Project on Concrete Mix Design for various grades of Concrete

PART 1 : Calculate the Concrete Mix Design for M35 grade concrete with fly ash .

AIM :

To prepare a concrete mix design of M35 grade Concrete with Fly Ash

INTRODUCTION :

• Concrete mix design is a systematic process of choosing an economical relative proportion of various ingredients from available materials that gives the concrete of the desired workability.
• The process of selecting suitable ingredients for producing concrete of required strength, durability, and workability as economical as possible is known as concrete mix design.
• concrete is a complex material and has the right mix of constituents of concrete, which if not done properly and will have an adverse effect on the properties of concrete.
• the compressive strength of concrete depends on the quality and quantity of cement, water, and aggregates.
• it also depends on the mixing, batching, placing, compaction and curving.

OBJECTIVES:

• The objective of this project is to produce a mix design for M35 grade concrete containing fly ash. The mix will be prepared as per IS METHOD: Concrete mix proportioning guidelines from IS 10262:2009 and IS456:2000.

CODES FOR CONCRETE MIX DESIGN:

IS 10262: 2009
IS 456: 2000
IS 8112
IS 9103
IS 3812 ( part 1)

STIPULATION FOR PROPORTIONING :

1. Grade designation = M35
2. type of cement = OPC 43
3. Type of mineral admixture = Fly Ash
4. Maximum nominal size of aggregate = 20 mm
5. Exposure condition = severe
6. maximum cement content = 450kg
7. Maximum water-cement ratio = 0.45
8. Specific Gravity of Cement = 3.15
9. Mineral Admixture = Fly ash
10. Specific Gravity of Fly ash = 2.90
11. Specific Gravity of
    Coarse Aggregate = 2.74
    Fine Aggregate = 2.74
    Admixture PCE based 1.12
12. Water Absorption
    Coarse aggregate = 0.5 %
    Fine aggregate = 1 %
13. chemical admixture type = Super plasticizer

PROCEDURE :

STEP 1

TARGET MEAN STRENGTH F'CK=fck+1.65*S

Where,fck=35N/mm^2 [M35]

For M35 S=5.0

Fck = fck+1.65s

Fck = 35+1.65×5

Fck = 43.25 N/mm2

STEP 2 -

SLECTION OF WATER CEMENT RATIO

AS, F'ck = 43.25N/mm^2

w/c =0.40 as per IS 10262;2019

EXPOSURE CONDITION = SEVERE

Table 5- is 456:2000

severe = w/c ratio = 0.45

M35 = w/c ratio = 0.40

Lower the water cement ratio better the workability

so, w/c is o.40

Therefore , minimum cement content = 320kg/m^3

STEP 3 -

SLECTION OF WATER CONTENT

Nomial size of aggregates = 20 mm

from Table 2 - IS10262:2009

Maximum water content = 186 litres or kg (for 25mm to 50 mm slump range)

The water content above is for a slump of 25 to 50 mm, but according to the specification our concrete requires a slump of 100 mm. Therefore, to get the desired slump, the water content must be increased. Clause 4.2 of IS1026 recommends increasing the water content by 3% to obtain an additional 25 mm slump. Therefore, to obtain a slump of 50 mm in addition to our concrete, the water content must be increased by 6%.

Water-content for 100mm Slump =186+(0.06*186)
=197.16 L
As we use super plasticizers we can reduce the water content to gain strength in the concrete. The amount of water-content to be reduced depends on the type of super plasticizer.

Percentage of Reduction in water content =30%
Water content requirement after SP =198 – (0.30*198)
=138.6
Adopted Water Content =140 L

STEP 4 ;

CALCULATION OF CEMENT AND FLY ASH CONTENT

Adopted Water Cement Ratio =0.40
Total Cementitious (Cement +Fly ash) requirement = Water Content / WaterCement ratio
=140/0.4
=350 Kg

Since flying ash is used, the amount of cementitious content (cement + fly ash) should be increased to get good performance and strength. The percentage of increasing cementitious content depends on experience and research. Here we have increased the cementitious content by 1

Final Cementitious Content (Cement+Fly ash)	= 350*1.10	=385 kg
Minimum Cement Content required for ‘severe’ exposure	=320kg/m^3	Table 5-IS456
Adopted Cementious content	=385 kg/mm^3	> 320kg/mm^3

