Stone
Stone is a 'naturally available building material' that has been used since the early ages of civilization. It is available in the form of rocks, which are cut into required size and shape and used as building blocks. It has been used around the world for the construction of everything from small residential buildings to large palaces and temples. There are Red Fort, Taj Mahal, Assembly in Bangalore and many medieval age palaces all over India Famous stone buildings.
Type of Stone
The stones used for civil engineering works can be classified in the following three ways:
- Geological
- Physical
- Chemical
Geological classification
On the basis of the origin of their formation, stones are classified into three main groups- igneous, sedimentary and metamorphic rocks.
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
(i) Igneous Rocks: These rocks are formed by the cooling and solidification of a mass of rocks. Their molten magnetic state of Earth's material. Generally igneous rocks are strong and sustainable. Granite, trap and basalt are rocks of this category, granite is slow formed.
Cooling of lava under thick cover from above. Therefore they have a crystalline surface. cooling of Lava on the Earth's upper surface results in a non-crystalline and glassy texture. Trap and basalt are related this category.
(ii) Sedimentary Rocks: Rocks existing due to the weathering action of water, wind and frost gets scattered. The decomposed material is transported by wind and water; water is the most powerful medium. Running water deposits its suspended substances at certain points of obstacles in its flow. These the deposited layers of material are consolidated under pressure and by heat. Chemical agents also contribute to consolidate deposits. The rocks thus formed are more uniform, fine-grained and denser their nature. They normally represent a bed or stratified structure. sandstone, limestone, mud Stones etc. belong to this class of rock.
(iii) Metamorphic Rocks: Pre-formed igneous and sedimentary rocks formed under go transformation due to the metamorphic action of pressure and internal heat. For example due to metamorphosis granite Grease becomes, mesh and basalt turns into schist and laterite, limestone turns into marble, sandstone becomes quartzite and clay stone becomes slate.
Physical classification
On the basis of composition, rocks can be classified as:
- Stratified Rocks
- Unstratified Rocks
- Foliated Rocks
(i) Stratified Rocks: These rocks have a layered structure. they have planes stratification or cracking. They can be easily divided along these planes. Sandstone, Limestone, Slate etc.
There are examples of this class of stones.
(ii) Unstratified Rocks: These rocks are not stratified. They have crystalline and compact
Grain they cannot be divided into thin slabs. Examples of such types are granite, trap, marble rocks etc.
(iii) Foliated Rocks: These rocks have a tendency to split only in a certain direction. The direction should not be parallel to each other in the case of stratified rocks. This type of structure is very common in the case of metamorphic rocks.
Chemical classification
Engineers like to classify rocks on the basis of their chemical composition as follows:
- Siliceous Rocks
- Argilaceous Rocks
- Calcareous Rocks
(i) Siliceous Rocks: The main material of these rocks is silica. They are hard and durable. Example such rocks are granite, mesh, sandstone etc.
(ii) Argilaceous Rocks: The main constituent of these rocks is argyl i.e. soil. these are stones hard and durable but they are brittle. They can't handle the shock. Slate and laterite are examples of such rocks.
(iii) Calcareous Rocks: The main constituent of these rocks is calcium carbonate. limestone is a gram rock of sedimentary origin whereas marble is a gram rock of metamorphic origin.