Here are only four major components that are usually required for concrete formation. The strength of this concrete mix is determined by the proportion on which these cement, sand, stones or aggregates are mixed. Maximum Water content (10262-table-2) 186 Lit. Cement, Sand, Coarse aggregate, and water with a suitable proportion of water. M25: 2. b) Type of cement :53 grade Ordinary Portland Cement conforming IS 12269. c) Maximum nominal size of coarse aggregate : 20 mm. Mix proportioning for a concrete of M25 grade is given in AI to A-ll. Method Statement For Backfilling Behind Abutment & Around Structures. Density of Cement = 1440 kg/m³. CALCULATION OF COARSE AGGREGATE AND FINE AGGREGATE PROPORTION, From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone III) for water-cement ratio of 0.50 =0.64 (a). But a water-cement ratio as low as 0.44 is seldom needed for foundation concrete. Water-Cement Ratio = 0.50. M25 grade concrete is made by mixing cement, sand and coarse aggregates in a 1: 1: 2 ratio ( 1 part is cement,1 part is sand and 2 part is cement) in which keeping the water-cement ratio between 0.4 and 0.6. Based on the trial , adopted water cement ratio 0.38, From the Table 5 of IS 456 maximum Water Cement Ratio is 0.50, As per MORT&H 5th revision Maximum Water Cement Ratio water cement ratio for moderate exposure is 0.45 , hence it is ok. From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 liter for 25 to 50 mm slump range but for an increase by about 3 percent for every additional 25 mm slump so here estimated water content for 125 mm slump = 186+(9/100) x 186 = 202 liter. 20, Maximum water-cement ratio=0.50 Based on experience, adopt water-cement ratio as 0.43, for the target mean strength and required workability 0.43<0.50, hence O.K. Values in this section should be based on the laboratory tests as per codebook. Degree of Supervision: Good: 9. Aggregate 10 mm = 679.50/ (1+(0.59/100)} = 676.0 kg, 3.Sand = 834.0/ (1+(1.87/100)} = 819.0 kg, 4.Water = 2568 -360 – 819 -554 – 676 = 160.0 kg. 1.Do the trial in dry position as in practical in batching plant you can cot use aggregate in SSD condition. design a concrete for strength m25 (i.e.25 ) specification of materials:- a) grade designation : m25 b) type of cement : opc 43 grade c) max nominal size of : 20mm down aggregate d) min. The maximum water-cement ratio for M25 grade concrete can be found from Table 5-IS456 given above. If the percentage of water used is less then there shall not be sufficient quantity of water to hydrate cement. Mix is stable, cohesive, and workable and had a true slump of about 75 mm. Maximum water cement ratio for M25 mix = 0.61 ( From from ACI 211.1-91 table A1.5.3.4) Hence selected W/C ratio is = 0.46 (based on trials) A-4)Estimation of mixing water and air content As mentioned earlier to adjust fresh concrete properties the water cement ratio will not be altered.ThusCement Content = (197.4/0.5) = 394.8 kg/m3. Now we had got reduction percentage of water , calculate of the required water = 202 – (202 x 32.28) % = 202 – 65.20 = 136.80 (For 75 mm slump increase 3% , for 100 mm increase 6% & increase 9 % for 125 mm slump). As per Table 3 of IS 10262- 2009,Nominal maximum size of aggregate = 20 mm,Fine Aggregate = Zone IIWater/cement = 0.5Volume of coarse aggregate per unit volume of total aggregate = 0.62. V. SELECTION OF WATER CONTENT b)Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}, f)Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of coarse, g)Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine. Thus,Volume of Coarse Aggregate ( CA ) per unit volume of total aggregate = 0.62 x 90% = 0.558Volume of Fine Aggregate ( FA ) = 1 – 0.558 = 0.442, a) Volume of concrete = 1 m3b) Volume of