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Project on Concrete Mix Design for various grades of Concrete

AAbha Mahato11 Apr 2022

Project on concrete Mix Design for Various Grades of Concrete:

1: AIM: To calculate the concrete Mix Designe for M35 grade concrete with fly ash and M50 garde concrete without fly ash.

2: INTRODUCTION: Concrete Mix Design involves a process of preparation in which a mix of ingredients creats the required strength and durability for the concrete structure. Because every ingredient in the mix consists of different properties , it's not an easy task to create a great concrete mix. It is imperative that all ingredients be tested to determine their physical properties and the bearing capacity of the project location. The ingredients to be tested: Water, fine aggregate, coarse aggregate,cement, chamicals, reinforcement, and soil. The values for the physical properties obtained after testing will be used as the basis for all concrete mix design considerations. This project consist of two parts, the first part deals with the M35 grade cement with fly ash as a part of it and second part is the design of M50 grade concrete without fli ash.

3: OBJECTIVE: The objective of the project is to produce a mix design for M35 grade concrete containing fly ash and M50 grade concrete. the mix will be prepared as per IS Method: Concrete mix proportioning guidlines from IS 10262:2009 and recommended guide lines from IS 10262:1982.

4: EQUATIONS USED:

Targate mean strength: f'ck=fck+1.65s

where,

  1. f'ck= Target average compressive strength at 28 days.
  • Cement content= water content/ water cement ratio.
  • Volume calculations:
  1. Volume of concrete
  2. Volume of cement = [Mass of cement]/ [specific gravity of cement]*1/1000
  3. Volume of water = [Mass of water]/ [ specific gravity of water]* 1/1000
  4. Volume of chemical admixture =[Mass of admixture]/ [specific gravity of admixture]*1/1000
  5. Volume of all aggregate =[ i-(ii+iii+iv)]
  6. Mass of coarse aggregate = (v)* volume of coarse aggregate* specific gravity of coarse aggregate*1000
  7. Mass of fine aggregate = (v)* volume of fine aggregate* specific gravity of Fine aggregate*1000

5:Part1: To calculate the concrete mix design for M35 grade concrete with fly ash:

M35 grade concrete with fly as

  1. Stipulations for concrete design mix
  • Grade designation: M35
  • Type of cement: OPC 43 Grade confirming to IS 8112
  • Type of mineral admixture: Fly ash confirming to IS 3812(part 1)
  • Maximum nominal size of aggregate: 20mm
  • Minimum cement content: 320 kg/m^3(Table no 5 of IS 456:2000- Exposure condition)
  • Maximum w/c ratio: 0.45 (Table 5 of IS 456:2000 )
  • Workability: 100mm ( slump value of pumpable concrete)
  • Exposure condition: sever (for Reinforced concrete)
  • Method of concrete placing: Pumping.
  • Degree of supervision : Good
  • Type of aggregate: Crushed anguler aggregate
  • Maximum cement content: 450 kg/m^3
  • Chemical admixture type: Super plasticizer.

ii. Test Data for Materials:

Cement used: OPC 43 grade conforming IS 8112

  • Specific gravity of cement: 3.15
  • Fly ash: confirming to IS 3812(part 1)
  • Specific gravity of Fly ash: 2.2
  • Chemical Admixture: Super plasticizer conforming toIS 9103
  • Specific gravity of coarse aggregate: 2.74
  • Specific gravity of fine aggregate: 2.74
  • Water absorption of coarse aggregate: 0.5%
  • Water absorption of fine aggregate: 1.0%
  • Free surface moisture of coarse aggregate: Nil
  • Free surface moisture of fine aggregate: Nil
  • sieve analysis: coarse aggregate confirming to table 2 of IS 383
  • sieve analysis: fine aggregate; Confirming to Grading Zone II of table 4 of IS 383

iii. Target Strength for Mix Proportioning:

  • f'ck= fck+ 1.65*s

where,

f'ck= Target average compressive strength at 28 days.

fck= charecteristics compressive strength at 28 days, and

s= standard deviation.

from table 1 of IS 10262: 2009, standard Deviation, s= 5N/mm^2

f'ck= 35+ 1.65*5= 43.25 N/mm^2

iv. Selection of Water-cement Ratio:

The maximum w/c ratio to design M35 grade concrete should be taken 0.45 from table 5 of IS 456:2000;

based on experience adopted w/c ratio is 0.44;

0.44<0.45, hence ok;

Adopted w/c ratio=0.44

v.Selection of water content: From table 2 of IS 10262:2009, maximum water content for 20mm aggregate = 186 liter(for 25 to 50mm slump range);

clause 4.2 suggests increase of 3% water content for every extra 25mm slump from 50mm slump. so a 6% is to be added to it.

