Common Building Stones

Here describe some commonly used stones are following:

a. Granite       b. Basalt and trap

c. Slate          d. Sand stone  

e. Marble        f. Laterite

g. Quartzite     h. Gneiss

Their qualities and uses are described below:

Basalt and Trap: The structure is medium to fine compact and grained. Their color varies from dark gray to black. Joints and Fractures are common. Their weight varies from  18 kN/m3 to 29 kN/m³. The compressive strength varies from 200 to 350 N/mm². These particular are igneous rocks. They are utilized as road metals, aggregates for concrete. They are also utilized for rubble masonry works for bridge piers, dams and river walls. They are utilized as pavement.

Granite: Granites are also igneous rocks. The color varies from light gray to pink. Structure is crystalline, fine to coarse grained. They take well polish. They are hard durable. Particular gravity is from range 2.6 to 2.7 and compressive strength is 100 to 250 N/mm2. They are utilized primarily for, river walls, bridge piers and for dams. They are utilized as pedestals and kerbs. The use of granite for institutional and monumental buildings is common. Polished granites are utilized as, cladding for columns, table tops and wall. They are utilized as coarse aggregates in concrete.

Sand stone: These are sedimentary rocks, and therefore stratified. They consist of feldspar and quartz. They are found in many colors like, grey, red, white, brown, buff, yellow and even dark gray. The particular gravity varies from 1.85 to 2.7 ranges and compressive strength varies from the range 20 to 170 N/mm². Its porosity varies from range 5% to 25%. Weathering of rocks renders it is not suitable as building stone. It is desirable to use sand stones having silica cement for heavy structures, if essential. They are utilized for masonry work, for, bridge piers, dams and river walls.

Slate: These are metamorphic rocks. They are composed of, mica, quartz & clay minerals. The structure is fine grained. They split along the planes of original bedding simply. Color varies from, greenish gray, dark gray purple gray to black. The particular gravity is range2.6 to 2.7. Compressive strength varies from 100 to 200 N/mm². They are utilized as slabs, roofing tiles , pavements etc.

Laterite: It is also metamorphic rock. It have sponges and porous structure. It contains high percentage of iron oxide. Its color can be, red, yellow, brownish, brown and grey. Its particular gravity is 1.85 and compressive strength varies from 1.9 to 2.3 N/mm2. It can be simply quarried in blocks. With seasoning it gains strength. When it is used as building stone, its outer surface should be plastered.

Marble: This is also metamorphic rock. It may take good polish. It is available in different pleasing colors like pink and white. Its specific gravity is 2.65 and compressive strength is 70-75 N/ mm². It is utilized for facing and ornamental works. It is utilized for flooring, columns steps etc.

Gneiss: It is a type of metamorphic rock. It is fine to coarse grains. Alternative dark and white bands are general. Pink, Light grey, greenish gray, purple and dark grey colored varieties are available. These stones are not preferred because of present ion of deleterious constituents in it. They can be used in minor constructions. Yet hard varieties can be used for buildings. The particular gravity varies from 2.5 to 3.0 and crushing strength varies from 50 to 200 N/mm2.

Quartzite: Quartzite is a type of metamorphic rocks. The structure is fine to coarse grained and frequently branded and granular. They are available in different colors such as gray, white yellowish. Quartz is the chief constituent with feldspar and mica in small quantities. The particular gravity varies from 2.55 to 2.65. Crushing strength varies from 50 to 300 N/mm2. They are utilized as building blocks & slabs. They are also utilized as aggregates for concrete.