IS 10262:2009 Guidelines for concrete mix design proportioning (WIth Design Mix Example)

IS 10262:2009

CONCRETE MIX PROPORTIONING – GUIDELINES

DATA FOR MIX PROPORTIONING

1.  Grade designation;
2.  Type of cement 
3.  Maximum nominal size of aggregate
4.  Minimum cement content
5.  Maximum water-cement ratio
6.  Workability
7.  Exposure condition as per table 4 and table 5 of  IS 456
8.  Maximum temperature of concrete at the time of placing
9. Method of transporting and placing
10. Early age strength requirement, if required
11. Types of aggregate
12. Maximum cement content
13. Whether admixture shall or shall not be used and the type of admixture and the condition of use.

 

1.      Target Strength of Mix Proportioning

 

                      f_ck’   = f_ck + 1.65s

Where;

f_ck’ = Target mean compressive strength at 28 days in N/mm²

f_ck = Characteristic compressive strength at 28 days in N/mm² and

s = Standard deviation N/mm²

 

2.      Standard Deviation  (TABLE 1 OF IS 10262)

 

Grade of concrete                                      Assumed standard deviation (S)

M10 and M15                                                                              3.5 N/mm²

M20 and M25                                                                              4.0 N/mm²

M30, M35, M40, M45, M50, M55 and M60                          5.0 N/mm²

3.      SELECTION OF WATER-CEMENT RATIO

      Mostly water-cement ratio given in Table 5 of IS 456 for respective environment exposure conditions may be used as starting point.

• According to table 5 of IS456 for RCC work maximum free water cement ratio according to environment exposure conditions should be;

Mild                      0.55

Moderate            0.50

Severe                  0.45

Very severe         0.45

Extreme               0.4

4.      SELECTION OF MAXIMUM WATER CONTENT. (TABLE 2 OF IS 10262)

        Selection of maximum water content per cubic metre of concrete for nominal maximum size of aggregate.

Sr no.	Nominal maximum size of aggregate	Maximum water content
1	10 mm	208 kg
2	20 mm	186 kg
3	40 mm	165 kg

Note: These quantities of mixing water are for use in computing cementitious material contents for trial batches.

• ·       Here water content corresponding to saturated surface dry aggregate.
• ·       Above table is for angular coarse aggregate and for 25 mm to 50 mm slump range.
• ·       The water estimate in above table can be reduced by approximately 10 kg for sub-angular aggregate, 20 kg for gravel with some crushed particles and 25 kg for rounded gravel to produce same workability. For the desired workability (other than 25 to 50 mm slump range), the required water content may be established by trial or an increase by about 3 percent for every additional 25 mm slump or alternatively by use of chemical admixtures confirming to IS 9103. (In short slump above 50 mm, the 3% of water increasing by every 25 mm additional slump.)

 

5.     SELECTION OF CEMENTITIOUS MATERIAL CONTENT

        The cementitious material content so calculated shall be checked against the minimum content for the requirement of durability and greater of the two values adopted. The maximum cement content shall be in accordance with IS 456.

6.      VOLUME OF COARSE AGGREGATE (TABLE 3 OF IS 10262)

 

      Volume of coarse aggregate per unit volume of total aggregate for different zones of fine aggregate. (Below table gives the coarse aggregate volume as per zone of FA)

Sr No.	Nominal maximum size of aggregate	Zone 4 FA	Zone 3 FA	Zone 2 FA	Zone 1 FA
1	10 mm	0.50	0.48	0.46	0.44
2	20 mm	0.66	0.64	0.62	0.60
3	40 mm	0.75	0.73	0.71	0.69

Note: Volume are based on aggregate in saturated surface dry conditions.

