What are the various Characteristics of good building stone?

Characteristics Of Stones

         > A building stone has the following characteristics

1. Structure of stone
2. Texture of stone
3. Durability
4. Hardness
5. Strength
6. Toughness
7. Porosity and absorption
8. Specific gravity
9. Resistance to fire
10. Resistance to electricity
11. Seasoning
12. Dressing
13. Appearance
14. Workability
15. Cost

 

1. Structure of stone

> Structure of stone indicates the composition of its mineral matter and their internal arrangement.

–         Should have uniform structure

–         Should be free from cavities, cracks, patches etc.,

–         Igneous rock has uniform structure

–         Igneous rock can take more load

–         Igneous rock is most suitable for construction works

 

2. Texture of stone

 > Texture of stone indicates the pattern in which the mineral matter is arranged in the stone

–         Homogeneous and crystalline in structure

–         Hard and compact

 

3. Durability

–         Resist the effect of atmospheric agencies like

•          wind,

•          rain,

•          temperature etc

–         It depends on Chemical composition and Physical structure

 

4. Hardness

•       Resistance against abrasive forces developed due to  friction, wear and tear is known as hardness

•       Expressed in Number

•       It varies from 1 to 10

•       More the number Harder is the stone

 

5. Strength

–         Resistance against crushing.

–         A good stone withstand higher loads.

–         Crushing strength varies between 15 to 100 N/mm²_.

 

6. Toughness

–         Resistance against impact

–         Should be hard and tough

–    Tough enough to withstand stresses developed due to vibration of machinery, moving loads over them

 

7. Porosity and absorption

–         Should be less porous

–      Highly porous stones disintegrate as the absorbed water may freeze and expand which results in cracking.

–     Should not absorb more than 5% of water by volume when immersed in water for 24 hours

 

8. Specific gravity

–         Ranges between 2.4 to 2.8

–         Higher Specific gravity stones are preferred for Dams, bridges, weirs etc

–         Less specific gravity stones  are preferred for domes and roof covers etc

 

9. Resistance to Fire

–   Should constitute minerals having equal coefficient of thermal expansion for better resistance to fire

–        Such stone is preferred for Construction

            Example : sand stone

 

10. Resistance to Electricity

–         Good building stones should offer greater resistance to electricity.

–         Dry stone                                   -   Good resistance

–         More porous stone                     -   Less resistance

–         Dense stones with low porosity  -   Preferred

            Examples : Marble, slate

 

11. Seasoning

–          Removal of quarry sap (internal moisture) is called seasoning.

–         Moisture make a stone  soft and damages it.

–         For effective seasoning stone is to be left for a period of 6 to 12 months in the presence of air and sun light.

 

12. Dressing

–         Dressing is bringing the stone to proper shape and size

–           Dressing is essential for ornamental and structural work  like  arches, corbels, sills etc

–          The stone becomes weak in strength and  durability when it undergoes dressing

 

13. Appearance

–         Important for the facing work of the building

–         Uniform texture

–         Light in colour

 

14. Workability

             Ease with which the stones can be handled

–         Cut

–         Dressed to different sizes

–         Should be economical to dress

15.Cost

             Depends on

                                - Type of stone

                                - Method of quarrying

                                - Transportation distance

                                - Mode of transport

Select best and economical stone.