Project on Concrete Mix Design for various grades of Concrete
TOPIC I. - Concrete mix Design For M35 grade of Concrete with Fly ash
To calculate the mix desgin of M 35 grade of Concrete for Stipulation for proportioning
- grade designation - M35
- Type of cement - OPC 43 grade
- Type mineral admixture - Fly ash
- Maximum nominal size of aggregate - 20mm
- Workability -100mm
- Exposure condition - severe for reinforced concrete
- Method of concrete placing- Pumping
- Chemical admixture- Superplasticizer
- Minimum cement content - 320kg/m3
- Maximum cement content - 450 kg/m3
- Specific Gravity of cement - 3.15
- Specific Gravity of fly ash - 2.2
- Specific Gravity of coarse & fine Aggregate - 2.74
PROCEDURE
1. Target Strength For mix Proportion
f'ck = fck +1.65s
Where,
f'ck = target avg compressive strength at 28 days.
fck = characteristics compressive strength at 28 days
S= standard deviations
From Table 1 - IS 10262-2009, Standard deviations, s= 5 N/mm2
Target Strength= 35+ (1.65 x 5) = 43.25 N/mm2
2. SELECTION OF WATER-CEMENT RATIO
From Table 5 - IS 456-2000, Maximum w/c ratio for severe condition=0.45
From Graph , Target means strength V/s W/c ratio.
W/c ratio = 0.36
From graphj 28 Days compressive strength v/s water-cement ratio
W/c Ratio = 0.41
Therefore, the lower value of the above three vale is adopted as Water-cement ratio for mix design
So, W/C ratio =0.36
3. SELECTION OF WATER CONTENT
from Table 2, maximum water content for 20mm aggregate
= 186 litre for 25-50mm skump
Estimated water content for 100,mm slump= 186+ ((6/100)*186) = 197 litre.
, As Superplasticizer is used, the water content can ve reduced upto 30%
Based on trial with Superplasticizer water content reduction of 29 % has been achieved.
197 x 0.71 = 140 litre
4. CALCULATION OF CEMENT and FLY ASH CONTENT
water - cement ratio = 0.36
Cementationous material ( cement + Fly ash) Content = 140/ 0.36 = 389 kg
From Table 5 of IS 456, minimum cement content for severe exposure 389 kg/m3
Fly ash its percentage decide on the basis of project requirements and quality materials
For find the fly Ash we have to consider 10% of cementationous material
Cementationous cement = 389 * 1. 10 = 458.84
W/C ratio = = 140/ 458.84= 0.30
Fly ash @30% of total cementationous material = 458.84X 30% = 137. 65 kg /m3
Cement = 458.84- 137.65 = 321.19 kg/m3
Saving of cement while using fly ash= 389- 321.19 = 67.81 kg/ m3
5. PROPORTION OF VOLUME OF COARSE AND FINE AGGREGATE CONTENTS
from Table 3 , volume of coarse aggregate corresponding to 20mm size of aggregate and fine Aggregate for water cement ratio of 0.50 -0.60
In the present water cement ratio is 0.36, therefore the volume of Coarse aggregate is required to be increased to decrease the fine Aggregate content.
As water cement ratio is lower 0.14, the proportion of volume of coarse aggregate is increased by 0.03
Therefore corrected proportion of volume of coarse aggregate for the water cement ratio 0.36 = 0.63
For pumpable concrete these value should be reduced by 10%
Therefore the volume of coarse aggregate= 0.63*0.9= 0.57
Volume of fine Aggregate content= 1-0.57 = 0.43
6. Mix calculation
a) Volume of concrete= 1m³
b) Volume of cement= (Mass of cement / sp. Gravity of cement ) x (1/1000)
= (321.19/3.15)* (1/1000)
= 0.102 m³
c) Volume of Fly ash= (Mass of Fly ash/ sp. Gravity of fly ash) x (1/1000
=( 137.19/2.2)*(1/1000)
= 0.062 m3
d) Volume of water= (Mass of water/ sp. Gravity of water) x (1/1000
= (140/1)*(1/1000)
=0.140m³
e) Volume of admixture @ 2% by mass of Cementationous material=(Mass of admixture/ sp. Gravity of admixture ) x (1/1000)
= (9.17/1.145)*(1/1000)
=0.008m³
f) Volume of all aggregate= [ a -(b+c+d+e)]
=[ 1-(0.102+ 0.062+ 0.140+0.008)]