 

(WHEN ONLY USE CEMENT)

EXAMPLE 1: Design the M40 Grade concrete from following data; 

•         Grade designation: M40
•         Type of cement: OPC
•         Exposure condition: Severe
•         Maximum nominal size of aggregate: 20 mm
•         Maximum water Cement: 0.45 
•         Minimum Cement content = 320  kg/m³ 
•         Workability: 100 mm (slump)
•         Method of concrete placing: Pumping
•         Type of aggregate: crushed angular aggregate
•         Maximum cement content: 450 kg/m³
•         Chemical admixture type: Superplasticizer
•         Sp. Gravity of materials    Cement = 3.15;  CA and FA = 2.74
•         Water absorption:   For CA = 0.5% and For FA= 1.0 %     
•         Free (surface) moisture: For CA and FA = Nil

·       Sieve analysis data :

For CA;   

IS Sieve Sizes (mm)	Analysis of CA Fraction         I                        II		Percentage of different fractions   I                      II                 60%              40%                                                                           100%                                                   Combined			remarks
20	100	100	60	40	100	Confirming to table 2   of IS 383
10	0	71.20	0	28.5	28.5
4.75		9.40		3.7	3.7
2.36		0

           

              For FA;    Confirming to grading Zone I of table 4   of IS 383.

•  Target strength for mix proportioning

                 f_ck’   = f_ck + 1.65s

                         = 40 + 1.65(5)

                         = 48.25 N/mm²

• Water cement ratio from table 5 of IS 456, max free water-cement ratio=0.45

          Based on experience, adopt water-cement ratio as 0.40

                  0.40 < 0.45. Hence O.K.

• From table 2, maximum water content for 20mm aggregate

                                                 = 186 litre (for 25 to 50 mm slump range)     

         Estimated water content for 100 mm slump = 186 + 6*186/100

                                                                                         = 197 litre

As superplasticizer is used, the water content can be reduced up to 20 percent and above.

Based on trial with superplasticizer water content reduction of 29 percent has been achieved. Hence, the arrived water content = 197 x 0.71 = 140 litre.

• Water- cement ratio = 0.40

                     Cement content = 140/ 0.40

                                                   = 350 kg/m³

   From table 5 of IS 456, minimum cement content for ‘severe’ exposure condition         = 320 kg/m³.

       350 kg/m³ > 320 kg/m³ hence, O.K.

             From table 3, volume of CA corresponding to 20 mm aggregate and FA (zone I) for water-cement ratio of 0.50 = 0.60.

               In the present case water-cement ratio is 0.40. Therefore, volume of CA is required to be increased to decrease the fine FA content. As the water-cement ratio is lower by 0.1, the proportion of volume of CA is increased by 0.02(at the rate of +/- 0.01 for every +/- 0.05 change in water-cement ratio).

         Therefore, corrected proportion of volume of CA for the water-cement ratio of 0.40=0.62

[Note: In case of CA is not angular one, then also volume of coarse aggregate may be required to be increased suitably, based on experience.]

For pumpable concrete these value should be reduced by 10 percent.

Therefore, volume of CA = 0.62 x 0.9 = 0.56

Volume of FA content = 1-0.56 = 0.44

       a. Volume of concrete= 1 m³

        b. V0lume of cement = (mass of cement / sp. gravity of cement ) x (1/1000)

                                               = (350/3.15) x (1/1000)

                                               = 0.111 m³

      c. Volume of water = (mass of water / sp. gravity of water) x (1/1000)

                                              = (140/1) x (1/1000)

                                             = 0.140 m³

          d. Volume of chemical admixture (superplasticizer) (@2% by mass of cementitious material)

                         = (Mass of chemical admixture/ sp. gravity of admixture) x (1/1000)

                  = (7/1.145) x (1/1000)

                       = 0.006 m³          

          e. Volume of all in aggregate  = [ a- (b+c+d) ]

                                                                 = 1 – (0.111+0.140+0.006)

