Project on Concrete Mix Design for various grades of Concrete

DESIGN OF M35 GRADE OF CONCRETE MIX USING FLYASH

1. Stipulations for Proportion.
   • Grade of concrete: M35
   • Type of cement: OPC 43 grade confirming to IS8112
   • Type of Mineral Admixtures: fly ash confirming to IS3812(Part 1)
   • Maximum size of aggregate:20 mm
   • Exposure condition: Severe (for reinforced concrete)
   • Minimum cement content :320kg/m³
   • Maximum water-cement ratio:0.45
   • Workability in terms of cement:100 mm (for pumpable concrete)
   • Method of concrete placing: pumping
   • Degree of supervision: Good
   • Type of aggregate: Crushed angular aggregate.
   • Maximum cement content :450kg/m³ (Clause 8.2.4.2. pg.19 IS456:2000)
   • Chemical admixtures type: Superplasticizer
2. Test Data for Materials.
   • Cement used: OPC 43
     1. Specific Gravity of cement:3.15
   • Fly ash confirming to IS3812(Part 1)
     1. Specific Gravity of fly ash: 2.2
   • Chemical Admixtures: superplasticizer confirming to IS9103
   • Specific Gravity of Aggregates
     1. Specific Gravity of coarse aggregate:2.74
     2. Specific Gravity of fine aggregate:2.74
3. Target Strength for Mix Proportioning.

   f_t =f_ck +1.65 S

   Where,

   S=Standard deviation given in table no. 1 of IS10262:2005

   Therefore the value of

   f_t =`35 +(1.65×5)`

   f_t = 43.25N/mm².

4. Selection of Water-Cement Ratio.
   • To calculate the water-cement ratio from graph 2 of IS4031:1968

   From the graph, we got the value 0.41.

   • The maximum water-cement ratio for a severe condition for reinforced concrete is 0.45.
   • So the minimum value opts for the mix design which is 0.41.
5. Selection of Water Content.

   From table 2 of 10262:2009

   Maximum water content for 20mm aggregate= 186 litres (for slump value of 25mm to 50mm)

   To calculate the water for 100mm slump = 186+`(6×186)/100`=197 kg.

   As a superplasticizer is used, the water content can be reduced by upto 30%.

   For this trail, we reduce the water content by 29%.

   Hence,

   Water content = `197× (1-0.29) `

   = 140 litres.

6. Calculation of Cement Content.
   • Water-cement ratio=0.41
   • Cementiouds material (cement + fly ash) = ` (140/0.41) ` = 341.46.
   • From table 5 of IS 456:2000, the minimum cement content for SEVERE exposure condition for reinforced concrete is 320 kg/m³_­­.
   • 46 kg/m³_­­ > 320 kg/m³_­­.
   • Hence, OK.
   • Now, to proportion a mix containing fly ash the following steps are suggested.
     1. The percentage of fly ash is based on project requirement and Quality of material.
     2. An increase in cementitious material content and its percentage may be based on experience and trial(for this example with an increase of 10% cementitious material content)
     3. Cementitious material= `341.46 × 1.10`

        = 375.606 kg/m³_­­.

     4. Water content = 140 kg/m³_­­.
     5. Water-cement ratio=`140/375.606`

        =0.372

     6. Fly ash @30% of total cementious material = 375.606× 0.30

        = 112.68 kg/m³_­­.

     7. Cement content =375.606-112.68

        = 262.926 kg/m³_­­.

     8. Cement saved using fly ash =341.46-262.926

        = 78.53 kg/m³_­­.

7. The proportion of Volume of Aggregates (Coarse and Fine Aggregate).

   From table 3 of IS10262:2009 volume of coarse aggregate corresponding to 200mm size aggregate and fine aggregate(Zone 1) for a water-cement ratio of 0.5= 0.6

   In the present case, the water-cement ratio = 0.41

   Therefore the volume of coarse aggregate has to be increased to decrease fine aggregate.

   As the water-cement ratio reduces by 0.09 the proportion of the volume of coarse aggregate increased by 0.02. (As the rate is for every 0.05 reduction in the w/c ratio add 2% to coarse aggregate ratio)

   Therefore the corrected volume of coarse aggregate for the water-cement ratio of 0.41 = 0.62

   Here we are using the pumping method for placing concrete,

   So, for pumpable concrete, this value is reduced by 10%

   Therefore,

   Volume of coarse aggregate = 0.62× 0.90 =0.56

   Volume of fine aggregate =1- 0.56 =0.44

8. Mix Calculations.
   1. Volume of Concrete = 1 m³.
   2. The volume of Cement =`(Mass of cement)/(Specific Gravity of Cement)×1/1000`

      = `262.926/3.15×1/1000`

      =0.0834 m³.

   3. The volume of Fly ash = `(Mass of Fly ash)/(Specific Gravity of Fly ash)×1/1000`

      = `112.86/2.2×1/1000`

      =0.0513 m³.

   4. The volume of Water =`(Mass of Water)/(Specific Gravity of Water)×1/1000`

      =`140/1×1/1000`

      =0.1400 m³.

   5. The volume of chemical admixtures =`(Mass of chemical Admixtures)/(Specific Gravity of Chemical Admixtures)×1/1000`

      =`7.51/1.145×1/1000`

      =0.006 m³.

   6. Volume of Aggregate(C.A. & F.A.) ={(a)- [(b)+(c)+(d)+(e)]}

      = {1-(0.0834+0.0513+0.1400+0.006)}

      =0.7193 m³.

   7. Mass of coarse aggregate = [(f)×volume of CA× Specific gravity of CA×1000]

      =0.7139×0.56×2.74×1000

      =1103.6939 kg.

