Project on Concrete Mix Design for various grades of Concrete

1)Project on Concrete Mix design for M35garde Concrete with flyash:-

Introduction:-

• Concrete is a composite material obtained by mixing Cement, sand, aggregates, and water in suitable proportions.
• Properties of concrete are controlled and influenced by various factors, out of them mix proportions play an important role in concrete strength and these proportions control the properties of strength.
• Mix design can be defined as the process of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing concrete of certain minimum strength and durability as economically as possible for the projects.

Aim:-

Mix design for M35 garde of Concrete with flyash.

Codes Considered for this Concrete Mix Design:-

1. IS 10262:2019
2. IS 456:2000
3. IS 3812 (Part 1)
4. IS 383
5. IS 269
6. IS 9103

Procedure:-

A)STIPULATIONS FOR PROPORTIONING

1. Grade designation : M35
2. Type of cement : OPC 43 grade conforming to IS 269
3. Type of mineral admixture : Fly ash conforming to IS 3812 (Part1)
4. Maximum nominal size of aggregate : 20 mm
5. Minimum cement content : 340kg/m^3 (From Table 5 of IS 456:2000)
6. Maximum water-cement ratio:0.45 (From Table 5 of IS 456:2000- Very Severe exposure condition)
7. Workability : 100 mm (slump)
8. Method of concrete placing : Pumpable
9. Degree of site control : Good
10. Type of aggregate : Crushed angular aggregate
11. Maximum cement content not including fly ash : 450 kg/m3
12. Chemical admixture type : Superplasticizer - normal

B)TEST DATA FOR MATERIALS

1. Cement used : OPC 43 grade conforming to IS 269
2. Specific gravity of cement : 3.15
3. Fly ash : conforming to IS 3812 (Part1)
4. Chemical admixture : Superplasticizer conforming to IS 9103
5. Specific gravity of a) Coarse aggregate: 2.74 [(SSD) Condition] b) Fine aggregate : 2.74 [(SSD) Condition] c) Fly ash : 2.2 d) Chemical admixture : 1.145
6. Water absorption a) Coarse aggregate : 0.5% b) Fine aggregate : 0.5%

7. The coarse and fine aggregates are wet and their total moisture content is 2% and 5% respectively. Therefore, the free moisture content in coarse and fine aggregate shall be as shown in below: A) Coarse aggregate : Free moisture = Total moisture content – Water absorption = 2.0 – 0.5 = 1.5% B) Fine aggregate : Free moisture = Total moisture content – Water absorption = 5.0 – 0.5 = 4.5%

8. Moisture content of aggregate [As per IS 2386 (Part3)] a) Coarse aggregate : 0.5% b) Fine aggregate : 1.0%

9. Sieve analysis: a) Coarse aggregate : Conforming to Table 7 of IS 383 b) Fine aggregate : Conforming to grading Zone II of Table 9 of IS 383

C)TARGET STRENGTH FOR MIX PROPORTIONING

f’ck = fck+1.65 S or f’ck = fck + X ; Whichever is higher.

where f’ck = target average compressive strength at 28 days,

fck = characteristic compressive strength at 28 days,

S = standard deviation,

X = factor based on grade of concrete

From IS 10262:2019 Table 2, standard deviation, S = 5 N/mm2

From IS 10262:2019 Table 1, X = 6.5.

Therefore, target strength using both equations, that is,

1. f’ck = fck+1.65 S = 35+1.65 × 5 = 43.25 N/mm2
2. f’ck = fck + 6.5 = 35+ 6.5 = 41.5 N/mm2

The higher value is to be adopted.

Therefore, target strength will be 43.25 N/mm^2 as 43.25 N/mm^2 > 41.5 N/mm^2.

D)APPROXIMATE AIR CONTENT

From IS 10262:2019, Table 3, the approximate amount of entrapped air to be expected in normal(non air entrained) concrete is 1.0% for 20 mm nominal maximum size of aggregate.

E)SELECTION OF WATER-CEMENT RATIO

From IS 10262:2019, Fig. 1, the free water-cement ratio required for the target strength of 43.25 N/mm2 is 0.38 for OPC 43

grade curve. This is lower than the maximum value of 0.45 prescribed for ‘ very severe’ exposure for reinforced concrete as per Table 5 of IS 456.

0.38 < 0.45, hence O.K.

