Selection criteria for selecting stone for face work of building.
1. Appearance: For face work it should have fine, compact texture; Light-coloured stone is preferred as dark colours are likely to fade out in due course of time.
2. Structure: A broken stone should not be dull in appearance and should have uniform texture free from cavities, cracks, and patches of loose or soft material.
Stratifications should not be visible to naked eye.
3. Strength: A stone should be strong and durable to withstand the disintegrating action of weather. Compressive strength of building stones in practice range between 60 to 200 N/mm2 .
4. Weight: It is an indication of the porosity and density. For stability of structures such as dams, retaining walls, etc. heavier stones are required, whereas for arches, vaults, domes, etc. light stones may be the choice.
5. Hardness: This property is important for floors, pavements, aprons of bridges, etc. The hardness is determined by the Mohr’s scale.
6. Toughness: The measure of impact that a stone can withstand is defined as toughness. The stone used should be tough when subjected to vibratory or moving loads.
1. Appearance: Stone to be used for construction should be decent in appearance and have uniform colour
2. Durability: A Good building stone should be durable i.e. it should resist atmospheric action and should be long lasting
3. Crushing strength: For a good stone, the crushing strength should be more than 100 N/mm2
4. Facility of dressing: Stones should be such that they can be dressed easily and economically.
5. Specific gravity: For a good building stone, the specific gravity should be more than 2.7
6. Water absorption: The percentage of water absorption of water by weight after 24 hours should not exceed 60%
7. Resistance to fire: Minerals in stones should be such that it should not catch fire easily.
8. Seasoning: Stones should be well seasoned before use.