Project on Concrete Mix Design for various grades of Concrete

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

AIM: To calculatethe Concrete Mix Design for M35 grades concrete with fly ash &M50 grade concrete without flyash.

INTRODUCTION:Concrete mix design is the method of finding the precise proportion of cement, sand and aggregate for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of cement:sand:Aggregates.The design is done according to the requirements of concrete strength, so we can achieve the desirable properties of concrete either it is fresh stage or in hardened stage .The fresh concrete properties like workability, setting time and hardened concrete properties like compressive strength , durability etc.are attained surely by this method use of additives like admixtures, retarders etc.other than basic ingredients are use to properties of mix. This projects consist of two parts, the first part deals with the design of M35 grade cement with fly ash as a part of it and second part is the designof M50grade concrete without flyash.

OBJECTIVE: The objective of this project is to produce a mix design for M35 grade concrete containing fly ash and M50 grade concrete. The mix will be prepared as IS Method concrete mix proportioning guideline from IS 10262:2009 and recommented guide lines from IS 10262:1982.

1)Target mean strength

f'ck= fck+1.65s

Where

• f'ck= Target average compressive strength at 28 days
• fck= Characeristics compressive strength at 28 days,and
• s=standard deviation

2)Cement content

cement content =water content/water-cement ratio

3)Volume calculations

• (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]x1/1000
• (d) Volume of cgemical admixture=[Mass of Admixture]/[Specific Gravity of Admixture]x1/1000
• (e) Volume of all in Aggregate=[a-(b+c+d)]
• (f) Mass of coarse aggregate=e x volume of Fine aggregate x Specific gravity of fine aggregate x1000
• (g) Mass of fine aggregate =e x volume of fine aggregate x Specific Gravity of fine aggregate x 1000

PART 1: To calculate the concrete mix design for M35 grade concrete with fly ash

M35 grade concrete with fly ash

Step 1: Stipulation 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 aggregate 20 mm

Minimum cement content 320 kg/cubic meter(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 (slum value of pumpable concrete)

Exposure condition Severe (for reinforced concrete )

Method of concrete placing Pumping

Degree of super vision Good

Type of aggregate Crushed angular aggregates

Maximum cement content 450 kg/cubic meter

Chemical admixture type Super plasticizer

STEP 2: TEST DATA FOR MATERIALS

Cement used OPC 43 Grade confirming to 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 to IS 9103

Specific gravity of coarse aggregate 2.74

Specific gravity of fine aggregate 2.74

water absorbtion of coarse aggregate 0.5%

water absorbtion of fine aggregate 1%

Free surface moisture of Fine aggregate Nil

Free surface moisture of coarse aggregate Nil

Sieve analysis coarse aggregate Conforming to table 2of IS 383

Sieve analysis Fine aggregate Conforming to grading zone II of table 4of IS 383

STEP 3: TARGET STRENGTH FOR MIX PROPOTIONING

f'ck=fck +1.65s

where

• f'ck=target average compressive strength at 28 days 35+1.65 x 5=43.25 n/ sq mm
• fck=characteristics compressive strength at 28 days and
• s= standars deviation

From table 1of IS 10262:2009,standard deviation,s=5 N/sq mm

Target mean strength =43.25 N/ sq mm

STEP 4: SELECTION OF WATER- CEMENT RATIO

The maximum water-cement ratio to design M50 grade Maximum w/c ratio =0.45

concrete can be found from table 5 of IS 456-2000

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 2of IS 10262:2009,maximum water content for 20 mm 186 litre (for 25 to 50mm slump range)

aggregate

Clause 4.2 suggests incresing of 3% of water content for every extra

25mm slump from 50mm slumps. so a 6% is to be added to it. 186+(6/100)*186=197 litre

Estimated water content foe 100mm slump

(Note: If super plasticizer is used,the water content can be reduced up

to 20% and above) 197*0.8=158 litre

Based on trails with super plasticizers water content raduction of 20%

has been achieved, Hence the arrived water content

Water required 158 litre

EP 6: CALCULATION OF CEMENT AND FLY ASH REQUIRED

Adopted w/c Ratio 0.44

Total cementious (cement + Fly ash)requirement= 158/0.44=359 kg/cubic m

water content/water cement ratio

The cementious content has to be increased in order to attain good workabiity and strength.The increment is required to determine on the basis of experience and research.Here we are increasing cementious content by 10%

Final cementious content 359 x 1.10=395 kg

From Table 5 of IS 456, Minimum cement content 'severe'exposure

condition 320 kg

395 kg/ cubic m hence ok.

