Project on Concrete Mix Design for various grades of Concrete

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

INTRODUCTION: Concrete mix design is a method of finding the precise portion of cement,sand and aggregatefor concrete to achieve the target strength in structures.therefore concrete mix design can be stated as concrete mix in term of cement:sand:aggregate.so we can achieve the desirable properties of concreteeither it is in fresh stage or hardened stage.

OBJECTIVE: The objective of this project is ro produce a mix design for M35 gharde of concrete containing flyash and M50 grade concrete.The mix will be prepared as per IS METHOD .concrete mix proportional guidelines from IS10262:2009 and recomended guidelines from IS10262:1982.

EQUATIONS USED:

1)Target mean Strength

f'ck=fck*1.65s

where

• f'ck=target average compressivce strength at 28 days
• fck=Characteristics compressivce strength at 28 days
• s=standard deviation

2) cement content

cement content=water content/ water-cement ratio

3)Volume Calculation

• a)volume of concrete
• b)volume of cement=[Mass of cement]/[specific gravity of cement]*1/1000
• c)volume of water=[mass of water]/[specific gravity of water]*1/1000
• d)volume of Chemical Admixture=[mass of admixture]/[specific gravity of admixture]*1/1000
• e)Volume of all in aggregate=[a-(b+c+d)]
• f)Mass of Coarse aggregate =e*Volume of Coarse aggregate *Specific gravity of coarse aggregate*100
• g)Mass of fine aggregate=e*Volume of fine aggregate *Specific gravity of fine aggregate*100

PART 1:To calculate the concrete mix design for m35 grade concrete with fly ash

M35 garde concrete with Fly Ash

Step 1: Stimulations for concrete design mix.

Grade Designation M35

Types of cement OPC43 Grade Confirming to IS 8112

Types of minerals admixture Fly ash Confirming to IS 3812(part 1)

Maximum nominal size of aggregate 20mm

Minimum cement content 320kg/m3 (Table 5 of IS 456:2000-Exposer Condition)

Maximum water-cement ratio 0.45(Table 5 of IS 456:2000-Exposer Condition)

Workability 100mm( slump value for pumpable concrete)

exposer condition severe(For reinforced concrete)

Method of concrete placing Pumping

Degree of supervision good

Types of aggregate Crushed Angular aggregate

Maximum cement content 450 kg/m3

Chemical Admixture types Superplasticizer

STEP 2: TEST DATA FOR MATERIALS

Cement used OPC43 Grade Confirming to IS 8112

Specific gravityof cement 3.15

Specific gravity of fly ash 2.2

chemical admixture Superplasticizer Confirming to IS 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 of moisture of course aggregate Nil

Free surface moisture of fine aggregate Nil

Sieve analysis of coarse aggregate Confirming to Table 2 of IS 383

Sieve analysis fine aggregate Confirming to Grading Zone II of table 4 of IS383

STEP 3) TARGET STRENGTH FOR MIX PROPORTIONING

f'ck=fck+1.65s

Where

• f'ck=target average compressivce strength at 28 days = 35+1.65*5=43.25N/mm2
• fck=Characteristics compressivce strength at 28 days
• s=standard deviation

From table 1 of IS 10262:2009,

Standard deviation= 5 N/mm2

STEP 4) SELECTION OF WATER-CEMENT RATIO

The maximum water cement ratio to design M50 grade concrete can be found from Table 5 of IS 456:2000

Maximum W/C Ratio=0.45

Based on experience adopted water cement ratio is .44

0.44<0.45 hence ok

Adopted w/c ratio =0.44

STEP 5) 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)

Clause 4.2 suggests increasing of 3% of water content for every extra 25mm slump
from 50mm slump. So a 6% is to be added to it 186+ (6/100)*186 = 197 litre.

Estimated water content for 100 mm slump

(Note: If Super plasticizer is used, the water content can be reduced up to 20% and
above.)