F)SELECTION OF WATER CONTENT

From IS 10262:2019, Table 4, water content = 186 kg (for 50 mm slump) for 20 mm aggregate.

Estimated water content for 100 mm slump (increasing at the rate of 3% for every 25 mm slump) =186 + 6% of 186 =197.16 kg

As superplasticizer is used, the water content may be reduced. Based on trial data, the water content reduction of 23 percent is considered while using superplasticizer at the rate 1.0 percent by weight of cement.

Hence the arrived water content = 197.16 - 23% of 197.16 = 151.81kg (say 152 kg)

G)CALCULATION OF CEMENT CONTENT

Water-cement ratio = 0.38

Cement content = 152/0.38 = 400 kg/m^3

To proportion a mix containing fly ash the following steps are suggested:

1. Decide the percentage fly ash to be used based on project requirement and quality of fly ash.
2. In certain situations, increase in cementitious material content may be warranted. The decision on increase in cementitious material content and its percentage may be based on experience and trials.

This trial is with increase of 10 percent cementitious material content.

Cementitious material content = 400 × 1.10 = 470 kg/m^3

Water content = 152 kg/m3

So, water-cementitious ratio = 152/470 = 0.323

Fly ash @ 30 percent of total cementitious material content = 470 × 30% = 141 kg/m^3

Cement (OPC) = 470 – 141 = 329 kg/m3

From IS 10262:2019, Table 5 of IS 456, minimum cementitious content for ‘very severe’ exposure condition = 340 kg/m3

470 kg/m^3 > 340 kg/m^3, hence O.K.

H)PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGRAGETE CONTENT

From IS 10262:2019, Table 5, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 = 0.62.

In the present case water-cementitious ratio is 0.323.

Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.177, the proportion of volume of coarse aggregate is increased by 0.0354 (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-cementitious ratio of 0.327 = 0.62 + 0.0354 = 0.655.

For pumpable concrete these values may be reduced by up to 10 percent. (see IS 10262:2019, clause: 5.5.2). Here, 10% reduction is considered.

Therefore, volume of coarse aggregate = 0.6555 × 0.9 = 0.5895m^3 (say 0.59 m^3).

Volume of fine aggregate content = 1 – 0.59 = 0.41 m3

I)MIX CALCULATIONS

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

1. Total volume = 1 m3
2. Volume of entrapped air in wet concrete = 0.01 m^3
3. Volume of cement = (Mass of cement/Specific gravity of cement) x (1/1000) = (329/3.15) x (1/1000) = 0.104 m^3
4. Volume of fly ash = (Mass of fly ash/Specific gravity of fly ash) x (1/1000) = (141/2.2) x (1/1000) = 0.0641m^3
5. Volume of water = (Mass of water/Specific gravity of water) x (1/1000) = (152/1) × (1/1000) = 0.152m^3
6. Volume of chemical admixture (superplasticizer) (@ 1.0 percent by mass of cementitious material) = (Mass of chemical admixture/Specific gravity of admixture) x (1/1000) = (4.70/1.145) x (1/1000) = 0.004 m^3
7. Volume of all in aggregate = [(1-2)-(3+4+5+6)] = (1-0.01) - (0.104 + 0.0641 + 0.152 + 0.004) = 0.666 m^3
8. Mass of coarse aggregate = Volume of all in aggregate × volume of coarse aggregate × Specific gravity of coarse aggregate × 1000 = 0.666× 0.59 × 2.74 × 1000 = 1076.655kg (say 1077kg)
9. Mass of fine aggregate = Volume of all in aggregate × Volume of fine aggregate × Specific gravity of fine aggregate × 1000 = 0.666 × 0.41 × 2.74 × 1000 = 748.184 (say 748kg)

MIX PROPORTIONS FOR TRIAL NUMBER 1

Cement = 329 kg/m^3

Fly ash = 141 kg/m^3

Water (Net mixing) = 152 kg/m^3

Fine aggregate (SSD) = 748 kg/m^3

Coarse aggregate (SSD) = 1077 kg/m^3

Chemical admixture = 4.70 kg/m^3

Free water-cementitious materials ratio = 0.323

ADJUSTMENT ON WATER, FINE AGGREGATE AND COARSE AGGREGATE (IF THE COARSE AND FINE AGGREGATE IS IN WET CONDITION)

1. Fine aggregate (Wet) : Mass of wet fine aggregate = mass of fine aggregate in SSD condition x [1 + (Free (surface) moisture/100)] = 748 x [1 + (4.5/100] = 781.66 kg/m^3 (say 782 kg/m^3)
2. Coarse aggregate (Wet) : Mass of wet coarse aggregate = mass of coarse aggregate in SSD condition x [1 + (Free (surface) moisture/100)] = 1077 x [1 + (1.5/100)] = 1093.155 kg/m^3 (say 1093 kg/m^3)

The coarse and fine aggregates, being wet, contribute water to the mix to the extent of free moisture over SSD condition. The quantity of this water is required to be subtracted from the calculated water content.

