is it illegal to draw in wet concrete

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Assistant Professor Civil & Environmental Engg

1. Concrete Mix Design Unit-Iii
2. Syllabus Concrete Mix Design • Mix Design for compressive force by I.S. Method, Road Notation Method, British method, Mix Blueprint for flexural Forcefulness
3. Concrete Mix Design • Physical mix design may be defines equally the art of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing physical of certain minimum strength & durability as economically every bit possible.
four. Objectives of Mix Design • The purpose of concrete mix design is to ensure the near optimum proportions of the elective materials to fulfill the requirement of the structure being built. Mix design should ensure following objectives. • To achieve the designed/ desired workability in the plastic stage • To achieve the desired minimum strength in the hardened stage • To achieve the desired durability in the given environment atmospheric condition • To produce physical every bit economically equally possible.
5. Basic Considerations • The following point must be considered while designing concrete mixes • Cost • Specification • Workability • Strength and Durability
half-dozen. Basic Considerations Toll • The cost of concrete is fabricated up of • Material Cost • Equipment Cost • Labour Price • The variation in the toll of materials arises from the fact that cement is several times costlier than aggregates. So it is natural in mix design to aim at as lean a mix as possible. Therefore, all possible steps should exist taken to reduce the cement content of a concrete mixtures without sacrificing the desirable properties of physical such equally strength and durability.
seven. Basic Considerations Specifications • The following signal may exist kept in heed while designing concrete mixes • Minimum Compressive Force required • Minimum water/ cement ratio • Maximum cement content to avoid shrinkage cracks • Maximum aggregate / cement ratio • Maximum density of physical in case of gravity dams
8. Basic Considerations
9. Bones Considerations Workability • The following points related to workability shall be kept in mind while designing concrete mixes. • The consistency of concrete should no more than that necessary for placing, compacting and finishing. • For physical mixes required high consistency at the time of placing, the use of water-reducing and set-retarding admixtures should be used rather than the add-on of more h2o • Wherever possible, the cohesiveness and finishibility of concrete should exist improved by increasing sand/ aggregate ratio than by increasing the proportion of the fine particles in the sand.
10. Workability
11. Strength and Durability Strength and durability • Strength and durability require lower w/c ratio. It is normally achieved not by increasing the cement content, just by lowering the h2o at given cement content. Water demand can by lowered past throughout control of the aggregate grading and by using water reducing admixtures.
12. Strength and Durability
13. Grade of Concrete • The concrete shall be in grades designated Group Grade designation Characteristics compressive strength of 150 mm cube at 28 days, N/mm2 Ordinary Concrete M10 M15 M20 10 fifteen 20 Standard Concrete M25 M30 M35 M40 M45 M50 M55 25 xxx 35 40 45 50 55 High Strength Concrete M60 M65 M70 M75 M80 60 65 lxx 75 lxxx
14. What is M 20 ? • Thousand refers to Mix • twenty refers to characteristic compressive strength of 150 mm cube at 28 days in N/mm2 • The minimum Form of Evidently Concrete (PCC) shall exist xv N/mm2 • The minimum class of reinforced Concrete ( RCC) shall exist 20 Due north/mm2
15. Nominal Concrete Mixes and Blueprint mix concrete Nominal Mix Concrete • The wide use of concrete as structure materials has led to the use of mixes of stock-still proportion, which ensures adequate force. These mixes are called nominal mixes. • They offering simplicity and Under normal circumstances, has margin of strength above that specified. • Nominal mix physical may be used for concrete of grades M5, One thousand 7.five, M10, M15 and M20.
16. Nominal Physical Mixes and Pattern mix concrete
17. Proportions of Ingredients in Nominal Mixes • The proportions of materials for nominal mix shall exist in accordance Grade Proportions C: FA: CA M5 1: 5:10 M 7.5 one:4:eight 1000 10 1:3:half-dozen M xv 1:two:4 Thousand 20 1:1.v:3
18. Design Mix Concrete • The concrete mix produced under quality control keeping in view the strength, durability, and workability is called the design Mix. • Others factors like compaction equipment's available, curing method adopted, blazon of cement, quality of fine and coarse aggregate etc. have to be kept in listen before arriving at the mix proportion. • The design mix or controlled mix is existence used more and more than in variety of important structures, because of better force, reduced variability, bacteria mixed with consequent economic system, also as greater assurance of the resultant quality.
19. Design Mix Physical
20. Factors Influencing Choice of Mix Design • According to IS 456:2000 and IS 1343:1980 the of import influencing the blueprint of concrete mix are • Grade of Physical • Blazon of Cement • Maximum nominal Size of Aggregate • Grading of Combined aggregate • Maximum H2o/ Cement Ratio • Workability • Durability • Quality Control.
21. Factors Influencing Choice of Mix Design Grade of Physical • The grade of concrete gives characteristic compressive force of concrete. It is i of the important factor influencing the mix design • The grade 1000 20 denotes characteristic compressive strength fck of 20 N/mm2. Depending upon the degree of control available at site, the concrete mix is to be designed for a target mean compressive force (fck) applying suitable standard deviation.
22. Factors Influencing Choice of Mix Design
23. Factors Influencing Selection of Mix Design Blazon of Cement • The rate of development of strength of concrete is influenced by the blazon of cement. • The higher the strength of cement used in physical, bottom will be the cement content. The use of 43 form and 53 grade of cement, gives saving in cement consumption as much equally 15 % and 25 % respectively, as compared to 33 grade of cement. For concrete of class M25 information technology is advisable to apply 43 and 53 grade of cement.
24. Types of Cement
25. Factors Influencing Choice of Mix Design Maximum Nominal Size of Aggregates • The maximum size of C.A is determined by sieve analysis. It is designated by the sieve size higher than larger size on which 15 % or more of the aggregate is retained. The maximum nominal size of C.A. should non be more than than one-forth of minimum thickness of the member. • For heavily reinforced physical members equally in the case of ribs of main beams, the nominal maximum size of the aggregate should usually be restricted to sum less than the minimum clear distance between the main bars or 5 mm less the minimum embrace to the reinforcement, whoever is smaller. • The workability of concrete increases with an increase in the maximum size of aggregate. But the smaller size of aggregates provide larger surface area for bonding with the mortar matrix which gives higher forcefulness.
