Project on Concrete Mix Design for various grades of Concrete

1.The concrete mix design foe M35 grade concrete with fly ash :

Aim : TO CALCULATE THE MIX DESIGN FOR M35 GRADE CONCRETE WITH FLY ASH.

INTRODUCTION :

         Each ingredients used in the concrete mix design is tested for its quality. the aggregates with good strength , shape, specific gravity,and free from organic matters are used.The water use is also of good quality, generally potable water is used. concrete with good quality improves its properties such as strength durability etc. The mix design which is prepared from suitable ingredients in respective propoertions itself improves the concrete properties. fly ash is afinely diveded powder throen out as awaste material at a thermal power plant using pulvarized fuel ash ( PFA ) is a finely diveded powderfor raising stram in the boilers. In builiding inmdustry , the use of fly ash a part repalcement od cement in mortar an dcement at the construction site has been made all over the world includinng India and is well known.

Step-1:

 Stipulations for proportioning : 

    a.Grade designation                                   : M35   

    b.Type of cement                                       : OPC 43 grade ( confirming to IS8112 )

    c.Type of mineral admixture                        : Fly Ash ( confirming to IS3821 part - 1 )

    d.Maximum nominal size of aggregate         : 20 mm

    e.Minimum cement content                         : 320 kg/mm^3 

    f. Maximum water cement ratio                   : 0.45

    g.Workability                                             : 100 mm ( slump )

    h.Exposure condition                                  : sever 

    i.Method of concrete placing                        : pumping

    j.Degree of supervsion                                : Good  

    k.Type of aggregate                                    : Crushed angular aggregate 

    l.Maximum cement ( OPC ) content              : 450 kg/mm^3

    m. Chemical admixture type                         : super plasticizer

step - 2

 Test data for materials :

     a. Cement used                                                      : OPC 43 grade ( confirming to IS8112

     b. Specific gravity of cement                                    : 3.15

     c. Fly Ash                                                               : 2.2

     d. Chemical admiure                                               : Super plasticizer ( confirming to IS1903)

     e. Specific gravity of coarse aggregate                      : 2.74

     f. Water absorption of coarse aggreagte                    : 0.5 percent 

     g.Water absorption of fine aggregate                        : 1.0 percent 

     h. Free surface moisture of Coarse aggregate            : NILL

     i. Free surface absobtion of Fine aggreagte                : NILL

Step- 3

  Target strength for Mix Proportioning : 

      f'ck = fck + 1.645s

  where , 

      f'ck = Target average compressive strength at 28 days,

      f'ck = Characteristic compressive strength at 28 days,     

       s    = standard deviation, and 

     From table 2, ( IS 10262:2009 ) standard deviation , s = 5 N/mm

     Therefore, target strength = 35+1.65*5 = 43.45 N/mm^2

Step - 4

     Selection of water cement ratio :

       From table 5 of IS 456, maximum water cement ratio = 0.45 

           Based on experince , adopt watrer- cement ratio as 0.45 .

                 0.45 = 0.45 hence , O.K

Step - 5 

    Slection of water content :

      From table 2,  maximum water content for 20mm aggregate = 186 liters ( for 25 to 50 mm slump range )

      Estimated water content for 100 slump = 186+(6/100)*186 = 197 liters

      As superplasticizers is used, the water content can be reduced up to 30 percent.

      Based on trails with superplasticizers water content reduction of 2 percent has been achived. 

           Hence , the arrived water content = 197 x 0.71 = 140 liters.

Step - 6 

     CALCULATION OF CEMENT AND FLY ASH CONTENT : 

        Water-cement ratio = 0.45

        cementicious material ( cement + fly ash ) content = (140/0.45) = 311 kg.

        From Table 5 of IS 456 , minimum cement content for ' sever ' exposure conditions 

                                 311kg/m^3  < 320 kg/m^3 , HENCE . O.K

       NOW,

             To proportion amix containing fly ash the following steps are sugested :

          a. Decide the peecentage of fly ash to be used based on project requirement and quality of materials 

          b. In certain situations increase in cemenmtious material content may be warranted, The decision on increase in cementicious material content and its percentage may be based on expercience and 

        Note - This illustrative example is with increase of 10 percent cementicious material content. 

  Therefore,

       Cementitious material content water content = (320 x 1.10)= 352 kg/m^3

         so, water-cement ratio = (140/352)= 0.397 

      Fly Ash @ 30% of total cementitious material content = (352 x 30% ) = 105 kg/m^3.

