What is Stone ?
Stone is a small piece of rock shaped or finished for a particular purpose or work . A hard earthen substance that combines and forms a big rocks.
Qualities of a good building stone/ various requirements of good building stone:
Stone is integral part of building materials. So following
are the qualities or requirements of a good building stone.
· Crushing strength: For a good building stone, the
crushing strength should be greater than l000kg per cm2.
· Appearance:
Good building stone should be a uniform
colour, and free from clay holes, spots of other colour bands etc. capable of
preserving the colour for longtime.
· Durability: A good building stone should be durable.
The factors like heat and cold alternative wet and dry, dissolved gases in
rain, high wind velocity etc. affect the durability.
· Fracture: For good building stone its fracture should
be sharp, even and clear.
· Hardness:
The hardness greater than 17, treated as
hard used in road works. It is between 14 to 17 & medium hardness, less 14
said be poor hardness.
· Percentage wear:
For a good building stone, the
percentage wear should be equal to or less then 3 percent.
· Resistance to fire:
A good building stone be fire
proof. Sandstone, Argillaceous stone resists fire quite well
· Specific gravity:
For a good building stone the
specific gravity should be greater then 8.7 or so.
· Texture:
A good building stone should have compact
fine crystalline structure should be free from cavities, cracks or patches of
stuff or loose material.
· Water absorption:
For a good building stone, the
percentage absorption by weight after 24 hours should not exceed 0.60.
· Seasoning:
Stones should be well seasoned before
putting into use. A period of about 6 to 12 months is considered to be
sufficient for proper seasoning.
· Toughness Index:
Impact test, the value of toughness
less than 13 – Not tough, between 13 and 19 – Moderate, greater than 19- high.
Characteristics of stones:
There are different factors that should be taken into
consideration while selecting suitable stone for particular work, one must be
known with its composition, characteristics, uses and place of availability.
1.
Granite –
· It is a igneous rock & composed of quart, feldspar
and mica and minerals.
· Granite is hard and durable with high resistance to
weathering.
· It is available in grey, green, brown and pink and red.
The texture varies with its quality
· Specify gravity 2.7 and compressive strength 700 to 1300 kg/cm2
· Granite is used for ornamental, road metal, railway
ballast, aggregate for concrete; for construction of bridges, piers and marine
works etc.
2.
Balast
· It is a igneous rock & it is compact, hard &
heavy.
· Balast can be available in red, yellow grey, blue and
greenish black colour.
· Specific gravity is 3 and compressive strength varies
1530 to 1890 kg/cm2.
· Used for ornamental, rail road ballast, aggregates for
concrete etc.
3.
Sand Stone:
· It is a sedimentary rock. Sand stone is available in
variety of formations fine grained, coarse grained compact or porous.
· Specific gravity of sand stone is 2.65 to 2.95.
· Available in white, green, blue, black, red and
yellow.
· Compressive strength is 650kgs / cm2
· Sand stone is used for ashlar works.
4.
Lime Stone:
· Sedimentary rock: It is available in a variety of
forms which differ from one another in colour Compaction, texture, hardness and
durable –
a.
Compact lime
stone b. Granular lime stone c. Magnesia lime stone d. Kanker lime stone f.
Used for paving, road metal, etc.
5.
Marble
· Marble is a metamorphic rock.
· It has high compactness.
· Suitable for decorative works, wall lining columns,
pile, table slabs, hearths, tiled floors, steps of stair case etc.
· Marble is available in white, blue, green, yellow
black and red colour.
6.
Slate:
· Slate is a metamorphic rock.
· Non-absorbent, compact fine grained and produce metallic
ringing sound when struck. It is available in black, dark blue, grey, reddish
brown etc.
· Used for providing damp proof course, paving dados etc.