Project on Concrete Mix Design for various grades of Concrete
AIM
To calculate the concrete mix Design for M35 grade concrete with fly ash and M50 grade concrete without fly ash
INTRODUCTION
Concrete Mix design is the method of finding the appropriate propotion of the cement sand and aggregate for concrete to attain the target strength in structure.atahe design is done according to the requirement of concrete strength.So we can achieve the adequate work ability,durability strength.Use of aadditives like admixtures retarders .. other thanbasic ingredients are used to improve the properties of mix.This project consist of two part,the first part deals with the design of M35 grade cement with fly ash as a part of it and second part is the design of M50 grade concrete without fly ash.
OBJECTIVE
The objective of this project is to produce a mix design for M35 concrete containing fly ash and M50 grade concrete.The mix will prepared as per IS method.concrete mix propotioning guidelines from IS 10262:2009 and recommented guide lines from IS 10262:1982.
EQUATION USED
Target mean strength
f'ck = fck+1.65s where,
f'ck=Target mean strength of concrete at 28 days
fck = compressive strength of concrete at 28 days
s =standared deviation obtained from the table in IS 10262 :2009
Cement content
Cement content= Water content/water cement ratio
Volume calculation
a) Volume of concrete is taken as 1M^3
b) Volume of cement =(mass of cement / specific gravity of cement)x 1/1000
c) Volume of water =(mass of water / specific gravity of water)x 1/1000
e) Volume of all aggregates =(a-(b+c+d))
f) Mass of coarse aggregate= ex Volume of coarse aggregate x specific gravity of coarse aggregate x 1000
g) Mass of fine aggregate = e x Volume of fine aggregate x specific gravity of fine aggregate x 1000
PART 1
To calculate the concrete mix design for M35 concrete with fly ash
M35 grade concrete with fly ash
STEP 1
Stipulation for concrete mix design
| Grade designation | M35 |
| Type of cement | OPC 43 Grade confirming to IS 8112 |
| Maximum nominal size size of aggregate | 20mm |
| Minimum cement content | 320 Kg / M^3 From table 5 of IS 456 : 2000 exposure conditon |
| Maximum W / C ratio | 0.45 From table 5 of IS 456 : 2000 exposure conditon |
| Workability | 100 mm Slump value for pumpable concrete |
| Exposure condition | severe(for reinforced concrete) |
| Method of concrete placing |
pumping |
| Degree of supervision | Good |
| Type of aggregate | Crushed angular aggregate |
| Maximum cement content | 450 Kg /m^3 |
| Chemical admixture type | Superplasticizer |
STEP 2
Test data for material
| Cement used | OPC 43 grade conforming IS 8112 |
| Specific gravity of cemennt | 3.15 |
| Chemical admixture | Superplasticizer confirming to IS 9103 |
| Specific gravity of coarse aggregate | 2.74 |
| Specific gravity of Fine aggregate | 2.74 |
| Specific gravity of fly ash used | 2.2 |
| Water absorption for coarse aggregate | 0.5% |
| Water absorption for Fine aggregate | 1% |
| Free surface moisture in Coarse aggregate | Nil |
| Free surface moisture in Fine aggregate | Nil |
| Sieve analysis Coarse aggregate | Conforming table 2of IS 383 |
| Sieve analysis Fine aggregate | Conforming to Grading zone 1 of table 4 of IS 383 |
STEP 3
Target strength for mix propotioning
f'ck = fck+1.65s where,
f'ck=Target mean strength of concrete at 28 days
fck = compressive strength of concrete at 28 days
s =standared deviation obtained from the table in IS 10262 :2009
here , From table s= 5
fck=35
f'ck=35+(1.65 x 5)
=43.25 N/mm^2
STEP 4
Maximum water cement ratio = 0.45 , From table IS 456-2000 for severe exposure
Based on experience water/cement ratio = 0.43 , 0.43< 0.45 , hence ok
Adopted water cement ratio = 0.43
STEP 5
Selection of water content
From table 2 of IS10262:2009 Maximum water content for 20mm aggregate =186 litr
Estimated water content for 100mm slump=186+6%of 186 (Clause 4.2 suggests increasing of 3% of water content every extra 25mm slump from 50mm slump.so a 6% is to be added to it)
=197 litr
A superplastisizer is used the water content can be reduced up to 20% and above based on trials water content reduction 25% is achieved. Hence arrived water content =197x0.75=148litr
STEP 6
Calculation of cement and fly ash required
Adopted water cement ratio=0.43
Total cementatious (Cement + fly ash) requirement =148/0.43=345Kg/m^3
from table 5 of IS 456 -2000 minimum cement content for severe exposure=320 Kg/m^3
The cementatious content has to be increased in order to attain good workability and strength.The increment required is dettermined on the basis of experience and research.Here we are increasing cementatious content by 10%.
