CONCRETE MIX DESIGN Sample Example IS 10262 2019

CONCRETE MIX DESIGN (Sample Example) IS 10262: 2019 1

ILLUSTRATIVE EXAPMPLE ON CONCRETE MIX PROPORTIONING (Annex A: IS 10262: 2019) 2

Given Data: Type of Construction: RCC Test Data Grade Designation : M 40 Cement Type : OPC 43 Specific Gravity Water absorption Free surface moisture Expected Water reduction Aggregate Size: 20 mm Cement 2. 88 - - - Workability: 75 mm (Slump) CA 2. 74 0. 5 % Nil - Exposure condition : Severe FA 2. 65 1% Nil - Concrete Placing : Non Pumpable Admixture 1. 145 - - 23 % 1 - - - Type of Aggregate : Angular Water Admixture: Superplasticizer Admixture percentage = 1 % F. A Zone : Zone II 3

Is M 40 grade sufficient for the given exposure condition? ? As per above table, for extreme environmental condition, the grade of concrete should be at least M 30 We are designing for M 40 Hence it is ok. 4

Step 1 : Target mean strength calculation Grade of concrete to be designed = M 40 Expression 1 : Therefore, Expression 2 : Therefore, Final target strength of concrete = Max. of above two = 48. 25 MPa 5

Step 2 : Selection of water-cement ratio Target mean strength of concrete = 48. 25 MPa 80 Curve from IS 10262: 2019 Water-cement ratio corresponding to target strength of 48. 25 MPa and for OPC 43 grade cement curve = 0. 36 28 DAY COMPRESSIVE STRENGTH OF CONCRETE, (MPa) OPC 33 70 OPC 43/ PPC OPC 53 60 Type of Concrete = RCC Exposure condition = Severe As per IS 456: 2000, Maximum permissible Water-cement ratio is 0. 45 50 40 30 20 10 0 0. 25 0. 35 0. 45 0. 55 Water -Cement Ratio 0. 65 Water-cement ratio adopted from chart is lower than the max. permissible value. Hence, water-cement Ratio = 0. 36 is acceptable. 6

Step 3 : Estimation of Air Content Nominal maximum size of aggregate is 20 mm Hence, From table 3, percentage of entrapped air = 1 % Table 4: Water content in mix depending on the max. nominal size of aggregate Size Water Content (kg) 10 mm 208 20 mm 186 40 mm 165 Step 4 : Selection of water content in the mix Nominal maximum size of aggregate is 20 mm Hence, From table 4, basic water content is 186 kg per cu. m of concrete Three corrections are to be applied to this basic value. 7

Aggregate Type Water reduction (kg) Angular 0 Subangular 10 Crushed gravels 20 Rounded gravels 25 Step 4(a) : Aggregate shape correction We have angular aggregates in the mix. Hence, this correction has no effect on basic water content of mix. Wc 1 = (186 - 0) = 186 kg/cu. m of concrete Step 4(b) : Slump value correction Default slump value = 50 mm The water quantity has to be increased by 3% for every increase of 25 mm slump. Expected slump in our mix = 75 mm Excess slump = (75 - 50) = 25 mm Hence, water content has to be increased by 3% Wc 2 = (186 + 0. 03× 186 ) = 191. 58 kg/cu. m of concrete Step 4(c) : Admixture correction Expected water reduction = 23 % Amount of water reduction achievable = 23% Hence, reduce the water content by 23%. Wc 3 = (191. 58 × 0. 77) = 148 kg/cu. m of concrete Therefore, final water content in the mix = 148 kg/ cu. m of concrete. 8

Step 5 : Calculation of cementitious content Minimum cement content = 320 kg/cu. m (RCC , Extreme) Maximum cement content = 450 kg/cu. m (As per IS 456: 2000) OK 9

Step 6 : Quantity of admixture Percentage of admixture = 1% As per IS 456: 2000, Max. permissible admixture content = 2% OK Step 7 : Proportion of coarse aggregate in the mix Nominal max. size of aggregate = 20 mm Zone of fine aggregate = Zone II Basic proportion of C. A = p = 0. 62 Two corrections are to be applied to this basic value. 10

For every decrease of w/c ratio by 0. 05, an increase of aggregate ratio by 0. 01 is recommended and vice versa. • Congested reinforcement = NO • Non-pumpable concrete. Step 7 (a) : Water-cement ratio correction Standard w/c ratio = 0. 5 w/c ratio adopted in mix = 0. 36 Change in w/c ratio = 0. 5 – 0. 36 = 0. 14 Factor of change = 0. 14/0. 05 = 2. 8 Proportion to be increased by = 2. 8× 0. 01 = 0. 028 Updated C. A Proportion = 0. 62+0. 028 = p 1 = 0. 648 Step 7 (b) : Congested reinforcement or pumpable concrete correction As there is no congestion in reinforcement and method of placing is nonpumpable. Hence, no need to reduce proportion of CA in the mix. Final C. A Proportion in the mix = p 2 = 0. 648 11

Step 8: Estimation of Fine aggregate proportion Therefore F. A proportion = 1 – 0. 648 = 0. 352 Step 9: Obtaining volume of ingredients (Table 3) 12

Mass of CA = 0. 695 × 0. 648 × 2. 74 × 1000 = 1234 kg / cu. m of concrete Mass of FA = 0. 695 × 0. 352 × 2. 65 × 1000 = 648 kg / cu. m of concrete Cement 412 kg / cu. m Water 148 kg / cu. m F. A (SSD) 648 kg / cu. m C. A (SSD) 1234 kg / cu. m Admixture 4. 12 kg / cu. m Free W/ C ratio 0. 36 C W CA FA Admixture 1 0. 36 3 1. 57 0. 01 13

Step 11: Site corrections Water absorption by CA = 0. 5 % Water absorption by FA = 1 % CA Free moisture = 0 % FA Free moisture = 0 % Extra water to be added because absorption by FA = 648 -642 = 6 kg/ cu. m Extra water to be added because absorption by CA = 1234 -1228 = 6 kg/ cu. m Final estimated water requirement = 148 + 6 = 160 kg/cu. m 14

Final Quantities after correction Cement 412 kg / cu. m Water 160 kg / cu. m F. A (SSD) 642 kg / cu. m C. A (SSD) 1228 kg / cu. m Admixture 4. 12 kg / cu. m Free W/ C ratio 0. 36 C W CA FA Admixture 1 0. 36 2. 98 1. 56 0. 01 15

Thank You!!! 16