26. Factors Influencing Choice of Mix Design Grading of Combined Aggregates • The relative proportions of the fine and coarse aggregate in a concrete mix is one of the important factors affecting the force of concrete. • For dumbo physical, information technology is essential that the fine and coarse aggregate be well graded. In the example when the aggregate bachelor from natural sources do non ostend to the specified grading, the proportioning of 2 or more aggregate become essential
27. Grading of Combined Aggregates
28. Factors Influencing Choice of Mix Pattern Maximum H2o/ Cement Ratio • Abram'southward h2o/Cement ratio states that for whatsoever given condition of test, the strength of a workability concrete mix is dependent only on water/cement ratio. The lower the water/Cement ratio, the greater is the compressive strength Workability • Workability of fresh physical determines the case with which a concrete mixture can be mixed, transported, placed, compacted and finished without harmful segregation and bleeding.
29. Factors Influencing Selection of Mix Design Immovability • Durability require low water/Cement ratio. Information technology is usually accomplished non by increasing the cement content, simply by lowering the water demand at a given cement content. • Water demand can be lowered by through control of the aggregate grading and by using water reducing admixtures
30. Method of Physical Mix Blueprint • Some of the commonly used mix pattern methods are • I.S. Method • A.C.I method • Road Note 4 method ( U.Grand. Method) • IRC 44 method • Capricious method • Maximum Density method • Fineness modulus method • Surface area Method • Nix pattern for high strength Concrete • Mix pattern for pumpable Concrete • DOE (British) Mix design method
31. IS Method of Mix Design • The Bureau of Indian Standards, recommended a set of procedure for design of concrete mix. The procedure is based on the research work carried out at national laboratories. • Data for mix design • The following basic data are required to exist specified for design a physical mix • Feature Compressive force just a few specified proportions of test results are expected to autumn of concrete at 28 days (fck) • Caste of workability desired • Limitation on water/Cement Ratio with the minimum cement to ensure acceptable durability • Blazon and maximum size of amass to be used. • Standard deviations of compressive force of physical.
32. IS Method of Mix Design • Target Strength for Mix Pattern • The target average compressive strength (fck) of physical at 28 days is given by • Fck= f ck + t.s Where, • Fck= target average compressive forcefulness at 28 days • F ck= characteristics compressive strength at 28 days • s= Standard deviation • t= a stastical value, depending upon the accustomed proportion of depression results and the number of tests.
33. IS Method of Mix Design • According to Is 456: 2000 and IS 1343:1980 te characteristic strength is defined as the value below which non more than than v percent of results are expected to autumn. In such cases the above equation reduced to • Fck= fck + i.65 south • The value of standard deviation is obtained from the table
34. IS Method of Mix Design
35. IS Method of Mix Design Step-Ii Selection of Water –Cement Ratio • Since unlike cements and aggregates of different maximum sizes, grading, surface texture shape and other characteristics may produce concrete of different compressive strength for the same gratis water cement ratio, the relationship between strength and gratuitous water cement ratio should preferable be established for the material actually to exist used. In the absence of such information, the preliminary gratis water-cement ratio corresponding to the target strength at 28 days may be selected from the relationship shown below
36. IS Method of Mix Pattern
37. IS Method of Mix Pattern • Alternatively, the preliminary gratuitous water cement ratio past mass corresponding to the average forcefulness may be selected from the relationship shown below using the bend corresponding to the 28 days cement strength to exist used for the purpose. All the same, this will demand 28 days for testing of cement.
38. IS Method of Mix Design
39. IS Method of Mix Design • The free water-cement ratio thus selected should be checked against limiting water-cement ratio for the requirements of durability as per table 5.4 and the lower of the ii values should be adopted.
40. IS Method of Mix Design
41. IS Method of Mix Design Step 3 Estimation of Air Content • Approximate amount of entrapped air to be expected in normal concrete is given in table ix.half dozen Nominal Maximum Size of Aggregates Entrapped Air, as percentage of volume of concrete ten iii % 20 2 % 40 1 %
42. IS Method of Mix Design Selection of H2o Content and fine to total aggregate ratio • For the desired workability the quantity of mixing water per unit volume of concrete and the ratio of fine aggregate (sand) to full aggregate by absolute volume are to be estimated from tabular array below as applicable. Depending upon the nominal maximum size and type of amass.
43. IS Method of Mix Pattern • Approximate Sand and water Content per Cubic Metre of Physical for Grades upwardly to Chiliad 35 Westward/C = 0.6 Workability= 0.8 C.F Nominal Maximum size of aggregate (mm) H2o Content per cubic metre of concrete (kg) Sand as per centum of full aggregate by accented volume 10 208 40 20 186 35 40 165 xxx
44. IS Method of Mix Design • Gauge Sand and Water Content per cubic metre of physical for grades higher up M 35 W/C = 0.35 Workability= 0.eight C.F. Nominal Maximum size of Aggregates Water Content per cubic metre of concrete (kg) Sand equally percentage full amass past accented volume of (%) 10 200 28 twenty 180 25
45. IS Method of Mix Design • Adjustment of values in h2o content and sand percentage for other conditions Alter in Condition Adjustment Required Water Content Percentage sand in full aggregate For sand confirming to grading Zones I , Three and 4 0 + one.5 percentage for zone I -one.5 percent for zone III -3.0 for zone Four Increase or decrease in values of compacting gene by 0.1 ± 3 % 0 Each 0.05 increase or decrease in gratis water cement ratio 0 ± 1 % -15 kg/m iii -7 % For rounded aggregates
46. Calculation of Cement Content • The cement content per unit volume of physical may be calculated from the free water-cement ratio obtained in step- 2, and the quantity of water per unit volume of concrete obtained in step-4 • The cement content and so obtained should be checked against the minimum cement content for the requirement of durability as per table 5 IS 456:2000 and the greater of the two value is adopted.