​Fly ash content requirement = 30% replacement = 385 *30/100
= 115.5 ~ 115 kg/mm^3
Cement Content requirement =Cementious content – Fly ash
=385-115
= 270 kg/mm^3

water cement ratio = 140/385 =0.36

• cement = 270 kg/mm^3
• saving of cement while using fly ash = 80 kg/mm^3
• fly ash being utilized =115 kg/mm^3

STEP 5:

COARSE AND FINE AGGREGATE RATIO

Table3-IS10262:2019

• Coarse Aggregate ratio = 0.60 (For W/C =0.5)
• Coarse Aggregate ratio for 0.40 w/c ratio = 0.62 (adding 0.01 for everydecrease .05 and vice versa)
• Final Fine Aggregate ratio = (1-0.62) = 0.38

STEP 6 :

MIX CALCULATION

• Volume of Concrete = 1 cu.m
• Total Volume of Cement = Cement/(S.G*1000)
  = 270/(3.15*1000)
  = 0.086 cu.m
• Total Volume of Fly ash = Flyash/(S.G*1000)
  = 115/(2.2*1000)
  = 0.052 cu.m
• Volume of Water =Water /(S.G*1000)
  = 140/(1*1000)
  = 0.140 cu.m
• Volume of Superplasticizers = Superplasticizers /(S.G*1000)
  = 7.6/(1.145*1000)
  = 0.006 cu.m
• Total Aggregates requirement = A – (B+C+D+E)
  =1 -(0.086 +0.052+0.140+0.006)
  =0.716 cu.m
• Coarse Aggregate (C.A) = F * C.A ratio * S.G * 1000
  = 0.716*0.62 *2.74 *1000
  = 1216 kg
• Fine Aggregate (F.A) = F * F.A ratio * S.G * 1000
  = 0.716*0.38*2.74 *1000
  =746 kg

RESULTS AND CONCLUSION :

• Cement = 270 kg/mm^3
• Flyash = 115 kg/mm^3
• Fine Aggregate = 746 kg/mm^3
• Coarse Aggregate (20mm) = 1216 kg/mm^3
• WATER = 140 L
• Chemical admixture = 7 kg/mm^3
• water cement ratio = 0.36

CEMENT : FA : CA = 270 : 746 : 1216

TRIAL MIX RATIO = (C:FA:CA) = (1 : 2.76 : 4.5)

• The slump shall be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirement.
• Two more trials having variation of 10% of water-cement ratio shall be carried out and a graph between three water- cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target for field trials.

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PART 2 : Calculate the Concrete Mix Design for M50 grade concrete without Fly ash

AIM :

To prepare a concrete mix design of M50 grade Concrete without Fly Ash

INTRODUCTION :

• Concrete mix design is a systematic process of choosing an economical relative proportion of various ingredients from available materials that gives the concrete of the desired workability.
• The process of selecting suitable ingredients for producing concrete of required strength, durability, and workability as economical as possible is known as concrete mix design.
• concrete is a complex material and has the right mix of constituents of concrete, which if not done properly and will have an adverse effect on the properties of concrete.
• the compressive strength of concrete depends on the quality and quantity of cement, water, and aggregates.
• it also depends on the mixing, batching, placing, compaction and curving.

OBJECTIVES:

• The objective of this project is to produce a mix design for M50 grade concrete . The mix will be prepared as per IS METHOD: Concrete mix proportioning guidelines from IS 10262:2009 and IS456:2000.

CODES FOR CONCRETE MIX DESIGN:

IS 10262: 2009
IS 456: 2000
IS 8112
IS 9103
IS 3812 ( part 1)

STIPULATION FOR PROPORTIONING :

1. Grade designation = M50
2. type of cement = OPC 53
3. Maximum nominal size of aggregate = 20 mm
4. Exposure condition = severe
5. Minimum cement content = 320 kg/mm^3
6. maximum cement content = 450kg/mm^3
7. Maximum water-cement ratio = 0.45
8. Specific Gravity of Cement = 3.15
9. Specific Gravity of
   Coarse Aggregate = 2.74
   Fine Aggregate = 2.74
   Admixture PCE based 1.12
10. Water Absorption
    Coarse aggregate = 0.5 %
    Fine aggregate = 1 %
11. chemical admixture type = Super plasticizer

