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vist :    http://www.sourceinfratech.com contact : 09966871942 important properties of concrete compressive strength/grade of concrete  The compressive strength of concrete is the charactersitic compressive strength of 150 mm concrete cubes at the age of 28 days in N/mm2. the characteristic strength is defined as the strenght of material below  which not more than 5 % if the test results are expected to fall. IS 456-2000 specifies the characteristic comprssive strength of 150 mm cube at the age of 28 days , as the grades of concrete varying from 15 to 80 disgnated as M 15 to M 80 basesd on the characteristic compressive strenght concrete is grades as given below..  

vist : http://www.sourceinfratech.com contact : Rao(09966871942) admixtures:  Admixtures are added to the concrete before or during mixing,to modify one or more of the specific properties of concrete in the fresh or hardened states.IS:9103 1979 lays down the procedures for evolution of admixtures for concrete.the different types of admixtures used are given below. 1. Accelerating admixtures : these are added to concrete to increase the rate of early strength development,which in turn facilitates earlier removal of form work.common accelerators are calcium chloride,fluosilicates and trietanlamine. 2.Retarding Admixtures : these are added to slow down the rate of setting of cement they are useful in hot weather concreting.common types of retarders are starches and cellulose products,sugar and hydroxyl-carboxylic acids. 3. Water Reducing or plasticizing Admixtures : the addition of plasticizer allows greater workability for given water cement ratio or alternatively retains o

http://www.sourceinfratech.com contact:09966871942 water: water plays an active role in the chemical process of hydration of cement and in curing of concrete.hence,the water used for mixing and curing of concrete should be clean and free from injurious amount of oils,acids,alkalies,salts,organic matter etc.that may be deleterious to concrete and  steel,drinking water is generally considered satisfactory for mixing of concrete. sea water should not be used for mixing and curing because of presence of harmful salts in it. the ph value of water should  not be less than 6. the physical and chemical tests for water should be done as per IS:3025

visit : http://www.sourceinfratech.com contact : 09966871942(Rao) tensile strength the tensile strength of concrete is very low and hence it is not taken in to account in the design of reinforced concrete.but it is an important property which affects the extent and width of cracks in the structure.according to IS456-2000,The tensile strenght of concrete can be calculated from the compressive strength  using the following relation. fcr =o.7 square root of fck n/mm2

visit : http://www.sourceinfratech.com contact : 09966871942     Ingrediants of concrete The main ingredient materials in concrete are a)       Cement       b) Aggregates   c) water Cement Cement is the binding material which is obtained by burning calcareous, siliceous and argillaceous materials   together in definite proportions at high temperature and grinding the resultant clinker in to a fine powder. Various types of cements have been developed for the use in different types of structures under different situations. According to IS:456-200,the types of cements and their suitability for a specific situations are given      

visit : http://www.sourceinfratech.com contact : 9966871942 concrete is a composite material consisting of cement,aggregate and water in suitable proportions.the chemical interaction between cement and water binds the aggregates in to a solid mass.fresh concrete will be plastic,so that it can be moulded to any desired shape in the moulds and compacted to form a dense mass.water has to be applied for few days over the concrete surface soon after its setting because the hydration reactions between cement and water continue for a longer period due to which hardening of concrete takes place.this period when concrete is kept moist during which concrete gains strength called curing period. Hence the strength of concrete increases with age. The process of solidification of concrete from plastic stage is called setting while gaining of strength after is called hardening.usually setting completes with in a maximum duration of 10 hours,while about 90% of hardening is completed by 28

visit : http://www.sourceinfratech.com/lightweightbricksmaterials.html contact: 09966871942 how do we caliculate the self weight of the beam? L=10m,size of the beam 300 * 500 mm sol : volume of the slab = 10*0.3*0.5 = 1.5cubic meter self weight of the RCC  = 2500 KG/M3 Weight of the slab = 2500 * 1.5 = 3750 kg = 3.5 tones