Project on Concrete Mix Design for various grades of Concrete

1.Mix design for M35 grade concrete with flyash

• Mix proportioning of concrete using flyash as part of replacement of OPC

Stipulation for proportiong.

1. Grade designation :M35
2. Type of cement :OPC43 grade
3. Type of mineral admixture : flyash conforming to IS8112
4. Maximum nominal size of aggregate :20mm
5. Minimum cement content :320kg/m^3 (From table 5 of IS456:2000)
6. Maximum water cement ratio : 0.45
7. Workability : 100mm (slump value for pumpable concrete.
8. Exposure condition : Severe for rcc
9. Method of concrete placing:pumping
10. degree of supervision : Good
11. Type of Aggregate : Crushed angular aggregate
12. Maximum cement content :450kg/m^3

Test data for materials:

1. cement used :OPC 33 grade conforming to IS8112
2. Specific gravity of cement :3.15
3. Flyash : Conforming to IS 3812 (part 1)
4. Specific gravity of flyash : 2.2
5. Chemical admixture : Superplasticizer confoming to IS 9103
6. Specific gravity of

coarse aggregate :2.74

fine aggregate : 2.74

g.Water Absorption

Coarse Aggregate : 0.5%

Fine Aggregate :1.0%

h.Free Surface moisture

Coarse Aggregate : Nill

Fine Aggregate : Nill

Sieve Analysis

Coarse Aggregate: conforming to table 2 os IS 383

Fine aggregate :conforming to grade Zone II of table 4 of IS 383

TARGET STRENGTH FOR MIX PROPORTIOING:

f'ck = fck + 1.65 S

when f'ck = target average compresive stregth at 28 days.

fck = Charateristic compressive stregh of 28 days.

S = Standard deviation.

From Table I of IS 10262:2009 standard deviation

S = 5 N/mm^2

Target Strength = 35+(1.65*5)

= 35+(8.25)

= 43.25

SELECTION OF WATER CEMENT RATIO:

from table 5 of IS 456:2000 for severe exposure, maximum water cement ratio as 0.45

SELECTION OF WATER CONTENT

from table 2 of IS 10262:2009 maximum water content for 20mm aggregate = 186 lit (25mm to 50mm slump range)

Estimated water content for 100 mm slump = 186 + 6/100*186 = 197 lit.

As superplasticizer is used, the water content can be reduced upto 30% based on trail water content reduction 29% is achived with plasticizeer.

Hence arrived water content = 197 * 0.71 = 140 litre

CALCULATION OF CEMENT CONTENT

water cement ratio = 0.45

Cementitious material ( Cement +flyash ) content

= 140 / 0.45 = 311kg/m^3

From Table 5 of minimum cement content for severe exposure condition = 320kg/m^3

320kg /m^3 > 311kg / m^3 Hence ok.

Now to proportion a mix containting flyash the following steps are suggested.

Hence 320 OK

Cementitious material content = 320 x 1.10 = 352kg/m^3

water content = 140kg/m^3

So, water content ratio = 140/352 = 0.394

flyash @30% total cementitious material content = 352*30% = 105m^3

Cement OPC = 352 - 105 = 247 kg/m^3

Saving of cement while using flyash = 320-247 = 73kg/m^3

Flyash being utilized = 105 kg/m^3

PROPOTION OF COARSE AND FINE AGGREGATE

From table 3 of IS 10262:2009 (in zone 1) water cement ratio of 0.5 = 0.6

Volume of coarse aggregate = 0.62x 0.9 = 0.56

Volume of Fine aggregate = 1 - 0.56 = 0.44

Mix calculation

Volume of concrete = 1M^3

Volume of cement = 247 / 3.15*1/1000 = 0.0784M^3

Voume of flyash = 105/2.2*1/1000 = 0.047

Volume of water = 140/1*1/1000 = 0.140M^3

Volume of chemical admixture = 7.6/1.145 * 1/1000 = 0.006M^3

Volume of aggregate (FA &CA) = (1-(0.0784+0.047+0.140+0.006)) = 1-0.2714 = 0.728M^3

Mass of Coarse aggregate = 0.728 * 0.56 *2.74 * 1000 = 1117kg/M^3

Mass of fine aggregate = 0.728 *0.44*2.74*1000 = 877kg/m^3

MIX PROPORTION

cement = 247 kg/m^3

flyash = 105

water = 140

Fine aggregate = 877

coarse aggregate = 1117

Chemical admixture = 7kg/m^3

Water cement ratio = 0.39

so mix ratio = 1:2.49:3.17

M50 GRADE CONCRETE MIX WITHOUT FLYASH

• Grade : M50
• type of cement : OPC 53
• maximum nominal size of aggregate : 20 mm
• minimum cement content : 320 kg/m^3 (table5)
• maximum water content. : 0.45 (table5)
• wokability :100 mm slump
• maximum cement content :450 kg/m^3

target mean strength f ck = 50+1.65x5= 58.25 n/mm^2
water cement ratio from table 5 = .44

slump for 100mm = 186+(6/100)x186= 197 lit

based on trials 29% reduced for plasticier= 197x0.71 =140 lit

caculation of cement required

cement content 140/.44= 318 kg/m^3

320 > 318 kg/m ^3 ok

so cement required is 320 kg/m^3

mix calculation

• voulume of concrete =1m^3
• vol of cement = 320/3.15 x 1/1000 =0.101 m^3
• vol of water. = 140/1x1/1000. =0.14 m^3
• vol of chemical admix =7.6/1.145 x1/1000 = .006 m^3
• vol of all aggregate. =1- (0.101+0.14+.006) =0.753 m^3
• vol of coarse aggregate =0.753x0.568x2.74x1000= 1172 kg/m^3
• vol of fine aggregate. =0.753x0.431x2.64x1000= 857 kg/m^3

MIX PROPORTIONS

• CEMENT 320 kg/m^3
• WATER. 140 l/m^3
• FINE AGGREGATE. 857 kg/m^3
• COARSE AGGREGATE 1172 kg/m^3
• CHEMICAL ADMIXTURE 7.18 kg/m^3
• WATER CEMENT RATIO 0.44

MIX PROPORTION 1:2.67:3.66