47. Footstep -half-dozen Adding of Aggregate Content • With the quantities of water and cement per unit volume of concrete and the ratio of fine to total aggregate already determined, the total aggregate content per unit volume of concrete may exist calculated from the following equations • V= [ West + C + 1 ten fa ] x one for fine aggregate …………………………i Sc p Sfa 1000 And V = [ W + C + 1 10 Ca ] ten 1 for coarse aggregate …………..two Sc (ane-p) Sca grand
48. Footstep -vi Calculation of Aggregate Content Where, • 5= Absolute volume of fresh concrete (m3) • W= Mass of H2o (kg) per m3 of concrete • C= Mass of Cement (Kg) per m3 of concrete • Sc= Specific gravity of cement say three.15 • P= ratio of fine amass to total aggregate by absolute volume • Fa and Ca = Total masses of fine aggregate and coarse amass (kg) / m3 of concrete mass respectively • Sfa, Sca= Specific gravities of saturated surface dry fine aggregate and fibroid aggregate respectively • Normally Sfa= 2.half-dozen and Sca= 2.seven
49. Trial Mixes • The Calculated mix proportions shall be checked past ways of trial batches. The quantity of fabric should be sufficient for at least three 150 mm size cube physical specimens
50. Case • Using I.Due south Method design a physical mix for reinforced physical structure for the post-obit requirement. • Design data • Characteristic compressive forcefulness= twenty N/mm 2 • Maximum size of aggregates= 20 mm (angular) • Degree of workability= 0.9 CF • Degree of quality Control= Good • Type of exposure= Mild
51. Case • Test data for Material • Cement used= Ordinary Portland cement of grade 43 with 28 days force 51 N/mm2 • SG= 3.xv • Bulk Density = 1450 kg/m3 • Aggregate Fine Aggregate Fibroid Aggregate • SG 2.66 2.75 • Bulk Density 1700 1800 • Water assimilation 1 0.five • Gratuitous Moisture ii Nil
52. Case Stride-I Target Hateful Strength • Fck= fck + ts • fck= 20 N/mm2 • T= 1.65 • S= 4 from table 9.5 for Grand twenty • Therefore • Fck= twenty + 1.65 x 4 • = 26.6 N/mm2 (Mpa)
53. Example Footstep-2 • Option of Water Cement Ratio • From the fig the complimentary water cement ratio required for the target mean forcefulness of 26.6 Due north/ mm2 is 0.v • From fig, for 28 days strength of cement 51 N/mm2, for curve D the free water cement ratio is 0.52 • From table the maximum free h2o cement ratio for mild exposure is 0.55 • Hence the free water cement ratio is taken as the minimum of to a higher place three values i.e. w/c = 0.5
54. Example Step –Three • Interpretation of Air Content • For maximum Size of aggregate of 20 mm, the air content is taken as 2 %
55. Example Step-4 Option of h2o and Sand Content • From table nine.7 for 20 mm nominal maximum size aggregate and sand confirming to grading zone –Two water content per cubic metre of physical = 186 kg and sand content as pct of total amass by absolute volume= 35 % • Water= 186 kg/m3 of concrete • Sand= 35 % of total aggregate by absolute volume
56. Instance • For change in values in water cement ratio, compaction factor and sand belonging to zone III the following adjustments required. Modify in Condition Water Content Pct Sand in total aggregate For Subtract in h2o cement ratio (0.6-0.5) that is 0.1 0.ane x i = two.0 0.05 0 -2.0 For increase in compacting factor (0.nine - 0.8) = 0.1 0.1 x 3 = 3 0.ane + 3 0 For Sand befitting to Zone III 0 -1.5 +3 -3.five
57. Example • Required Water Content = 186 + ( 186 x 3 / 100) • = 186 + 5.58 • = 191.6 lit /m3 = required sand content as percentage of total aggregate by absolute volume= 35 – 3.5 = 31.5 %
58. Example Determination of Cement Content • Water Cement ratio= 0.5 • Water = 191.6 lit= 191.6 kg • Therefore W/c = 0.5 • 191.6 = 0.5 • C • C=383.4 kg/m3 • = 383kg/m3 > 300 kg / m3 therefore O.M.
59. Case Determination of fine and fibroid Aggregates • Consider volume of Physical= 1 m3 • Merely entrapped air in wet concrete = 2 % • Therefore volume of fresh concrete= 1 – 2 100 1- 0.02 Five= 0.98 m3
sixty. Example • With the quantities of water and cement per unit volume of physical and the ratio of fine to full amass already determined, the total aggregate content per unit of measurement volume of physical may be calculated from the post-obit equations • V= [ W + C + one 10 fa ] x i for fine aggregate ………………ane Sc p Sfa 1000 0.98 = [ 191.6 + 383 + 1 + fa ] ten 1 3.15 0.315 2.66 1000 980 = 313.187 + 1.nineteen fa fa= 558.75 kg mass of F.A
61. Example And Five = [ W + C + 1 x Ca ] x 1 for coarse amass …………..2 Sc (one-p) Sca 1000 0.98 = [ 191.6 + 383 x one 10 Ca ] x ane three.15 (1-0.315) 2.75 1000 980 = 313.187 + 0.5308 Ca Ca= 1256.24 kg mass of C.A
62. Instance Water Cement F.A C.A 191.6 li 383 kg 558.75 kg 1256.24 kg 0.five ane 1.46 3.28 Water Cement F.A C.A 383 = 0.264 k 3 1450 558.75 = 0.328 m 3 1700 1256.24 = 0.698 thousand 3 1800 0.5 i.0 i.242 two.644
63. Example Water Cement F.A C.A 25 li 50 kg 73 kg 164 kg
64. Example • Pattern a Concrete mix for M 25 form equally per IS 10262 for the following data: • Feature Compressive Forcefulness in the field at 28 days 25 N/mm2 • Maximum Size of Aggregate= 20 mm • Degree of Workability 0.9 CF • Degree of Quality Control= Good • Type of Exposure = Moderate
65. Example Test data for Material • Cement Used : Ordinary Portland Cement of Course 33 satisfying the requirement of IS: 269-1989 • Specific Gravity of Cement: three.15 • Specific Gravity; • Fibroid Aggregate=two.65 • Fine Amass= two.six • Water absorption • Coarse Aggregate 0.6 % • Fine aggregate= 1.2 % • Free moisture • Coarse aggregate Null • Fine aggregate 2 % • CA accommodate to table 2 of IS 383-1970 FA is natural river Sand Confirming to Zone I of Table 383-1970
66. Example Footstep-I • Target mean Strength of Concrete • Fck= fck + ts • fck= 25 Northward/mm2 • T= i.65 from table 9.iv • Southward= iv.0 from table nine.v for M 25 grade of concrete • Fck= 25 + 1.65 10 4 • = 31.vi Northward/mm2
67. Instance Step-two • Selection of Water-Cement Ratio • From fig nine.one the free water cement ratio required for the target mean strength of 31.half-dozen N/mm 2 is 0.44 • Now, from table v.iv the maximum complimentary water cement ratio for moderate exposure is 0.5 • Hence, the free water cement ratio is taken as the minimum of above two value i.e • W= 0.44 C
68. Example Footstep Iii Estimation of air Content • For maximum Size of Aggregate of xx mm, the air content is taken equally two.0 %
69. Example Step-4 • Selection of Water and Sand Content • From tabular array 9.7 for 20 mm nominal maximum size aggregates and sand confirming to grading Zone-II, water content per cubic metre of concrete = 186 kg and sand content every bit per centum of total amass by absolute volume = 35 % i.e. • Water = 186 kg/m3 • Sand = 35 % of total aggregate past absolute Book.
70. Example • For Change in values in water-Cement ratio, compaction factor and sand belonging to zone I the following adjustments are required.
