The material which is used for the construction work in its original form or in modified form is known as construction materials .It may also be termed as building material or civil engineering material .Selection of suitable construction material for a particular work ,entirely depends upon the properties of material .So ,a civil engineer should have a thorough knowledge about all the construction materials so that the optimum utilization of the material is possible which results the most economic and safe structure .The different building material like cement , lime, marble, plastic, metal, bricks, blocks, timber, paint, glass etc.
Stone is the oldest material of the Construction industry. From the ancient time, it has been used as building material at different construction sites in INDIA as well as in other parts of the world. Stone is found in nature in many forms. Different types of stones are suitable at different locations. Selection of a suitable stones depends upon the requirement of the structure and availability of the varieties of stone. So, to select a suitable building stone for a particular work a sound knowledge of different varieties of stones is essential.
CLASSIFICATION OF ROCKS
Stones are obtained from the rocks. So the properties of stone depend upon the parent rock. The rocks have the following classification:
- Geological Classification
- Physical Classification
- Chemical Classification
This type of classification is based on the mode of formation of rock. That is, how the parent rock of the stone comes into existence. In this classification, three types of rocks are identified as construction material i.e :
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
IGNEOUS ROCKS :
The name igneous, related to the word ‘ignite’ .A very hot and molten material found deep below the earth is known as magma. Due to high pressure, this material i.e. magma also known as molten lava is in viscous form. When due to some reason, this magma gets some cooling effect , it starts to solidify resulting the igneous rocks. So, the rock which is formed due to the solidification of molten lava or magma is known as Igneous Rocks. The structure of the rocks is mainly depends upon the cooling effects and stages of cooling. The igneous rocks may be further divided into following sub division :
- Volcanic rocks
- Plutonic rocks
- Hypabyssal rocks
Basalt , Granite , Syenite ,Dolerite are the examples of Igneous Rocks.
SEDIMENTARY ROCKS :
Sedimentary rocks are formed by the solidification of various disintegrated material like sand, pebbles, rocks, dead sea organisms etc. The various weathering agencies like wind, sun, rain, water, frost etc are responsible for the disintegration of materials and transportation of these to a particular low lying places. Under the process of compression and compaction these deposited materials are converted into a hard mass known as Sedimentary Rocks. Sedimentary rocks show different layers in their structure because of continuous deposition of materials layer by layers. Each layer of the Sedimentary rock may have different composition, colour, thickness, structure etc.
The properties of these rocks depend upon the various materials which are being transported and type of bonding between them. The rocks show well defined bedding planes and can be split up along these bedding planes. Mechanical, chemical and organic processes in one form or in combination are responsible for the formation of these rocks. Sedimentary rocks are known as secondary rocks, stratified rocks or aqueous rocks.
Gypsum, Sandstone, Limestone, Shale are examples of Sedimentary Rocks.
METAMORPHIC ROCKS :
Some times due to earth movements , temperature changes,chemically acting fluids, pressure, heat, the igneous rocks or sedimentary rocks may undergo considerable changes. These changed rocks are known as Metamorphic Rocks. These changes may be in shape , structure , colour , and sometimes , even in their mineral composition. The process of change in structure due to these forces is known as Metamorphism . The nature of the metamorphic rock depends upon the action causing metamorphic rocks. Metamorphic rocks are one of the popular used construction materials in India as well.
Metamorphic rocks are originally either igneous or sedimentary rocks . For example, Marble is metamorphosed form of limestone . The changes that take place during metamorphism is in solid state. Marble, Quartzite, Slates, Serpentine, Gneiss are examples of Metamorphic Rocks .