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Project on Concrete Mix Design for various grades of Concrete

SSanthoshkumar K14 Sept 2022

Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash

AIM

  • To Prepare the Mix Design for M35 Grade of Concrete with Flyash and M50 Grade of Concrete without Flyash as Per the Indian Standards

INTRODUCTION

  • Mix Design of Concrete is the Propotioning of Concrete ingredients which are used to provide strength and Durability of the concrete using IS Codes
  • IS Method Concreet mix proportioning IS 10262-2019 and IS 456

PROCEDURE

The Stipulations of M35 Grade of Concrete are followed as

  1. Grade designation : M35
  2. Type of cement : OPC 43 grade conforming to IS 8112
  3. Type of mineral admixture: Fly ash confirming to IS 3812 ( Part 1)
  4. Maximum nominal size of aggregates : 20mm
  5. Minimum cement content : 320 kg/m^3 (Table :5 IS 456-2000,based on exposure condition)
  6. Maximum water-cement ratio : 0.45 (Table :5 IS 456-2000,based on exposure condition)
  7. Workability :100mm slump value of pumpable concrete
  8. Exposure condition : Severe ( for reinforced concrete)
  9. Method of concrete placing : Pumping
  10. Degree of supervision : Good
  11. Type of aggregate: Crushed angular aggregate
  12. Maximum cement content : 450 kg/m^3.
  13. Chemical admixture type : Superplaticizer.

TEST DATA FOR MATERIALS

    1. Cement used : OPC 43 grade confirming to IS 8112
    2. Specific gravity of cement : 3.15
    3. Fly ash : Conforming to IS 3812 part 1
    4. Specific gravity of flyash : 2.2
    5. Chemical admixture : Superplaticizer conforming to IS 9103
    6. Specific gravity of Coarse aggregate : 2.74
    7. Specific gravity of Fine aggregate : 2.74
    8. Water absorption of Coarse aggregate : 0.5%
    9. Water absorption ofFine aggregate : 1%
    10. Aggregate : Conforming to grading Zone 1 of table 4 IS 383.

TARGET STRENGTH FOR MIX PROPORTIONING

  • f’ck =fck + 1.65 s
    where,
    f’ck = target average compressive strength at 28 days,
    fck = characteristics compressive strength at 28 days, and
    s = standard deviation.
  • From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2.
  • Therefore, Target strength = 35 + 1.65 x 5 = 43.25 N/mm2.

SELECTION OF WATER•CEMENT RATIO

  • Maximum water-cement ratio =0.45 (for severe condition ,from table 5 of IS 456-2000)
  • On experience water- cement ratio =0.4
  • 0.4 <0.45, Hence OK.

SELECTION OF WATER CONTENT


  • From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litre (for 25 to 50 mm slump range) Estimated water content for 100 mm slump = 186+ (6/186) = 197 litre.
  • As superplaticizer is used, the water content is reduced upto 30%
  • Based on trials water content reduction of 29% is achieved with plasticizer
  • Hence arrived water content = 197*0.71 = 140 litres

CALCULATION OF CEMENT CONTENT

  • Water - cement ratio = 0.4
  • Cementatious material ( Cement +flyash ) = 140/0.4 =350 kg/m3
    From Table 5 of IS 456, Minimum cement content for ‘Moderate’ exposure conditions 320kg/m3
    = 350 kg/m3 > 320 kg/m3 hence ok.
  • To proportion the mix containing flyash the following steps are suggested The percentage of flyash need to be decided based on project requirement and qualityof materials.
  • In some cases increase in cementatious materials can be warrned . Increase in cementatious material content and its percentage may be based on experience and trial
  • In this increase of 10% cementatious material content is considered
  • Cementatious material content = 350*1.1 =385 kg/m3
  • Water content = 140 Litres
  • So, water- cement ratio = 140/385 =0.364
  • Fly ash at 30% total cementatious material content = 35-30% =115 kg/m3
  • Cement (OPC) =385-115 =270 kg/m3
  • Saving of cement while using flyash = 350-270=80 kg/m3
  • Fly ash beign utilized = 115 kg/m3

PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

From table 3 of IS 10262:2009 ,volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate

(Zone 1 ) for water- cement ratio =0.6

In present case the water - cement ratio is 0.4

Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content .

As the water- cement ratio is lowered by 0.1, the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)

Hence the corrected value ofcoarse aggregate for the water-cemnt ratio = 0.64

( If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably ,based on experience)

For pumpable concrete, these are reduced by 10 %

Volume of coarse aggregate = 0.64*0.9 = 0.576

Volume of fine aggregate = 1-0.576 =0.424

MIX CALCULATIONS


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

  • Volume of concrete = 1 m3
  • Volume of cement = (Mass of cement / Specific gravity of cement ) *1/1000

= (270/3.15 )*1/1000 =0.086 m3

  • Volume of flyash = (Mass of flyash / Specific gravity of flyash )*1/1000

= (115/2.2) *1/1000 = 0.052m3

  • Volume of water = ( Mass of water / Specific gravity of water)*1/1000

= (140/1)*1/1000 =0.140 m3

  • Volume of chemical admixture = ( Mass of admixture / specific gravity of admixture)*1/1000

=( 7.6/1.14)*1/1000 =0.006 m3

  • Volume of aggregate ( Fine and coarse) = a- (b+c+d+e)

= 1-(0.086+0.052+0.140+0.006) =0.716 m3

  • Mass of coarse aggregate = f* Volu me of coarse aggregate * Specific gravity of coarse aggregate *1000

= 0.716*0.576*2.74*1000 =1130 kg

  • Mass of fine aggregate = f* Volume of fine aggregate* Specific gravity of fine aggreate*1000

