Project on Concrete Mix Design for various grades of Concrete
Calculate the Concrete Mix Design for M35 grade concrete with fly ash.
- Procedure to carry out mix design for M35 grade concrete is as given below.
1. Data Collection
Here, we will assume the missing data.
- Grade of concrete = M35
- Type of cement = OPC 43 grade conforming to IS 8112
- Type of mineral admixture = Fly Ash conforming to IS 3812 (Part 1)
- maximum nominal size of aggregate = 20 mm
- Minimum cement content = 300 kg/m^3 from Table-5 of IS 456:2000
- Maximum water-cement ratio = 0.5 from Table-5 of IS 456:2000
- Workability = 100 mm (Slump value for pumpable concrete)
- Exposure condition = Moderate (for reinforced concrete)
- Method for concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate : Crushed Angular
- Maximum cement content : 450 kg/m^3
- Chemical Admixture : Super plasticizer
2. Test data for materials :
a) Cement Used : OPC 43 grade conforming to IS 8112
b) Specific Gravity of cement : 3.15
c) Fly Ash : conforming to IS 3812 (Part 1)
d) Specific gravity of :
Fly Ash = 2.2
e) Chemical admixture : Superplasticizer conforming to IS 9103
f) Specific Gravity of :
Fine aggregate = 2.74
Coarse aggregate = 2.74
g) Water absorption :
Fine aggregate = 1 %
Coarse aggregate = 0.5%
h) Free surface moisture :
Fine aggregate = NIL
Coarse aggregate = NIL
i) Seive analysis
Coarse aggregate : it should conform Table 3 of IS 383
Fine aggregtae : It should conform Table 4 of IS 383
3. Target Mean Strength
f'ck = fck + 1.65S
f'ck = Target compressive strength at 28 days
fck = Characteristic compressive strength at 28 days
S = Standard Deviation
So from Table 1 of IS 10262 : 2009, S = 5 N/mm^2
So, f'ck = 35 + 1.65(5) = 43.25 N/mm^2
4. Selection of w/c ratio
From Table 5 of IS 456 : 2000 fro moderate condition, Maximum w/c ratio = 0.5
Based of experience, adopted w/c ratio is 0.45
0.45 is less than 0.5 Hence, OK.
5. Selection of water content
From Table 2 of IS 10262 : 2009, Maximum water content for 20mm aggregate = 186 litre for slump value of 25mm to 50mm slump.
Here, Slump value is 100mm
Hence adding 6% (3% for every 25mm increase in slump)
So, 186 + 6% = 197 litre
As super plasticizer is used, water content can be reduced to 30 %
based on experience, taking 29 %
hence 197 x 0.71 = 140 liter
6. Calculation of cement content :
Water-cement ratio = 0.45
Cement + Fly Ash content = 140/0.45 = 311 kg/m^3
Hence, taking 438 kg/m^3
From Table 5 of IS 456, minimum cement content for moderate exposure condition is 300 kg/m^3 Hence, OK.
Now, to proportion a mix containing fly ash, following steps needs to be carried out.
a. The percentage of fly ash needs to be decided based on project requirement and quality of the material.
b. In some cases, increase in cementitious materials may be alarming as it is based on experience, hence we will only increase by 10%
so,
Cementitious material content = 311 x 1.10 = 342 kg/m^3
Water content = 140 liter
w/c ratio = 140 / 342 = 0.41
Fly ash as 30% of total cementitious material = 342 x 0.3 = 102.6 kg/m^3
Cement (OPC) = 342 x 0.7 = 239.4 kg/m^3
saving of cement using fly ash = 311 - 239.4 = 71.6 kg/m^3
7. Proportion of volume of coarse and fine aggregate :
From Table 3 of IS 10262 : 2009, volume of coarse aggregate corrresponding to 20mm size aggregate and fine aggregate (zone-1) for water-cement ratio = 0.6
Here, we hahve considered w/c ratio as 0.45
- Therefore, the volume of coarse aggregate needs to be decreased to increase the fiine aggregate content.
- As w/c ratio is lower by 0.15 the proportion of coarse aggegate is to be increased by 0.03 (at +/-0.01 for every +/-0.05 change in the water cement ratio.
- Therefore the corrected volume for w/c ratio of 0.45 is 0.63
for pumpabe concrete, these values are decreased by 10% so, 0.567
Volume of fine aggregate content = 1 - 0.567 = 0.433
8. Mix calculations :
a) Volume of concrete = 1m^3
b) Volume of cement = Mass of cement / Specific gravity of cement x 1 / 1000
= 239.4 / 3.15 x 1 / 1000
= 0.076 m^3
c) Volume of fly ash = Mass of fly ash / Specific gravity of fly ash x 1 / 1000
= 102.6 / 3.15 x 1 / 1000
= 0.047 m^3
d) Volume of water = Mass of water / Specific gravity of water x 1 / 1000
= 140 / 1000
= 0.140
e) Volume of chemical admixture = Mass of chemical admixture / Specific gravity of chemical admixture x 1 / 1000
= 7.6 / 1.145 x 1 / 1000
= 0.006 m^3 (conforming to IS 9103)
f) Volume of aggregate (FA+CA) = a - b - c - d - e = 1 - 0.076 - 0.047 - 0.140 - 0.006 = 0.724 m^3
g) Mass of coarse aggregate = e x Volume of coarse aggregate x Specific gravity of coarse aggregate x 1000
= 0.724 x 0.567 x 2.74 x 1000 = 1124 kg/m^3
h) Mass of fine aggregate = e x Volume of fine aggregate x Specific gravity of fine aggregate x 1000
= 0.724 x 0.433 x 2.74 x 1000 = 859 kg/m^3
9. Mix proprtion for Trial No 1
Cement = 239.4 kg/m^3
Fly Ash = 102.6 kg/m^3
Water = 140 kg/m^3
Fine aggregate = 859 kg/m^3
Coarse aggregate = 1124 kg/m^3
W/c Ratio = 0.41
Trial Mix Ratio = 1 : 2.51 : 3.28
10. The slump should be measured and water content shall be adjusted to achieve the required slump value.The mix proportion shall be reworked and checked for the urability requirements.