Cementious material content 395

New water cement ratio 158/395=0.4

Fly ash content is taken as 30% of the total cementious content 395 x 3=118.5 kg/cu.m

Cement required 395-118=277 kg/ cu. m

Cement quantity saved due to fly ash addition 350-277=73 kg/ cu m

Cementious material, cement and fly ash required is 395 kg/cu.m ,277 kg/ cu.m and 118 kg/ cu.m and the new water cement ratio is0.4 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 mmsize aggregate and fine aggragate (Zone II) 0.62

for water cement ratio of 0.50 is

In the present case water-cement ratio is 0.44. Therfore, volume of coarse aggregate is required to increase 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).

Therfore corrected proportion of volume of coarse aggregate for 0.632

the water-cement ratio of 0.44

For pumpable concrete this values should be reduced up to 10% 0.632 x 0.9=0.568

Therfore , volume of coarse aggregate

volume of fine aggregate 1-0.568=0.431

Volume of fine aggrgate and coarse aggregate is 0.431 and 0.568

STEP 8: MIX CALCULATIONS

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

a) Volume of concrete 1 cu. m

b)Volume of cement = [Mass of cement]/[Specific Gravity

of cement] x 1/1000 (277/3.15) x (1/1000)=0.087cu.m

c) Volume of 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)=0.158 cu.m

e)Volume of chemical admixture =[Mass of admixture]/[Specific

Gravity of admixture ]x 1/1000 (7.6/1.145)x (1/1000)=0.006 cu.m

f) Volume of all in aggregate =[a-(b+c+d+e)] [1-(0.087+0.053+0.158+0.006)]=0.696cu.m

g) Mass of coarse aggregate =f x volume of coarse aggragate x 0.696x0.568x2.74x1000=1077 kg/ cu.m

Specific gravity of fine aggregate x 1000

h) Mass of fine aggregate =f x volume of fine aggregate x specific 0.696 x 0.431x2.74x1000=822 kg/ cu.m

Gravity of fine aggregate x 1000

STEP 9: MIX PROPORTION

Cement 277 kg/cu.m

Fly ash 118 kg/cu.m

water 158 kg/cu.m

Fine aggregate 822 kg/cu.m

Coarse aggregate 20mm 1077 kg/cu.m

Chemical admixture 7.18kg/cu.m

Water-cement ratio (lowest w/c ratio is selected)

Mix proportion by weight

Step 10: The slump shall be maesured, the water content and dosage of admixture shall be adjusted by 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 trial having variation of 10% of water-cement ratio shall be carried out and graph between three water-cement ratio and corresponding strength shall be plotted work out the mix propotion for the given target for field trials.

PART 2: To calculate the concrete mix design for M50 grade concrete without fly ash.

M50 Grade concrete without fly ash

STEP 1: Stipulations for concrete design mix

Grade designation M50

Type of cement OPC 53 Grade confirming to IS 12269-1987

Maximum nominal size aggregate 20 mm

Minimum cement content 320 kg/cubic meter(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 (slum value of pumpable concrete)

Exposure condition Severe (for reinforced concrete )

Method of concrete placing Pumping

Degree of super vision Good

Type of aggregate Crushed angular aggregates

Maximum cement content 450 kg/cubic meter

Chemical admixture type Super plasticizer

STEP 2: TEST DATA FOR MATERIALS

Cement used OPC 53 Grade confirming to 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 2.64

water absorbtion of coarse aggregate 0.5%

water absorbtion of fine aggregate 1.0%

Free surface moisture of Fine aggregate Nil

Free surface moisture of coarse aggregate Nil

Sieve analysis coarse aggregate Conforming to table 2 of IS 383

Sieve analysis Fine aggregate Conforming to grading zone II of table 4 of IS 383

STEP 3: TARGET STRENGTH FOR MIX PROPOTIONING

f'ck=fck +1.65s

where

• f'ck=target average compressive strength at 28 days 50+1.65 x 5=58.25 n/ sq mm
• fck=characteristics compressive strength at 28 days and
• s= standars deviation

