Project on Concrete Mix Design for various grades of Concrete
Q1]
AIM: -
Mix Design of M35 grade concrete with fly Ash.
1. STIPULATIONS OF PROPORTIONING: -
| a | Grade Designation |
M 35 |
| b | Type of Cement | OPC 43 Grade conforming to IS 8112 |
| c | Type of mineral admixture | Fly ash conforming to IS 3812 (part 1) |
| d | Maximum nominal size of Aggregate | 20 mm |
| e | Maximum water-cement ratio | 0.45 |
| f |
Exposure conditions (as per Table 3 and Table 5 of IS 456) |
severe (for reinforced concrete) |
| g | Workability | 100 mm(slump) |
| h | Method of concrete placing | pumping |
| i | Degree of supervision | Good |
| j | Type of aggregate | Crushed Angular Aggregate |
| k | Minimum cement content (OPC content) | 320 kg/m3 |
| l | Chemical admixture Type | Superplasticizer- normal |
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 Admixture |
1.145 |
| g | Specific gravity of: | |
| 1) Coarse Aggregate | 2.74 | |
| 2) Fine Aggregate | 2.74 | |
| h | Water Absorption: | |
| 1) Coarse Aggregate | 0.5 % | |
| 2) Fine Aggregate | 1.0 % | |
| i | Free (surface) Moisture: | |
| 1) Coarse Aggregate | Nil | |
| 2) Fine Aggregate | Nil | |
| j | Sieve Analysis: | |
| 1) Coarse Aggregate | Conforming to Table 2 of IS 383:1970 | |
| 2) Fine Aggregate |
Conforming to grading zone 1 of Table 4 of IS 383:1970 |
3. TARGET STRENGTH FOR MIX PROPORTIONING: -
`F't = Fck + 1.65*s`
where
F't = target average compressive strength at 28 days.
Fck = characteristic compressive strength at 28 days, and
s = Standard deviation (FROM TABLE 1 IS 10262:2009)
From Table 1, Standard deviation, s=5 N/mm2
Therefore, Target Strength = 35+1.65*5
= 43.25 N/mm2
4. SELECION OF WATER-CEMENT RATIO: -
From Table 5 of IS 456, For "severe" exposure condition.
Maximum water-cement ratio= 0.45
Calculation of water-cement ratio from Fig.1 of IS 10262:2019: -
From Fig 1, the free water-cement ratio required for the target strength of 43.25 N/mm2 is 0.40 for OPC 43
grade curve. This is lower than the maximum value of 0.45 prescribes for "severe" exposure for reinforced concrete as per Table 5 of IS 456.
0.40 < 0.45, hence O.K.
5. SELECTION OF WATER CONTENT: -
From table 2,
Maximum water content for 20mm aggregate = 186 litres (for 25 to 50mm slump range)
Estimated water content for 100mm slump.
(Increasing at the rate of 3 percent for every 25mm slump).
= 186 + (6/100) *186 = 197 litre.
As superplasticizer is used, the water content can be reduced up to 30 %.
Based on trials with superplasticizer water content reduction of 29% has been achieved. Hence, the arrived water content
197* 0.71= 140 litres.
6. CALCULATION OF CEMENT AND FLY ASH CONTENT: -
Water-cement ratio = 0.4
Cementitious material (cement+fly ash) content= 140/0.4 = 350 kg/m3
From Table 5 of IS 456, minimum cement content
for severe exposure conditions = 320 kg/m3
350 kg/m3 > 320 kg/m3, hence, O.K.
Now, to proportion a mix containing fly ash the following steps are suggested: -
a) Decide the percentage fly ash to be used based on project requirement and quality of materials.
b) 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 trial
Cementitious material content = 350*1.10 = 385 kg/m3
Water Content = 140 kg/m3
So, Water-Cementitious ratio
= 140/385
= 0.364
Fly ash @ 30% of total cementitious material content = 385* 30% = 115 kg/m3
Cement (OPC) = 385-115 = 270 kg/m3
Saving of cement while using fly ash = 350 - 270 = 80kg/m3, and
Fly ash being utilized = 115 kg/m3
7. PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT: -
From Table 3 of IS 10262:2009, and as per clause 5.5 of IS 10262:2019
Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone 1) for water-cement ratio of 0.5 = 0.6
In the present case water-cement ratio is 0.40. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.10, the proportion of volume of coarse aggregate is increased by 0.02(at the ate of -/+ 0.01 for every +/- 0.05 change in water-cement ratio).