Estimated water content for 100mm slump = 186+ (6/100)*186=197 liter.

based on trials with super plasticizer water content reduction of 20% has been achieved , hence the arrived water content

= 197-(20/100)*197=157.6 or 158 liters;

Water required 158 liters;

vi.Calculation of cement and Fly ash required:

Adopted w/c ratio 0.44;

Total cementitious (cement+Fly ash) requirment= water content/ water cement ratio= 158/0.44=359 kg/m^3;

The cemntitious content has to be increased in order to attain good workability and strength. The increment required is Determined on the basis of experience and research, Here we are increasing cementitious content by 10%

Final cementitious content= 359*1.10=395 kg; From table 5 of IS 456:2000 , minimum cement content for 'sever' exposure conditions is 320 kg.

395 kg> 320kg hence ok.

cementitious material content= 395 kg; New water/cement ratio= 158/395= 0.4

Fly ash content is taken as 30% of the total cementitious contemt= 395*0.3= 118.5 kg;

cement required= 395-118.5= 277kg;

cement quantity saved due to fly ash addition= 350-277 =73 kg;

cementitious material , cement and fly ash required is respectively 395kg, 277kg, 118 kg, and the new water/ cement ratio is 0.4;

vii.Volume of coarse aggregate and fine aggregate content

From Table 3 of (IS 10262:2009) volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone II) for water cement ratio of 0.5 is 0.62;

In the present case w/c ratio is 0.44 therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the w/c ratio lower by 0.06. The proportion of volume of coarse aggregate is increased by 0.02( at the rate of -/+ 0.01 for every +/- 0.05 change in w/c ratio).

Therefore , corrected proportion of volume of coarse aggregate for w/c ratio of 0.44 = 0.632

For pumpable concrete these values should be reduced upto 10% there fore, volume of coarse aggregate= 0.632* 0.9= 0.568.

voume of fine aggregate content= 1- 0.568= 0.431;

volume of fine and coarse aggregate is 0.431 and 0.568;

viii:MIX CALCULATION:

The mix calculations as per unit volume of concrete shall be as follows:

  1. Volume of concrete = 1 m^3;
  2. Volume of cement = [Mass of cement ]/ [specific garvity of cement]*1/1000= [277/3.15]*[1/1000]= 0.087m^3;
  3. Volume of fly ash = [Mass of fly ash]/ [specific gravity of fly ash]*[1/1000]= [118/2.2]*[1/1000]= 0.053 m^3;
  4. Volume of water =[ Mass of water]/[ sp. gr. of water]*[1/1000]= [158/1]*[1/1000]= 0.158m^3;
  5. Volume of chemical admixture = [Mass of admixture]/[ sp.gr. of admixture]*[1/1000]= [7.6/1.145]*[1/1000]=0.006m^3;
  6. Volume of all aggregate= 1.-(2.+3.+4.+5.)=[1-(0.087+0.053+0.158+0.006)]= 0.696m^3;
  7. Mass of coarse aggregate= 6.* Volume of CA* Specific gravity of CA*1000= 0.696* 0.568 * 2.74*1000=1077 kg/m^3
  8. Mass of fine aggregate = 6.*volume of FA* specific gravity of FA* 1000= 0.696* 0.431*2.74* 1000= 822kg/m^3;

ix: Mix Proportions:

  1. Cement = 277 kg/m^3;
  2. Fly ash = 118 kg/ m^3;
  3. water = 158 l/m^3;
  4. Fine aggregate = 822 kg/m^3;
  5. Coarse aggregate 20mm= 1077kg/m^3;
  6. Chemical Admixture = 7.18 kg/m^3;

Water cement ratio ( lowest w/c ratio is selected)= 0.4 ;

Mix proportion By weight = 1:2.08:2.72

6: PART 2: To calculate the concrete mix design for M50 grade concrete without Fly ash:

M50 grade concrete without flyash

i.Stipulations for concrete design mix

  • Type of cement: OPC 53 grade confirming to IS BIS 12269- 1987;
  • Maximum nominal size of aggregate: 20mm;
  • Minimum cement content : 320kg/m^3 ( Table 5 of IS 456:2000- Exposure condition);
  • Maximum w/c ratio: 0.45 ( table 5 of IS 456:2000 Exposure condition)
  • workability: 100mm (slump value for pumpable concrete);
  • Exposure condition : sever (for reinforced concrete)
  • Meathod of concrete placing : pumping:
  • Degree of supervision : Good
  • Type of aggregate: Crushed anguler aggregate
  • Maximum cement content: 450 kg/m^3
  • Chemical admixture type: Super plasticizer.

ii. Test Data for Materials:

  • Cement used : OPC 53 garde confirming IS 12269-1987;
  • specific gravity of cement: 3.15;
  • chemical admixture: super plasticizer confirming to IS 9013;
  • Specific gravity of coarse aggregate: 2.74
  • Specific gravity of fine aggregate: 2.64
  • Water absorption of coarse aggregate: 0.5%
  • Water absorption of fine aggregate: 1.0%
  • Free surface moisture of coarse aggregate: Nil
  • Free surface moisture of fine aggregate: Nil
  • sieve analysis: coarse aggregate confirming to table 2 of IS 383
  • sieve analysis: fine aggregate; Confirming to Grading Zone II of table 4 of IS 383

iii. Target strength for Mix proportion:

  • f'ck= fck+ 1.65*s

where,

f'ck= Target average compressive strength at 28 days.

fck= charecteristics compressive strength at 28 days, and

s= standard deviation.

from table 1 of IS 10262: 2009, standard Deviation, s= 5N/mm^2;

now, f'ck= 50+ 1.65* 5= 58.25 N/mm^2;

Target mean strength = 58.25 N/mm^2;

iv. Selection of Water-cement Ratio:

The maximum w/c ratio to design M50 grade concrete should be taken 0.45 from table 5 of IS 456:2000;for Sever Exposure.

based on experience adopted w/c ratio is 0.44;

0.44<0.45, hence ok;

Adopted w/c ratio=0.44

v.Selection of water content: From table 2 of IS 10262:2009, maximum water content for 20mm aggregate = 186 liter(for 25 to 50mm slump range);

clause 4.2 suggests increase of 3% water content for every extra 25mm slump from 50mm slump. so a 6% is to be added to it.

Estimated water content for 100mm slump = 186+ (6/100)*186=197 liter.

based on trials with super plasticizer water content reduction of 20% has been achieved , hence the arrived water content

= 197-(20/100)*197=157.6 or 158 liters;

Water required 158 liters;

vi.Calculation of cement and Fly ash required:

Adopted w/c ratio 0.44;

cement content = 158/0.44= 359kg/m^3;

From Table5 of IS 456:2000, minimum cement content for 'sever' exposure conditions =320kg/m^3;

as 359kg/m^3 > 320kg/m^3 hence ok;

Cement required is 359kg/m^3

vii.Volume of coarse aggregate and fine aggregate content

From Table 3 of (IS 10262:2009) volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone II) for water cement ratio of 0.5 is 0.62;

In the present case w/c ratio is 0.44 therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the w/c ratio lower by 0.06. The proportion of volume of coarse aggregate is increased by 0.02( at the rate of -/+ 0.01 for every +/- 0.05 change in w/c ratio).

Therefore , corrected proportion of volume of coarse aggregate for w/c ratio of 0.44 = 0.632

For pumpable concrete these values should be reduced upto 10% there fore, volume of coarse aggregate= 0.632* 0.9= 0.568.

voume of fine aggregate content= 1- 0.568= 0.431;

volume of fine and coarse aggregate is 0.431 and 0.568;

viii:MIX CALCULATION:

The mix calculations as per unit volume of concrete shall be as follows:

  1. Volume of concrete = 1 m^3;
  2. Volume of cement = [Mass of cement ]/ [specific garvity of cement]*1/1000=(359/3.15)/(1/1000)= 0.114m^3;
  3. volume of water= [Mass of water]/[specific gravity of water]*1/1000= (158/1)*[1/1000]= 0.158m^3;
  4. Volume of chemical admixture = [Mass of admixture]/[ sp.gr. of admixture]*[1/1000]= [7.6/1.145]*[1/1000]=0.006m^3;
  5. Volume of all aggregate= 1.-(2.+3.+4.)=[1-(0.114+0.158+0.006)]= 0.722m^3;
  6. Mass of coarse aggregate= 6.* Volume of CA* Specific gravity of CA*1000= 0.722* 0.568 * 2.74*1000=1123kg/m^3
  7. Mass of fine aggregate = 6.*volume of FA* specific gravity of FA* 1000= 0.722* 0.431*2.64* 1000= 821kg/m^3;

ix: Mix Proportions:

  • Cement: 359 kg/m^3
  • Water : 158 liters/m^3
  • Fine aggregate: 821 kg/m^3;
  • coarse aggregate 20mm: 1123 kg/m^3
  • chemical admixture: 7.18 kg/m^3

water cement ratio: 0.44

Mix proportion by weight: 1:2.28:3.12

7:RESULT:

Mix proportion by weight od M35 grade of concrete with fly ash is 1:2.08:2.72 and it's water cemnt ratio was fpund to be 0.4.

Mix proportion by weight of M50 grade of concrete without fly ash is 1:2.28:3.12 and it's water cement ratio was founf to be 0.44.

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