demerits: Lower strength, higher water absorption, and requires plastering for protection against moisture.