Proportioning of concrete mix

This module covers the proportioning of concrete mix as per BIS standard (IS10262:2009)

1. CE6002 CONCRETE TECHNOLOGY Module 3 PROPORTIONING OF CONCRETE MIX

2. CONCRETE MIX PROPORTIONING Determination of the proportion of the concrete ingredients such as cement, fine aggregate, coarse aggregate, water and admixtures is called concrete mix. A proper mix design only can gives the specified properties such as workability, strength, permeability and durability with economy. Types: Nominal mix Design mix 2/26/2018 Dr.V.Kannan 2

3. TYPES OF MIX PROPORTIONING 1. Nominal mix: As per IS456:2000, fixed mix proportions are available for various grade of concrete is called nominal or standard mix. Usually, this method is suitable the grade of concrete up to M20 or lesser. Example: 2/26/2018 Dr.V.Kannan 3 Grade of concrete Nominal Mix proportions M10 1:3:6 M15 1:2:4 M20 1:1:3

4. TYPES OF MIX PROPORTIONING 2. Design mix: In this type, the concrete mix proportioning is determined on the basis of requirements of concrete on fresh and hardens properties (target mean strength). And to get desired strength, special procedures is to be followed which are available in IS10262-2009 and IS456-2000. Deign mix will give desired properties as like More suitable for higher grade of concrete 2/26/2018 Dr.V.Kannan 4

5. PRINCIPLE / AIM OF MIX PROPORTIONING The grade of concrete, their characteristic strength’s and standard deviations The type of cement The types and sizes of aggregates and their sources of supply The nominal maximum sizes of aggregates Maximum and minimum cement content in kg/m 3 Water cement ratio The degree of workability of concrete based on placing Conditions Air content inclusive of entrained air The maximum/minimum density of concrete The maximum/minimum temperature of fresh concrete Type of water available for mixing and curing The source of water and the impurities present in it. 2/26/2018 Dr.V.Kannan 5

6. STANDARD DEVIATION Standard deviation generally indicates the deviation of a set of variables (RESULTS) from the mean value. Also, a low value of standard deviation indicates more consistent results. On the other hand, higher values represent inconsistent results. Mathematically standard deviation is stated as, the root mean square deviation of all the result. This is denoted by σ. Where, x = Compressive strength of sample μ = Average strength of Samples (x/n) n = Total number of samples for a batch of mix 2/26/2018 Dr.V.Kannan 6

7. FACTOR AFFECTING THE MIX DESIGN / STRENGTH OF CONCRETE Grade designation: Higher grade of concrete (M80 or above) will influence the mix design and subsequent strength of concrete due to the requirements of materials quality, degree of supervision, admixtures etc. Type and grade of cement: For very high compressive strength of concrete, Portland cement of 53 grade can be used. Similarly, where earlier strength is required, rapid hardening cement can be used 2/26/2018 Dr.V.Kannan 7

8. FACTOR AFFECTING THE MIX DESIGN / STRENGTH OF CONCRETE 3. Maximum nominal size of coarse aggregates: If the size of the aggregate is increased, workability will be increased but the strength will be decreased. Grade of combined aggregates: Single sized aggregate may lead the bleeding and segregation of the concrete mix and subsequent strength loss. 5. Fineness modulus: In order to get proper workability and strength, the fineness modulus value for fine and coarse aggregate should be within the prescribed value. 2/26/2018 Dr.V.Kannan 8

9. FACTOR AFFECTING THE MIX DESIGN / STRENGTH OF CONCRETE 6. Water cement ratio: More water cement ratio will give high workability and reduction in strength. Less water cement ratio makes the concrete difficult to handle. 7. Quality control: The concrete materials quality and degree of supervision also may affect the mix design process and strength of concrete. Poor materials will lead the strength reduction. 2/26/2018 Dr.V.Kannan 9

10. ADVANTAGES / IMPORTANCES OF CONCRETE MIX DESIGNS 1. Good quality concrete   2. Nominal mix concrete   3. Best use of available materials 4. Desired Concrete Properties 2/26/2018 Dr.V.Kannan 10

