Use Of Artificial Sand
Now a days, in construction of roads, buildings, dams, canals, etc., cement concrete plays an important role. Concrete is an artificial stone resulting from hardening of rationally chosen mixture of binding material, water and aggregate (Sand and crushed stone or gravel). The mixture of these materials, before it hardens, is called concrete mix. Particles of sand and crushed stone from a stone are car-cass in concrete. Cement paste resulting from the 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 labour 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 coarse 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 30% to 50% 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. In routine average wastage of sieving are about 35% and extra Labour cost involved.
To overcome these difficulties Akashganga had developed artificial sand making machine which makes 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.
The particle shape of fine aggregates is very important for making concrete. Recent tests however have shown that a good quality concrete made from the sand having cubicle particles and sharp edges, gives higher tensile strength. Same way rounded sand particles gives more compression strength to the concrete. So to achieve both the effect it is recommended that the sand particles should be cubicle with grounded edges. Where concrete of high strength and good durability is required, fine aggregates confirming to zone one to zone four may be used. The concrete mix design is very important.
The fine aggregates grading becomes progressively finer from zone one to zone four, the ratio of fine aggregates to course aggregates should be progressively reduced. Actual ratio of fine to course aggregates for any particular mix will depends upon the actual grading, particle shape and surface texture of both fine and course aggregates. Use of zone four sand is not recommended for reinforced concrete purpose. Experiments have shown that considerable variation in strength of mortar may occur owing to the form and variety of the sand particles. The strength of mortar may differ by about 50% of average. Sand particles should however be hard for more strength. It is not possible in river sand, that all particles should be of higher strength. This can be achieved only by making sand with the help of machines. In machine made sand we can use the raw material of higher strength. From the above following are the requisites of sand :