Project on Concrete Mix Design for various grades of Concrete

1. Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash?

AIM :

To calculate the Concrete mix design for M35 grade concrete with fly ash.

INTRODUCTION :

•  Concrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Portland cement is the commonly used type of cement for production of concrete. Concrete technology deals with study of properties of concrete and its practical applications.

• In a building construction, concrete is used for the construction of foundations, columns, beams, slabs and other load bearing elements.

•  There are different types of binding material is used other than cement such as lime for lime concrete and bitumen for asphalt concrete which is used for road construction

• Various types of cement are used for concrete works which have different properties and applications. Some of the type of cement are Portland Pozzolana Cement (PPC), rapid hardening cement, Sulphate resistant cement etc.

Grade of concrete

• Grade of concrete denotes its strength required for construction. For example, M35 grade signifies that compressive strength required for construction is 35 MPa. The first letter in grade “M” is the mix and 35 is the required strength in MPa.

•  Based on various lab tests, grade of concrete is presented in Mix Proportions. For example, for M35 grade, Lets say the mix proportion can be 1:1:2, where 1 is the ratio of cement, 1 is the ratio of sand and 2 is the ratio of coarse aggregate based on volume or weight of materials.

•  The strength is measured with concrete cube or cylinders by civil engineers at construction site. Cube or cylinders are made during casting of structural member and after hardening it is cured for 28 days. Then compressive strength test is conducted to find the strength.

•  Regular grades of concrete are M15, M20, M25 etc. For plain cement concrete works, generally M15 is used. For reinforced concrete construction minimum M20  and above grade of concrete are used.

OBJECTIVES :

• The main objective is to produce concrete as economically as possible by addition of flyash
• To achieve desired workability, durability and minimum strength of M35 grade concrete

CONCRETE MIX DESIGN CODES :

• IS 10262: 2009
• IS 456:2000
• IS 8112
• IS 9103
• IS 3812 (PART 1)

FORMULAS :

• Target mean strength :f'ck = fck + 1.65s

              where, 

                       f'ck = target mean strength 

                       fck  = compressive strength at 28 days od concrete

                       s     = standard deviation (IS 10262:2009 , table -1)

• volume of cement : (mass of cement / specific gravity of cement) x 1 /1000
• volume of water    : (mass of water /specific gravity of water) x 1 / 1000
• volume of chemical admixture : (mass of chemical admixture / specific gravity of chemical admixture) x 1 /1000
• volume of fly ash  : (mass of fly ash  / specific gravity of fly ash) x 1 /1000
• volume of concrete : 1 m^3
• volume of aggregates : (volume of concrete -(volume of cement + volume of fly ash +volume of water + volume of  admixture)
• mass of coarse aggregates : volume of aggregate x volume of coarse aggregate x specifc gravity of coarse aggregate x 1000
• mass of fine aggregate : volume of aggregate x volume of fine aggregate x volume of fine aggregate x specific gravity of fine aggregate x 1000

PROCEDURE AND CALCULATION :

      1. Target mean strength 

          f'ck = fck +1.65 x s

               here,  fck= 35 N/mm^2  (for M35)

  From table 1 : IS 10262 : 2009, we considered the value of s,

          s = 5N/mm^2

         f'ck = 35 +(1.65 x 5)

               = 43.25 N/mm^2

     2. Selection of Water Cement Ratio 

        For M35 grade;

       Lets say, 

                 Exposure condition : Extreme (for reinforced concrete)

    From table 5 : IS 456 : 2000

        The value of exposure condition for extreme is 0.40

             for M35 = water/cement ratio =0.45

        when the water cement ratio is lower the better gets the workability

        so, 0.40 < 0.45

        here, the water cement ratio  = 0.40

        Minimum cement content = 360 kg/m^3

      3. Selection of water content

         Assume :

                    Nominal size of aggregate = 20mm

    From table 2 : IS 10262 : 2009

          Minimum water content = 186 litres

          Slump ranges from 25 to 50 mm

      Here the superplasticizers reduced to 20%

           Therefore, [100 -20] = 80

                              = 186 x 80/100

                              = 148.8 ~ 149

           Water  content = 149 litres

      4. Calculation of cementitious content (cement + fly ash )    

         Water cement ratio = 0.40 (w/c)

         Water content = 149 kg/ltrs  (w)