71. Alter in Condition Aligning Required Water Content Percentage Sand in total Amass (i) For Decrease in Water-Cement ratio (0.vi – 0.44) that is 0.16 Therefore 0.16 x ane = 3.two 0.05 0 -three.2 (ii) For Increase in Compacting factor (0.9 - 0.8)= 0.1 Therefore 0.1 10 iii = 3.0 0.i +three 0 (three) For Sand Conforming to Zone-I of tabular array iv of IS 383-1970 0 +1.v
72. Example • Required water Content = 186 + ( 186 x 3 ) 100 = 191.6 lit / m3 Required Sand Content every bit Percentage of Total amass by absoluter Volume p= 35 – 1.7 = 33.3 %
73. Instance Footstep- V Decision of Cement Content • H2o Cement Ratio = 0.44 • H2o = 191.6 lit = 191.vi kg • Therefore, • W= 0.44 C 191.half dozen = 0.44 C C= 435.45 kg/m3 > 300 kg /m3 This cement content is adequate for 'Moderate Exposure' condition, according to table five IS 456-2000)
74. Example Determination of fine and Fibroid content: • Consider volume of concrete = 1 m3 Only, entrapped air in wet concrete= 2 % Therefore, absolute volume of fresh concrete= 1 – 2 100 = 1 – 0.02 V= 0.98 m3 Therefore,
75. Example • V= [ Westward + C + 1 x fa ] x 1 for fine amass…1 Sc p Sfa thousand And 0.98= [ 191.6 + 436 + ane + fa ] x one 3.15 0.33 2.half dozen 1000 980 = 191.six + 138.41 + i.xv fa fa= 562.76 kg = 563 kg mass of F.A.
76. Example Similarly, Five = [ Due west + C + 1 10 Ca ] 10 1 for coarse amass……..2 Sc (ane-p) Sca grand • 0.98 = [ 191.6 + 436 x ane x Ca ] x i 3.15 (1-0.333) ii.65 1000 980 = 191.half-dozen + 138.41 + 0.5657 Ca Ca= 1149 kg/m3 mass of C.A.
77. Example • Mix Proportions (By Mass) H2o Cement F.A. C.A 191.6 li 436 kg 563 kg 1149 kg 0.44 i 1.29 two.64
78. Example Water Cement F.A. C.A 22 li 50 kg 64.5 kg 132 kg
79. Example Stride 8 Adjustment for water assimilation and free surface wet in F.A. and C.A • For h2o Cement ratio of 0.44 quantity of h2o required = 22 lit • C.A absorbs 0.half-dozen % of water past mass • Therefore extra quantity of water to be added • 0.6 x 132 = 0.792 lit (+) 100 F.A contains 2 % free wet past mass Quantity of water to be deducted = two x 64.v = 1.29 (-) 100 Actual quantity of h2o to be added = 22 + 0.792 – ane.29 = 21.5 lit
fourscore. Example • Actual quantity of sand (FA) required later assuasive for mass of complimentary water • = 64.v + 1.29 = 65.79 kg • Actual quantity of C.A required • = 132 - 0.792 • = 131.21 kg Water Cement F.A. C.A 21.l li 50 kg 65.79 kg 131.21 kg
81. Example • Design a physical mix from the following data past I.S. method • Target hateful Strength= 35 N/mm2 • Maximum Size of Aggregate = twenty mm • Westward/C ratio = 0.43 • Water required per m3 of concrete= 190 kg • Sand as per centum of total aggregate by absolute Book = 35 % • Entrapped air in concrete= two % • Sp gravity of Cement= iii.xv • Sp gravity of fine aggregate= 2.6 • Sp gravity of Coarse amass.= ii.7
82. Example Step-I Target hateful Strength • Fck=35 N/mm2 Step-II Option of H2o-Cement Ratio: • W/C ratio = 0.43 Step-3 Estimation of air Content • Entrapped air = ii % Step-IV • Selection of water and sand Content • Quantity of water per m3 of concrete = 190 kg • Sand Content = 35 % of total aggregate by absolute Book
83. Example Stride-V • Cement Content • H2o-Cement Ratio = 0.43 • Water = 190 kg • W = 0.43 c 190 = 0.43 C C= 441 .86 kg/m3
84. Example Determination of F.A and C.A Content • Consider Book of Concrete = 1 m 3 • But, entrapped air = 2 % • Therefore Absolute Volume of press Physical • V= ane – two 100 V= 0.98 m3
85. Example • V= [ Due west + C + 1 ten fa ] 10 1 for fine amass ………………1 Sc p Sfa 1000 0.98 = [ 190 + 442 + 1 + fa ] 10 1 3.xv 0.35 2.half-dozen g 0.98 = [ 190 + 140.32 + 1.098 fa] ten 1 1000 fa= 591.69 kg/m3 fa= 592 kg/m3 Mass of FA
86. Example Similarly, 5 = [ Westward + C + i x Ca ] x one for coarse aggregate……..2 Sc (ane-p) Sca g • 0.98 = [ 190 + 442 10 i ten Ca ] x ane • iii.14 (1-0.35) 2.seven 1000 • 980 = 190 + 140.32 + 0.569 Ca • Ca= 1142 kg/m3 Mass of CA
87. Instance • Mix Proportion (past mass) • Quantity for 1 bag of Cement H2o Cement F.A C.A 190 442 592 1142 0.43 i 1.34 2.58 Water Cement F.A C.A 21.5 50 67 129
88. The ACI Method of Mix Design • In the United states of america the method suggested by ACI is widely used. It has the advantages of simplicity in that information technology applies every bit well, and with more than or less identical procedure to rounded or athwart aggregate, to normal or lightweight amass and to air-entrained or non-air-entrained concretes. • The ACI method is based on the fact that for a given size of well graded aggregates water content is largely contained of mix proportions, i.e. Water content regardless of variation in water/cement ratio and cement content.
89. The ACI Method of Mix Pattern • This method assumes that the optimum ratio of the bulk volume of coarse aggregates and on the grading of fineness aggregates regardless of shape of particles. This method also assumes that fifty-fifty after complete compaction is done, a definite percentage of air remains which is inversely proportional to the maximum size of aggregate.
ninety. The ACI Method of Mix Design • The steps by steps operation in the ACI method are Footstep-ane Data to be nerveless • Fineness modulus of FA • Unit of measurement weight of dry CA • Specific gravity of FA and CA saturated surface dry out condition. • Specific gravity of Cement • Absorptions characteristics of both CA and FA
91. The ACI Method of Mix Pattern Footstep-2 • Calculation mean design Strength, from the minimum strength specified, using standard deviation: • fm= fmin + K.S • Where, • F m= Specified minimum strength (Characteristic Force) • K= Abiding dependency upon the probability of certain no of results likely to fall fck= taken from tabular array 9.4 • Due south= Standard Deviation from table nine.v
92. IS Method of Mix Design
93. The ACI Method of Mix Design Step-three Estimation of H2o-Cement Ratio • Water Cement ratio is estimated from table 9.10 for the mean design Strength.