Final cementitious content = 345 X 1.10
= 380 Kg
Cementatious material content =380 kg/m^3
New water cement ratio =148/380=0.39
Fly ash content is taken as 30% of the
total cementatious content = 380 x 30%
= 114Kg /m^3
Cement required =380-114=266Kg/m^3
Saving cement with fly ash =345-266
=79Kg
Cementatious material, Cement and fly ash required is 380 Kg/m^3, 266Kg/m^3, 79Kg/m^3 and the new Water cement ratio is 0.39
STEP 7
volume of coarse aggregate and fine aggregate content
From table 5 of IS10262 :2009 volume of aggregate corresponding 20mm size aggregate zone 1 for water cement ratio =0.6
in the precent water cement ratio =0.39
the volume of coarse aggregate increased to decrease fine aggregate content
as water cement ratio is lower by 0.10 the propotion volume of coarse aggregate is increased by 0.02
corresponding volume of coarse aggregate for water cement ratio 0.39=0.62
if coarse aggregate is not granular type the volume of coarse aggregate may be required to increased.
for pumbable concrete these value decreased by 10%. so volume of coarse aggregate=0.62x0.9=0.56
volume of fine aggregate=1-0.56=0.44
STEP 8
Mix calculation
Volume of concrete=1m^3
volume of water= (mass of water/specific gravity of water)x1/1000
=(148/1 )x 1/1000
=0.148m^3
Volume of cement = (266/3.15)x 1/1000
=0.084m^3
Volume of fly ash = (114/2.2) x 1/1000
=0.051m^3
Volume of chemical admixture=(2% of cementatious material 380x 2% =7.6)
=(7.6/1.145)x1/1000 =0.006m^3
Volume of fine and coarse aggregate=1-(0.148+0.084+0.051+0.006)
=0.711m^3
Mass of coarse aggregate=0.711x0.56x2.74x1000
=1091Kg/m^3
Mass of fine aggregate =0.711x0.44x2.74x1000
=857Kg/m^3
STEP 9
MIX PROPOTIONS
Cement=266Kg/m^3
Fly ash =114 Kg/m^3
Water =148Kg/m^3
Chemical admixtures=7.6Kg/m^3
Fine aggregate =857Kg/m^3
coarse aggregate=1091Kg/m^3
Water cement ratio = 0.39
Mix propotion by weight= 1 : 2.25 : 2.87
STEP 10
The slump shall be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial.The mix propotion shall be reworked for the actual water content and checked for durability requirements.
STEP 11
Two more trials having variation of 10% of water cement ratio shall be carried out and a graph between three water cement ratios and corresponding strength shall be plotted to workout the mix propotion for the given target for field trials.