                                                                      = 0.743 m³

      f. Mass of CA =  e x Volume of CA x Sp. gravity of CA x 1000

                                 = 0.743 x 0.56 x 2.74 x 1000

                     = 1140 kg

      g.  Mass of FA = e x Volume of FA x Sp. gravity of FA x 1000

                                  = 0.743 x 0.44 x 2.74 x 1000

                                 = 896 kg

 

Hence, for Trial Number 1;

•  Cement = 350 kg/m³
•  Water = 140 kg/m³
•  Fine aggregate = 896 kg/m³
•  Coarse aggregate = 1140 kg/m³
•  Chemical admixture = 7 kg/m³
•  Water-cement ratio = 0.4

 

{NOTE:

             Aggregate should be used in saturated surface dry condition. If otherwise, when computing the requirement of mixing water, allowance shall be made for the free (surface) moisture contributed by the fine and coarse aggregate are dry, the amount of mixing water should be increased by an amount equal to the moisture likely to be absorbed by the aggregate. Necessary adjustment are also required to be made is mass of aggregate. The surface water and percent water absorption of aggregate shall be determined according to IS 2386.}

•         The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial, if required. The mix proportions shall be rewoked for the actual water content and checked for durability requirement.
•        Two more trial having variation of +/- 10% of water cement ratio in above paragraph shall be carried out and a graph between three water cement ratios ad their corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, durability requirement shall be met.  

 (WHEN We USE CEMENT + FLY ASH/GGBFS)

EXAMPLE 2: Design the M40 Grade concrete from following data; 

•         Grade designation: M40
•         Type of cement: OPC
•         Type of mineral admixture: Fly ash
•         Exposure condition: Severe
•         Maximum nominal size of aggregate: 20 mm
•         Maximum water Cement: 0.45 
•         Minimum Cement content = 320  kg/m³ 
•         Workability: 100 mm (slump)
•         Method of concrete placing: Pumping
•         Type of aggregate: crushed angular aggregate
•         Maximum cement content: 450 kg/m³
•         Chemical admixture type: Superplasticizer
•         Sp. Gravity of materials    Cement = 3.15;  CA and FA = 2.74
•         Water absorption:   For CA = 0.5% and For FA= 1.0 %     
•         Free (surface) moisture: For CA and FA = Nil

·       Sieve analysis data :

For CA;   

IS Sieve Sizes (mm)	Analysis of CA Fraction         I                        II		Percentage of different fractions   I                      II                 60%              40%                                                                           100%                                                   Combined			remarks
20	100	100	60	40	100	Confirming   to table 2   of IS 383
10	0	71.20	0	28.5	28.5
4.75		9.40		3.7	3.7
2.36		0

           

              For FA;    Confirming to grading Zone I of table 4   of IS 383.

•  Target strength for mix proportioning

                 f_ck’   = f_ck + 1.65s

                         = 40 + 1.65(5)

                         = 48.25 N/mm²

• Water cement ratio from table 5 of IS 456, max free water-cement ratio=0.45

          Based on experience, adopt water-cement ratio as 0.40

                  0.40 < 0.45. Hence O.K.

• From table 2, maximum water content for 20mm aggregate

                                                 = 186 litre (for 25 to 50 mm slump range)     

         Estimated water content for 100 mm slump = 186 + 6*186/100

                                                                                         = 197 litre

As superplasticizer is used, the water content can be reduced up to 20 percent and above.

Based on trial with superplasticizer water content reduction of 29 percent has been achieved. Hence, the arrived water content = 197 x 0.71 = 140 litre.

• Water- cement ratio = 0.40

                     Cement content = 140/ 0.40

                                                   = 350 kg/m³

   From table 5 of IS 456, minimum cement content for ‘severe’ exposure condition         = 320 kg/m³.

       350 kg/m³ > 320 kg/m³ hence, O.K.

•  Now, to proportion a mix containing fly ash the following steps are suggested:

1.        Decide the percentage fly ash to be used based on project requirement and quality of materials.
2.       In certain situations increase in cementitious material content may be warranted. The decision on increase in cementitious materials content and its percentage may be based on experience and trial.

