Project on Concrete Mix Design for various grades of Concrete

Calculate the Concrete Mix Design for M35 grade concrete with fly ash

Grade designation: M35

Type of cement: OPC 53 grade confirming to IS 8112

Type of mineral admixture: Fly ash

Maximum nominal size of aggregates: 20mm

Minimum cement content: 340kg / m3 (From table-5 of IS 456: 2000 - Exposure condition)

Maximum water-Cement ratio: 0.45 (From table-5 of IS 456: 2000 - Exposure condition)

Workability: 100mm (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 aggregate

Maximum cement content: 450kg/ m3

Chemical admixture type: Superplasticizer

Test data of materials:

Cement used: OPC 53 grade confirming to IS 8112

Specific gravity of cement: 3.15

Fly ash

Specific gravity of fly ash

Chemical admixture: Superplasticizer confirming to IS 9103

Specific gravity of;

Coarse aggregate: 2.74

Fine aggregate: 2.74

Water absorption:

Coarse aggregate: 0.5 %

Fine aggregate: 1%

Free surface moisture;

Coarse aggregate: Nil, since this is using for dry condition

Fine aggregate: Nil

Sieve Analysis:

Coarse aggregate: Confirming to Table 2 of IS 383

Fine aggregate: Confirming to grading Zone II of table 4 of IS 383

Target Strength of Mix proportion:

f'ck = fck + 1.65 S

From table-1 of IS 10262 : 2009, Standard deviation, S = 5 N/mm2)

fck = 35+(1.65 x 5) =43.25 N/mm2

Selection of water cement ration:

From Table 5 of IS 456: 2000 for severe exposure,

Maximum w/c ratio = 0.45

Adopted W/C ratio = 0.45

Selection of water content;

From table-2 of IS 10262: 2009, maximum water content is 186 L

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 superplasticizers is used, the water content can be reduced up to 20% and above. The amount of water-content to be reduced depends on the type of super plasticizer.

Percentage of Reduction in water content = 20%

Water content requirement after SP = =198 – (0.20*198) = 157.73

Adopted Water Content = 160 L

Calculation of cement content

Water Cement Ratio = 0.45

Cement content = Water Content / Water Cement ratio

= 160/0.45 = 355.55 kg

Proportion of volume of coarse aggregate fine aggregate content:

From table3 of IS 10262 : 2009 volume of coarse aggregate

Coarse Aggregate ratio for 0.45 w/c ratio = 0.63

Volume of coarse aggregate value = 1-(0.63) = 0.37

MIX CALCLUATION

Volume of concrete = 1m3

Volume of cement = (Mass of cement / Specific gravity of cement) x (1/1000)

= ( 275 / 3.15 ) x (1/1000) = 0.087 m3

Volume of Fly ash = 118/(2.5*1000) = 0.041m3

Volume of water = 160/(1*1000) = 0.160m3

Volume of chemical admixture = 2.35/(1.12*1000) = 0.002m3

Volume of aggregate = a- (b+c+d+e)

= 1 -(0.087 +0.041+0.160+0.002) = =0.71 m3

Mass of coarse aggregate = 0.71*0.63 *2.74 *1000 = 1225.6 kg

Mass of fine aggregate = 0.71*0.37*2.74 *1000 = 719.8 kg

Mix Design for M35 grade concrete with fly ash

Cement = 275kg /m3

Water = 160L

Fly ash = 118kg /m3

Fine Aggregate = 720kg/m3

Coarse Aggregate = 1226 kg

Chemical admixture = 2kg /m3

Therefore Mix Ratio of M35 Grade concrete by weight is Cement: Flyash: F.A : C.A : Water = 1:0.4:2.6:4.46:0.58

2) Mix Design for M50 grade concrete without Fly ash

Grade designation : M50

Type of cement: OPC 43 grade confirming to IS 8112

Maximum nominal size of aggregates : 20mm

Minimum cement content : 340kg / m3 (From table-5 of IS 456: 2000 - Exposure condition)

Maximum water-Cement ratio : 0.45 (From table-5 of IS 456: 2000 - Exposure condition)

Workability : 100mm (Slump value for pumbable conrete)

Exposure condition : Severe (For reinforced concrete)

Method of concrete placing : Pumping

Degree of supervision : Good

Type of aggregate : Crushed angular aggregate

Maximum cement content : 450kg/ m3

Chemical admixture type : Superplasticizer

Specific Gravity
Cement = 3.15
Fine Aggregate = 2.61
Coarse Aggregate (20mm) = 2.65
Coarse Aggregate (10mm) = 2.66

Minimum Cement (As per contract) =400 kg / m³
Maximum water cement ratio (As per contract) = 0.45

Mix Calculation: –

1. Target Mean Strength = 50 + ( 5 X 1.65 ) = 58.25 Mpa
2. Selection of water cement ratio:-
   Assume water cement ratio = 0.35
3. Calculation of water: –
   Approximate water content for 20mm max. Size of aggregate = 180 kg /m³(As per Table No. 5 , IS : 10262 ). As plasticizer is proposed we can reduce water content by 20%.

Now water content = 180 X 0.8 = 144 kg /m³

4. Calculation of cement content:-
   Water cement ratio = 0.35
   Water content per cum of concrete = 144 kg
   Cement content = 144/0.35 = 411.4 kg / m³
   Say cement content = 412 kg / m³(As per contract Minimum cement content 400 kg / m³)
   Hence O.K.
5. Calculation for C.A. & F.A.:

Volume of concrete = 1 m³
Volume of cement = 412 / ( 3.15 X 1000 ) = 0.1308 m³
Volume of water = 144 / ( 1 X 1000 ) = 0.1440 m³
Volume of Admixture = 4.994 / (1.145 X 1000 ) = 0.0043 m³
Total weight of other materials except coarse aggregate = 0.1308 + 0.1440 +0.0043 = 0.2791 m³

Volume of coarse and fine aggregate = 1 – 0.2791 = 0.7209 m³
Volume of F.A. = 0.7209 X 0.33 = 0.2379 m³ (Assuming 33% by volume of total aggregate)

Volume of C.A. = 0.7209 – 0.2379 = 0.4830 m³

Therefore weight of F.A. = 0.2379 X 2.61 X 1000 = 620.919 kg/ m³

Say weight of F.A. = 621 kg/ m³

Therefore weight of C.A. = 0.4830 X 2.655 X 1000 = 1282.365 kg/ m³

Say weight of C.A. = 1284 kg/ m³

Considering 20 mm: 10mm = 0.55: 0.45
20mm = 706 kg .
10mm = 578 kg .
Hence Mix details per m³
Increasing cement, water, admixture by 2.5% for this trial

Cement = 412 X 1.025 = 422 kg
Water = 144 X 1.025 = 147.6 kg
Fine aggregate = 621 kg
Coarse aggregate 20 mm = 706 kg
Coarse aggregate 10 mm = 578 kg
Admixture = 1.2 % by weight of cement = 5.064 kg.

Water: cement: F.A.: C.A. = 0.35: 1: 1.472: 3.043