Project on Concrete Mix Design for various grades of Concrete
ANSWERS
1.AIM:-To determine the mix proportion of concrete grade M35 with Fly ash.
REQUIREMENTS OF CODE BOOKS AND TESTS:
- IS 456:2000
- IS 10262:2009
- IS 8112
- IS 383
- IS 9103
- IS 12089
TEST FOR MATERIALS
- IS 2386
- IS 2720
2.SELECTION OF MATERIALS
The selection of materials are taken based on the requirement conditions on project or structure.
3.TEST DATA FOR MATERIALS
Materials should be tested in the laboratory as per tests given in the codebook and their properties should be found. The Standard values are taken here for calculation purpose from test reports and codebooks.
|
Cement |
OPC 53 |
Confirming to |
|
|
Specific Gravity of Cement |
3.15 |
Test – IS: 2720 |
|
|
Mineral Admixture |
Fly ash |
Confirming to IS12089 |
|
|
Specific Gravity of Fly ash |
2.90 |
||
|
Chemical Admixture |
@0.6% |
IS9103 |
|
|
F |
Specific Gravity of |
Test – IS 2386 |
|
|
Coarse Aggregate |
2.74 |
||
|
Fine Aggregate |
2.74 |
||
|
Admixture PCE based |
1.12 |
||
|
G |
Water Absorption of aggregates |
Test – IS 2386 |
|
|
Coarse aggregate |
0.5 % |
||
|
Fine aggregate |
1 % |
||
|
H |
Sieve Analysis aggregates. |
Test – IS 2386 |
|
|
Coarse aggregate |
Confirming to |
||
|
Fine aggregate |
Zone II |
Confirming to |
|
4.TARGET STRENGTH FOR MIX PROPORTIONS OF M35 GRADE CONCRETE
Target mean strength F’ck=fck+1.65*s
Here S is standard deviation taken from table 8 IS456:2000
Fck=35,S=5
F’ck=35+1.65*5
F’ck=43.25 N/mm2
5.SELECTION OF WATER-CEMENT RATIO
The water cement ratio can be calculated by three steps.
Step 1:Draw the graph in between the compressive strength and water cement ratio
Step 2: Draw the graph in between the compressive strength and water cement ratio (IS 4031:1968) taken 7 days compressive strength y-axixs
Step 3:The maximum water-cement ratio for different grade of concrete is given in Table 5-IS456
|
Maximum W/C ratio |
=0.45 |
|
|
Adopted W/C ratio |
=0.45 |
HERE WE TAKE LEAST VALUE OF THREE STEPS BECAUSE OF LOW WORKABILITY GIVES HIGH STRENGTH.
6.SELECTION OF WATER CONTENT
|
Maximum Water Content |
=186 L |
The maximum size of Aggregates are 20 mm( table 2 IS 456:2000)
Above water-content is for 25 to 50mm slump but the slump we require is 100mm. hence we need to increase the water content to get the required slump for good workability. Clause 4.2 of IS1026 suggests an increase of 3% of water content from its original value for every increase of 25mm. Here we have a 50mm increase in the water content hence we have to increase the water content by 6 %.
Water-content for 100mm Slump=186+(0.06*186)
=197.16 L
Since super plasticizers are used water content can be reduced to get good strength of concrete. Percentage of reduction of water depends on the type of super plasticizers used in the concrete.
|
Percentage of Reduction in water content |
=20% |
|
Water content requirement after SP |
=198 – (0.20*198) |
|
=157.73 |
|
|
FINAL Water Content |
=160 L |
7.CALCULATION OF CEMENT AND FLY ASH CONTENT
|
Adopted Water Cement Ratio |
=0.45 |
|
Total Cementitious (Cement +Fly ash) requirement |
= Water Content / Water Cement ratio |
|
=160/0.45 |
|
|
=355.55 kg |
Since Fly ash is used the amount of Cementitious content (Cement+ Fly ash) shall be increased to get good workability and strength. the percentage of increase depending on experience and research. Here we increased the cementitious content by 1.1 %.