      Cement ( OPC) = (352 - 247) = 247 kg/m^3.

           saving of cement while using fly ash = ( 320 - 247) = 73 kh/m^3. and 

           Fly ash being utilized = 105 kg/m^3. 

Step - 7 

   PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT : 

    From table 3. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate ( zone 1) for water-cement ratio of 0.45 = 0.60. 

   In the present case water- cement  ratio is 0.45 .

  Therefore, volume of coarse aggregate is required to be increased to decrease the lime aggregate content.

   As the W/C ratio islower 0.10 . The proportion of volume of coarse aggregate is increased by 0.02 ( at the rate of -/+ 00.01 for every -/+  change in W/C ratio). 

  Therefore , corrected proportion of volume of coiarse aggregate for water-cement ratio of 0.45 = 0.62 .

   Note - In case of the ciarse aggregate is not angular one, then also volume of coarse aggregate may be required to be increased suitably.

 Therefore, Based on experience

    For PUMPABLE concrete these values should be reduced by 10 percdent. 

       so , Volume of coarse aggregate = (0.62 x 0.9) = 0.56 . 

             Volume of fine aggregate     = ( 1-0.56)     = 0.44 .

Step - 8

  MIX CALCULATION : 

    The mix calculations per unit voilume of concrete shall be as follows :

    A. Volume of concrete                                                          = 1m3

    B. Volume of cement                                                            = Mass of cement / specific gravity of cement * 1/1000

                                                                                              = (247/3.15)*1/1000

                                                                                              = 0.078m3.

    C. Volume of fly ash                                                             = Mass of fly ash / specific gravity of fly ash *1/1000

                                                                                              = (105/2.2)*1/1000

                                                                                              = 0.047m3.

   D. Volume of water                                                                = Mass of water / specific gravity of water *1/1000

                                                                                               = (140/1)*1/1000

                                                                                               = 0.14m3.

   E. Volume of chemical admixture                                             = Mass of admixture / specific gravity of admixtutre                                                                                                               *1/1000

                                                                                               = ( Superplaticizer) @ 2.0% by mass ( 7/1.0145*1/1000)

                                                                                               =  as of cementious material = 0.007m3.

   F. Volume of all in aggregate                                                   = [ A -(B+C+D+E) ]

                                                                                               = 1-(0.078+0.047+0.140+0.007)

                                                                                               = 0.728m3.

  G. Mass of coarse aggregate                                                    = F * volume of coarse aggregate * specific gravity of                                                                                                            coarse aggregate *100

                                                                                               = 0.728*0.56*2.74*1000

                                                                                               = 1125 kg/m3.

  H. Mass of fine aggregate                                                        = F * VOLUME of fine aggregate *specific gravity of FA*1000

                                                                                               = 0.728 * 0.44*2.74*1000

                                                                                               = 884 kg/m3 .

Step - 9 

   MIX PROPORTIONS FOR trail NUMBER 1 : 

                Cement                  = 247 kg/m3

                Fly Ash                  = 105 kg/m3

                Water                    = 140 liters

                Fine aggregate       = 884 kg/m3

                Coarse aggreagte   = 1125 kg/m3

               Chemical admixture = 7.7 kg/m33

             hence, The MIX RATIO ARRIVED IS 1:3.57:4.55

2. THE CONCRETE MIX DESIGN FOR M50 GRADE WITHOUT USING FLY ASH :

Aim : TO CALCULATE MIX DESIGN OF M50 GRADE CONCRETE WITHOUT USING FLY ASH.

INTRODUCTION:

         The proportions used for the mix design are to calculated as the assumption of the values that are suited to get the required compressive strength.

STEP - 1

    Stipulations for proportioning: 

        a. Grade designation                                  :  M50

        b. Type of cement                                      : OPC 43 Grade ( confirming to IS 8112)

        C. Maximum nominal size of aggregate        : 20mm

        d. Minimum cement content                       : 320 kg/mm^3

        e. Maximum water cement ratio                  : 0.45

        f. Workability                                             : 100m ( slump)

        g. Exposure condition                                 : sever

        h. Method of concrete placing                      : Pumping

        i. Degree of supervision                               : Good 

        j. Type of aggregate                                    : Crushed angular aggregate 

        k. Maximum cement content                        : 450 kg/m^3

        l.Chemical admixture type                           :  Super plasticizers.

