M-20 Design Mix

8/10/2019 M-20 Design Mix

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1 INTRODUCTIONM/s. S. R. Constructions, Hyderabad, is Proposing for Construction of G + 5 Floors Apartments

at Ameerpet, Hyderabad. For the proposed work design of concrete mix for M-20 grade of

concrete was taken up in our laboratory. The important criteria kept in view while designing the

concrete mixes are strength, durability and workability of concrete. Various methods employed

for concrete mix design, such as, ACI, and IS have been referred to. The mix proportion is

arrived at theoretically, based on IS recommendations. Appropriate modifications are made

depending on the material properties observed and also the specific requirements of the job.

Concrete cubes are casted and tested for compressive strength at the end of 7 days and 28 days.

2 MATERIALS

A) Cement Parashakthi OPC 53 Grade

B) Fine Aggregate Natural River Sand

C) Coarse Aggregate 20.0 mm

3 DATA FOR MIX DESIGN/DESIGNSConcrete proposed to be used for Footings, Pedestals, Plinth Beams, Columns, Roof

Beams & Roof Slab

Grade of Concrete M-20

Desired Workability of Concrete(Slump) Not Specified

Expected Degree of Quality Control Control Level-B*

Maximum Size of Aggregate 20.0 mm

Maximum W/C Ratio 0.50 (As per IS)

Type of Environmental exposure

conditions

Moderate**

Minimum Cement Content 350 Kg/cu.m. (As per client requirement)

Maximum Cement Content As per IS

Target mean compressive strength of

concrete at 28 days

For M-20 it is 28.25 N/sq.mm.

* Site Control Level-B corresponds to proper storage of cement, volume-batching of concrete

making materials except cement, cement by weight only, controlled addition of water,

occasional checking of all materials, aggregate grading and moisture content and periodical

checking of workability and strength.

** IS: 456 2000 (Reaffirmed 2005) describes moderate as Concrete surfaces sheltered from

severe rain or freezing whilst wet. Concrete exposed to condensation and rain. Concrete

continuously under water. Concrete in contact or buried under non-aggressive soil / ground

water. Concrete surfaces sheltered from saturated salt air in coastal area.


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4 CHARACTERISTICS OF MATERIALSA CEMENT PARASHAKTHI OPC 53 GRADE

Test Conducted Results Requirements as per

IS:12269 2013

Consistency (%) 32.3 Not specified

Initial setting time (minutes) 180 Shall not be less than 30 minutes

Final setting time (minutes) 330 Shall not be more than 600 minutes

Compressive Strength

3 days (MPa) 31.4 Shall not be less than 27.0 MPa

7 days (MPa) 44.1 Shall not be less than 37.0 MPa

28 days (MPa) TYC Shall not be less than 53.0 MPa

B FINE AGGREGATE (NATURAL RIVER SAND)Gradation

IS Sieve

Designation

(mm)

Cumulative Percentage Requirements as per IS: 383-1970 (RA 2002)

(Percentage Passing)

Retained Passing Zone-I Zone-II Zone-III

10.000 0 100 100 100 100

04.750 4.0 96.0 90-100 90-100 90-100

02.360 9.2 90.8 60-95 75-100 85-100

01.180 30.5 69.5 30-70 55-90 75-100

00.600 57.9 42.1 15-34 35-59 60-79

00.300 91.1 8.9 5-20 8-30 12-40

00.150 98.4 1.6 0-10 0-10 0-10Remarks: The sample supplied satisfies the requirements of Grading Zone-II as per

IS: 383-1970 (Reaffirmed 2002)

C COARSE AGGREGATES

Gradation (20.0 mm Down)

IS Sieve

Designation

(mm)

Cumulative Percentage Requirements as per IS: 383-1970 (RA 2002)

(Percentage Passing)Retained Passing

Graded Single Size

40.00 0 100 100 100

20.00 4.8 95.2 95-100 85-100

12.50 60.3 39.7 -- --10.00 73.6 26.4 25-55 0-20

04.75 99.8 0.2 0-10 0-5

Remarks: The sample supplied of 20.0 mm satisfies the requirements of Gradedaggregate

as per IS: 383-1970 (RA 2002)

Specific Gravity Bulk Density

(Kg./Cu.m.)

Rodded Loose

Fine Aggregate 2.58 Fine Aggregate 1674 1521

20.0 mm 2.67 20.0 mm 1557 1396


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5 SUGGESTED CONCRETE MIX PROPORTION (BY WEIGHT)

Grade Aggregate

Max. size

(mm)

Suggested Mix

Proportions

C:FA:CA**

Water

Cement

ratio

(max)

Slump

Obtained

(mm)

Cement

Content*

(Kg/cu.m)

Compressive

Strength

(N/sq.mm)

07

Days

28

Days

M-20 20 1 : 1.99 : 3.50 0.46 50 350 22.1 TYC

6 SUGGESTED CONCRETE MIX PROPORTION (BY VOLUME)

Grade Aggregate

Max. size

(mm)

Suggested Mix Proportions

C : FA : CA

1 Bag Cu.m Cu.m

Water per bag of

cement

(Ltrs.)

Cement Content*

(Kg/cu.m)

M-20 20 1 : 0.065 : 0.125 23.0 350

* This has to be verified at site.

** Cement: Fine Aggregate: Coarse AggregateTYC Test yet to be conducted

REMARKS: (1) Correction for water absorption of sand and coarse aggregate to be applied at site.

Note: 1. The results relate only to the items tested.2. Report shall not be reproduced, except in full, without the written approval of the laboratory.

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M-20 Design Mix