         Cementitious content = 149 /0.40 

                                     c  = 372.5 ~ 370 kg/m^3

         Minimum cement content = 360 kg/m^3

                    360 < 370 kg/m^3 

          Hence OK,

           Where, the value incresed by 10%

                    370 x 0.10 + 370 = 407 kg/m^3

                                       w = 149 kg

            Water cement ratio = 149/407 = 0.366

           The total cementitious material content at 30% of fly ash

                                            = 407 x 30/100 

                                            = 122 kg/m^3

           Cement (OPC) = 407 - 122 = 285 kg/m^3

          Usage of flyash instead of cement 

                        = 370 - 285

                        = 85 kg/m^3

          Therefore the flyash = 122 kg/m^3

      5. Volume of course and fine aggregates

             Here,

                    According to the Zone-1, from table-4 of IS 383 , the fine aggregate is sieved 

                    Accordding to the Table -2 from IS 383 , the coarse aggregate is sieved

            From table 3 IS 10262 : 2009

           Nominal size of aggregates = 20 mm (Zone 1)

             Therefore,

                          Volume of Coarse aggregate = 0.60

              The water cement ratio is 0.4 (+/- 0.01 for every +/- 0.005 ) is considered

                 Therefore,

                              The volume of coarse aggregate is 0.62

                              So , the volume of fine aggregate = 1-0.62

                                                                               = 0.38

       6. Calculation of mix proportion

           a) Volume of concrete       = 1 m^3

           b) Volume of cement         =  (285/3.15) x 1 /1000

                                                       =  0.090 m^3

           c) Volume of flyash            = (122/2.2) x 1/1000

                                                       = 0.055 m^3

           d) Volume of water            = (149/1) x 1/1000

                                                       = 0.149 m^3

           e) Volume of admixture     = (7.6/1.145) x 1/1000

                                                       = 0.006 m^3

           f) Volume of coarse and fine aggregate = a - (b + c + d +e)

                                                       = 1 - (0.090 + 0.055 + 0.149 + 0.006)

                                                       = 0.7 m^3

           g) Mass of coarse aggregate   = 0.7 x 0.62 x 2.74 x 1000 

                                                        = 1189.16 kg/m^3

           h) Mass of fine aggregate   = 0.7 x 0.38 x 2.74 x 1000

                                                       = 728.28 kg/m^3

RESULTS :

              Trial mix :

                               cement  = 285 kg/m^3

                                flyash   = 122 kg/m^3

                                 water   = 149 kg/m^3

                                 coarse aggregate = 1189 kg/ m^3

                                  fine aggregate     = 728 kg/m^3

                                  chemical admixture = 7.6 kg/m^3

                                  water cement ratio = 0.366

                Trial mix ratio  = 285 : 728 : 1189

                                         = 1 : 2.55 :4.17 ( cement : fine aggregate : coarse aggregate )

CONCLUSION :

• This trail mix ratio sholud match the workability , durability , and as well as the minimum strength of the concrete which is a M35 grade 
• If it does not satisfy the above criteria two or more trails for increase of 10% should be done
• Hence,this mix design helps to give a brief about the mix design about the M35 grade concrete using fly ash      

 AIM :

        To Calculate the concrete mix design for M50 grade concrete without flyash.

INTRODUCTION :

•  Concrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Portland cement is the commonly used type of cement for production of concrete. Concrete technology deals with study of properties of concrete and its practical applications.

• In a building construction, concrete is used for the construction of foundations, columns, beams, slabs and other load bearing elements.

•  There are different types of binding material is used other than cement such as lime for lime concrete and bitumen for asphalt concrete which is used for road construction

• Various types of cement are used for concrete works which have different properties and applications. Some of the type of cement are Portland Pozzolana Cement (PPC), rapid hardening cement, Sulphate resistant cement etc.

Grade of concrete

• Grade of concrete denotes its strength required for construction. For example, M35 grade signifies that compressive strength required for construction is 35 MPa. The first letter in grade “M” is the mix and 35 is the required strength in MPa.

• Based on various lab tests, grade of concrete is presented in Mix Proportions. For example, for M35 grade, Lets say the mix proportion can be 1:1:2, where 1 is the ratio of cement, 1 is the ratio of sand and 2 is the ratio of coarse aggregate based on volume or weight of materials.

•  The strength is measured with concrete cube or cylinders by civil engineers at construction site. Cube or cylinders are made during casting of structural member and after hardening it is cured for 28 days. Then compressive strength test is conducted to find the strength.

•  Regular grades of concrete are M15, M20, M25 etc. For plain cement concrete works, generally M15 is used. For reinforced concrete construction minimum M20  and above grade of concrete are used.