`((0.5-w/c ratio)/0.05)*0.01+0.6`
=`((0.5-0.4)/0.05)*0.01+0.6`
=0.62
Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.4= 0.62.
As per clause 4.4.1 of IS 10262:2009, For pumpable concrete, these values should be reduced by 10%.
Therefore, volume of coarse aggregate= 0.62*0.9= 0.56
Volume of fine aggregate content = 1-0.56= 0.44
8. MIX CALCULATIONS: -
a) Volume of concrete= 1 m3
b) Volume of cement= (mass of cement/specific gravity of cement)*1/1000
= `(270/3.15)*1/1000`
= 0.086 m3
c) Volume of fly ash= (mass of fly ash/specific gravity of fly ash)*1/1000
= `(115/2.2)*1/1000`
= 0.052 m3
d) Volume of water= (mass of water/specific gravity of water)*1/1000
= `(140/1)*1/1000`
= 0.140 m3
e) Volume of chemical admixture
(superplasticizer @ 2% by mass = (mass of admixture/specific gravity of admixture)*1/1000
of cementitious material)
= `((0.02*385)/1.145)*1/1000`
= `(7.7/1.145)*1/1000`
= 0.007 m3
f) Volume of all in aggregate= [a - (b+c+d+e)]
= [1- (0.086+0.052+0.14+0.006)]
= 0.715 m3
g) Mass of coarse Aggregate= f* volume of coarse aggregate* Specific gravity of coarse aggregate*1000
= 0.715*0.56*2.74*1000
= 1097 kg
h) Mass of fine Aggregate= f*volume of fine Aggregate* Specific gravity of fine Aggregate*1000
= 0.716*0.44*2.74*1000
= 862 kg
MIX PROPORTIONS FOR TRIAL NUMBER 1
Cement = 270 kg/m3
Fly Ash= 115 kg/m3
Water= 140 kg/m3
Fine Aggregate= 862 kg/m3
Coarse Aggregate= 1097 kg/m3
Chemical Admixture= 7.7 kg/m3
Water-cement ratio= 0.364
The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial, if required. The mix proportion shall be reworked for the actual water content and checked for durability requirements.
Two more trials having variation of +/- 10% of water cement ratio in above proportion shall be carried out and a graph between 3 w/c ratios and their corresponding strength shall be plotted to work out the mix proportions for the given target strength.However, durability requirement shall be met.
Q2]
AIM: -
Mix Design of M50 grade concrete without fly Ash.
- STIPULATIONS OF PROPORTIONING: -
|
a |
Grade Designation |
M 50 |
|
|
b |
Type of Cement |
OPC 43 Grade conforming to IS 8112 |
|
|
c |
Maximum nominal size of Aggregate |
20 mm |
|
|
d |
Maximum water-cement ratio |
0.45 |
|
|
e |
Exposure conditions (as per Table 3 and Table 5 of IS 456) |
severe (for reinforced concrete) |
|
|
f |
Workability |
100 mm(slump) |
|
|
g |
Method of concrete placing |
pumping |
|
|
h |
Degree of supervision |
Good |
|
|
i |
Type of aggregate |
Crushed Angular Aggregate |
|
|
j |
Minimum cement content (OPC content) |
320 kg/m3 |
|
|
k |
Chemical admixture Type |
Superplasticizer- normal |
|
- TEST DATA FOR MATERIALS: -
|
a |
Cement used |
OPC 43 grade conforming to IS 8112 |
|
b |
Specific gravity of cement |
3.15 |
|
c |
Chemical Admixture |
Superplasticizer conforming to IS 9103 |
|
d |
Specific gravity of Admixture |
1.145 |
|
e |
Specific gravity of: |
|
|
1) Coarse Aggregate |
2.74 |
|
|
2) Fine Aggregate |
2.74 |
|
|
f |
Water Absorption: |
|
|
1) Coarse Aggregate |
0.5 % |
|
|
2) Fine Aggregate |
1.0 % |
|
|
g |
Free (surface) Moisture: |
|
|
1) Coarse Aggregate |
Nil |
|
|
2) Fine Aggregate |
Nil |
|
|
h |
Sieve Analysis: |
|
|
1) Coarse Aggregate |
Conforming to Table 2 of IS 383:1970 |
|
|
2) Fine Aggregate |
Conforming to grading zone 1 of Table 4 of IS 383:1970 |
- TARGET STRENGTH FOR MIX PROPORTIONING: -
`F't = Fck + 1.65*s`
where
F't = target average compressive strength at 28 days.