11. Two more trials having variation of 10% in clause 10 shall be carried out and a graph between 3 water content ratios and corresponding strength shall be plotted to work out the mix proportion for the given target strength for field trials. It is important to jkeep in mind that the durability should be met.
2. Calculate the Concrete Mix Design for M50 grade concrete without fly ash.
- Procedure to carry out mix design for M35 grade concrete is as given below.
1. Data Collection
Here, we will assume the missing data.
- Grade of concrete = M50
- Type of cement = OPC 43 grade conforming to IS 8112
- maximum nominal size of aggregate = 20 mm
- Minimum cement content = 300 kg/m^3 from Table-5 of IS 456:2000
- Maximum water-cement ratio = 0.5 from Table-5 of IS 456:2000
- Workability = 100 mm (Slump value for pumpable concrete)
- Exposure condition = Moderate (for reinforced concrete)
- Method for concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate : Crushed Angular
- Maximum cement content : 450 kg/m^3
- Chemical Admixture : None
2. Test data for materials :
a) Cement Used : OPC 43 grade conforming to IS 8112
b) Specific Gravity of cement : 3.15
c) Chemical Admixture : None
d) Specific gravity of :
Fine aggregate = 2.74
Coarse aggregate = 2.74
e) Water absorption :
Fine aggregate = 1 %
Coarse aggregate = 0.5%
f) Free surface moisture :
Fine aggregate = NIL
Coarse aggregate = NIL
e) Seive analysis
Coarse aggregate : it should conform Table 3 of IS 383
Fine aggregtae : It should conform Table 4 of IS 383
3. Target Mean Strength
f'ck = fck + 1.65S
f'ck = Target compressive strength at 28 days
fck = Characteristic compressive strength at 28 days
S = Standard Deviation
So from Table 1 of IS 10262 : 2009, S = 5 N/mm^2
So, f'ck = 50 + 1.65(5) = 58.25 N/mm^2
4. Selection of w/c ratio
From Table 5 of IS 456 : 2000 fro moderate condition, Maximum w/c ratio = 0.5
Based of experience, adopted w/c ratio is 0.45
0.45 is less than 0.5 Hence, OK.
5. Selection of water content
From Table 2 of IS 10262 : 2009, Maximum water content for 20mm aggregate = 186 litre for slump value of 25mm to 50mm slump.
Here, Slump value is 100mm
Hence adding 6% (3% for every 25mm increase in slump)
So, 186 + 6% = 197 litre
6. Calculation of cement content :
Water-cement ratio = 0.45
Cement content = 197/0.45 = 437.77
Hence, taking 438 kg/m^3
From Table 5 of IS 456, minimum cement content for moderate exposure condition is 300 kg/m^3 Hence, OK.
7. Proportion of volume of coarse and fine aggregate :
From Table 3 of IS 10262 : 2009, volume of coarse aggregate corrresponding to 20mm size aggregate and fine aggregate (zone-1) for water-cement ratio = 0.6
Here, we hahve considered w/c ratio as 0.45
- Therefore, the volume of coarse aggregate needs to be decreased to increase the fiine aggregate content.
- As w/c ratio is lower by 0.15 the proportion of coarse aggegate is to be increased by 0.03 (at +/-0.01 for every +/-0.05 change in the water cement ratio.
- Therefore the corrected volume for w/c ratio of 0.45 is 0.63
for pumpabe concrete, these values are decreased by 10% so, 0.567
Volume of fine aggregate content = 1 - 0.567 = 0.433
8. Mix calculations :
a) Volume of concrete = 1m^3
b) Volume of cement = Mass of cement / Specific gravity of cement x 1 / 1000
= 438 / 3.15 x 1 / 1000
= 0.139 m^3
c) Volume of water = Mass of water / Specific gravity of water x 1 / 1000
= 197/1000
= 0.197
d) Volume of chemical admixture = None
e) Volume of aggregate (FA+CA) = a - b - c = 1 - 0.139 - 0.197 = 0.664
f) Mass of coarse aggregate = e x Volume of coarse aggregate x Specific gravity of coarse aggregate x 1000
= 0.664 x 0.567 x 2.74 x 1000 = 1031 kg/m^3
g) Mass of fine aggregate = e x Volume of fine aggregate x Specific gravity of fine aggregate x 1000
= 0.664 x 0.433 x 2.74 x 1000 = 787 kg/m^3
9. Mix proprtion for Trial No 1
Cement = 438 kg/m^3
Water = 197 kg/m^3
Fine aggregate = 787 kg/m^3
Coarse aggregate = 1031 kg/m^3
W/c Ratio = 0.45
Trial Mix Ratio = 1 : 1.79 : 2.35
10. The slump should be measured and water content shall be adjusted to achieve the required slump value.The mix proportion shall be reworked and checked for the urability requirements.
11. Two more trials having variation of 10% in clause 10 shall be carried out and a graph between 3 water content ratios and corresponding strength shall be plotted to work out the mix proportion for the given target strength for field trials. It is important to jkeep in mind that the durability should be met.