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Stone As a Building Material

Classification of Rocks(Stones)CHEMICAL CLASSIFICATION Argillaceous Rocks:Argillaceous or clay stones are those stones which contain (alumina Al2O3) (clay) as principal constituent. These stones are less durable stones. Eg. Clay. Silicious Rocks:The stones which contain (Silica SiO2) as principal constituent are called silicious rocks. These stones are durable stones. Eg Granite Sandstone etc. Calcareous Rocks: The stones which contain calcareous material (CaCO3) as principal constituent are called calcareous rocks. Eg Marble Stone, Lime Stone.

PHYSICAL CLASSIFICATION:Stratified Rocks: The rocks which are split into thin slabs or layers easily are called stratified rocks. Eg Slate,Sand Stone.

Unstratified Rocks: These rocks do not show sign of stratification and can not be easily split into thin slabs or layers are called unstratified rocks. Eg Basalt, Granite.

GEOLOGICAL CLASSIFICATION: Igneous or Primary Rocks: These are primary rocks which are formed from molten magma. They represent different structural features depending upon the condition of solidification and composition Eg. basalt, trap Sedimentary or Secondary Rocks: These are secondary rocks and are formed by the denudation and deposition of previously existing rocks due to weathering actions.Metamorphic or Tertiary Rocks: Rocks which are formed due to metamorphic action of pressure or internal heat or by both (or) alteration of original structure due to heat and excessive. Eg. Marble.

Stone classified according to qualities affecting use

It is used in foundations of buildings.It is used in construction of dams, barrages, etcIn its crushed (powdered form) it is used as artificial sand.It is used as raw material for manufacturing of cement.It is used as decorative material in buildings.It is also used as parts of buildings such as lintels and arches, etcIt is also used as thin slabs for building roofing and flooring.It is also used for ornamental works in buildings.In its broken form it is in the manufacturing of concrete.Uses of Stone

To qualify as a construction material, stone should have the following qualities:

Strength: It is power of stone to sustain pressure or resistance to crushing force.Average crushing strength of stone is 3 tons per square inch. Most types of stone have more than adequate compressive strength. The shear strength of stone, however, is usually about 1/10 of its compressive strength.

Hardness: Hardness denotes several qualities of stones such as resistance to cutting and resistance to abrasion Hardness is important when stone is used for flooring, paving, and stair treads.

Durability: Resistance to the weathering effects of rain, wind, heat, and frost action is necessary for exterior stonework. It depends upon:Chemical composition,Physical structure,Resistance to weathering effects,

Appearance: Appearance factors include color, grain, and texture. Highly colorful stones are preferred for architectural purpose but those are soft and thus less durable. Therefore, lighter stones are preferred than to darker ones.

Workability: A stones hardness and grain texture must allow it to be quarried, cut and shaped.

Fire resistance:A good building stone should be fire resistant. Some stones such as basalt and trap resist fire very well but some varieties of igneous and metamorphic stones are very weak against fire.

Stones used in building construction GraniteGranite is an igneous rock, ordinarily composed of feldspar, mica, and silica or quartz.

Qualities of GraniteThe hardest and most durable granites contain a greater proportion of quartz and a smaller proportion of feldspar and mica.Granite has a pearly lustre. The colour of common granite varies from white through yellow to deep red, and the stone is generally classified as gray and red.Medium grained stone is best fitted for building construction.Fine grained stone can be carved and polished, but, on account of its extreme hardness, it cannot be worked readily.

ClassificationGranites are classified under four grades depending upon the compressive strength and abrasive resistance as specified below

Sandstone

A Type of Sedimentary rockSandstone consists of fragments of other rocks cemented together. The cementing material may be silica, oxide of iron, clay, or carbonate of lime.Qualities of sandstone The best stone is characterized by small grains with a small proportion of cementingmaterial. When broken, it has a bright, clear, sharp fracture.The colours of sandstone are white, cream, yellow, dark brown, blue, and redTechnical Information of different Sandstones

Metamorphic RocksMarbleMetamorphosed limestone gives the masonry material known as marble. It is easily dressed to a smooth surface and polished, and is considered one of the most valuable building materials. Qualities of marbleMarble can be obtained in many colours, some of which are white, gray, red, blue, green, and black.It is easy to carve the finer the grains of the stone, the more suitable it is for this purpose.It resists frost and moisture well, but like all limestones it does not withstand fire.ClassificationMarble has been classified into 10 groups by Bureau of Indian Standards (IS 11301969) on the basis of colour, shade and pattern.1. Plain White Marble 2. Panther Marble3. White Veined Marble 4. Plain Black Marble5. Black Zebra Marble 6. Green Marble7. Pink Adanga Marble 8. Pink Marble9. Grey Marble 10. Brown Marble

Limitation of StonesDressing of stones is tedious, laborious and time consuming job.Desired strength and quality not available at moderate rates especially in plain areas.RCC, Steel are alternatives to stones and gives more strength and flexibility.Stone structure design cant give freeness and flexibility to the designer.

Deterioration of stones:Alternate wetness and drying.Frost.Impurities in atmosphere.Living organisms.Nature of mortar.Rain water.Temperature variations.Vegetable growth.