Cement, Energy and Environment

Sand etc.,) is picking up in India in major ci es. Use of scien fically produced Manufactured Sand as an alterna ve to river sand is the need of the hour and will provide a long term solu on to Indian Construc on Industry. Manufactured Sand Manufactured sand is crushed fine aggregate produced from a source material and designed for use in concrete or for other specific products. Only source materials with suitable strength, durability and shape characteris cs should be used. Produc on generally involves crushing, screening and possibly washing. Separa on into discrete frac ons, recombining and blending may be necessary. Crushing Manufactured Sand is produced by feeding hard stones of varying sizes to primary and secondary crushers (Jaw crusher and Cone crusher), for size reduc on and these crushed stones are further crushed in Ver cal Sha Impact (VSI) crusher to reduce the par cle size to that of sand. The VSI crusher by its unique design and ac on of a ri on produces well- shaped fine aggre Ver cal Sha Impact Crusher gate par cles that are cubical and angular. The process of a ri on also enables the reduc on of surface roughness of the fine aggregate par cles to some extent. During the produc on processes, it is ensured that sand stockpiles are not contaminated with weathered/highly altered rock or with clay and other contaminants. Crushing of mul ple source rocks into a single sand stockpile is also not be permi ed unless it can be demonstrated that such a process is under blending control and produces a consistent product. The fine par cles obtained, as a by-product during crushing of rocks to produce coarse aggregates (by jaw crusher and/or cone crusher) is known as Crusher Dust/Quarry Dust. This o en contains higher percentage of dusty, flaky par cles and par cle sizes are un-controlled. This is not suitable for construc on, as they result in higher water demand leading to lack of control on workability / reten on of workability as well as strength issues. Screening and Washing With built-in process of different stages of screening, Manufactured Sand plants ensure proper grading for be er par cle size distribu on. By washing, the percentage of micro fines (passing 75 micron) is controlled below 10% by weight. The washing facility also provides keeps the Manufactured Sand in wet or par ally wet condi on. This will help to reduce the water absorp on rate by Manufactured Sand during concrete manufacturing and hence be er workability and workability reten on. 2