94. The ACI Method of Mix Design Average Compressive Strength at 28 days Constructive H2o-Cement Ratio (By Mass) Non-Air Entrained Concrete Air-entrained Concrete 45 0.38 - twoscore 0.43 - 35 0.48 0.4 30 0.55 0.46 25 0.62 0.53 20 0.7 0.61 15 0.8 0.71
95. The ACI Method of Mix Design • The water Cement ratio obtained from Force betoken of view is to be checked against maximum W/C Ratio given for special exposure status given in table ix.xi and minimum of the two is to be adopted.
96. The ACI Method of Mix Design • Requirement of ACI for W/C Ratio and Strength for Special Exposure Condition
97. Exposure Condition Maximum West/C ratio, normal density aggregate physical Minimum Design Forcefulness, depression Density aggregate Concrete, MPA Concrete Intended to be Watertight (a) Exposed to fresh Water (b) Exposed to brackish or sea Water 0.5 0.45 25 thirty Concrete Exposed to freezing and Thawing in a moist Condition: (a) Kerbs, gutters, guard rails or sparse sections 0.45 30 Other elements 0.5 25 In presence of de-icing chemicals 0.45 30 For corrosion protection of reinforced concrete exposed to de- icing salts, brackish water, sea water or spray from the sources. 0.iv 30
98. The ACI Method of Mix Pattern • Make up one's mind maximum size of aggregate to be Used. More often than not RCC piece of work 20 mm and Pre-stressed Concrete 10 mm Size are Used • Decide Workability in terms of slump for the type of job in hand. Full general guidance tin be taken from table nine.12.
99. The ACI Method of Mix Blueprint Type of Construction Range of slump mm Reinforced foundation walls and footings 20-fourscore Evidently ground, cassions and substructure wall 20-80 Beams and Reinforced Wall 20-100 Building Cavalcade 20-100 Pavement and Slabs 20-eighty Mass Concrete 20-lxxx
100. The ACI Method of Mix Pattern Pace-4 Minimum Water Content and entrapped air content: • Decide maximum size of aggregate to exist used. More often than not for RCC work xx mm and for pre-stressed concrete 10 mm size are used. • Make up one's mind workability in terms of slump for the type of chore in paw. Recommended value of slump for various types of structure as given in table 9.12
101. The ACI Method of Mix Design Step-five Cement Content • Cement Content is computed past dividing the water content by the h2o/ Cement Ratio Step-6 • Bulk Book of Dry Rodded Coarse Aggregate per Unit Volume of Concrete • Table 9.thirteen for a decided value of slump and maximum size of aggregate, decide the mixing water content and entrapped air content.
102. Table nine.13 Workability Water Content, kg/m 3 of Concrete for indicated maximum aggregate Size Non- air entrained Concrete Workability ten mm 12.5 mm 20mm 25 mm xl mm fifty chiliad seventy mm 150 mm Slump 30-l mm 205 200 185 180 160 155 145 125 80-100 mm 225 215 200 195 175 170 160 140 150-180 mm 240 230 210 205 185 180 170 - Approx entrapped air content 3 two.5 2 i.v 1 0.v 0.3 0,two
103. Table ix.13 Workability Water Content, kg/1000 iii of Physical for indicated maximum aggregate Size Air entrained Concrete Workability ten mm 12.5 mm 20mm 25 mm 40 mm fifty m lxx mm 150 mm Slump 30-50 mm 180 175 165 160 145 140 135 120 80-100 mm 200 190 180 175 160 155 150 135 150-180 mm 215 205 190 185 170 165 160 -
104. Table nine.13 Workability Water Content, kg/m iii of Concrete for indicated maximum aggregate Size Air entrained Concrete Workabili ty Water Content, kg/m 3 of Concrete for indicated maximum aggregate Size Air entrained Physical ten mm 12.5 mm 20mm 25 mm 40 mm 50 k 70 mm 150 mm Slump 30-l mm 180 175 165 160 145 140 135 120 lxxx-100 mm 200 190 180 175 160 155 150 135 150-180 mm 215 205 190 185 170 165 160 - Recomme nded air Content Mild Exposure 4.5 four 3.v 3.0 ii.5 2.0 ane.5 1.0 Moderate Exposure six.0 5.5 5.0 4.v 4.5 4.0 3.5 3.0 Extreme Exposure vii.v 7.0 6.0 6.0 five.5 5.0 4.5 four.0
105. The ACI Method of Mix Design • Knowing the values of maximum size of coarse aggregates and fineness modulus (FM) of fine aggregate, majority volume of dry rodded aggregate per unit volume of concrete is selected from table 9.xiv • Dry out Majority of Coarse Aggregate per unit of measurement Volume of Concrete equally Given by ACI
106. Maximum Size of Aggregate Bulk Volume of Dry out Rodded Coarse Aggregate per unit volume of concrete for fineness modulus of sand FM 2.iv two.6 2.eight 3.0 10 0.5 0.48 0.46 0.44 12.v 0.59 0.57 0.55 0.53 20 0.66 0.64 0.62 0.half dozen 25 0.71 0.69 0.67 0.65 forty 0.75 0.73 0.71 0.69 50 0.78 0.76 0.74 0.72 70 0.82 0.8 0.78 0.76 150 0.87 0.85 0.83 0.81 (a) The value given volition produce a mix that is suitable for reinforced concrete structure. For less workable concrete the value may be increased by x percent for workable concrete such as pumpable concrete the value may exist reduced by upto 10 percent (b) From the minimum force specified estimate the boilerplate design strength either by using coefficient of variation (c) Observe the water/cement ratio from the tabular array 9.14
107. The ACI Method of Mix Design Step-7 • The weight of CA per cubic metre of Concrete is Calculated by multiplying the bulk Book with bulk density of CA Step-eight Estimate of Density of fresh Concrete • Knowing the maximum Size of Coarse Aggregates, the density of fresh Concrete is estimated as
108. The ACI Method of Mix Design • First Estimate of Density of Fresh Concrete as Given by ACI Maximum Size of Aggregates Non air-entrained air kg/m3 Airentrained kg/m3 10 2285 2190 12.v 2315 2235 20 2355 2280 25 2375 2315 twoscore 2420 2355 50 2445 2375 70 2465 2400
109. The ACI Method of Mix Pattern Step-9 • Accented volumes of ingredients per cubic metre of concrete are obtained by knowing the specific gravity of cement, h2o CA and FA Step- x • Trial mix proportions are calculated and adjustments for field conditions like free moisture and water absorption by aggregates are made. Step-eleven • A trial mix is then made to study the properties of concrete in respect of workability, cohesiveness, finishing quality and 28 days compressive strength. The proportion of CA and FA may exist changed to get desired properties.