Fck = characteristic compressive strength at 28 days, and
s = Standard deviation (FROM TABLE 1 IS 10262:2009)
From Table 1, Standard deviation, s = 5 N/mm2
Therefore, Target Strength = 50+1.65*5
= 58.25 N/mm2
- SELECION OF WATER-CEMENT RATIO: -
From Table 5 of IS 456, For "severe" exposure condition.
Maximum water-cement ratio= 0.45
Calculation of water-cement ratio from Fig.1 of IS 10262:2019: -
From Fig 1, the free water-cement ratio required for the target strength of 58.25 N/mm2 is 0.340 for OPC 43 grade curve. This is lower than the maximum value of 0.45 prescribed for "severe" exposure for reinforced concrete as per Table 5 of IS 456.
0.340 < 0.45, hence O.K.
- SELECTION OF WATER CONTENT: -
From table 2,
Maximum water content for 20mm aggregate = 186 litres (for 25 to 50mm slump range)
Estimated water content for 100mm slump.
(Increasing at the rate of 3 percent for every 25mm slump).
= 186 + (6/100) *186 = 197 litre.
As superplasticizer is used, the water content can be reduced up to 30 %.
Based on trials with superplasticizer water content reduction of 29% has been achieved. Hence, the arrived water content
197* 0.71= 140 litres.
- CALCULATION OF CEMENT AND FLY ASH CONTENT: -
Water-cement ratio = 0.34
Cement content= 140/0.34 = 411 kg/m3
From Table 5 of IS 456, minimum cement content
for severe exposure conditions = 320 kg/m3
411 kg/m3 > 320 kg/m3, hence, O.K.
- PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT: -
From Table 3 of IS 10262:2009, and as per clause 5.5 of IS 10262:2019
Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone 1) for water-cement ratio of 0.5 = 0.6
In the present case water-cement ratio is 0.340. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.10, the proportion of volume of coarse aggregate is increased by 0.02(at the ate of -/+ 0.01 for every +/- 0.05 change in water-cement ratio).
=`((0.5-w/c ratio)/0.05)*0.01+0.6`
=`((0.5-0.34)/0.05)*0.01+0.6`
=0.632
Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.34= 0.632.
As per clause 4.4.1 of IS 10262:2009, For pumpable concrete, these values should be reduced by 10%.
Therefore, volume of coarse aggregate= 0.632*0.9= 0.57
Volume of fine aggregate content = 1-0.57= 0.43
- MIX CALCULATIONS: -
a) Volume of concrete= 1 m3
b) Volume of cement= (mass of cement/specific gravity of cement) *1/1000
= `(411/3.15)*1/1000`
= 0.130 m3
c) Volume of water= (mass of water/specific gravity of water) *1/1000
= `(140/1)*1/1000`
= 0.140 m3
d) Volume of chemical admixture
(superplasticizer @ 2% by mass = (mass of admixture/specific gravity of admixture) *1/1000
of cementitious material)
= `((0.02*411)/1.145)*1/1000`
= `(8.22/1.145)*1/1000`
= 0.0072 m3
e) Volume of all in aggregate= [a - (b+c+d)]
= [1- (0.130+0.14+0.0072)]
= 0.723 m3
f) Mass of coarse Aggregate= e* volume of coarse aggregate* Specific gravity of coarse aggregate*1000
= 0.723*0.57*2.74*1000
= 1129 kg
g) Mass of fine Aggregate= e*volume of fine Aggregate* Specific gravity of fine Aggregate*1000
= 0.723*0.43*2.74*1000
= 852 kg
MIX PROPORTIONS FOR TRIAL NUMBER 1
Cement = 411 kg/m3
Water= 140 kg/m3
Fine Aggregate= 852 kg/m3
Coarse Aggregate= 1129 kg/m3
Chemical Admixture= 8.22 kg/m3
Water-cement ratio= 0.34
The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial, if required. The mix proportion shall be reworked for the actual water content and checked for durability requirements.
Two more trials having variation of +/- 10% of water cement ratio in above proportion shall be carried out and a graph between 3 w/c ratios and their corresponding strength shall be plotted to work out the mix proportions for the given target strength. However, durability requirement shall be met.