Step - 2

    Test datafor materials :

          a. cement used                                         : OPC 43Grade ( confirming to IS 8112)

          b. Specific gravity of cement                      : 3.15

          c. Chemical admixture                               : Super plasticizer ( confirming to IS1903)

          d. Specific gravity of coarse aggregate        : 2.74

          e. Specific gravity of fine aggregate            : 2.74

          f. Water absorbtion of coarse aggregate      : 0.5 percent

          g. Water absorbtion of fine aggregate         : 1.0 percent 

          h.Free surface moisture of Coarse aggregate : NILL

          i. Free surface moisture of fine aggregate      : NILL

Step - 3

    Target strength for Mix proportioning :

       f'ck = fck + 1.65 s

         Where, 

       f'ck = Target average compressive strength at 28 days,

       fck  = Characteristic compressive strength at 28 days,

        s    = Standard deviation , and 

     From table 2 , (IS 10262:2009) Standard deviation s= 5N/mm.

Therefore ,Target strength = ( 50+ 1.62*5) = 58.25 N/mm^2.

Step - 4 

 Selection of Water- cement ratio : 

  From table 5 of IS 456 , maximum water-cement ratio = 0.45  

Based on experience Adopt water - cement ratio as 0.4 .

                      0.4 < 0.45 hence , O.K .

Step - 5 

   Selection of Water content : 

      From tabel 2, maximum water content 20mm aggregate = 186 litre ( for 25 mm to 50mm slump range ).

      Estimated water content for 100mm slump = ( 186+ 6/100*186) = 197 liters.

     As superpalsticizers is used, the water content can be reduced up to 30 percent. 

    Based on trails with superplasticizer water content reduction of 2percent has been achived . Hence , the arrived water content = ( 197 *0.71) = 140 liters.

Step - 6 

   Calculation of cement content : 

        Water- cement ratio = 0.4 

        Cementitious material =  (140/0.4) = 350kg/m^3

        From table 5 of IS 456, Mimimum cement content for sever exposure conditions = 320kg/m^3.

             350 kg/m^3 > 320kg/m^3 Hence O.K.

Step - 7 

     Proportion of volume of coarse aggregate and fine aggregate content : 

     From table 3 , volume of coars eaggregate coresponding to 20 mm size aggregate and fine aggregate ( zone 1) foe water cement ratio opf 0.45 = 0.60.

 In present case water cement ratio is 0.45  .

 Therefore , volume of coarse aggregate is required to be increased to deacrease the lime aggregate content.

 As the w/c ratio is lower as 0.10, the proportion of volume of coarse aggregate may be required to be increased suitabely.

 Based on experience, Foe pumpable concrete these values should be reduced by 10 percent. 

Therfore, Volume of coarse aggregate = ( 0.62 x 0.9 ) = 0.56 

              Volume of fine aggregate content = ( 1-0.56) = 0.44

Step - 8 

      MIX CALCULATIONS 

           The mix calculations per unit voume of concrete shall be as follows: 

           A. Volume of concrete                         = 1m3

           B. Volume of cement                           = ( Mass of cement / specific gravity of cement * 1/1000)

                                                                    = ( 350/3.15 *1/1000)

                                                                    = 0.111m3

          C . Volume of Water                             = (Mass of water / specific gravitry of water * 1/1000

                                                                    = (140/10*1/1000)

                                                                    = 0.14m3

         D. Volume of chemical admixture            = (Mass of admixture / specific gravity of admixture * 1/1000)

          Supwerplasticizer @ 2.0% by mass of cementitious  = 7/1.145 *1/1000 

                                                                     = 0.006m3

         E. Volume of all in aggregate                   = [ A-( B+C+D) ]

                                                                      =( 1- (0.111+0.140+0.006)]

                                                                      = 0.743 m3

         F. Mass of coarse aggregate                     = (E* Volume of coarse aggregate * specific gravity of cpoarse aggregate *1000)

                                                                      = (0.743*0.56*2.74/1000) 

                                                                      = 1140 kg/m3

          G. Mass of fine aggregate                       = (E * volume of fine aggregate * specific gravity of fine aggregate * 1000)

                                                                      = 0.728*0.44*2.74*100                                                                      = 896 kg/m3

 Step - 9 

     MIX PROPERTIONS FOR TRAIL NUMBER 1 :

                 Cement                    = 350kg/m3

                 Water                       = 140 kg/m3                 

                 Fine aggregate          = 896 kg/m3

                 Coarse aggregate      = 1140 kg/m3

                 Chemical admixture   = 7kg/m3

                 Water cement ratio    = 0.4

     HENCE ,  The Mix Ratio arrived is = 1:2.56:3.25