11. Methods of mix design 1. ACI mix design method 2. DOE method 3. USBR mix design 4. British mix design 5. Mix design for pumpable concrete 6. Mix design using BIS guidelines (being in syllabus) 2/26/2018 Dr.V.Kannan 11

12. MIX DESIGN USING BIS GUIDELINES / DATA’S REQUIRED FOR MIX DESIGN 1. Grade of concrete 2. Maximum size of aggregate 3. Minimum cement content 4. Maximum W/C ratio 5. Workability in terms of slump 6. Exposure condition 7. Maximum temperature at the pouring point 8. Early age strength (if required) 9. Grading zone of fine aggregate 10. Type of aggregate 11. Maximum cement content 12. Admixture used 13. Specific gravity of all the materials used 14. Moisture content (free) 2/26/2018 Dr.V.Kannan 12

13. MIX DESIGN PROCEDURE AS PER IS10262:2009 1. Target mean strength of concrete ( f ck ʹ): f ck ʹ = f ck + 1.65 S (N/mm 2 ) Where, f ck = Characteristics compressive strength at 28 days S = Standard deviation (Ref: IS10262:2009, Table 1) 2/26/2018 Dr.V.Kannan 13

14. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 2. Selection of water cement ratio (w/c): From Table 5 of IS456:2000, it can be taken depending upon the exposure conditions (0.4 – 0.6) . 2/26/2018 Dr.V.Kannan 14

15. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 3. Selection of water content: From Table 2 of IS10262:2009, maximum water content = 186 kg (25 mm – 50 mm slump) [For additional slump 3% may be added for every 25 mm slump] 2/26/2018 Dr.V.Kannan 15

16. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 4. Calculation of cement content: It can be calculated by W/C ratio Check by minimum cement content from Table 5 of IS456:2000. Example: W=186 kg W/C = 0.45 C = W/0.45 = 186/0.45 = 413.33 kg 2/26/2018 Dr.V.Kannan 16

17. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 5. Volume of coarse aggregate and fine aggregate content: The proportion of volume of coarse aggregate and fine aggregate can be determined from Table 3 of IS10262:2009 (selected depending upon the fine aggregate ZONE). 2/26/2018 Dr.V.Kannan 17

18. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 6. Mix calculation: The mix calculation per unit volume of concrete shall be as follows; (a) Volume of concrete = 1 m 3 (b) Volume of cement/Cement + admixture = (c) Volume of water = (d) Volume of chemical admixtures (If need) = (e) Volume of aggregates (fine and coarse) = a-( b+c+d ) (f) Mass of coarse aggregate (CA) = e x Volume of CA x Specific gravity of CA x 1000 (g) Mass of fine aggregate (FA) = e x Volume of FA x Specific gravity of FA x 1000 2/26/2018 Dr.V.Kannan 18

19. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 7. Mix proportion: Cement = kg/m 3 Water = kg/m 3 Fine aggregate = kg/m 3 Coarse aggregate = kg/m 3 Chemical admixture = kg/m 3 Water cement ratio = 2/26/2018 Dr.V.Kannan 19

20. MIX DESIGN PROCEDURE AS PER IS10262:2009 (cont.) 8. Mix Ratio: Cement (1) : Fine aggregate/Cement : Coarse aggregate / Cement Example: 1:2:4 2/26/2018 Dr.V.Kannan 20 (1) : :

21. EXAMPLE-1(May/June2016) Design of M30 concrete mix as per IS:10262-2009, concrete mix proportioning guidelines. The following are the design data’s for proportioning: Grade designation : M30 Type of cement : OPC 43 grade confirming to IS8112 Maximum nominal size of aggregate : 20 mm Minimum cement content : 350 kg/m 3 Maximum water cement ratio : 0.50 Workability : 25-50 mm (slump) Exposure condition : Moderate Degree of supervision : Good Type of aggregate : Crushed angular aggregate Maximum cement content : 450 kg/m 3 Chemical admixture : Not recommended Specific gravity of cement : 3.15 Specific gravity of Coarse aggregate : 2.68 Specific gravity of Fine aggregate : 2.65 Water absorption: Coarse aggregate : 0.6 percent Fine aggregate : 1 percent Free surface moisture: Coarse aggregate : Nil Fine aggregate : Nil Sieve analysis: Fine aggregate : Confirming to Zone I of IS383 2/26/2018 Dr.V.Kannan 21

