Criteria For Selection Of Stones | Stone As A Building Material | Stones | Construction Materials | By Ashutosh Nautiyal

Criteria For Selection Of Stones

• For structural purposes, the selection of stone is governed by various parameters. 

• For the selection of stone, the site engineer looks into the properties required for the intended work and selects the stone.

Criteria For Selection Of Stones

The criteria for selection of stone as a building material is based upon the following parameters:-

Chemical Composition 

• Chemical properties and composition of the stone must be tested and verified because different elements and different compounds in stones have different properties.

Cost

• The transportation charges, difficulties in quarrying and cutting, the ornamental features and the durability of a stone influence its cost largely.

• There is a great contribution by the cost of dressing to the cost of stone masonry.

Durability

• Stones selected should be capable of resisting adverse effects of natural forces like wind, rain and heat.

• The durability of the stone is greatly determined by its resistance to fire and weathering.

• For face works, stones with good weather resistance should be used.

Appearance 

• Appearance is a primary requirement for the selection of the stone.

• The colour and ability to receive polish greatly influence the appearance.

• For carving, attractive fine-grained stones with homogeneous distribution are used.

Colour

• A stone with uniform and the attractive colour is durable if its grains are compact.

• The colour of stone along with its shape and arrangement of mineral constituents greatly influence its fashion and ornamental value.  

• The designer selecting the stone should be aware of the variation of colour of the stone after long exposure and in polluted atmospheres.

Structure

• Structured stones are suitable for the superstructures.

• For foundation works, unstratified rocks are preferred.

Specific Gravity

• For the construction of dams, retaining walls, harbours, etc. a heavier variety of stones should be used.

• For a good building stone, specific gravity is between 2.4 and 2.8.

Strength

• For the selection of stone as a building block, strength is an important property to be looked for.

• For any building block, minimum crushing strength should be 3.5 N/sq. mm as recommended by Indian Standard Code.

Hardness 

• For road works, coefficient of hardness should be at least 17.

• For building work stones, coefficient of hardness should be less than 14.

• The stones used in floors and pavements should be able to resist abrasive movement caused by the movement of men and materials over them.

Toughness

• For road works, the toughness index of the stone should be more than 19.

• Stones having toughness index 13 to19 are medium tough.

• Stones having toughness index less than 13 are poor.

Percentage Of Wear

 

• The percentage of wear should not exceed 2% for a good stone.

Porosity and Absorption

• Building stones should not be porous.

• The percentage of water absorbed by the stone when it is immersed underwater for 24 hours should not be more than 5% for a good stone.

Bio-deterioration 

• There are both chemical and mechanical effects when certain trees and creepers thrust their roots into the joints of stones.

• Special microbes can grow on the surface and in minute fissures, their by-products lead to flaking and discolouration of stones. 

*Self Typed
*Source- Internet, Books and Self-Analysis