PROCEDURE :

STEP 1

TARGET MEAN STRENGTH F'CK=fck+1.65*S

Where,fck=50N/mm^2 [M50]

For M50 S=5.0

Fck = fck+1.65s

Fck = 50+1.65×5

Fck = 58.25 N/mm2

STEP 2 -

SLECTION OF WATER CEMENT RATIO

AS, F'ck = 58.25N/mm^2

w/c =0.40 as per IS 10262;2019

EXPOSURE CONDITION = SEVERE

Table 5- is 456:2000

severe = w/c ratio = 0.45

M50 = w/c ratio = 0.40

Lower the water cement ratio better the workability

so, w/c is o.40

Therefore , minimum cement content = 320kg/m^3

STEP 3 -

SLECTION OF WATER CONTENT

Nomial size of aggregates = 20 mm

from Table 2 - IS10262:2009

Maximum water content = 186 litres or kg (for 25mm to 50 mm slump range)

The water content above is for a slump of 25 to 50 mm, but according to the specification our concrete requires a slump of 100 mm. Therefore, to get the desired slump, the water content must be increased. Clause 4.2 of IS1026 recommends increasing the water content by 3% to obtain an additional 25 mm slump. Therefore, to obtain a slump of 50 mm in addition to our concrete, the water content must be increased by 6%.

Water-content for 100mm Slump =186+(0.06*186)
=197.16 L
As we use super plasticizers we can reduce the water content to gain strength in the concrete. The amount of water-content to be reduced depends on the type of super plasticizer.

Percentage of Reduction in water content =30%
Water content requirement after SP =198 – (0.30*198)
=138.6
Adopted Water Content =140 L

STEP 4 ;

CALCULATION OF CEMENT CONTENT

Adopted Water Cement Ratio =0.40
Cement centent = Water Content / WaterCement ratio
=140/0.4
=350 Kg/mm^3

minimum cement content = 320 kg/m^3

HENCE OK

water cement ratio = 140/350 =0.4

STEP 5:

COARSE AND FINE AGGREGATE RATIO for zone 1

Table3-IS10262:2019

• Coarse Aggregate ratio = 0.60 (For W/C =0.5)
• Coarse Aggregate ratio for 0.40 w/c ratio = 0.62 (adding 0.01 for everydecrease .05 and vice versa)
• Final Fine Aggregate ratio = (1-0.62) = 0.38

STEP 6 :

MIX CALCULATION

• Volume of Concrete = 1 cu.m
• Total Volume of Cement = Cement/(S.G*1000)
  = 350/(3.15*1000)
  = 0.111 cu.m
• Volume of Water =Water /(S.G*1000)
  = 140/(1*1000)
  = 0.140 cu.m
• Volume of Superplasticizers = Superplasticizers /(S.G*1000)
  = 7.6/(1.145*1000)
  = 0.006 cu.m
• Total Aggregates requirement = A – (B+C+D)
  =1 -(0.111 + 0.140+0.006)
  =0.743 cu.m
• Coarse Aggregate (C.A) = F * C.A ratio * S.G * 1000
  = 0.743*0.62 *2.74 *1000
  = 1262 kg/mm^3
• Fine Aggregate (F.A) = F * F.A ratio * S.G * 1000
  = 0.743*0.38*2.74 *1000
  =774 kg/mm^3

RESULTS AND CONCLUSION :

• Cement = 350 kg/mm^3
• Fine Aggregate = 774kg/mm^3
• Coarse Aggregate (20mm) = 1262 kg/mm^3
• WATER = 140 L
• Chemical admixture = 7 kg/mm^3
• water cement ratio = 0.40

CEMENT : FA : CA = 350 : 774 : 1262

TRIAL MIX RATIO = (C:FA:CA) = (1 : 2.2 : 3.6)

• The slump shall be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements
• Two more trials having variation of 10% of water-cement ratio shall be carried out and a graph between three water- cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target for field trials.

FINAL RESULT :

Mix Proportion by weight of M35 grade of concrete with fly ash is 1 : 2.76 : 4.5 and its water-cement ratio was found to be 0.36.

Mix Proportion by weight of M50 grade of concrete without fly ash is 1 : 2.2 : 3.6 and its water-cement ratio was found to be 0.4.