22. EXAMPLE-1 (Cont) Solution: 1. Target mean strength: f ck ʹ = f ck + 1.65 S By referring Table 1 of IS10262:2009, S= 5 f ck ʹ = 30+ 1.65 x 5 = 38.25 N/mm 2 2. Selection of water cement ratio: By referring Table 5 of IS456:2000. Adopt 0.45 < 0.5 (maximum water cement ratio for moderate exposure) 2/26/2018 Dr.V.Kannan 22

23. EXAMPLE-1 (Cont) 3. Selection of water content: By referring Table 2 of IS 10262:2009 Water content (W) for 25mm-50mm slump is 186 litres 4. Calculation of cement content: Water cement ratio is = 0.45 i.e , W/C = 0.45 Therefore cement content, C = W/0.45 = 186/0.45 = 413 kg/m 3 > 350 kg/m 3 Hence O.K . 2/26/2018 Dr.V.Kannan 23

24. EXAMPLE-1 (Cont) 5. Volume of coarse aggregate and fine aggregate: From Table 3 of IS10262:2009 for Zone I fine aggregate with 20 mm sized aggregate; Coarse aggregate volume = 0.6 Fine aggregate volume = 1-0.6 = 0.4 2/26/2018 Dr.V.Kannan 24

25. EXAMPLE-1 (Cont) The mix calculation per unit volume of concrete shall be as follows; Volume of concrete = 1 m 3 (b) Volume of cement/ admixture = = = 0.131 m 3 (c) Volume of water = = = 0.186 m 3 2/26/2018 Dr.V.Kannan 25

26. EXAMPLE-1 (Cont) (d) Volume of chemical admixtures (If need) = = 0 (e) Volume of aggregates (fine and coarse) = a-( b+c+d ) = 1-(0.131+0.186+0) = 0.683 m 3 (f) Mass of coarse aggregate (CA) = e x Volume of CA x Specific gravity of CA x 1000 = 0.683 x 0.6 x 2.68 x 1000 = 1098 kg (g) Mass of fine aggregate (FA) = e x Volume of FA x Specific gravity of FA x 1000 = 0.683 x 0.4 x 2.65 x 1000 = 724 kg 2/26/2018 Dr.V.Kannan 26

27. EXAMPLE-1 (Cont) 7. Mix proportion for trial 1: Cement (C) = 413 kg/m 3 Water (W) = 186 kg/m 3 Fine Aggregate (FA) =724 kg/m 3 Coarse aggregate (CA) = 1098 kg/m 3 Water cement ratio (w/c) = 0.45 8. Trial Mix ratio: 1: 1.75 : 2.65 2/26/2018 Dr.V.Kannan 27

28. EXAMPLE-2(Nov/Dec 2016, Apr/May 2017) Design of M40 concrete mix as per IS:10262-2009, concrete mix proportioning guidelines. The following are the design data’s for proportioning: Grade designation : M40 Type of cement : OPC 43 grade confirming to IS8112 Maximum nominal size of aggregate : 20 mm Minimum cement content : 320 kg/m 3 Maximum water cement ratio : 0.45 Workability : 100 mm (slump) Exposure condition : Severe (for reinforced concrete) Method of concrete placing : Pumping Degree of supervision : Good Type of aggregate : Crushed angular aggregate Maximum cement content : 450 kg/m 3 Chemical admixture : Superplasticizer confirming to IS9103 Specific gravity of cement : 3.15 Specific gravity of Coarse aggregate : 2.74 Specific gravity of Fine aggregate : 2.74 Water absorption: Coarse aggregate : 0.5 percent Fine aggregate : 1 percent Free surface moisture: Coarse aggregate : Nil Fine aggregate : Nil Sieve analysis: Fine aggregate : Confirming to Zone I of IS383 2/26/2018 Dr.V.Kannan 28