OBJECTIVES :

• The main objective is to produce concrete as economicallyas possible
• To achieve desired workability, durability and minimum strength of M50 grade concrete

CONCRETE MIX DESIGN CODES :

• IS 10262: 2009
• IS 456:2000
• IS 8112
• IS 9103
• IS 3812 (PART 1)

FORMULAS :

• Target mean strength :f'ck = fck + 1.65s

              where, 

                       f'ck = target mean strength 

                       fck  = compressive strength at 28 days od concrete

                       s     = standard deviation (IS 10262:2009 , table -1)

• volume of cement : (mass of cement / specific gravity of cement) x 1 /1000
• volume of water    : (mass of water /specific gravity of water) x 1 / 1000
• volume of chemical admixture : (mass of chemical admixture / specific gravity of chemical admixture) x 1 /1000
• volume of concrete : 1 m^3
• volume of aggregates : (volume of concrete -(volume of cement + volume of fly ash +volume of water + volume of  admixture)
• mass of coarse aggregates : volume of aggregate x volume of coarse aggregate x specifc gravity of coarse aggregate x 1000
• mass of fine aggregate : volume of aggregate x volume of fine aggregate x volume of fine aggregate x specific gravity of fine aggregate x 1000

PROCEDURE AND CALCULATION :

       1. Target mean strength 

          f'ck = fck +1.65 x s

               here,  fck= 50 N/mm^2  (for M50)

        From table 1 IS 10262 : 2009

                 S = 5 N/mm^2

                f'ck = 50 +(1.65 x 5)

                      = 58.25 N/mm^2

       2. Selection of Water Cement Ratio 

        For M50 grade;

       Lets say, 

                 Exposure condition : Extreme (for reinforced concrete)

    From table 5 : IS 456 : 2000

        The value of exposure condition for extreme is 0.40

             for M35 = water/cement ratio =0.45

        when the water cement ratio is lower the better gets the workability

        so, 0.40 < 0.45

        here, the water cement ratio  = 0.40

        Minimum cement content = 360 kg/m^3

        3. Selection of water content

           Assume :

                      Nominal size of aggregate = 20mm

       From table 2 : IS 10262 : 2009

          Minimum water content = 186 litres

          Slump ranges from 25 to 50 mm

        Here the superplasticizers reduced to 20%

           Therefore, [100 -20] = 80

                              = 186 x 80/100

                              = 148.8 ~ 149

           Water  content = 149 litres

        4. Calculation of cement content

            Water cement ratio = 0.40 (w/c)

            Water content = 149 kg/ltrs  (w)

            Cement content = 149 /0.40 

                                     c  = 372.5 ~ 373 kg/m^3

            Minimum cement content = 360 kg/m^3

                      360 < 373 kg/m^3  

                Hence OK.

        5. Volume of course and fine aggregates

             Here,

                    According to the Zone-1, from table-4 of IS 383 , the fine aggregate is sieved 

                    Accordding to the Table -2 from IS 383 , the coarse aggregate is sieved

          From table 3 IS 10262 : 2009

                 Nominal size of aggregates = 20 mm (Zone 1)

              Therefore,

                          Volume of Coarse aggregate = 0.60

               The water cement ratio is 0.4 (+/- 0.01 for every +/- 0.005 ) is considered

                Therefore,

                              The volume of coarse aggregate is 0.62

                              So , the volume of fine aggregate = 1-0.62

                                                                               = 0.38

         6. Calculation of mix proportion

                         a) Volume of concrete             = 1 m^3

                         b) Volume of cement               =  (373/3.15) x 1 /1000

                                                                           =  0.118 m^3

                         c) Volume of water                  = (149/1) x 1/1000

                                                                           = 0.149 m^3

                         d) Volume of admixture           = (7.6/1.145) x 1/1000

                                                                            = 0.006 m^3

                         e) Volume of coarse and fine aggregate  = a - (b + c + d )

                                                                             = 1 - (0.118 + 0.149 + 0.006)

                                                                             = 0.727 m^3

                         f) Mass of coarse aggregate       = 0.727 x 0.62 x 2.74 x 1000 

                                                                              = 1235.02 kg/m^3

                         g) Mass of fine aggregate           = 0.727 x 0.38 x 2.74 x 1000

                                                                            = 756.9 kg/m^3

RESULTS 

              Trial mix :

                               cement  = 373 kg/m^3

                                 water   = 149 kg/m^3

                                 coarse aggregate = 1235.02 kg/ m^3

                                  fine aggregate     = 756.9 kg/m^3

                                  chemical admixture = 7.6 kg/m^3

                                  water cement ratio = 0.40

                Trial mix ratio  = 373 : 756.9 : 1235.02

                                         = 1 : 2.02 : 3.31 ( cement : fine aggregate : coarse aggregate )

 CONCLUSION

• This trail mix ratio sholud match the workability , durability , and as well as the minimum strength of the concrete which is a M50 grade 
• If it does not satisfy the above criteria two or more trails for increase of 10% should be done
• Hence,this mix design helps to give a brief about the mix design about the M50 grade concrete