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Concrete Mix Design – M 20 Grade Of Concrete

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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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

If you have a query, you can ask a question here.

384 comments on "Concrete Mix Design – M 20 Grade Of Concrete"

ramana p says:

sir how is calculation hand mixing concrete for raw material’s

syed says:

what type of cement is used for lean concrete used under the superstructures like Type-1, Type-11, Type-V etc.

rajaguru p says:

sir, i am studying b.tech final year. i am doing project on geo polymer concrete ( used in fly ash ) pls send me the m20 mix design for fly ash material.

raghavan.s says:

sir can we find plastic limt and liquid limit by way of nomagraphs if so how

yasar arafat says:

how cal.steel in slab

ziya khan says:

if superplatisizer increases in mix desire.what has effective w/c ratio and workability.

s.Murugesh says:

1cubic meter =30bags cement,so 1cft box=0.85bags of cement,or generally for measuring purpose one box of 1ftx1ftx1.25ft is considered for 1 bag of cement

JAGMOHAN says:

HOW WE CALCULATE TARGET MEAN STRENGTH (TMS)

NEHA says:

check IS10262:2009 (PHRA 3.2)

ISAYA S.F.NICHODEMAS says:

what is meant by ‘bleeding of concrete?
Differentiate between asphalt cement and asphalt concrete

om says:

More water in concrete tha bleeding of concrete, it must be ratio of w/c Properlay for better Result

Uday says:

1 1.5 3 ratio 1 cum rcc 8 bags cement 400kg in use

B. D. Bade says:

Thank you very much for providing required information about mix design in very short and specific way

Bob says:

tel me? how the honeycomb is formd in Rcc structure?
how to repair the formation of honey comb?

Pijush Kanti Mandal says:

how calculation of hand mixing concrete M20 grade and simple process to execute the concreting work in local field

cleayriew says:

grade 20-cant i know what strength of this design ??? because i just use 260kg of cement content..and the strength archive that target …please tell me..how much the compressive strength cube test report for this design??

ankita mishra says:

i am ankita mishra i am doing B.E 4th sem..
actually i participate in concrete technology in tech fest in my clg bt there came some problem about strenghth………..

lasudi n. jagila says:

i am lasudi n. jagila, civil eng(struc…). i bring forward my great thanx to the fellow engs to give very short explanation but very satisfactory.

ROHAN says:

how calculation of hand mixing concrete M20 & M30 grade and simple process to execute the concretiing in local field

sivakumar says:

I would like to know how to convert 1 unit of river sand (in Tamilnadu) into cu ft. Simply how many cu ft is 1 Unit of River Sand. (here in TN they quote only in Units, and not explaining the no. of Cu Ft.) Thanks

manikandan says:

i know about this 100 cu ft is equal to 1 unit of river sand and also it is the local measurment of blue metals.

Stephano felix says:

What is the grade number of ratio 1:3:6

manikandan says:

sir, what is the indian standard in the concrete design

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