110. Example-I Blueprint a Concrete mix Using ACI method for a multi-Storied building for the following data • 28 days characteristic Compressive Strength= thirty Mpa • Type of Cement Bachelor= Ordinary Portland Cement • Desired Slump= 80-100 mm • Maximum Size of aggregate = xx mm • Standard Deviation from past Records = 4.5 Mpa • Specific Gravities for FA= two.65 • Specific Gravity for CA= 2.7 • For Cement= 3.15 • Majority density of CA= 1600 kg/m3 • Fineness modulus of FA= 2.8 • CA captivated one % moisture and sand • Contains 1.5 % costless surface moisture • Assume whatsoever other information
111. Example-I Solution Stride-I • Mean Blueprint Strength • fm= fmin + 1000.S • = 30 + 1.65 x 4.5 • = 37.425 Mpa • From table ix.iv • Assume 5 % of test results are expected fall • Grand= 1.65
112. Case-I Pace-II • Estimation of H2o-Cement Ratio • From tabular array ix.1 for mean pattern strength of 37.425 Mpa, the estimated W/C ratio is 0.45 • From tabular array 9.11, for exposure condition "concrete intended to be watertight and exposed to fresh water", the maximum • w/C ratio is 0.5 • Hence adopt a water cement ratio of 0.45
113. The ACI Method of Mix Blueprint Boilerplate Compressive Strength at 28 days Effective Water-Cement Ratio (By Mass) Not-Air Entrained Physical Air-entrained Concrete 45 0.38 - forty 0.43 - 35 0.48 0.4 30 0.55 0.46 25 0.62 0.53 20 0.vii 0.61 15 0.8 0.71
114. Exposure Condition Maximum Due west/C ratio, normal density aggregate concrete Minimum Design Force, depression Density aggregate Concrete, MPA Concrete Intended to exist Watertight (a) Exposed to fresh Water (b) Exposed to brackish or body of water Water 0.v 0.45 25 thirty Concrete Exposed to freezing and Thawing in a moist Condition: (a) Kerbs, gutters, guard rails or thin sections 0.45 xxx Other elements 0.5 25 In presence of de-icing chemicals 0.45 xxx For corrosion protection of reinforced concrete exposed to de- icing salts, brackish h2o, bounding main water or spray from the sources. 0.4 30
115. Case-I • Mixing water content and entrapped air content • Maximum size of aggregates = 20 mm • Desired Slump= 80-100 • Therefore from table 9.thirteen • Mixing water Content = 200 kg/m3 of Concrete • Entrapped air Content = 2 %
116. Table ix.xiii Workability H2o Content, kg/m 3 of Concrete for indicated maximum amass Size Non- air entrained Concrete Workability x mm 12.5 mm 20mm 25 mm xl mm 50 m 70 mm 150 mm Slump 30-50 mm 205 200 185 180 160 155 145 125 80-100 mm 225 215 200 195 175 170 160 140 150-180 mm 240 230 210 205 185 180 170 - Approx entrapped air content three 2.five 2 1.five i 0.5 0.3 0,2
117. Table ix.13 Workability Water Content, kg/m 3 of Concrete for indicated maximum aggregate Size Air entrained Physical Workability 10 mm 12.five mm 20mm 25 mm 40 mm 50 thou 70 mm 150 mm Slump 30-50 mm 180 175 165 160 145 140 135 120 fourscore-100 mm 200 190 180 175 160 155 150 135 150-180 mm 215 205 190 185 170 165 160 -
118. Table ix.13 Recomme nded air Content Mild Exposure 4.5 iv 3.5 3.0 2.5 2.0 i.5 1.0 Moderate Exposure half dozen.0 5.5 5.0 4.5 four.5 four.0 iii.5 three.0 Extreme Exposure 7.5 7.0 half-dozen.0 half-dozen.0 five.5 v.0 4.five 4.0
119. Example-I Step-4 • Cement Content • W/C ratio = 0.45 • 200 = 0.45 C C= 445 kg/m3 Water = 200 kg/m3 of concrete
120. Example-I Step-v • Majority Volume of Dry Rodded CA: • Maximum Size of CA= 20 mm • Fineness modulus of FA= two.viii • Therefore table 9.14 • The bulk volume of dry rodded CA is 0.62 per unit volume of Concrete
121. Maximum Size of Aggregate Bulk Volume of Dry out Rodded Coarse Aggregate per unit volume of concrete for fineness modulus of sand FM 2.4 2.6 2.8 3.0 ten 0.5 0.48 0.46 0.44 12.5 0.59 0.57 0.55 0.53 twenty 0.66 0.64 0.62 0.6 25 0.71 0.69 0.67 0.65 40 0.75 0.73 0.71 0.69 50 0.78 0.76 0.74 0.72 lxx 0.82 0.8 0.78 0.76 150 0.87 0.85 0.83 0.81 (a) The value given will produce a mix that is suitable for reinforced concrete construction. For less workable physical the value may be increased by 10 percent for workable physical such as pumpable concrete the value may be reduced by upto 10 percentage (b) From the minimum strength specified estimate the average design strength either by using coefficient of variation (c) Find the water/cement ratio from the table 9.14
122. Case-I Footstep-6 • Weight of CA = 0.62 ten 1600 • = 992 kg/m3 • Therefore density of CA is 1600 kg/m3
123. Instance-I Step-7 • Dry density of fresh Concrete • For maximum Size of CA = 200 mm and non air entrained Concrete, • From tabular array 9.fifteen dry density of fresh Concrete = 2355 kg/m3
124. Instance-I Footstep-8 • Mass of all the known Ingredient of Concrete • Mass of water= 200 kg/m3 • Mass of Cement= 445 kg/m3 • Mass of CA= 992 kg/m3 • Mass of FA = 2355-[ 200 + 445 + 992] = 718 kg/m3
125. Example-I Sr.no Ingredient Mass, kg/m3 Absolute Volume m3 1 Cement 445 445 = 0.141 m3 3.15 x 1000 ii H2o 200 200= 0.2 m3 1 x g iii CA 992 992 = 0.367 m3 ii.7 x 1000 four Entrapped Air two % 2 10 1 = 0.02 % 100 Total Accented Volume 0.728 m3
126. • Hence, Volume of FA required = 1-0.728 • = 0.272 m 3 • Mass of FA = 0.272 x 2.65 ten chiliad • = 720.eight kg/m iii • Adopt mass of FA = 720.eight kg/m three • = 721 kg/m 3 • Estimated quantities of material per cubic metre of concrete are • Cement= 445 kg • FA= 721 kg • CA= 992 kg • Water= 200 kg • Full 2358 kg/m3 of Concrete
127. Case-I • Density of fresh Concrete is 2358 kg/m3 as against 2355 Water Cement F.A C.A 200 445 kg 721 kg 992 kg 0.45 1 1.62 2.23 H2o Cement F.A C.A 22.5 kg l kg 81 kg 111.five
128. Example-I • Aligning for water assimilation and free surface moisture • F.A Contains 1.5 % gratuitous surface wet • Total surface wet of FA = i.v x 721 100 = 10.82 kg (-) Mass of FA in field status = 721 + 10.82 = 731.83 kg/m3 Say 732 kg/m3 CA absorbs 1 % of wet, Quantity of water absorbed by CA = i x 992 100 = 9.92 kg (+) Therefore mass of CA in field Status = 992 – 9.92 = 982 kg/m3