1) Water content contributed by wet coarse aggregate = Mass of wet coarse aggregate – mass of SSD condition coarse aggregate = 1093 - 1077 = 16 kg

2) Water content contributed by wet fine aggregate = Mass of wet fine aggregate – mass of SSD condition fine aggregate = 782 – 748 = 34 kg

The requirement for added water = 152 - 16 - 34 = 102 kg/m^3

MIX PROPORTIONS AFTER ADUSTMENT FOR WET AGGREGATES

Cement = 329 kg/m^3

Fly ash = 141 kg/m^3

Water (to be added) = 102 kg/m^3

Fine aggregate (Wet) = 782 kg/m^3

Coarse aggregate (Wet) = 1093 kg/m^3

Chemical admixture = 4.70 kg/m3

Free water-cementitious materials ratio = 0.323

2)Project on Concrete Mix design for M50 garde Concrete without flyash:-

Introduction:-

• Concrete is the construction material consisting of cement, fine aggregate (sand) and coarse aggregate mixed with water which becomes harder with time.
• Water Cement ratio in concrete plays an important role in influencing various properties such as workability, strength and durability.
• Mix design can be defined as the process of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing concrete of certain minimum strength and durability as economically as possible for the projects,

Aim:-

Mix design for M50 garde of Concrete without flyash.

Codes Considered for this Concrete Mix Design:-

1. IS 10262:2019
2. IS 456:2000
3. IS 3812 (Part 1)
4. IS 383
5. IS 269
6. IS 9103

Procedure:-

A)STIPULATIONS FOR PROPORTIONING

• a) Grade designation : M50
• b) Type of cement : OPC 53 grade conforming to IS 269
• c) Maximum nominal size of aggregate : 20 mm
• d) Minimum cement content : 360kg/m^3 (From Table 5 of IS 456:2000)
• e) Maximum water-cement ratio:0.40 (From Table 5 of IS 456:2000- Extreme exposure condition)
• f) Workability : 120 mm (slump)
• g) Method of concrete placing : Pumpable
• h) Degree of site control : Good
• i) Type of aggregate : Crushed angular aggregate
• j) Maximum cement content not including fly ash : 450 kg/m3
• k) Chemical admixture type : Superplasticizer - normal

B)TEST DATA FOR MATERIALS

• a) Cement used : OPC 43 grade conforming to IS 8112
• b) Chemical admixture : Superplasticizer conforming to IS 9103
• c) Specific gravity : 1) Coarse aggregate (at SSD condition) : 2.74

  2) Fine aggregate (at SSD condition) : 2.65

  3) Chemical admixture : 1.145

• d) Water absorption: 1) Coarse aggregate : 0.5%

  2) Fine aggregate : 1.0%

• e) The coarse and fine aggregates are wet and their total moisture content is 2 % and 5% respectively. Therefore, the free moisture content in coarse and fine aggregate shall be as shown in (f) below.
• f) Free (surface) moisture:

  1) Coarse aggregate : Free moisture = Total moisture content – Water absorption = 2.0 – 0.5 = 1.5%

  2) Fine aggregate : Free moisture = Total moisture content – Water absorption = 5.0 – 1.0 = 4.0%

• g) Specific gravity of cement : 3.15
• h) Chemical admixture : Superplasticizer conforming to IS 9103
• i) Specific gravity of 1) Coarse aggregate: 2.74 [(SSD) Condition]

2) Fine aggregate : 2.74 [(SSD) Condition]

• j) Water absorption 1) Coarse aggregate : 0.5%

2) Fine aggregate : 0.8%

• k) Moisture content of aggregate [As per IS 2386 (Part3)] 1) Coarse aggregate : Nil

2) Fine aggregate : Nil

• l) Sieve analysis: 1) Coarse aggregate : Conforming to Table 7 of IS 383

2) Fine aggregate : Conforming to grading Zone II of Table 9 of IS 383

C)TARGET STRENGTH FOR MIX PROPORTIONING

f’ck = fck+1.65 S or f’ck = fck + X ; Whichever is higher.

where f’ck = target average compressive strength at 28 days,

fck = characteristic compressive strength at 28 days,

S = standard deviation,

X = factor based on grade of concrete

From IS 10262:2019 Table 2, standard deviation, S = 5 N/mm2

From IS 10262:2019 Table 1, X = 6.5.