Based on trials with Super plasticizer water content reduction of 20% has been 197*0.8 - 158 litre
achieved, Hence the arrived water content
Water required 158 litres

STEP 6: CALCULATION OF CEMENT AND FLY ASH REQUIRED

Adopted w/c Ratio 0.44
Total cementitious (Cement + fly ash)requirement = 158/0.44 = 359 kg/m3
Water content/ Water Cement ratio
The cementitious 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 X 1.10 = 395 kg
From Table 5 of IS 456, Minimum cement content for 'Severe' exposure conditions 320 kg
395 kg/mº> 320 kg/m3 hence ok.
Cementitious material content 395
New water cement ratio 158/395 =0.4
Fly ash content is taken as 30% of the total cementitious content 395 X.3 = 118.5 kg/m²
Cement required 395 – 118 = 277 kg/m3
Cement quantity saved due to fly ash addition 350-277 = 73 kg/m3
Cementitious material, cement and fly ash required is 395 kg/m², 277 kg/m and 118 kg/m and the new water-cement ratio is 0.4
respectively

STEP 7: 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 II) for water-cement ratio of 0.50 is 0.62

In the present case water-cement ratio is 0.44. Therefore, volume of coarse aggregate is required to be increased to decrease the fine
aggregate content. As the water-cement ratio is 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 water-cement ratio).

Therefore, corrected proportion of volume of coarse aggregate for the water-cement
ratio of 0.44 0.632
For pumpable concrete these values should be reduced up to 10%. Therefore, volume 0.632 x 0.9 -0.568.
of coarse aggregate

Volume of fine aggregate content 1-0.568 =0.431
Volume of fine aggregate and coarse aggregate is 0.431 and 568

STEP 8: MIX CALCULATIONS

The mix calculations as per unit volume of concrete shall be as follows:
a) Volume of concrete 1m3
b) Volume of cement = [Mass of cement] /[Specific Gravity of Cement] x 1/1000 (277/3.15) X (1/1000) =0.087m?
c) Volume of fly ash = [Mass of fly ash] /[Specific Gravity of fly ash] x 1/1000 (118/2.2) X(1/1000) =0.053
d) Volume of water = [Mass of water] /[Specific Gravity of water] x 1/1000 (158/1) X (1/1000) = 0.158m2
e) Volume of chemical admixture = [Mass of admixture] /[Specific Gravity of (7.6/1.145) X (1/1000) -0.006 m
admixture] x 1/1000
f) Volume of all in aggregate =[a-(b+c+d+e)] [1-(0.087+0.053+0.158+0.006)] = 0.696m
g) Mass of coarse aggregate=fx Volume of Coarse Aggregate x Specific Gravity of Fine
Aggregate x 1000 0.696x 0.568 x 2.74 x 1000 = 1077 kg/m3
h) Mass of fine aggregate=fx Volume of Fine Aggregate x Specific Gravity of Fine
Aggregate x 1000 0.696x0.431x 2.74 x 1000 = 822 kg/m2

STEP 9: MIX PROPORTIONS

Cement 277 kg/m3
Fly ash 118 kg/m3
Water 158 Um
Fine aggregate 822 kg/m2
Coarse aggregate 20mm 1077 kg/m3
Chemical admixture 7.18 kg/m
Water-cement ratio (lowest W/C ratio is selected) 0.4
Mix Proportion By weight 1:2.08:2.72

STEP 10: 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

STEP 11: 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.

PART 2:To Calculate the Concrete Mix Design for MSO grade concrete without fly ash:

M5O grade concrete without Fly ash

STEP 1: Stipulations for Concrete design mix

Grade designation M5O.
Type of cement OPC 53 Grade confirming to IS BIS 12269 - 1987

Maximum nominal size of aggregate 20 mm

Minimum cement content 320 kg/m3 (Table 5 of IS 456:2000- Exposure condition)

Maximum water-cement ratio 0.45 (Table 5 of IS 456:2000 Exposure condition)

