JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II BUILDING MATERIALS, CONSTRUCTION AND PLANNING Previous Question Paper (September/October - 2023 - R15)

The field tests conducted on stones to assess their suitability for construction include:

1. Test for Appearance and Structure: A visual inspection to check for uniformity in color, absence of cracks, flaws, or cavities, and a compact, crystalline structure.
2. Test for Strength: A simple hammer test where a stone is struck with a hammer; a good building stone should produce a clear ringing sound and should not break easily.
3. Test for Weight: A rough estimation to ensure the stone is dense and heavy, as higher density generally indicates better quality and lower porosity.
4. Test for Hardness: Scratching the surface with a knife or steel point to check for resistance; a good stone should not show significant signs of abrasion or scratching.

The cross-section of a tree trunk reveals several distinct concentric layers, starting from the center and moving outwards:

1. Pith (Medulla): The innermost central core, consisting of soft cellular tissue. It is the oldest part of the tree and provides no structural strength.
2. Heartwood: The central portion surrounding the pith, consisting of dead cells. It is dark in color, dense, and provides the primary structural support for the tree.
3. Sapwood: The outer layer of wood between the heartwood and the cambium layer. It contains living cells and transports sap; it is lighter in color and less durable than heartwood.
4. Cambium Layer: A thin layer of active cells between the sapwood and the inner bark, responsible for the growth of new wood cells.
5. Inner Bark (Bast): Protects the cambium layer and carries food prepared by the leaves to other parts of the tree.
6. Outer Bark: The outermost protective layer consisting of dry, dead cells that shield the tree from external physical and environmental damage.

A sketch would show these layers as concentric circles, with Medullary Rays radiating outward from the pith to the bark, serving to hold the annual rings together.