3.        The illustrative example is with increase of 10% cementitious material content.

            Cementitious materials content = 350 x 1.10 = 385 kg/m³

           Water content = 140 kg/m³

So that,

            Water cement ratio = 140/385 = 0. 364

Fly ash @ 30% of total cementitious material content = 385 x 30/100

                                                                                                = 115 kg/m³

Cement (OPC) = 385 – 115

                          = 270 kg/m³

Saving of cement while using fly ash = 350 – 270 = 80 kg/m³, and

Fly ash being utilized =    115 kg/m³ 

  From table 3, volume of CA corresponding to 20 mm aggregate and FA (zone I) for water-cement ratio of 0.50 = 0.60.

               In the present case water-cement ratio is 0.40. Therefore, volume of CA is required to be increased to decrease the fine FA content. As the water-cement ratio is lower by 0.1, the proportion of volume of CA is increased by 0.02(at the rate of +/- 0.01 for every +/- 0.05 change in water-cement ratio).

         Therefore, corrected proportion of volume of CA for the water-cement ratio of 0.40=0.62

[Note: In case of CA is not angular one, then also volume of coarse aggregate may be required to be increased suitably, based on experience.]

For pumpable concrete these value should be reduced by 10 percent.

Therefore, volume of CA = 0.62 x 0.9 = 0.56

Volume of FA content = 1-0.56 = 0.44

  

     a. Volume of concrete= 1 m³

      b.  V0lume of cement = (mass of cement / sp. gravity of cement ) x (1/1000)

                                               = (270/3.15) x (1/1000)

                                               = 0.086 m³

      c. Volume of fly ash = Mass of fly ash/ Sp. gravity of fly ash ) x (1/1000)

                                              = (115/1) x ( 1/1000)

                                               = 0.052 kg/m³

       d. Volume of water = (mass of water / sp. gravity of water) x (1/1000)

                                              = (140/1) x (1/1000)

                                             = 0.140 m³

      e. Volume of chemical admixture (superplasticizer) (@2% by mass of cementitious material)

                         = (Mass of chemical admixture/ sp. gravity of admixture) x (1/1000)

                  = (7/1.145) x (1/1000)

                       = 0.007 m³          

      f. Volume of all in aggregate  = [ a- (b+c+d+e) ]

                                                                 = 1 – (0.086+0.052+0.140+0.007)

                                                                      = 0.715 m³

     g. Mass of CA =  e x Volume of CA x Sp. gravity of CA x 1000

                                 = 0.715 x 0.56 x 2.74 x 1000

                     = 1097 kg

    h.  Mass of FA = e x Volume of FA x Sp. gravity of FA x 1000

                                  = 0.715 x 0.44 x 2.74 x 1000

                                 = 862 kg

 

Hence, for Trial Number 1;

•  Cement = 270 kg/m³
•         Fly ash = 115 kg/m³
•  Water = 140 kg/m³
•  Fine aggregate = 862 kg/m³
•  Coarse aggregate = 1097 kg/m³
•  Chemical admixture = 7.7 kg/m³
•  Water-cement ratio = 0.364

 

{NOTE:

             Aggregate should be used in saturated surface dry condition. If otherwise, when computing the requirement of mixing water, allowance shall be made for the free (surface) moisture contributed by the fine and coarse aggregate are dry, the amount of mixing water should be increased by an amount equal to the moisture likely to be absorbed by the aggregate. Necessary adjustment are also required to be made is mass of aggregate. The surface water and percent water absorption of aggregate shall be determined according to IS 2386.}

•         The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial, if required. The mix proportions shall be rewoked for the actual water content and checked for durability requirement.
•        Two more trial having variation of +/- 10% of water cement ratio in above paragraph shall be carried out and a graph between three water cement ratios ad their corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, durability requirement shall be met.  

Thank You !