|
Final Cementitious |
= 356*1.1 |
|
|
=391.6 kg |
||
|
Minimum Cement Content |
=340kg |
Table 5-IS456 |
|
Adopted Cementitious content |
=391.6 kg |
> 340kg.hence ok |
|
Fly ash content requirement |
= 391.6 * 0.30 = 117.48 =118 kg |
30% replacement |
|
Cement Content requirement |
=Cementitious content – Fly ash =391.6-117.48 = 274.12 |
Calculation of Super Plasticizers @ 0.6 percent to the mass of cementitious content = = 391.6*(0.6/100) = 2.35 kg
8 .COARSE AND FINE AGGREGATE
|
Coarse Aggregate ratio |
= 0.62 |
Table3-IS10262 |
|
Coarse Aggregate ratio |
= 0.63 |
(adding 0.01 for every |
|
Final Fine Aggregate ratio |
= 0.37 |
(1-0.63) = 0.37 |
9.MIX CALCULATIONS OF M35 GRADE CONCRETE
|
Volume of Concrete |
= 1 m3 |
|
Total Volume of Cement |
= Cement/(S.G*1000) = 275/(3.15*1000) = 0.087 m3 |
|
Total Volume of Fly ash |
= Fly ash/(S.G*1000) = 118/(2.5*1000 = 0.041 m3 |
|
Volume of Water |
=Water /(S.G*1000) = 160/(1*1000) = 0.160 m3 |
|
Volume of Super plasticizers |
= Super plasticizers /(S.G*1000) = 2.35/(1.12*1000) = 0.002 m3 |
|
Total Aggregates requirement |
= A – (B+C+D+E) =1 -(0.087 +0.041+0.160+0.002) =0.71 m3 |
|
Coarse Aggregate (C.A) |
= F * C.A ratio * S.G * 1000 = 0.71*0.63 *2.74 *1000 = 1225.6 kg |
|
Fine Aggregate (F.A) |
= F * F.A ratio * S.G * 1000 = 0.71*0.37*2.74 *1000 =719.8 kg |
10.Cement , Fly ash, Sand, Aggregate ,Water and Super plasticizer needed for M35 grade concrete
|
MATERIALS |
QUANTITY |
|
Cement |
275 kg/m3 |
|
Fly ash |
118 kg/m3 |
|
Fine Aggregate |
720 kg/m3 |
|
Coarse Aggregate (20mm) |
1226 kg/m3 |
|
WATER |
160 L |
|
PCE based Super Plasticizer |
2 L |
Therefore Mix Ratio of M35 Grade concrete by weight is Cement: F.A : C.A : =1:2.62:4.46.
M50 GRADE WITHOUT FLY ASH
1.AIM:-To determine the mix proportion of concrete grade M50.
REQUIREMENTS OF CODE BOOKS AND TESTS:
- IS 456:2000
- IS 10262:2009
- IS 8112
- IS 383
TEST FOR MATERIALS
- IS 2386
- IS 2720
2.SELECTION OF MATERIALS
The selection of materials are taken based on the requirement conditions on project or structure.
|
Grade Designation |
M35 |
|
|
Type of Cement |
OPC 53 |
|
|
Maximum Nominal |
20mm |
|
|
Minimum Cement Content |
340kg |
|
|
Maximum Cement Content |
450kg |
As per code |
|
Maximum W/C ratio |
0.45 |
|
|
Workability(pumpable) |
100mm |
|
|
Chemical Admixture |
PCS Type |
|
|
Type of exposure |
Very sever |
3.TEST DATA FOR MATERIALS
Materials should be tested in the laboratory as per tests given in the codebook and their properties should be found. The Standard values are taken here for calculation purpose from test reports and codebooks.
|
Cement |
OPC 53 |
Confirming to |
|
|
Specific Gravity of Cement |
3.15 |
Test – IS: 2720 |
|
|
Chemical Admixture |
@0.6% |
IS9103 |
|
|
F |
Specific Gravity of |
Test – IS 2386 |
|
|
Coarse Aggregate |
2.74 |
||
|
Fine Aggregate |
2.74 |
||
|
Admixture PCE based |
1.12 |
||
|
G |
Water Absorption of aggregates |
Test – IS 2386 |
|
|
Coarse aggregate |
0.5 % |
||
|
Fine aggregate |
1 % |
||
|
H |
Sieve Analysis aggregates. |
Test – IS 2386 |
|
|
Coarse aggregate |
Confirming to |
||
|
Fine aggregate |
Zone II |
Confirming to |
|
4.TARGET STRENGTH FOR MIX PROPORTIONS OF M35 GRADE CONCRETE
Target mean strength F’ck=fck+1.65*s
Here S is standard deviation taken from table 8 IS456:2000
Fck=50, S=5
F’ck=50+1.65*5
F’ck=58.25 N/mm
5.SELECTION OF WATER-CEMENT RATIO
The water cement ratio can be calculated by three steps.
