November 21, 2024
CONCRETE / CONCRETE MIX DESIGN

Mix Design of M20 Grade of Concrete with OPC cement

tsquarecivilengineeringby tsquarecivilengineering0

    • Grade of Concrete : M20
    • Type of Cement : OPC 53 grade confirming to IS 269
    • Maximum Nominal Size Aggregate : 20 mm
    • Minimum Cement content : 240Kg/cum
    • Maximum Water- Cement Ratio : 0.6
    • Workability : 100 ± 25 mm (slump)
    • Exposure Condition : Moderate 
    • Method of Concrete Placing : Pumping or Bucket
    • Degree of Supervision : Good
    • Type of Aggregate : Crushed angular Aggregate
    • Chemical admixture type : Super plasticizers Confirming IS 9103:1999

2. Material Properties

    • Cement : Ultratech OPC 53 grade confirming to IS 269
        • Specific Gravity of cement : 3.15
    • Chemical Admixture : BASF Master Glenium Sky 8511
        • Specific Gravity of Admixture : 1.07
    • Specific Gravity
        • Coarse aggregate
            • 20mm : 2.69
            • 12.5mm : 2.67
            • Ratio of aggregate: 20mm-50% & 12.5mm-50%
        • Fine aggregate
            •   Crushed stone aggregate : 2.57
        • Water: 1
    • Water Absorption
        • Coarse aggregate
            • 20mm : 0.37%
            • 12.5mm : 0.54%
        • Fine aggregate
            •   Crushed stone aggregate : 2.35%
        • Free Surface Moisture
            • Fine aggregate : Nil
            • Coarse aggregate: Nil
        • Sieve Analysis
            • Coarse aggregate:
IS Seive Sizes % Passing IS Requirement as per IS 383 Table 2 Ratio Confirming to IS 383 table 2
Single Sized Graded 50% 50%  
  20 mm 12.5 mm 20 mm 12.5 mm   20 mm 12.5 mm Combined 100%
20 95.01 100 85-100 100 100 47.505 50 97.51
12.5 0 99.15 – 85-100 90-100 0.00 49.575 49.58
10 2.54 51.07 0-20 0 – 45 40 – 85 1.27 25.535 26.81
4.75 0.88 0.42 0-5 0-10 0 – 10 0.44 0.21 0.65
PAN 0 0 – – – 0 0 0

Sieve Analysis of Coarse Aggregate, M20 grade concrete

    • Fine Aggregate: Confirming to grading Zone II of table 4 of IS 383 Note:- as per field trials for pumpable concrete fine aggregate should pass zone II; According to IS 383 clause No. 31.2.2 allows to use crushed stone sand as fine aggregate for concrete .According to IS 383-2016 for crushed stone sand, the permeassible limit on 150 micron IS sieve is increased to20%.
IS Seive Sizes % Passing Ratio RS:Msand Specification Combined Passing
0 1 IS 383 Zone II
  R Sand M Sand R Sand M Sand    
4.75 0 100 0 100 90-100 100
2.36 0 85.88 0 85.88 75-100 85.88
1.18 0 58.95 0 58.95 55-90 58.95
600 0 38.87 0 38.87 35-59 38.87
300 0 21.47 0 21.47 8-30 21.47
150 0 9.74 0 9.74 0-10 9.74

Sieve Analysis of Fine Aggregate, M20 grade concrete

All in aggregate:

IS Seive Sizes 28.5% 28.5% 43% Specification Combined Passing
20mm 12.5mm c sand min-max
40 100 100 100 100-100 100.00%
20 95.01 100 100 95-100 98.58%
4.75 0.88 0.42 100 30-50 43.37%
0.6 0 0 38.87 10-35 16.71%
0.15 0 0 9.74 0-6 4.19%

Sieve Analysis of All in Aggregate, M20 grade concrete

3. Target Mean Strength 

    • As per MORTH the Target Mean Strength for M-20 Grade = 30Mpa

4. Selection of water/Cement Ratio (W/C)

    • As per the specification max Water/Cement + Binder = 0.6

5. Water content Calculation

Ref Tab 2 , IS 10262 , Maximum water content per cum for 20mm Aggregate = 186 litre for  50 mm slump

= 186 + (0.06 * 186) (add 3% for every 25 mm increase )

= 197 lit

Based on trials with super plasticizers, water content reduced by 27%,hence the arrived water content = 141.96lit, So Let us add water 142 lit

6. Cementious content Calculation

Water-Cementitious Ratio = 0.6

Cementious content (Cement OPC 53 ) = 237

Say Cementitious content = 240 kg/m3

Cement = 240 kg/m3

Based on experience and lab trials, Based on experience and lab trials, super plasticizer = 0.8 %

7. Aggregate content Calculation

Ref Tab 3 of IS 10262 , for Sand Zone II ,  volume of coarse aggregate

per unit vol of total aggregate for 0.5 water-cement ratio = 0.62

Adjust for W/c ratio : Add @ 0.01 for every decrease in 0.05=  -0.02

Therefore , corrected proportion = 0.6

Adjust for pumpability , i.e decrese by 10% = 0.54 %

Based on experience  Considering Volume of coarse aggregate = 0.57

Therefore, Volume of Fine aggregate   = 0.43

8. Mix volume Calculation per cubic meter of concrete

a) Volume of concrete = 1 m3

b)  Volume of cement = (Mass of cement /specific gravity of cement) × 1000 =240/(3.15×1000)= 0.0762 m3

c) Volume of water = (Mass of water /specific gravity of water)× 1000 = 0.142 m3

d) Volume of admixture = (Mass of admixture /specific gravity of admixture)× 1000 = (240×0.8)/(100×1.07×1000)=0.00179 m3

e) Volume of all in aggregate =[a-(b+c+d)] =1-(0.0762+0.142+0.00179)=0.78   

f) Mass of coarse aggregate(CA)

1) 20 mm = e × volume of CA × sp. gravity × % of 20mm × 1000 = 0.78*0.57*2.69*0.5*1000= 598kg/m3, Say 598 kg/m3

2) 12 mm = e× volume of CA × sp. gravity × % of 12mm × 1000 = 0.78*0.57*2.67*0.5*1000 = 593.55 kg/m3 Say  594 kg/m3

g) Mass of Fine aggregate = e× volume of FA × sp. gravity × 1000 =0.78*0.43*2.57*1000= 861.99kg/m3 Say  862 kg/m3

9. Details of Mix Design

  • cement = 240 kg
  • 20mm = 598 kg
  • 12mm = 594 kg
  • Crushed stone sand = 862 kg
  • Chemical admixture = 1.92 kg
  • Free Water = 142 kg
  • Water-Cement Ratio = 0.6
  • Concrete density = 2437 kg/m3

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