=0.69
g) Mass of coarse aggregate= f* volume of Coarse aggregate* Sp gravity* 1000
=0.69 *0.57*2.74*1000 =1077.64 kg
h) Mass of fine aggregate= f* volume of fine aggregate* Sp gravity* 1000
= 0.69*0.43*2.74*1000 =812.958 kg
7. MIX PROPORTION FOR M35 .
Cement = 321.19kg/m3
Fly ash =116 kg/m3
Water =140 kg/m3
Fine Aggregate = 812.96 kg/m3
Coarse aggregate = 1077.64 kg/m3
Chemical admixture = 9.17 kg/m3
W/c ratio = 0.30
Result- the mix ratio for M35 gtrade of concrete with fly ash will - 1 : 2.53 : 3.35
TOPIC II Concrete mix Design For M50 grade of Concrete without Fly ash
To calculate the mix desgin of M 50 grade of Concrete for Stipulation for proportioning
- grade designation - M50
- Type of cement - OPC 43 grade
- Maximum nominal size of aggregate - 20mm
- Workability -100mm
- Exposure condition - severe for reinforced concrete
- Method of concrete placing- Pumping
- Chemical admixture- Superplasticizer
- Minimum cement content - 320kg/m3
- Maximum cement content - 450 kg/m3
- Specific Gravity of cement - 3.15
- Specific Gravity of coarse & fine Aggregate - 2.74
PROCEDURE
1. Target Strength For mix Proportion
f'ck = fck +1.65s
Where,
f'ck = target avg compressive strength at 28 days.
fck = characteristics compressive strength at 28 days
S= standard deviations
From Table 1 - IS 10262-2009, Standard deviations, s= 5 N/mm2
Target Strength= 50+ (1.65 x 5) = 58.25 N/mm2
2. SELECTION OF WATER-CEMENT RATIO
From Table 5 - IS 456-2000, Maximum w/c ratio for severe condition=0.45
From graph 28 Days compressive strength v/s water-cement ratio
W/c Ratio = 0.34
Therefore, the lower value of the above three vale is adopted as Water-cement ratio for mix design
So, W/C ratio =0.34
3.SELECTION OF WATER CONTENT
from Table 2, maximum water content for 20mm aggregate
= 186 litre for 25-50mm skump
Estimated water content for 100,mm slump= 186+ ((6/100)*186) = 197 litre.
, As Superplasticizer is used, the water content can ve reduced upto 30%
Based on trial with Superplasticizer water content reduction of 29 % has been achieved.
197 x 0.71 = 140 litre
4. CALCULATION OF CEMENT CONTENT
water - cement ratio = 0.34
Cementationous material ( cement + Fly ash) Content = 140/ 0.34 = 411.76 kg =412kg (approx)
From Table 5 of IS 456, minimum cement content for severe exposure 412 kg/m3
412 kg > 320kg
5. PROPORTION OF VOLUME OF COARSE AND FINE AGGREGATE CONTENTS
from Table 3 , volume of coarse aggregate corresponding to 20mm size of aggregate and fine Aggregate for water cement ratio of 0.50 -0.60
In the present water cement ratio is 0.36, therefore the volume of Coarse aggregate is required to be increased to decrease the fine Aggregate content.
As water cement ratio is lower 0.16, the proportion of volume of coarse aggregate is increased by 0.03
Therefore corrected proportion of volume of coarse aggregate for the water cement ratio 0.34 = 0.63
For pumpable concrete these value should be reduced by 10%
Therefore the volume of coarse aggregate= 0.63*0.9= 0.57
Volume of fine Aggregate content= 1-0.57 = 0.43
6. Mix calculation
a) Volume of concrete= 1m³
b) Volume of cement= (Mass of cement / sp. Gravity of cement ) x (1/1000)
= (412/3.15)* (1/1000)
= 0.130 m³
c) Volume of water= (Mass of water/ sp. Gravity of water) x (1/1000
= (140/1)*(1/1000)
=0.140m³
d) Volume of admixture @ 2% by mass of Cementationous material=(Mass of admixture/ sp. Gravity of admixture ) x (1/1000)
= (8.24/1.145)*(1/1000)
=0.007m³
e) Volume of all aggregate= [ a -(b+c+d)]
=[ 1-(0.130+ 0.140+0.007)]
=0.723
g) Mass of coarse aggregate= e* volume of Coarse aggregate* Sp gravity* 1000
=0.723 *0.57*2.74*1000 =1129.18 kg
h) Mass of fine aggregate= e* volume of fine aggregate* Sp gravity* 1000
= 0.723*0.43*2.74*1000 =851.84 kg
7. MIX PROPORTION FOR M50 .
Cement = 412kg/m3
Water =140 kg/m3
Fine Aggregate = 851.84 kg/m3
Coarse aggregate = 1129.18 kg/m3
Chemical admixture = 8.24 kg/m3
W/c ratio = 0.34
Result- the mix ratio for M50 gtrade of concrete without fly ash will - 1 : 2.06 : 2.74