Concrete Mix Design – M 20 Grade Of Concrete

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1. REQUIREMENTS
a) Specified minimum strength = 20 N/Sq mm

b) Durability requirements
i) Exposure Moderate
ii) Minimum Cement Content = 300 Kgs/cum

c) Cement
(Refer Table No. 5 of IS:456-2000)
i) Make Chetak (Birla)
ii) Type OPC
iii) Grade 43

d) Workability
i) compacting factor = 0.7

e) Degree of quality control Good

2. TEST DATA FOR MATERIALS SUPPLIED
a) CEMENT
i) Specific gravity = 3.05
ii) Avg. comp. strength 7 days = 46.5 more than 33.0 OK
28 days = 55.0 more than 43.0 OK

b) COARSE AGGREGATE
i) 20mm Graded
Type Crushed stone aggregate
Specific gravity = 2.68
Water absorption = 1.46
Free (surface) moisture = 0

sieve_analysis_m20_grade_of_concrete

c) FINE AGGREGATE (Coarse sand)
i) Type Natural (Ghaggar)
Specific gravity = 2.6
Water absorption = 0.5
Free (surface) moisture = 1.4

sieve_analysis_fine_m20_grade_of_concrete

3. TARGET MEAN STRENGTH (TMS)
a) Statistical constant K = 1.65
b) Standard deviation S = 4.6
Thus, TMS = 27.59 N/Sqmm

4. SELECTION OF W/C RATIO
a) As required for TMS = 0.5
b) As required for ‘Moderate’ Exposure = 0.55
Assume W/c ratio of 0.5

5. DETERMINATION OF WATER & SAND CONTENT
For W/C = 0.6
C.F. = 0.8
Max. Agg. Size of 20 mm
a) Water content = 186 Kg/cum
b) Sand as percentage of total aggregate by absolute volume = 35 %

Thus,
Net water content = 180.42 Kg/cum
Net sand percentage = 33 %

adjustments-m20-grade-concrete

6. DETERMINATION OF CEMENT CONTENT
W/c ratio = 0.5
Water content = 180.42 Kg/cum
Thus, Cement content = 360.84 Kg/cum Adequate for moderate exposure Say 360 Kg/cum

7. DETERMINATION OF COARSE AND FINE AGGREGATE CONTENT
Assume entrapped air as 2 %
Thus,
0.98 cum = [180.42+360/3.05 + {1/0.33}*{fa/2.6}]/1000
& 0.98 cum = [180.42+360/3.05 + {1/0.67}*{Ca/2.68}]/1000
Hence,
fa = 584 Kg/cum
Ca = 1223.8 Kg/cum

The final mix proportions of M-20 grade of concrete become:-

mix-design-concrete-m20

Note: 1 The above recommended mix design must be verified, by actual cube tests.
2 The mix design is based on the quality and grading of the materials actually supplied, by the client.
Any variation in quality and gradation will result in changes in the mix design.

This mix design was submitted by a regular contributor to this site. We are thankful to him for his excellent service.

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Comments
  • SHUBHENDU SARKAR September 20, 2013 at 1:43 pm

    what is the formula of vrtical column L length

  • Jayagandan October 1, 2013 at 8:24 am

    Friends i am doing 3rd yr in chennai, i need a guide to guide me……….

  • KAZEEM January 13, 2014 at 3:58 am

    PLEASE, EXPLAIN HOW TO PLACE REINFORCEMENT ON SITE

  • Narayanan January 18, 2014 at 5:29 am

    i need these mix design details, please sent to my mail id

  • suji February 10, 2014 at 9:35 am

    can you please tell me….. how to derive mix design for M20 and M25 concrete….. if fine aggregate and cement is partially replaced by waste materials like glass, slag and etc…

  • Ravindra Jataria July 1, 2014 at 6:58 am

    Pls. Explain the quantity in cum of cement fine aggregate&coarse aggregate for m20mix

  • MUTHU KUMAR.A July 16, 2014 at 8:19 am

    good

  • Uttam Ghadigaonkar July 28, 2014 at 8:51 am

    I have a17 years experience in building repairs and structure repairs and my core is billing and estimated I want a job expected salary 45000 per mounth

  • SANGEETHA July 30, 2014 at 9:45 am

    how to choose final year main project..

  • jose joseph August 2, 2014 at 3:22 am

    pls sed me mix designs of M 20 AND M 30 MIX WITH MANUFACTURED SAND

  • Post a comment

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