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interaction of concrete mix with water coating on the grains of sand and crushed stone, fills the voids between them, lubricates the aggregate and imparts mobility (fluidity) to the concrete mix. When the cement paste hardens, it binds the aggregate into an artificial stone or concrete. High quality concrete mixture may be produced only with deep knowledge of all manufacturing procedures, a proper choice of quality constituents and their optimum ratio, suitable procedures for preparing concrete mixes, for placing, compacting and hardening them in order to obtain concrete structure of high quality, high strength, durability and low cost. Concrete is one of the major building materials in all branches of modern construction. Possibility of controlling the properties of concrete within a wide range by using appropriate in gradients. the concrete mix should possess adequate plasticity and can readily be shaped in to durable structural items of various sizes and shapes at no considerable labor expenditure. The proper sand with requisite fineness module can achieve the above requisite. The natural river sand is a cheapest resources of sand. Natural sand is weathered and worn out particles of rocks and is of various grades or of size. Depending on the account of wearing. But now a days these resources are erasing very fast. Due to dams constructed on every river the natural sand producing capacity reduce to a considerable extent. Due to fast development of the country the consumption of the sand is also increased. The sand available in the riverbed is very course and contains very much percentage of silt and clay. The silt and the clay presents in the sand reduces the strength of the concrete and holds dampness. Fine particles below 600 microns must be up to at least 35% to 40% for good results. At present these particles are not present in river sand up to the required quantity. Digging the sand, from riverbed in access quantity, is hazardous to environment. The deep pits dug in the riverbed, effects on ground water level. Erosion of the nearby land is also due excess sand lifting. Government has banned for lifting Sand from riverbed in many areas. The sand available and allowed to lift, is of inferior quality. The natural
river sand is the product of sedimentation. Mica, coal, fossils and
other organic impurities
are present in the river sand. The increase of these impurities above certain percentage
makes the sand useless
for concrete work. There is discrepancy in the sand
in two trucks lifted from same source. Hence for important work and to achieve
the quality each truck of sand should be tested. For
getting required fineness module the
sand should be sieved. For this reason to fulfill the requirement of fine aggregate (Sand) some alternative material must be found. In foreign countries alternative to river sand is already in use. Fine cubical particles of stone below 4.75 mm are used, to replace the river sand. But as these particles have sharp edges and rough surface texture, its use in concrete requires some admixtures to increase the plasticity of the wet concrete and mortar. Such machine made sand contains flaky particles, which decreases the workability and requires more water cement ratio. The effect of more water in the concrete reduces its ultimate strength to a substantial amount. To avoid these deficiencies the surface texture of the sand particles should be smooth and edges should be rounded. To overcome
these difficulties we have developed artificial machine made sand similar to river sand.
The sand manufactured by our machine
is having good surface texture and edges
of the granules of the
sand are rounded.
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