Workability 100 mm (slump value for pumpable concrete)
Exposure condition Severe (For Reinforced Concrete)
Method of concrete placing Pumping
Degree of supervision Good
Type of aggregate Crushed Angular Aggregates
Maximum cement content 450 kg/m3

Chemical admixture type Super Plasticizer

STEP 2: TEST DATA FOR MATERIALS

Cement used opc 53 Grade conforming IS 12269-1987
Specific gravity of cement 3.15
Chemical admixture Super Plasticizer conforming to IS 9103
Specific gravity of coarse aggregate 2.74
Specific gravity of fine aggregate 2.63
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 Coarse 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 IS383

STEP 3: TARGET STRENGTH FOR MIX PROPORTIONING

ftk -fck 1.65s
Where

• f'ck target average compressive strength at 28 days 50 1.65 x5=58.25 N/mm2
• fck = characteristics compressive strength at 28 days, and
• s standard deviation

From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2.
Target mean strength 58.25 N/mm2

STEP 4: SELECTION OF WATER-CEMENT RATIO

The maximum water-cement ratio to design M50 grade concrete can be found

from Table 5 of IS 456-2000 for severe exposure. Maximum W/C ratio =0.45

Based on experience adopted water cement ratio is .44
0.44<0.45, hence 0k

Adopted w/c ratio=O. 44

STEP 5: 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)
Clause 4.2 suggests increasing of 3% of water content for every extra 25mm slump
from 50mm slump. So a 6% is to be added to it 186+(6/10)*186 = 197 litre
Estimated water content for 100 mm slump
(Note: If Super plasticizer is used, the water content can be reduced up to 20% and
above.) 197 x 0.8= 158 litre
Based on trials with Super plasticizer water content reduction of 20% has been
achieved, Hence the arrived water content

Water required 158 litres

STEP 6: CALCULATION OF CEMENT REQUIRED

Adopted w/c Ratio 0.44
Cement Content 158/0.44= 359 kg/m3
From Table 5 of IS 456, Minimum cement content for Severe' exposure conditions 320kg/m3
359 kg/m3 > 320 kg/m3 hence 0k.

Cement required is 359 kg/m3

STEP 7: 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 II) for water-cement ratio of 0.50 is 0.62.

In the present case water-cement ratio is 0.44. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is 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 water-cement ratio).
Therefore, corrected proportion of volume of coarse aggregate for the water-cement
ratio of 0.44 0.632

0.632 x 0.9=0.568.
For pumpable concrete these values should be reduced up to 10%. Therefore, volume 1-0.576=0.431

Volume of the fine aggregate and the coarse aggregate is 0.431 & 0.568.

STEP 8: MIX CALCULATIONS

The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete 1m3
b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement) x 1/1000 (359/3.15) X (1/1000) -0.114m3
c) Volume of water = CMass of water] / [Specific Gravity of water] x 1/1000 (158/1) X (1/1000) 0.158m:
d) Volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture]x 1/1000 (7.6/1.145)X (1/1000) =0.006 mg
e) Volume of all in aggregate = [1-(0.114+0.158+0.006)]= 0.722m3
f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine
Aggregate x 1000 0.722*0.568*2.74*1000=1123 kg/m3
g) Mass of fine aggregate= e x Volume of fine Aggregate x Specific Gravity of Fine
Aggregate x 1000 0.722*0.431*2.64*1000=821 kg/m3

STEP 9: MIX PROPORTIONS

Cement 359 kg/m3
Water 158 l/m3
fine aggregate 821 kg/m3
Coarse aggregate 20mm 1123 kg/m3
Chemical admixture 7.18kg/m3
Water-cement ratio Mix Proportion By weight 0.44


STEP 10: 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
STEP 11: 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.

Result:Mix proportion by weight of M35 grade of concrete with fly ash is 1:2.08:2.72 and its water-cement ratio was found to be 0.4.

Mix proportion by weight of M50 grade of concrete without fly ash is 1:2.28:3.12 and its water-cement ratio was found to be 0.44.