29. EXAMPLE-2 (Cont) Solution: 1. Target mean strength: f ck ʹ = f ck + 1.65 S By referring Table 1 of IS10262:2009, S= 5 f ck ʹ = 40+ 1.65 x 5 = 48.25 N/mm 2 2. Selection of water cement ratio: By referring Table 5 of IS456:2000. Adopt 0.4 < 0.45 (maximum water cement ratio for moderate exposure) 2/26/2018 Dr.V.Kannan 29

30. EXAMPLE-2 (Cont) 3. Selection of water content: By referring Table 2 of IS 10262:2009 Water content (W) for 25mm-50mm slump is 186 litres Water content (W) for 100 mm slump is = 186 + 6/100*186= 197 Litres [3% water is increase for every 25 mm slump increments] In this mix design, superplasticizer is going to use, hence the water content can be reduced up to 30%. Therefore revised water content = 197 – 0.3x197 = 138 Litres . 2/26/2018 Dr.V.Kannan 30

31. EXAMPLE-2 (Cont) 4. Calculation of cement content: Water cement ratio is = 0.4 i.e , W/C = 0.4 Therefore cement content, C = W/0.45 = 138/0.45 = 345 kg/m 3 > 320 kg/m 3 Hence O.K . 2/26/2018 Dr.V.Kannan 31

32. EXAMPLE-2 (Cont) 5. Volume of coarse aggregate and fine aggregate: From Table 3 of IS10262:2009 for Zone I fine aggregate with 20 mm sized aggregate and w/c ratio of 0.5; Coarse aggregate volume = 0.6+0.02 (for correction of w/c ratio) = 0.62 It can be reduce to 10%, for pumpable concrete (Ref:IS10262-2009, C-4.4.1) = 0.9 x 0.62 = 0.56 Fine aggregate volume = 1-0.56 = 0.44 2/26/2018 Dr.V.Kannan 32

33. EXAMPLE-2 (Cont) The mix calculation per unit volume of concrete shall be as follows; Volume of concrete = 1 m 3 (b) Volume of cement/ admixture = = = 0.109 m 3 (c) Volume of water = = = 0.138 m 3 2/26/2018 Dr.V.Kannan 33

34. EXAMPLE-2 (Cont) (d) Volume of chemical admixtures (If need) = = = 0.0058 (e) Volume of aggregates (fine and coarse) = a-( b+c+d ) = 1-(0.109+0.138+0.0058) = 0.75 m 3 (f) Mass of coarse aggregate (CA) = e x Volume of CA x Specific gravity of CA x 1000 = 0.75 x 0.56 x 2.74 x 1000 = 1151 kg (g) Mass of fine aggregate (FA) = e x Volume of FA x Specific gravity of FA x 1000 = 0.75 x 0.44 x 2.74 x 1000 = 904 kg 2/26/2018 Dr.V.Kannan 34

35. EXAMPLE-2 (Cont) 7. Mix proportion for trial 1: Cement (C) = 345 kg/m 3 Water (W) = 138 kg/m 3 Fine Aggregate (FA) = 904 kg/m 3 Coarse aggregate (CA) = 1151 kg/m 3 Chemical admixture (SP) = 7 kg/m 3 Water cement ratio (w/c) = 0.4 8. Trial Mix ratio: 1: 2.62 : 3.33 2/26/2018 Dr.V.Kannan 35

36. EXAMPLE-3(Nov/Dec 2016, Apr/May 2017) Design of M40 grade pumpable concrete with fly ash mix as per IS:10262-2009, concrete mix proportioning guidelines. The following are the design data’s for proportioning: Grade designation : M40 Type of cement : OPC 43 grade confirming to IS8112 Maximum nominal size of aggregate : 20 mm Minimum cement content : 320 kg/m 3 Maximum water cement ratio : 0.45 Workability : 100 mm (slump) Exposure condition : Severe (for reinforced concrete) Method of concrete placing : Pumping Degree of supervision : Good Type of aggregate : Crushed angular aggregate Maximum cement content : 450 kg/m 3 Chemical admixture : Superplasticizer confirming to IS9103 Specific gravity of cement : 3.15 Specific gravity of fly ash : 2.2 Specific gravity of Coarse aggregate : 2.74 Specific gravity of Fine aggregate : 2.74 Water absorption: Coarse aggregate : 0.5 percent Fine aggregate : 1 percent Free surface moisture: Coarse aggregate : Nil Fine aggregate : Nil Sieve analysis: Fine aggregate : Confirming to Zone I of IS383 2/26/2018 Dr.V.Kannan 36