129. Example-I • Net Quantity of Mix Water = 200 -10.82+ 9.92 = 199.10 kg • Final mix proportions (for 1 m3 of concrete) H2o Cement F.A. C.A. 199.10 kg 445 kg 732 kg 982 kg
130. The British Method • The traditional British method has been replaced by the department of the environment for normal mixes, known as DOE(British) mix pattern method. • The following steps are Involved in DOE Method Footstep-I • Find the target hateful strength from the specified Characteristic Strength • ft= fck + k.Southward • Where, • ft= target mean strength • fck= feature Force • Southward= Standard Deviation • K= hazard factor or probability factor Physical MIX Design
131. Step-II Determination of gratis h2o cement ratio • From the given type of cement and aggregate, obtain the compressive forcefulness of physical corresponding to free westward/c ratio of 0.five Type of Cement Type of Coarse Amass 3 vii 28 91 Ordinary or Sulphate Resisting Cement Uncrushed Crushed 22 27 30 36 42 49 49 56 Rapid Hardening Portland Cement Uncrushed Crushed 29 34 37 43 48 55 54 61 CONCRETE MIX DESIGN
132. • Now prefer the pair of information i.e. compressive strength read from table ix.sixteen and due west/c ratio mark point 'P'. Through this betoken draw a dotted curve parallel to neighbouring curve. Using this new curve we read the w/c ratio every bit against target strength ft calculated in footstep ane • Check this w/c ratio for durability considerations and prefer the lower value Minimum grade 30 35 xl 45 fifty Maximu 1000 w/c ratio 0.65 0.6 0.55 0.5 0.45 Maximu m cement content 275 300 325 350 400 Concrete MIX Blueprint
133. Fig.i Relation between compressive forcefulness and free water cement ratio  mark a bespeak respective to force f1, at water cement ratio 0.5.  depict a bend parallel to the nearest curve, through this bespeak Using the new curve, Read off ( abscissa) the h2o cement ratio corresponding to the target mean forcefulness (ordinate) Free water-cement ratio CONCRETE MIX DESIGN
134. Step-three Conclusion of h2o Content • Depending upon the type and maximum nominal size of aggregate and workability the water content is estimated as • West= ii West fa + 1 W ca 3 three • Where, • Due west fa= free water content appropriate to the blazon of fine amass • West ca= free water content appropriate to the type of coarse amass CONCRETE MIX DESIGN
135. Level of Workability Very Low Low Medium High Clarification Slump 0-ten 10-thirty thirty-60 60-180 Vee-bee >12 12-vi 6-3 3-0 Compaction Cistron 0.75- 0.85 0.85-0.ix 0.ix- 0.93 >0.93 Maximum Size of Agg Type of aggregate H2o Content x mm Uncrushed 150 180 205 225 Crushed 180 205 230 250 twenty Uncrushed 135 160 180 195 Crushed 170 190 210 225 xl Uncrushed 115 140 160 175 Crushed 155 175 190 205 Concrete MIX Pattern
136. • Reduction in water content when wing ash is Used % of wing ash Reduction in Water content Kg/m3 10 5 v 5 10 20 ten 10 10 15 thirty fifteen 15 xx 20 40 20 twenty 25 25 50 25 25 30 30 Concrete MIX Blueprint
137. Stride 4 - Determination of Cement Content • The Cement Content if the mix is calculated from the selected w/c ratio • Cement Content = water content Due west/C ratio Concrete MIX Design
138. Pace-5 Determination of aggregate Cement Ratio • Absolute volume occupied past the amass • = ane- Cement Content (kg) – Water Content (kg) yard 10 Sc thousand x Sw Where, Sc= Specific gravity of cement particles Therefore Total aggregate content (kg/m3) = accented volume occupied by the aggregate 10 1000x Sa Where Sa= Specific gravity of aggregate
139. Physical MIX DESIGN
140. Step-6 Determination of FA and CA • Depending on the gratuitous water cement ratio, the nominal maximum size of fibroid amass, the workability and grading zone of fine amass is determined from fig nine.5 (a), 9.5 (b) and 9.5 (c) • One time the proportion of FA is obtained, multiplying past the weight of full amass gives the weight of fine aggregate. Then coarse amass is calculated every bit • Fine aggregate content = full aggregate content ten proportion of fine aggregate • Coarse amass content = Total amass content – fine aggregate content Physical MIX DESIGN
141. Conclusion of FA and CA
142. Determination of FA and CA
143. FIG3-Recommendedproportionoffineaggregateasa functionoffreewater–cementratio
144. Proportion of Unlike sizes of CA Aggregate iv.75- 10 mm x-20 mm 20-twoscore mm Blazon-I 33 67 - Type-II 18 27 55 CONCRETE MIX Design
145. Step-7 Determination of concluding Proportion • The proportion so worked out should exist tried for their specified force and suitable adjustment are made to obtain the proportion. CONCRETE MIX Pattern
146. Example • Pattern a Physical mix Using, DOE Method for a reinforced Concrete Work for the following data: • Required Characteristic Compressive Strength= 35 Mpa at 28 days • Type of Cement Used= Sulphate Resisting Portland Cement • Desired Slump= fifty mm • Maximum Size of Aggregate= xx mm • Blazon of Aggregate= Uncrushed • Specific Gravity = 2.65 • Fine amass conforms to grade Zone III with percent passing 600 micron sieve beingness 70 % • Exposure Condition = Moderate • Standard Deviation= 5.0 Defective Rate= 5 % Physical MIX Blueprint
147. Instance • Mix Design Without wing ash: • Target Mean Strength: • Ft= fck+ kS • fck= 35 Northward/mm 2 • Standard Deviation= 5.0 • K= 1.65 • ft= 35 + 1.65 x 5 • = 43.25 N/mm 2 CONCRETE MIX DESIGN
148. Example Decision of free Water-Cement Ratio • For type of Cement Sulphate resisting Portland cement and uncrushed aggregate 28 days compressive strength from tabular array nine.xvi is 42 MPA • For Compressive Strength equal to 42 MPA and w/c ratio 0.5, marking 'P' in fig and describe a dotted bend parallel to the neighbouring curve Using this new curve once more ft= 43.25 North/mm2 the W/C ratio is read as 0.48 • From table ix.17 from immovability point of view the maximum west/c ratio is 0.6 • Hence Adopt the minimum due west/c ratio every bit 0.48 Physical MIX DESIGN
