Sand has had a long and useful history for mankind. For example, sand was used as early as 6,000 B.C. to grind and polish stones that made tools shaper. Around 3,000 B.C., the first glass beads appeared in Egypt, made in a process that used melted sand.

But the creation of sand-and-gravel deposits has a much longer history. These deposits, while vital to the modern construction and road-building industry, are the result of geological erosive forces of water, wind and ice. They are generally found in river and stream valleys where they have been deposited by water, and in ridges and hills where they were left behind by receding glacial action and subsequently altered by erosive forces.

Material washing

Around the U.S., as much as 70 percent of sand and gravel is processed from riverbed dredging and what are known as dry feed areas, the deposits found in ridges and hills. The rest comes from aggregate quarries. Dry feed areas and quarries tend to produce material that of consistent quality over a period of time.

Sand and gravel are often dug up from under water by using a dredge, which can be as large as a three-story house. The dredge floats in a natural or artificial pond, or in a river or stream. It uses buckets on a continuous chain or rotary cutting heads and a suction hose to remove material from below the water's surface. Equipment on the dredge separates material particles from the sand and gravel. Boom conveyors on the dredge then deposit the waste sand in the area already mined. A large dredge can handle 1,000 tons of material per hour.

Material produced by dredging is the least predictable in quality, quantity and gradation, as underwater cave-ins may cause changes in gradation or tonnage. In these cases, producers must take the material as it comes, and more work is required to sort the usable material from the waste material

Today, the processing of sand is a multi-billion-dollar business, with operations ranging from very small plants supplying sand and gravel to a few local building contractors, to very large, highly automated plants supplying hundreds of truck loads each day to a variety of customers over a large area.

Air separation

Because sand and gravel are usually delivered as loose, easily handled materials that are composed of a range of grain sizes, they are readily compacted while retaining good internal drainage characteristics. This makes them a preferred and stable material for fills and as a base course for pavements and other structures.

Hydraulic Cylinder

When combined with a Portland cement binder, sand and gravel become the principal ingredients in a usually strong and long-lasting construction material – concrete – whether used in its plastic state and placed in forms, or precast as pipe, block and other structural components. Combined with asphalt, sand and gravel become the aggregate forming the major element of asphaltic concrete – widely and efficiently used as a paving material.

The most common sand is composed of particles of quartz and feldspar; quartz sand particles are colorless or slightly pink, while feldspar sand has a pink or amber color.