37. EXAMPLE-3 (Cont) Solution: 1. Target mean strength: f ck ʹ = f ck + 1.65 S By referring Table 1 of IS10262:2009, S= 5 f ck ʹ = 40+ 1.65 x 5 = 48.25 N/mm 2 2. Selection of water cement ratio: By referring Table 5 of IS456:2000. Adopt 0.4 < 0.45 (maximum water cement ratio for moderate exposure) 2/26/2018 Dr.V.Kannan 37

38. EXAMPLE-3 (Cont) 3. Selection of water content: By referring Table 2 of IS 10262:2009 Water content (W) for 25mm-50mm slump is 186 litres Water content (W) for 100 mm slump is = 186 + 6/100*186= 197 Litres [3% water is increase for every 25 mm slump increments] In this mix design, superplasticizer is going to use, hence the water content can be reduced up to 30%. Therefore revised water content = 197 – 0.3x197 = 138 Litres . 2/26/2018 Dr.V.Kannan 38

39. EXAMPLE-3 (Cont) 4. Calculation of cement content: Water cement ratio is = 0.4 We know that, W/C = 0.4 Therefore cement content, C = W/0.4 = 138/0.4 = 345 kg/m 3 > 320 kg/m 3 Hence O.K. [To add fly ash or other mineral admixture, 10% of cement content may be added ] The cementitious material content = 1.1x345 = 380 kg/m 3 Let us use fly ash at 30% Therefore; Fly ash content = 0.3x380 = 114 kg/m 3 Cement content = 0.7x380 = 266 kg/m 3 2/26/2018 Dr.V.Kannan 39

40. EXAMPLE-3 (Cont) 5. Volume of coarse aggregate and fine aggregate: From Table 3 of IS10262:2009 for Zone I fine aggregate with 20 mm sized aggregate and w/c ratio of 0.5; Coarse aggregate volume = 0.6+0.02 (for correction of w/c ratio) = 0.62 It can be reduce to 10%, for pumpable concrete (Ref:IS10262-2009, C-4.4.1) = 0.9 x 0.62 = 0.56 Fine aggregate volume = 1-0.56 = 0.44 2/26/2018 Dr.V.Kannan 40

41. EXAMPLE-3 (Cont) Volume of concrete = 1 m 3 (b) Volume of cement = = = 0.084 m 3 (c) Volume of fly ash = = = 0.052 m 3 (d) Volume of water = = = 0.138 m 3 2/26/2018 Dr.V.Kannan 41

42. EXAMPLE-3 (Cont) (e) Volume of chemical admixtures (If need) = = = 0.0066 (f) Volume of aggregates (fine and coarse) = a-( b+c+d+e ) = 1-(0.084+0.054+0.138+0.0066) = 0.71 m 3 (f) Mass of coarse aggregate (CA) = f x Volume of CA x Specific gravity of CA x 1000 = 0.71 x 0.56 x 2.74 x 1000 = 1090 kg (g) Mass of fine aggregate (FA) = f x Volume of FA x Specific gravity of FA x 1000 = 0.71 x 0.44 x 2.74 x 1000 = 856 kg 2/26/2018 Dr.V.Kannan 42

43. EXAMPLE-3 (Cont) 7. Mix proportion for trial 1: Cement (C) = 266 kg/m 3 Fly ash (F) = 114 kg/m 3 Water (W) = 138 kg/m 3 Fine Aggregate (FA) = 856 kg/m 3 Coarse aggregate (CA) = 1090 kg/m 3 Chemical admixture (SP) = 7.6 kg/m 3 Water cement ratio (w/c) = 0.4 8. Trial Mix ratio: 1 : 2.25 : 2.86 2/26/2018 Dr.V.Kannan 43

44. THANK YOU 2/26/2018 Dr.V.Kannan 44