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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

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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

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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
  • Er.s.syed abdul kader,B.E September 23, 2008 at 3:14 pm

    i am a civil engineer… nom i am working in construction field.. please send me ratio tabulation of m20& m25 etc….

    thank you

  • Er Sanjay Kr Sahu September 28, 2008 at 5:01 pm

    It may be good but what is location from where samples were taken? as CA/ FA qualities are different at different locations. I hope in next he will provide the location too, so that our fellow engrs, can use without any hassle.

  • Anil Nair October 2, 2008 at 8:08 am

    i am a civil engineer… nom i am working in construction field.. please send me ratio tabulation of m20& m25 etc….

    thank you

  • vivek October 9, 2008 at 11:53 am

    i am into construction field,pls send me the values of compressive strength to be attained for M15,M20,M30 for 7days,14days,28 days

  • A.kumaraswamy October 9, 2008 at 1:04 pm

    Sir,
    I am a civil engineer,and searching for a job.I want mix ratios and design for M15,M20 etc….

  • obinna October 13, 2008 at 11:56 am

    am a civil engineer.pls send the various grades of concrete for construction,where they are
    use in construction,their characteristics strenght and mix ratio.

  • obinna October 13, 2008 at 1:25 pm

    am a student in civil engineering,pls,send factoers to be considered on economical reinforcement
    concrete structures in both design and construction to me.thanks

  • Melaku October 16, 2008 at 7:06 am

    I am hydraulic engineer please send me ratio of cement gravel, sand and water for the weakest grade to the strongest grade of concrete in tabular form.
    I thank you very much.

  • Saneesh October 16, 2008 at 5:51 pm

    i am a civil engineer. Plese send the classification of Mixes and it casting ratios

  • naidu October 18, 2008 at 4:14 pm

    i am acivil engineer,working in maytas infra as a Dy.manager. please send the desin mixes of M20 AND what are formats
    maintained usevally.

    Thanks & Regards,
    Naidu.

  • Raj Dhanshetti October 19, 2008 at 5:10 am

    I am a civil Engineer.can u send me the mix design details for diff Grade
    s of concrete and concern areas which we are using.

    Regards,
    Raj

  • rajendra October 20, 2008 at 3:17 pm

    Sir,
    how to decide grade of concrete from mix design. pls give me suggestion regarding the same, i am very confuse about that,II

  • arun.k October 22, 2008 at 7:10 am

    sir, how to design for high strength concrete please send me

  • vijay kumar gupta October 26, 2008 at 7:34 am

    i am a civil engineer… nom i am working in construction field.. please send me ratio tabulation of m20& m25 etc….

  • vijay kumar gupta October 26, 2008 at 7:36 am

    I want mix ratios and design for M15,M20 etc…

  • paul tensingh October 29, 2008 at 12:15 pm

    hi Im working in interior field.. Now i am going back 2 civil side… could u please tell me the deffertiation of concretes… thank u!

  • Deeno November 3, 2008 at 3:27 am

    How strong is 20N/Sq mms?
    For 3 storey building, would it suffice?

  • Prakash L M November 13, 2008 at 4:40 am

    Hi Im working in construction field.. please send me detailed of various concrete grades with
    ratio & send latest technology details.

  • manoranjan dhal November 13, 2008 at 10:56 am

    Sir,
    how to decide M 30 grade of concrete from mix design in ppc . pls give me suggestion regarding the same.

    Regard

    manoranjan dhal

  • shambu herur November 18, 2008 at 6:42 am

    Sir,
    i am doing my m.tech.now m in final semester doin project
    of carbon fibre reinforced concrete so send me the procedure and
    were i get the corbon fibre……..

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