From table 1of IS 10262:2009,standard deviation,s=5 N/sq mm

Target mean strength =58.25 N/ sq mm

STEP 4: SELECTION OF WATER- CEMENT RATIO

The maximum water-cement ratio to design M50 grade Maximum w/c ratio =0.45

concrete can be found from table 5 of IS 456-2000 for

severe exposure

Based on experience adopted water cement ratio is, 0.44

0.44<0.45,hence ok

Adopted w/c ratio = 0.44

STEP 5: SELECTION OF WATER CONTENT

From table 2of IS 10262:2009,maximum water content for 20 mm 186 litre (for 25 to 50mm slump range)

aggregate

Clause 4.2 suggests increasing of 3% of water content for every extra

25mm slump from 50mm slumps. so a 6% is to be added to it. 186+(6/100)*186=197 litre

Estimated water content foe 100mm slump

(Note: If super plasticizer is used,the water content can be reduced up

to 20% and above) 197x0.8=158 litre

Based on trials with super plasticizers water content raduction of 20%

has been achieved, Hence the arrived water content

Water required 158 litre

STEP 6: CALCULATION OF CEMENT RAQUIRED

Adopted w/c Ratio

Cement Content

From table 5 of IS 456,Minimum cement content for 'severe' exposure

conditions.

359 kg/cu.m > 320kg/cu.m hence ok.

Cement required is 359 kg/cu.m

STEP 7: VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

from table 3 of (IS 10262:2009) Volume of coarse aggregate

corresponding to 20 mmsize aggregate and fine aggragate (Zone II) 0.62

for water cement ratio of 0.50 is

In the present case water-cement ratio is 0.44. Therfore, volume of coarse aggregate is required to increase 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).

Therfore corrected proportion of volume of coarse aggregate for 0.632

the water-cement ratio of 0.44

For pumpable concrete this values should be reduced up to 10% 0.632 x 0.9=0.568

Therfore , volume of coarse aggregate

volume of fine aggregate 1-0.568=0.431

Volume of fine aggrgate and coarse aggregate is 0.431 and 0.568

STEP 8: MIX CALCULATIONS

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

a) Volume of concrete 1 cu. m

b) Volume of cement = [Mass of cement]/[Specific Gravity

of cement] x 1/1000 (359/3.15) x (1/1000)=0.114cu.m

c) Volume of water = [Mass of water]/[Specific gravity of water]x

1/1000 (158/1)x(1/1000)=0.158 cu.m

d) Volume of chemical admixture =[Mass of admixture]/[Specific

Gravity of admixture ]x 1/1000 (7.6/1.145)x (1/1000)=0.006 cu.m

e) Volume of all in aggregate =[a-(b+c+d+e)] [1-(0.114+0.158+0.006)]=0.722cu.m

f) Mass of coarse aggregate =f x volume of coarse aggragate 0.696x0.568x2.74x1000=1077 kg/ cu.m

x Specific gravity of fine aggregate x 1000

g) Mass of fine aggregate =f x volume of fine aggregate x specific 0.722 x 0.568x2.74x1000=1123 kg/cu.m

Gravity of fine aggregate x 1000

STEP 9: MIX PROPORTION

Cement 359 kg/cu.m

water 158 kg/cu.m

Fine aggregate 821 kg/cu.m

Coarse aggregate 20mm 1123 kg/cu.m

Chemical admixture 7.18 kg/cu.m

Water-Cement ratio 0.44

Mix proportion by weight 1:2.28:3.12

Step 10: The slump shall be maesured, the water content and dosage of admixture shall be adjusted by 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 trial having variation of 10% of water-cement ratio shall be carried out and graph between three water-cement ratio and corresponding strength shall be plotted work out the mix propotion for the given target for field trials.

RESULTS:

Mix proportion by weight of M35 gradegrade 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 garde of concrete without Fly ash is 1:2.28:3.12 and its water-cement ratio was found to be 0.44.