sandanditsstructure,texture,colouranduses.pdf
- 1. CONTENT 1. What is sand ? 2. Composition of sand 3. Colours of sand 4. Different types of sand 5. Classes of sand
- 2. What is sand ? Sand is a mixture of small grains of rock and granular materials which is mainly defined by size, being finer than gravel and coarser than silt. And ranging in the size from 0.06 mm to 2 mm. Particles which are larger than 0.0078125 mm but smaller than 0.0625 are termed as silt . Sand is made by broken pebbles or erosion and weathering of rocks, which is carried by seas or rivers. And freezing and thawing during the winter break up the rock and sand is made. Sometimes sand on beaches can also be made by small broken up pieces of coral, bone and shell which are broken up by predators and then battered by the sea, or bones of fishes or oceanic animals. Sand can also be considered as textural type of soil or soil type. A sandy soil contains 85% of sand sized particles by mass.
- 3. Composition of sand Sand comprises of unconsolidated granular materials consisting of either rock fragments or mineral particles or oceanic materials. It is made of silicate minerals and silicate rock granular particles. Typically Quartz is a dominant mineral as it possess highly resistant properties to weather. Other rock forming minerals like amphiboles and mica are found in sand. Most sand in the beach is made up of gray or tan quartz and feldspar. However, most common mineral in the sand is quartz also known as Silicon dioxide( by combine of silicon and oxygen). Feldspar is the most found group of minerals on the earth's surface and forms about 65% of terrestrial rocks. When the sea and wind whip up on the shores, they transport these tiny granules to the beach and make up sand with this combination.
- 4. Colours of sand Light brown colour : White sand : It is made up of eroded limestone, coral shell fragements Black sand : It contains volcanic minerals and lava segments and coral deposits. Pink sand : Foraminifera, a microscopic organism which has reddish pink shell is responsible for colour. Coral, shells and calcium are also present in this mix. Red Orange colour : It is formed due to Iron oxide White grey colour :
- 5. Different types of sand Green sand Desert sand Sea sand Gypsum of sand : This types of sand contain calcium sulphites dehydrates. Glass sand : It contains silicon dioxide Silica sand : It is pure quartz. Pit sand : It is obtained by forming pits into the soil. It is sharp, angular,porous and free from harmful salts. Clay and other impurities should be washed before used. Fine sand clay when rubbed with hands should not leave any stain on it or it indicates presence of clay. River sand : Found at river beds and banks. Fine, round and polished due to rubbing action of water currents. Has less frictional strength, almost white in colour. Grains are smaller than pit sand and hence more suitable for plastering work.
- 6. Classes of sand Depending on particle grain size:- Very coarse Coarse Medium Fine-grained Classification of sand according to size Coarse sand : All particles should pass through no.4 seive. This type of sand is used in concrete work. Fine sand : All the sand particles should pass through no.16 seive. This is used in plastering. Moderately coarse sand : All the sand particles should pass through no.8 seive . This type of sand is used in mortar and masonry works.