Step 1:Draw the graph in between the compressive strength and water cement ratio
Step 2: Draw the graph in between the compressive strength and water cement ratio (IS 4031:1968) taken 7 days compressive strength y-axixs
Step 3:The maximum water-cement ratio for different grade of concrete is given in Table 5-IS456
|
Maximum W/C ratio |
=0.45 |
|
|
Adopted W/C ratio |
=0.45 |
HERE WE TAKE LEAST VALUE OF THREE STEPS BECAUSE OF LOW WORKABILITY GIVES HIGH STRENGTH.
6. SELECTION OF WATER CONTENT
|
Maximum Water Content |
=186 L |
The maximum size of Aggregates are 20 mm( table 2 IS 456:2000)
Above water-content is for 25 to 50mm slump but the slump we require is 100mm. hence we need to increase the water content to get the required slump for good workability. Clause 4.2 of IS1026 suggests an increase of 3% of water content from its original value for every increase of 25mm. Here we have a 50mm increase in the water content hence we have to increase the water content by 6 %.
Water-content for 100mm Slump=186+(0.06*186)
=197.16 L
Since super plasticizers are used water content can be reduced to get good strength of concrete. Percentage of reduction of water depends on the type of super plasticizers used in the concrete.
|
Percentage of Reduction in water content |
=20% |
|
Water content requirement after SP |
=198 – (0.20*198) =158.4 |
|
FINAL Water Content |
=159 L |
7.CALCULATION OF CEMENT AND FLY ASH CONTENT
|
Adopted Water Cement Ratio |
=0.45 |
|
Total Cementitious (Cement +Fly ash) requirement |
= Water Content / Water Cement ratio |
|
=159/0.45 |
|
|
=353 KG |
|
Minimum Cement Content |
=340kg |
Table 5-IS456 |
|
Adopted Cementitious content |
=353 KG |
> 340kg.hence ok |
Calculation of Super Plasticizers @ 0.6 percent to the mass of cementitious content = 353*(0.6/100) = 2.12 L
8 .COARSE AND FINE AGGREGATE
|
Coarse Aggregate ratio |
= 0.62 |
Table3-IS10262 |
|
Final Fine Aggregate ratio |
= 0.38 |
(1-0.62) = 0.38 |
9.MIX CALCULATIONS OF M50 GRADE CONCRETE
|
Volume of Concrete |
= 1 m3 |
|
Total Volume of Cement |
= Cement/(S.G*1000) = 353/(3.15*1000) = 0.112 m3 |
|
Volume of Water |
=Water /(S.G*1000) = 159/(1*1000) = 0.159 m3 |
|
Volume of Super plasticizers |
= Super plasticizers /(S.G*1000) = 2.112/(1.12*1000) = 0.00188 m3 |
|
Total Aggregates requirement |
= A – (B+C+D+E) =1 -(0.112 +0.159+0.00188) =1-0.2728 M3 =0.727 M3 |
|
Coarse Aggregate (C.A) |
= F * C.A ratio * S.G * 1000 = 0.727*0.62 *2.74 *1000 = 1235 KG |
|
Fine Aggregate (F.A) |
= F * F.A ratio * S.G * 1000 = 0.727*0.38*2.74 *1000 =757 KG |
10.Cement , Fly ash, Sand, Aggregate ,Water and Super plasticizer needed for M50 grade concrete
|
MATERIALS |
QUANTITY |
|
Cement |
353 kg/m3 |
|
Fine Aggregate |
757 kg/m3 |
|
Coarse Aggregate (20mm) |
1235 kg/m3 |
|
WATER |
159 L |
|
PCE based Super Plasticizer |
2 L |
Therefore Mix Ratio of M35 Grade concrete by weight is Cement: F.A : C.A : =1:2.14:3.49.