Therefore, target strength using both equations, that is,

1. a) f’ck = fck+1.65 S = 50+1.65 × 5 = 58.25 N/mm2
2. b) f’ck = fck + 6.5 = 50+ 6.5 = 56.5 N/mm2

The higher value is to be adopted.

Therefore, target strength will be 58.25 N/mm^2 as 58.25 N/mm^2 > 56.5 N/mm^2

D)SELECTION OF WATER-CEMENT RATIO

From IS 10262:2019 Fig. 1, the free water-cement ratio required for the target strength of 58.25 N/mm^2 is 0.34 for OPC 53 grade curve.

This is lower than the maximum value of 0.40 prescribed for ‘extreme’ exposure for reinforced concrete as per Table 5 of IS 456.

0.34< 0.40, hence O.K.

E)SELECTION OF WATER CONTENT

From IS 10262:2019 Table 4, water content = 186 kg (for 25 to 50 mm slump) for 20 mm aggregate.

Estimated water content for 120 mm slump = 186 + 9%of 186 = 202.74 kg

As superplasticizer chemical is used, the water content may be reduced 20 to 30%.

Let, the water content reduction of 25 percent is considered while using superplasticizer at the rate 1.0 percent by weight of cement.

Hence the water content = 202.74- 25%of 202.74 = 152.055(say 152kg)

F)CALCULATION OF CEMENT CONTENT

Water-cement ratio = 0.34

Cement content = 148/0.34= 435.29kg/m^3(say 435kg/m^3)

From Table 5 of IS 456, minimum cement content for ‘severe’ exposure condition = 360 kg/m3.

435 kg/m^3 > 360 kg/m^3. Hence, O.K.

G)PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

From IS 10262:2019 Table 5, the proportionate volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 = 0.62

In the present case the water-cement ratio is 0.34.

Therefore, the volume of coarse aggregate is required to be increased to decrease the fine aggregate content.

As the water-cement ratio is lower by 0.16, the proportion of volume of coarse aggregate is increased by 0.032 (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 0.34 = 0.62 + 0.032= 0.652.

Volume of fine aggregate content = 1 – 0.652 = 0.348

H)MIX CALCULATIONS

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

• a) Total volume = 1 m^3
• b) Volume of entrapped air in wet concrete = 0.01 m^3
• c) Volume of cement = (Mass of cement/Specific gravity of cement) x (1/1000)

= (435/3.15) x (1/1000) = 0.138 m^3

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

= (148/1) x (1/1000) = 0.148m^3

• e) Volume of chemical admixture (superplasticizer) (@ 1.0 percent by mass of cementitious material) = (Mass of chemical admixture/Specific gravity of admixture) x (1/1000)

=(4.35/1.145) x (1/1000)

=0.0039m^3

• f) Volume of all in aggregate = [(a-b)-(c+d+e)]

= [(1-0.01) – (0.138 + 0.148 + 0.0039)] = 0.700 m^3

• g) Mass of coarse aggregate = (Volume of all in aggregate × Volume of coarse aggregate × Specific gravity of coarse aggregate × 1000)

=0.700 x 0.652 x 2.74 x 1000

=1250.536kg(Say 1251kg)

• h) Mass of fine aggregate = (Volume of all in aggregate × Volume of fine aggregate × Specific gravity of fine aggregate × 1000)

=0.700 x 0.348 x 2.74 x 1000

=667.464kg (Say 667kg)

MIX PROPORTIONS FOR TRIAL NUMBER 1

Cement = 435 kg/m^3

Water = 148 kg/m^3

Fine aggregate (Dry) = 667 kg/m^3

Coarse aggregate (Dry) = 1251 kg/m^3

Chemical admixture = 4.35 kg/m^3

Free water-cement ratio = 0.34

RESULT: Mix Ratio = 1 : 1.53 : 2.88