Most types of sand are formed due to soil erosion, weathering of rocks, broken pebbles and gravel made by rivers, ravines and many others.
Sand can be defined as a mixture of granular material and small granular grains of rock.
It is also generally defined by size i.e. it is rough and thicker than silt, ranging in size from 0.06 mm to 2 mm.
The fundamental structure of sand mostly consists of subliminal granular materials consisting of rock fragments or mineral particles or oceanic materials.
It is primarily composed of silicate minerals and silicate rock granular particles.
The most prominent component is quartz because it has extremely resistant properties to the climate, quartz can be generally known as silicon dioxide.
Some other heavy minerals such as tourmaline, zircon and rock-forming materials such as micas and amphiboles can also be found in sand.
Sand is found in various colors like white, black, white-gray, light brown, etc.
It is considered as a multipurpose topographic material used extensively for all kinds of civil engineering works.
Sand is one of the major components of concrete thus important for concrete works.
Different Types of Sand:
There are various types of sand classification as follows:
Types of Sand Based on Colour:
According to the characteristic colour, there are 6 types of sand as follows:
This sand is white in colour primarily composed of eroded limestone as the principal component.
In addition, white sand might also comprise magnetite, chlorite, glauconite, coral, and shale fragments.
It is black in colour basically composed of volcanic materials, lava fragments and coral deposits.
It is reddish-pink in colour characterize by a microscopic organism generally known as foraminifera.
Pink sand also contains coral, shells, and calcium.
Red-orange sand has the characteristic red color.
This is due to the presence of iron oxide.
White-brown sand has finely rounded grains and whitish-gray color.
This type of sand is usually well graded.
Light brown sand:
As the name itself suggests, it is light brown essentially consists of round grains.
Types of Sand Based on size (ASTM classification):
According to the size of the sand particles, there are 3 types of sand as follows:
The sand that passes through 16 number sieve is known as fine sand generally used in plastering work.
|1.19 mm||No. 16||0.0469|
|1.00 mm||No. 18||0.0394|
|0.841 mm||No. 20||0.0331|
Moderately Coarse Sand:
Sand passing through the 8 number sieve is called moderately coarse sand used for mortar and masonry works.
|2.38 mm||No. 8||0.0937|
|2.00 mm||No. 10||0.0787|
|1.68 mm||No. 12||0.0661|
The sand that passes through 4 number sieve is called coarse sand, usually used for concrete works.
|4.76 mm||No. 4||0.187|
|4.00 mm||No. 5||0.157|
|3.36 mm||No. 6||0.132|
Types of SandS Based on Miscellaneous Factors:
There are 18 types of sand-based on various miscellaneous factors as follows:
It consists of a mixture of particles that originate from tropical and subtropical marine environments (i.e. coral sands mostly originate from bio-degradation of limestone or skeletal materials of marine organisms).
Coral sand can only be understood as light colored sand, mostly composed of calcareous fragments of biogenic origin.
Around Hawaii, Polynesia, Indonesia, the Indian Ocean and the Australian North Coast, the Red Sea and many others, coral sand is plentiful within the Caribbean.
However, real and pure coral sands are discovered solely within the vicinity of coral reefs.
It contains silicon dioxide as the main ingredient.
Glass sand is an important source of silica for the glass and chemical industries.
This type of glass sand is also used for water purification and filtration process, road works and concrete works.
It contains calcium sulfate dihydrate as the major ingredient also known as gypsum (CaSO4. 2-2-25).
Gypsum is a rare ingredient in the sand because it is reasonably soluble in water.
However, there exists a large dune area in New Mexico referred to as the White Sands National Monument which consists entirely of tabular gypsum grains.
Gypsum sand exists in New Mexico because this state does not have a very wet climate.
The area also has no sea outlet, meaning that the gypsum grains dissolved in the rainwater have no escape from the area and may eventually form sand grains.
Ooid sands mostly consist of round pellets and spherical coated sedimentary grains.
It also contains calcium carbonate as the main ingredient.
Ooids are small round minerals, usually less than 1 mm in diameter.
Pit sand is a type of sand that is obtained from pits present in the soil, they are principally sharp, angular and porous.
They do not contain a significant quantity of dangerous substances.
Fine pit sand does not cause any stains when rubbed between the fingers used for mortar.
It is sand obtained from river bed and banks, river sand grains are fine, spherical and mostly polished because of the rubbing of streams of water.
The river sand is characterized by a big white colour.
The sand of the river is relatively less than that of pit sand, hence it is more desirable for plastering works.
Since the river sand is relatively pure, it is suitable for all types of civil engineering works and constructions.
One drawback of river sand is that it has low friction power due to rounding.
It is mostly obtained from the seashore.
Therefore it is river sand, it is fine, rounded and polished due to the rubbing of streams of water.
Sea sand in the civil engineering field has a slightly lighter brown color, which is relatively less desirable because it contains excessive amounts of salts.
Such salts absorb moisture from the atmosphere result in permanent moisture and efflorescence when used in building.
This sand contains a significant amount of organic material which is decomposed methodically in the mortar body thus reduces their strength and life span.
Due to all these reasons, as far as possible sea sand should not be used for construction works.
Greensand is a type of sand that contains some green materials.
As the name itself suggests, desert sand is the kind of sand found in deserts.
It is primarily composed of small rocks and rock fragments.
Mixed Carbonate Silicate Sand:
It is made from a combination of natural as well as inorganic sand grains.
It is mainly made up of small skeletons, seashells, forams, corals and many others.
It contains garnets as the foremost element, garnet is a mineral.
It is fairly unstable mostly used for steel casting works.
It is largely found in volcanic energetic or affected areas.
Volcanic sand is relatively dark in color and has various characteristics.
Occasionally, a significant amount of coal is also found in volcanic sand.
Heavy Mineral Sand:
It consists of high mass molecules capable of forming a stable structure.
It is common all over world used extensively for the construction of various structures.
Sand with Hematinic Pigment:
It contains hermitic pigments in his composition.
Hematite refers mostly to a mineral that imparts a reddish color.
Extraction of sandS:
Sand is mostly construction material usually extracted from riverside by mining.
Nowadays, the main source of sand extraction is river and marine.
Land mines have been slightly burned due to declining inland resources.
Sea sand should be systematically cleaned to remove salt and other impurities.
If the sand is not washed well and contains salt, there is a high probability of failure of the constructed structure as the salt will contaminate the metal structures.
Sand found in the desert is inappropriate for the regaining of concrete and land.
The most typical types of sand found on non-tropical coasts and continental areas is called silica and normally in the form of quartz.
Magnetite and volcanic obsidian produce very thick black sand.
Greensand exists where there is a mixture of basalt, chlorite and glauconitic.