cement = (Mass of cement / Specific gravity of cement) x (1/100)= (383.2/3.15) x (1/1000) = 0.122 m3c) Volume of water = (Mass of water / Specific gravity of water) x (1/1000)= (191.6/1) x (1/1000) = 0.1916 m3d) Volume of total Aggregates = a – (b + c ) = 1 – (0.122 + 0.1916) = 0.6864 m3e) Mass of Coarse Aggregates = 0.6864 x 0.558 x 2.84 x 1000 = 1087.75 kg/m3f) Mass of Fine Aggregates = 0.6864 x 0.442 x 2.64 x 1000 = 800.94 kg/m3, Cement = 383.2 kg/m3Water = 191.6 kg/m3Fine Aggregates = 800.94 kg/m3Coarse Aggregate = 1087.75 kg/m3Water/cement ratio = 0.5, It will satisfy both durability & economy.For casting trial -1, mass of ingredients needed will be calculated for 4 no’s cube assuming 25% wastage.Vol of Concrete needed for 4 cubes = 4 x (0.153 x1.25) = 0.016878 m3Cement = (383.2 x 0.016878) kg/m3 = 6.47 kgWater = (191.6 x 0.016878) kg/m3 =3.23 kgCoarse Aggregate = (1087.75 x 0.016878) kg/m3 =18.36 kgFine Aggregates = (800.94 x 0.016878) kg/m3 = 13.52 kg. Based on experience, adopt water-cement ratio as 0.5. Maximum Nominal Aggregate Size: 20 mm: 4. In this case water / cement ratio is reduced by 10% keeping water content constant. For preliminary calculation, water cement ratio as given is IS-456-Table 5 (also given below) for different environmental exposure condition, may be used. Exposure Condition: Normal: 8. This is caused by the delayed puzzolanic activity of the fly ash. Here is the comprehensive table for concrete mix ratio of various grades of concrete (M7.5, M10, M15, M20, M25, M30, M35, M40), with water content ratio. Dampness In The Building – Causes, effects, and Solution, Stress-strain Curve for Mild Steel explained, Darcy Weisbach Equation Derivation for Head Loss in the pipe, What is T Beam, its advantages and disadvantages, What is Perfect, Imperfect and Redundant Truss, Branches of Surveying explained completely. The exposure condition limits the minimum cement content, maximum water – cement ratio and minimum grade of concrete. We take 0.42 as a ratio of W/C. AI STIPULATIONS FOR PROPORTIONING. Calculation of Cement Content: 1. Water/Cement Ratio - an overview ScienceDirect Topics. Thus, it has achieved desired workability by satisfying the requirement of 50-75 mm slump value . What is Standard MixThis is an old technique for mixing concrete in a manner like 1 cement: 2 sand : 3 aggregates by their volume. 2.Batch for trial is given in dry position. Your email address will not be published. Therefore, target strength of concrete = 25 + 1.65 x 4 = 31.6 N/mm². Type of Aggregate : Crushed Angular Aggregate: 10. Type of Cement: OPC 53 grade confirming to IS-12269-1987: 3. An increase of 0.05 in the water/cement ratio will entail a reduction in the coarse aggregate fraction by 0.01. Weight of Cement = 1440 x 0.28 = 403.2 Kg. 1 Maximum Water Cement Ratio (MORT&H 1700-3 A) 0.45 2 Adopted Water Cement Ratio 0.43 A-5 Selection of Water Content 1 Maximum Water content (10262-table- 2) 186 Lit. As we knowWater/cement ratio = 0.5Estimated water content = 191.6 kg /m3As per IS 456 Table No 5Minimum cement Content = 300 kg/m3 ( mild exposure condition )383.2 kg/m3 > 300 kg/m3, (OK)Now check for durability requiremnt from IS 456In the present scenario against mild exposure and for the case of reinforced concrete the minimum cement content is 300 kg/m3 which is less than 383.2 kg/m3.So,Cement content adopted = 383.2 kg/m3.According to IS: 456 clause 8.2.4.2Maximum cement content = 450 kg/m3. If the water/cement ratio is less than 0.5 (standard value), the volume of coarse aggregate is needed to be increased to decrease the fine aggregate content. The notion of water–cement ratio was first developed by Duff A. Abrams and published in 1918. 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