PART 2
To calculate the concrete mix design for M50 concrete without fly ash
M50 grade concrete without fly ash
STEP 1
Stipulation for concrete mix design
| Grade designation | M50 |
| Type of cement | OPC 53 Grade confirming to IS 8112 |
| Maximum nominal size size of aggregate | 20mm |
| Minimum cement content | 320 Kg / M^3 From table 5 of IS 456 : 2000 exposure conditon |
| Maximum W / C ratio | 0.45 From table 5 of IS 456 : 2000 exposure conditon |
| Workability | 100 mm Slump value for pumpable concrete |
| Exposure condition | severe(for reinforced concrete) |
| Method of concrete placing |
pumping |
| Degree of supervision | Good |
| Type of aggregate | Crushed angular aggregate |
| Maximum cement content | 450 Kg /m^3 |
| Chemical admixture type | Superplasticizer |
STEP 2
Test data for material
| Cement used | OPC 53 grade conforming IS 8112 |
| Specific gravity of cemennt | 3.15 |
| Chemical admixture | Superplasticizer confirming to IS 9103 |
| Specific gravity of coarse aggregate | 2.74 |
| Specific gravity of Fine aggregate | 2.74 |
| Water absorption for coarse aggregate | 0.5% |
| Water absorption for Fine aggregate | 1% |
| Free surface moisture in Coarse aggregate | Nil |
| Free surface moisture in Fine aggregate | Nil |
| Sieve analysis Coarse aggregate | Conforming table 2of IS 383 |
| Sieve analysis Fine aggregate | Conforming to Grading zone 1 of table 4 of IS 383 |
STEP 3
Target strength for mix propotioning
f'ck = fck+1.65s where,
f'ck=Target mean strength of concrete at 28 days
fck = compressive strength of concrete at 28 days
s =standared deviation obtained from the table in IS 10262 :2009
here , From table s= 5
fck=50
f'ck=50+(1.65 x 5)
=58.25 N/mm^2
Target mean strength = 58.25N/mm^2
STEP 4
Maximum water cement ratio = 0.45 , From table IS 456-2000 for severe exposure
Based on experience water/cement ratio = 0.43 , 0.43< 0.45 , hence ok
Adopted water cement ratio = 0.43
STEP 5
Selection of water content
From table 2 of IS10262:2009 Maximum water content for 20mm aggregate =186 litr
Estimated water content for 100mm slump=186+6%of 186 (Clause 4.2 suggests increasing of 3% of water content every extra 25mm slump from 50mm slump.so a 6% is to be added to it)
=197 litr
A superplastisizer is used the water content can be reduced up to 20% and above based on trials water content reduction 25% is achieved. Hence arrived water content =197x0.75=148litr
STEP 6
Calculation of cement required
Adopted water cement ratio=0.43
Total cement requirement =148/0.43=345Kg/m^3
from table 5 of IS 456 -2000 minimum cement content for severe exposure=320 Kg/m^3
345 Kg/m^3 >320 Kg/m^3
STEP 7
volume of coarse aggregate and fine aggregate content
From table 5 of IS10262 :2009 volume of aggregate corresponding 20mm size aggregate zone 1 for water cement ratio =0.6
in the precent water cement ratio =0.39
the volume of coarse aggregate increased to decrease fine aggregate content
as water cement ratio is lower by 0.10 the propotion volume of coarse aggregate is increased by 0.02
corresponding volume of coarse aggregate for water cement ratio 0.39=0.62
if coarse aggregate is not granular type the volume of coarse aggregate may be required to increased.
for pumbable concrete these value decreased by 10%. so volume of coarse aggregate=0.62x0.9=0.56
volume of fine aggregate=1-0.56=0.44
STEP 8
Mix calculation
Volume of concrete=1m^3
volume of water= (mass of water/specific gravity of water)x1/1000
=(148/1 )x 1/1000
=0.148m^3
Volume of cement = (345/3.15)x 1/1000
=0.109m^3
Volume of chemical admixture=(2% of cementatious material 380x 2% =7.6)
=(7.6/1.145)x1/1000 =0.006m^3
Volume of fine and coarse aggregate=1-(0.148+0.109+0.006)
=0.737m^3
Mass of coarse aggregate=0.737x0.56x2.74x1000
=1131Kg/m^3
Mass of fine aggregate =0.737x0.44x2.74x1000
=889Kg/m^3
STEP 9
MIX PROPOTIONS
Cement=345Kg/m^3
Water =148Kg/m^3
Chemical admixtures=7.6Kg/m^3
Fine aggregate =889Kg/m^3
coarse aggregate=1131Kg/m^3
Water cement ratio = 0.43
Mix propotion by weight= 1 : 2.57 : 3.27
STEP 10
The slump shall be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial.The mix propotion shall be reworked for the actual water content and checked for durability requirements.
STEP 11
Two more trials having variation of 10% of water cement ratio shall be carried out and a graph between three water cement ratios and corresponding strength shall be plotted to workout the mix propotion for the given target for field trials.
RESULT
Mix proportion by weight of M35 grade of concrete with fly ash is 1:2.25 : 2.87 and water cement ratio was found to be 0.39.
Mix proportion by weight of M50 grade of concrete without fly ashis 1:2.57 : 3.27 and water cement ratio was found to be 0.43