SAND  Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.  the most common constituent of sand is silica (silicon dioxide, or SiO2), usually in the form of quartz. SOURCES OF SAND Sand is formed by the weathering of rocks. Based on the natural sources from which sand is obtained, it is classified as follows:  Pit sand  River sand  Sea sand PIT SAND  This sand is obtained by forming pits in soils.  It is excavated from a depth of about 1-2 m from the ground level.  This sand is found as deposits in soil and it consists of sharp angular grains, which are free from salts. Pit Sand  It serves as an excellent material for mortar or concrete work.  Pit sand must be made free from clay and other organic materials before it can be used in mortar.  A coating of oxide of iron over the sand grains should be removed. RIVER SAND  This sand is widely used for all purposes. It is obtained from the banks or beds of rivers and it consists of fine rounded grains. The presence of fine rounded grains is due to mutual attrition under the action of water current. River sand  The river sand is available in clean conditions.  The river sand is almost white in color. SEA SAND  This is obtained from sea shores.  It is brown in color and it also has the fine rounded grain. Sea sand DREDGED SAND DESPOSITION Sea sand  As it is obtained from sea it contains salt, which is used in attracting moisture from atmosphere.  Such absorption causes dampness and disintegration of work.  It is generally not used for engineering purpose due to its retards setting action of cement. It is normally used for non structural purposes. Crushed Stone Sand / Artificial Sand  It is a substitute for River Sand, fine aggregates which manufactured by crushing either granite or basalt rock using 3 stage crushing process.  This sand is manufactured in conformance to IS Codes and is an effective alternative to river sand. CLASSIFICATION OF SAND  Based on the grain size distribution  Fine sand: The sand passing through a sieve with clear openings of 1.5875 mm is known as fine sand. Fine sand is mainly used for plastering. .  Coarse sand: The sand passing through a sieve with clear openings of 3.175 mm is known as coarse sand. It is generally used for masonry work.  Gravelly sand: The sand passing through a sieve with clear openings of 7.62 mm is known as gravelly sand. It is generally used for concrete work.