Sand & Gravel

 

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz.

The second most common form of sand is calcium carbonate, for example aragonite, which has mostly been created, over the past half billion years, by various forms of life, like coral and shellfish. It is, for example, the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean.

 

Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel is sub-categorized by the Udden-Wentworth scale into granular gravel (>2 to 4 mm or 0.079 to 0.16 in) and pebble gravel (>4 to 64 mm or 0.2 to 2.5 in). One cubic yard of gravel typically weighs about 3000 pounds (or a cubic metre is about 1,800 kilograms).

Gravel is an important commercial product, with a number of applications. Many roadways are surfaced with gravel, especially in rural areas where there is littletraffic. Globally, far more roads are surfaced with gravel than with concrete or tarmac; Russia alone has over 400,000 km (250,000 mi) of gravel roads. Both sand and small gravel are also important for the manufacture of concrete.

 

 

For further information, please click on the link below: 

https://en.wikipedia.org/wiki/Sand

http://en.wikipedia.org/wiki/Gravel

 

 


 

 

Source:

Wikipedia, The Free Encyclopedia

 


 

 

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