149. Example Step-3 • Determination of Water Content: • For Desired slump = l mm • Maximum size of CA= xx mm • From table 9.18 water content is 180 kg/m3 Concrete MIX Blueprint
150. Instance Pace-iv Determination of Cement Content: • Due west/C ratio obtained from step 2 is 0.48 and water is 180 kg/m3 • W/C = 0.48 • 180 = 0.48 C Therefore C= 375 kg/m3 of Physical This is satisfactory every bit it is greater than minimum Cement Content of 300 kg/m3 CONCRETE MIX DESIGN
151. Instance Step: v • Aggregate Cement Ratio • Specific gravity of aggregate is two.65 • Therefore fig ix.4 wet density of physical is 2400 kg/m3 • Therefore mass of full amass • = 2400 – 180- 375 • = 1845 kg/m3 • Alternatively Volume occupied past aggregate • = 1- 375 – 180 = 0.7009 m3 100x iii.fifteen 1000 ten 1 Therefore full Amass Content = 0.7009 x 1000 ten 2.65 = 1875 kg/m3 CONCRETE MIX Pattern
152. Example Pace-6 Determination of FA and CA Content • For, Maximum size of aggregate = twenty mm • Slump= fifty mm • Free Westward/C ratio = 0.48 • Percent aggregate Passing • 600 micron sieve = 70 % • From fig ix.five (b) the proportion of fine aggregate i.s 30 % • Mass of FA = 30 ten 1875 = 557 kg/m3 • 100 • Mass of CA = 1875 – 557.i • = 1299.9 kg/m3 • = 1300 kg/m3 CONCRETE MIX Blueprint
153. Example Footstep 7 • The estimated Quantity are: Water Cement F.A C.A 180 kg 375 kg 557 kg 1300 kg 0.48 one ane.485 three.46 Physical MIX DESIGN
154. RoadNote No. iv Method Of Mix Design CONCRETE MIX DESIGN
155. Road NOTE No. 4 METHOD OF MIX Design Proposed past the Road Research Laboratory, United kingdom (1950) Introduction In this method, the aggregate to cement ratios are worked out on the basis of type of amass, max size of aggregate and dissimilar levels of workability. The relative proportion of aggregates is worked on footing of combined grading curves. This method facilitates use of different types of fine and fibroid aggregates in the same mix. The relative proportion of these tin can be easily calculated from combined grading curves. The values of aggregate to cement ratio are available for angular rounded or irregular coarse aggregate. CONCRETE MIX Blueprint 156
156. Procedure 1. The boilerplate compressive forcefulness of the mix to exist designed is obtained past applying control factors to the minimum compressive forcefulness. 2. w/c ratio is read from compressive strength v/due south w/c ratio graph. 3. Proportion of combined aggregates to cement is determined from tables, for maximum size 40 mm and 20 mm. 4. If the amass available differs from the standard grading, combine FA and CA so every bit to produce one of the standard grading. five. The proportion of cement, water, FA and CA is determined from knowing the water/cement ratio and the aggregate/cement ratio. 6. Summate the quantities of ingredients required to produce i m3 of concrete, by the absolute volume method, using the specific gravities of cement and aggregates. Physical MIX DESIGN 157
157. CONCRETE MIX Pattern 158 Method In Particular Detect The Target Mean Strength Physical is designed for strength college than feature strength equally a margin for statistical variation in results and variation in degree of control exercised at site. This higher strength is defined every bit the target mean force. Target mean strength = Feature strength + K * s
158. Determine water/cement ratio The relation between Target Hateful Strength and water cement ratio for unlike cement curves is given in IS 10262 CONCRETE MIX DESIGN 159
159. Physical MIX DESIGN 160  Finding cement content
160. Physical MIX DESIGN 161  The Relative Proportion Are Worked Out A trial proportion is taken and combined gradation is worked out for e.thou. 35% fine amass 20% 10mm downwards aggregate, 45% 20mm down aggregate.
161. Concrete MIX Blueprint 162 Combined gradation is plotted and pushed towards Platonic curve past increasing or decreasing the sand content
162. Concrete MIX Pattern 163  Adding Of Cement Content Plastic Density = (1x Sc + one.45x Sfa +0.75x Sca10 +one.six x Sca20 + westward/c)x grand ten (1− Ea) five.26 Sc= Specific gravity of cement Sfa =Specific gravity of fine aggregate Sca10=Specific gravity of 10mm coarse amass Sca20=Specific gravity of 20mm coarse aggregate W/c = water to cement ratio Ea = Entrapped air % Cement Content (Kg/m3) = Plastic density /(i+a/c ratio + w/c ratio) If weight of cement is "C" the full weight per m3 will be C +1.45C + 0.75C +i.6C + 0.46C=v.26C
163. Drawbacks Of Route Note No. 4 Method This method leads to very high cement contents and thus is condign obsolete. In many cases use of gap graded aggregate becomes unavoidable. In many parts of the country the practice is to use 20mm coarse aggregates without 10mm aggregates. This is considering of quality of 10mm aggregates produced from jaw crusher is very poor .Gap grading does non fit in to the standard combined grading curves of RRL method. Sand available in some parts of country is graded that information technology is high on fibroid fraction (1.18mm and higher up) and low on fines (600micron and beneath). It is difficult to arrange the sand content to match whatever of the standard combined grading curves .The combined grading curve oftentimes cuts across more one standard curves in such cases CONCRETE MIX DESIGN 164
164. Unlike aggregate to cement ratios are given for different levels of workability ranging from low to high. But these levels of workability are non defined in terms of slump, compaction factor or Vee Bee time as in example of other methods. The fine aggregate content cannot be adjusted for unlike cement contents. Hence the richer mixes and leaner mixes may accept same sand proportion, for a given gear up of materials. CONCRETE MIX DESIGN 165
165. References • Concrete Technology by: R.P. Rethaliya • Physical Technology by . M.S. Shetty • Internet websites • http://www.foundationsakc.org/
166. Thanks… Concrete MIX Design