= 0.716*0.424*2.74*1000 = 831kg

MIX PROPORTIONS

  • Cement = 270 kg/m3
  • Fly ash = 115 kg/m3
  • Water = 140 kg/m3
  • Fine aggregate = 831 kg/m3
  • Coarse aggregate = 1130 kg/m3
  • Chemical admixture = 7 .6 kg/m3
  • Water- cement ratio = 0.364

Mix ratio of M35 Grade of Concrete 1: 2.15: 2.94

RESULT

The mix design for M 35 grade of concrete with flyash is 1: 2.15:2.94 .The Proportion of Design mix have a several trials and finalaize the mix propotion of design mix

M50 Grade of Concrete without Flyash :-

AIM

  • To Prepare the Mix Design for M50 Grade of Concrete without Flyash as Per the Indian Standards

INTRODUCTION

  • Mix Design of Concrete is the Propotioning of Concrete ingredients which are used to provide strength and Durability of the concrete using IS Codes
  • IS Method Concreet mix proportioning IS 10262-2019 and IS 456

PROCEDURE

The Stipulations of M50 Grade of Concrete are followed as

  1. Grade designation : M50
  2. Type of cement : OPC 53 grade conforming to IS 8112
  3. Type of mineral admixture: Fly ash confirming to IS 3812 ( Part 1)
  4. Maximum nominal size of aggregates : 20mm
  5. Minimum cement content : 320 kg/m^3 (Table :5 IS 456-2000,based on exposure condition)
  6. Maximum water-cement ratio : 0.45 (Table :5 IS 456-2000,based on exposure condition)
  7. Workability :50-75 mm slump value of pumpable concrete
  8. Exposure condition : Severe ( for reinforced concrete)
  9. Method of concrete placing : Pumping
  10. Degree of supervision : Good
  11. Type of aggregate: Crushed angular aggregate
  12. Maximum cement content : 450 kg/m^3.
  13. Chemical admixture type : Superplaticizer.

TEST DATA FOR MATERIALS

    1. Cement used : OPC 53 grade confirming to IS 8112
    2. Specific gravity of cement : 3.15
    3. Chemical admixture : Superplaticizer conforming to IS 9103
    4. Specific gravity of Coarse aggregate : 2.74
    5. Specific gravity of Fine aggregate : 2.67
    6. Water absorption of Coarse aggregate : 0.5%
    7. Water absorption ofFine aggregate : 1%

TARGET STRENGTH FOR MIX PROPORTIONING

  • f’ck =fck + 1.65 s
    where,
    f’ck = target average compressive strength at 28 days,
    fck = characteristics compressive strength at 28 days, and
    s = standard deviation.
  • From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2.
  • Therefore, Target strength = 50 + 1.65 x 5 = 58.25 N/mm2.

SELECTION OF WATER•CEMENT RATIO

  • Maximum water-cement ratio =0.35

SELECTION OF WATER CONTENT

  • From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litre (for 25 to 50 mm slump range) Estimated water content for 100 mm slump = 186+ (3/186) = 191.58 litre.
  • As superplaticizer is used, the water content is reduced upto 20%
  • Based on trials water content reduction of 20% is achieved with plasticizer
  • Hence arrived water content = 197*0.80 = 153 litres

CALCULATION OF CEMENT CONTENT

  • Water - cement ratio = 0.35
  • Cement material = 153/0.35 =437 kg/m3
    From Table 5 of IS 456, Minimum cement content for ‘Moderate’ exposure conditions 320kg/m3
    = 437 kg/m3 > 320 kg/m3 hence ok.

PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

From table 3 of IS 10262:2009 ,volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate

(Zone 1 ) for water- cement ratio of 0.50 =0.6

In present case the water - cement ratio is 0.35

Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content .

As the water- cement ratio is lowered by 0.1, the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)

Hence the corrected value ofcoarse aggregate for the water-cemnt ratio 0.35= 0.65

For pumpable concrete, these are reduced by 10 %

Volume of coarse aggregate = 0.65*0.9 = 0.585

Volume of fine aggregate = 1- 0.585 = 0.415

MIX CALCULATIONS


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

  • Volume of concrete = 1 m3
  • Volume of cement = (Mass of cement / Specific gravity of cement ) *1/1000

= (437/3.15 )*1/1000 =0.139 m3

  • Volume of water = ( Mass of water / Specific gravity of water)*1/1000

= (153/1)*1/1000 =0.153 m3

  • Volume of chemical admixture = ( Mass of admixture / specific gravity of admixture)*1/1000

=( 6.81/1.145)*1/1000 =0.006 m3

  • Volume of aggregate ( Fine and coarse) = a- (b+c+d)

= 1-(0.139+0.153+0.006) =0.702 m3

  • Mass of coarse aggregate = e* Volume of coarse aggregate * Specific gravity of coarse aggregate *1000

= 0.702*0.585*2.74*1000 =1125 kg

  • Mass of fine aggregate = e* Volume of fine aggregate* Specific gravity of fine aggreate*1000

= 0.702*0.415*2.67*1000 = 779 kg

MIX PROPORTIONS

  • Cement = 437 kg/m3
  • Water = 153 kg/m3
  • Fine aggregate = 779 kg/m3
  • Coarse aggregate = 1125 kg/m3
  • Chemical admixture = 6.81 kg/m3
  • Water- cement ratio = 0.35

Mix ratio of M50 Grade of Concrete 1: 1.78: 2.57

RESULT

The mix design for M 50 Grade of concrete is 1: 1.78: 2.57 .The Proportion of Design mix have a several trials and finalized the mix proportion of design mix

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