STONE

STONE

Stone or rock is a ‘naturally available building material’ a solid collection of one or more minerals which has been used from the early age of civilization. Marble, granite, quartz are some of the examples for stones. It is available in the form of rocks, which is cut into the required and desirable size and shape and then it is used as a building block. It has been used to construct small residential buildings, temples and large palaces all over the world.

Type of Stones

Stones that are used for civil engineering works are classified into the following three ways:

Ø Geological ( Based on their origin of formation stones)

§  Igneous Rocks: Rocks that are formed by cooling and solidifying of the rock masses from their molten magma of volcano. Granite, trap and basalt are the examples for igneous rocks. These rocks are strong and durable.

§  Sedimentary Rocks: These rocks are formed by deposition of suspended materials at earth surface and within water bodies. Sandstones, limestones, mudstones etc. belong to this class of rock.

§  Metamorphic Rocks: Above mentioned rocks undergo metamorphism action due to temperature change and pressure change results in the formation of metamorphic rock. Example are limestone changes to marble, sandstone becomes quartzite and mudstone becomes slate.

Ø Physical (Based on the structure)

§  Stratified rocks

§  Unstratified rocks

Ø Chemical(On the basis of their chemical composition)

§  Silicious rocks

§  Argillaceous rocks

§  Calcareous rocks

Properties of Stones

1) Strength: Strength is an important property to be looked into before selecting stone as a building block.

2) Density: Denser stones are stronger. Lightweight stones are weak.

3) Structure: Structured Stones should be easily dressed and suitable for the superstructure.

4) The appearance of the stone: good appearance stones are used for face works in buildings. ex: Marble and granite

5) Weathering of stone: Rain and wind cause loss in the good appearance of stones. Hence stones with good weather resistance should be used for face works in structures and buildings.

6) Resistance to Fire: stones should be resistant to fire.Though poor in strength is good in resisting fire.

Properties of a good building stone:

·      It should be resistant to fire.

·      It must be polished properly.

·      It should have high strength and durability.

·      It should be good in appearance.

·      It should have a uniform colour.

·      It should have low water absorption rate.

Uses of Stones:

Stones are used for various works in civil engineering

1.  Stones are used for construction of roads.

2.  Stones are used for flooring.

3.  Stones are also used as aggrigates.

4.  Good appearance stones are used for face works in buildings.

5.   Polished marbles and granite are commonly used for face works.

6.  Stones are used for paving of roads, footpaths and open spaces round the buildings.

7.  Crushed stones are used as railway ballast.

8.  Stones are also used in the constructions of bridges, dams and retaining walls.

Tests on Stones

Stone used in civil engineering should have certain properties, so the following tests are conducted

1.  Crushing strength test

2.  Water absorption test

3.  Abrasion test

4.  Impact test

5.  Acid test.

Commonly used building stones

1.  Basalt and Trap: These are igneous rocks. They are used as road metals, concrete aggregates. Basalt is used in railway tracks.

2.  Sand stone: These are sedimentary rocks.sand stones    consist of qurtz and feldspar. They are used for masonry work, for dams, bridge piers and river walls.

3.  Granite: Granite stones are mainly used for piers, walls of the river and dams. Polished granites are used as table tops, column and wall cladding. They are used in concrete as coarse aggregates.

4.  Marble: This rock is metamorphic. It can be polishable. It is used for ornamental and façade works. It is used for columns, steps of flooring.