Silt Factor


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Role of FM of sand

The grading and maximum size of aggregates is important parameters in any concrete mix. They affect relative proportions in mix, workability, economy, porosity and shrinkage of concrete etc. Experience has shown that very fine sands or very coarse sands are objectionable – the former is uneconomical, the latter gives harsh unworkable mixes. Thus the object in this paper is to find the best fineness modulus of sand to get the optimum grading of combined aggregate (all-in-aggregate), which is most suitable, and for economy. In general, the grading of aggregates, which do not have a deficiency or excess of any size of aggregate and give a smooth grading curve, produce the most suitable concrete mix. Further a cohesive mix is also desired for the pumped concrete produced by RMC Plant. In the present investigations, effect of the grading of river sand particles has been investigated for a good Concrete mix. Sand has been sorted in three categories i.e. Fine, Medium, and Coarse. These w...
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Softening point IS 1205 1978

Hot the bitumen in oven or on hot plate at 75oc – 110oc above softening point say at 90oc + softening point of bitumen and pour it in the rings Balls weights 3.5 gms and dia of Ball is 9.5 mm After 30 min in air place it in beaker 600 ml and keep it in apparatus the temp of Distilled water should be 0oc and heat it at the rate of 5oc /min place the thermometer and note down the temp when balls touched the lower plate. For CRMB 55 the Softening point is 55oc For CRMB 50 the softening point is 50oc And For CRMB 60 the Softening point is 60oc For Bitumen having the Softening point above 80oc use Glysrine in place of water and the starting temp should be 35oc In IS 1205 1978 the water bath is written to perfotm the test first keep the beaker with sample in water bath for 15 min at 5oc and then allow to rise the temp at 5oc per min.
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Joints in concrete 456/IRC 58

Concrete joints are provided to compensate thermal expansion and contraction. The structural separation of concrete members to allow independent movement without damage. They are designed to absorb thermal expansion of concrete. They are commonly provided in bridges, slabs, railways. Bitumen Fibre Board, Dura Board Normally structures exceeding 45 m in length are designed with one or more expansion joints. The pre planned cutting grooves are given in concrete where occurrence of cracks are expected. The depth of groove is 25% of total thickness of the concrete member. Grooves are given in a straight line. These are due to shrinkage or temperature variations. Cutting grooves with blade. Providing glass strips panels not exceeding 3 sqm area in flooring When the work cannot be completed in a single day, construction joints are provided in concrete. These are common in big rafts, beams where joint is provided at L/3 Nito bond, Sika latex,Bitumen Fibre Board, Dura Board
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