   8. Mass of coarse aggregate =[(f)×volume of FA× Specific gravity of FA×1000]

      =0.7139×0.44×2.74×1000

      =867.1880 kg.

9. Mix Proportion for the Trail.

• Cement - 262.926 kg/m³_­­.
• Fly ash - 112.68 kg/m³_­­.
• Water - 140 kg/m³_­­.
• Fine aggregate - 867.1880 kg.
• Coarse aggregate - 1103.6939 kg/m³_­­
• Chemical Admixtures - 7.51 kg/m³_­­(@2% of total cementitious material)
• Water-cement Ratio - 0.372

Trail Mix Ratio = 1 : 2.30 : 2.94

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CONCRETE MIX DESIGN FOR M50 GRADE OF CONCRETE

1. Stipulations for Proportion.
   • Grade of concrete: M50
   • Type of cement: OPC 53 grade confirming to IS8112
   • Type of Mineral Admixtures: fly ash confirming to IS3812(Part 1)
   • Maximum size of aggregate:20 mm
   • Exposure condition: Very Severe (for reinforced concrete)
   • Minimum cement content :340kg/m³
   • Maximum water-cement ratio:0.45
   • Workability in terms of cement:100 mm (for pumpable concrete)
   • Method of concrete placing: pumping
   • Degree of supervision: Good
   • Type of aggregate: Crushed angular aggregate.
   • Maximum cement content :450kg/m³(Clause 8.2.4.2. pg.19 IS456:2000)
   • Chemical admixtures type: Superplasticizer
2. Test Data for Materials.
   1. Cement used: OPC 53
      1. Specific Gravity of cement:3.15
   2. Chemical Admixtures: superplasticizer confirming to IS9103
   3. Specific Gravity of Aggregates
      1. Specific Gravity of coarse aggregate:2.74
      2. Specific Gravity of fine aggregate:2.74
3. Target Strength for Mix Proportioning.

   f_t =f_ck +1.65 S

   Where,

   S=Standard deviation given in table no. 1 of IS10262:2005

   Therefore the value of

   f_t =`50 +(1.65×5)`

   f_t = 58.25N/mm².

4. Selection of Water-Cement Ratio.
   • To calculate the water-cement ratio from fig. 1 of IS10262:2019

   From the graph, we got a value of 0.335.

   • The maximum water-cement ratio for the extra severe condition for reinforced concrete is 0.45.
   • So the minimum value has opted for the mix design which is 335.
5. Selection of Water Content.

   From table 2 of 10262:2009

   Maximum water content for 20mm aggregate= 186 litres (for slump value of 25mm to 50mm)

   To calculate the water for 100mm slump = 186+`(6×186)/100`=197 kg.

   As a superplasticizer is used, the water content can be reduced by upto 30%.

   For this trail, we reduce the water content by 29%.

   Hence,

   Water content = `197× (1-0.29) `

   = 140 litres.

6. Calculation of Cement Content.
   1. Water-cement ratio=0.335
   2. Cementiouds material = ` (140/0.335) ` = 417.91 kg/m³_­­.
   3. From table 5 of IS 456:2000, the minimum cement content for the VERY SEVERE exposure condition for reinforced concrete is 340 kg/m³_­­.
   4. 91 kg/m³_­­ > 340 kg/m³_­­.
   5. Hence, OK.
7. The proportion of Volume of Aggregates (Coarse and Fine Aggregate).

   From table 3 of IS10262:2009 volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate(Zone 1) for a water-cement ratio of 0.5= 0.6

   In the present case the water-cement ratio = 0.335

   Therefore the volume of coarse aggregate has to be increased to decrease fine aggregate.

   As the water-cement ratio reduces by 0.165 the proportion of the volume of coarse aggregate increased by 0.03. (As the rate is for every 0.05 reduction in the w/c ratio add 2% to coarse aggregate ratio)

   Therefore, the corrected volume of coarse aggregate for the water-cement ratio of 0.335 = 0.63

   Here we are using the pumping method for placing concrete,

   So, for pumpable concrete, this value is reduced by 10%

   Therefore,

   Volume of coarse aggregate = 0.63× 0.90

   =0.567

   The volume of fine aggregate =1- 0.567

   =0.433

8. Mix Calculations.
   • Volume of Concrete = 1 m³.
   • Volume of Cement =`(Mass of cement)/(Specific Gravity of Cement)×1/1000`

   = `417.91/3.15×1/1000`

   =0.133 m³.

   • The volume of Water =`(Mass of Water)/(Specific Gravity of Water)×1/1000`

   =`140/1×1/1000`

   =0.1400 m³.

   • The volume of chemical admixtures =`(Mass of chemical Admixtures)/(Specific Gravity of Chemical Admixtures)×1/1000`

   =`8.358/1.145×1/1000`

   =0.007 m³.

   • Volume of Aggregate(C.A. & F.A.) ={(a)- [(b)+(c)+(d)]}

   = {1-(0.133+0.140+0.007)}

   =0.72 m³.

   • Mass of coarse aggregate = [(f)×volume of CA× Specific gravity of CA×1000]

   =0.72×0.567×2.74×1000

   =1118.57 kg.

   • Mass of coarse aggregate =[(f)×volume of FA× Specific gravity of FA×1000]

   =0.72×0.433×2.74×1000

   =854.22 kg.

9. Mix Proportion for the Trail.

   Cement - 417.91 kg/m³_­­.

   Water - 140 kg/m³_­­.

   Fine aggregate - 854.22 kg.

   Coarse aggregate - 1118.57 kg/m³_­­

   Chemical Admixtures – 8.358 kg/m³_­­ (@2% of total cementitious material)

   Water-cement Ratio - 0.372

   Trail Mix Ratio = 1 : 2.04 : 2.68

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