Answer:
Sand and gravel are used extensively in construction. In the preparation of concrete, for each tonne of cement, the building industry needs about six to seven times more tonnes of sand and gravel (USGS, 2013b). Thus, the world’s use of aggregates for concrete can be estimated at 25.9 billion to 29.6 billion tonnes a year for 2012 alone. This production represents enough concrete to build a wall 27 meters high by 27 meters wide around the equator. Aggregates also contribute to 90% of asphalt pavements and 80% of concrete roads and the demand for aggregates stems from a wide range of other sectors, including the production of glass, electronics, and aeronautics. Added to this are all the aggregates used in land reclamation, shoreline developments, and road embankments (for which the global statistics are unavailable), plus the 180 million tonnes of sand used in the industry.
Explanation:
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