Project on Concrete Mix Design for various grades of Concrete
1)CONCRETE MIX DESIGN FOR M35 GRADE CONCRETE WITH FLY ASH
Aim:
To calculate concrete mix design for M35 grade concrete with fly ash
INTRODUCTION:
concrete mix design is the method of finding the precise proportion of cement ,sand & aggregate for concrete to achieve the target strength in structures .
OBJECTIVE:
The objective of the project is to produce a mix design M35 grade concrete with fly ash .The mix will be prepared as per IS method.
PROCEDURE:
Step 1:stipulations
A)Grade designation:M35
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 :20mm
E)Minimum cement content :340kg/m^3(from table 5 of IS 456:2000 Exposure condition )
F)Maximum w/c ratio:0.45(from table 5 of IS 456:2000 -exposure condition )
G)workability :100mm(slump test for pumpable concrete )
H)Exposure condition :very severe (for reinforced concrete )
I)Method of concrete placing:pumping
J)Degree of supervision :Good
K)Type of aggregate :crushed angular aggregate
L)Maximum cement content :450kg/m^3
M)chemical admixture type :super plasticizer
Step 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 :2.9
E)chemical admixture :super plasticizer conforming to IS 9103
F)specific gravity of coarse aggregate :2.74
Specific gravity of fine aggregate :2.74
G)water absorption
Coarse aggregate :0.5%
Fine aggregate :1.0%
H)free surface moisture
Coarse aggregate :nil
Fine aggregate :nil
I)sieve analysis
Coarse aggregate :conforming to table 2 of IS 383
Fine aggregate :conforming to grading zone 1 of table 4 of IS 383
step 3:Target strength for mix proportioing
F'ck=fck+1.65s
From table of IS 10262:2009 standard deviation
s=5 N/mm^2
=35+(1.65×5)
Target strength =43.25 N/mm^2
Step 4:selection of w/c ratio:
from table 5 od IS456:2000 for very severe exposure ,max w/c ratio=0.45
Based on experience adopt w/c ratio as 0.40
0.40<0.45 hence ok
step 5: selection of water content
Table 2 of IS 10269:2009 max water content for 20mm aggregate :186lit for 25mm to 50mm slump range
Estimated water content for 10mm slump =186+6/100×186
=197lit
As super plasticizer is used ,the water content can be reduced up to 30%
Based on trails water content reduction 20% is achieved with plasticizer
Hence the arrived water content =197×(100-20)%
=197×80%
water content =158lit
step 6 :calculation of cement content
w/c ratio=0.4
158/0.45=351 kg/m^3
From table 5 of IS 456 minimum content for very severe exposure condition =351 kg/m^3
350kg/m^3 > 320 kg/m^3 hence ok
Now the percentage of fly ash needs to be decided based on project requirement & quantity of materials .
In some cases increases in cementitious materials can be warranted .Increase in cementitous materials can be warranted .Increase in cementitious material content & its percentage may be based on experience & trial
Increase of 10% cementitious material content
Cementitious material content =351×1.10=386kg/m^3
Water content =140kg/m^3
So w/c ratio =158/386=0.409
Fly ash content is taken as 30% total cementitious material content =386×30%
Fly ash =115 kg/m^3
Saving of cement while using fly ash =350-271
=79kg/m^3
Fly ash =115 kg/m^3,cement =271 kg/m^3
w/c ratio =0.4
Step 7: Proportion of volume of course & fine aggregate content :
From table 3 of IS 10262:2009 ,volume of coarse aggregate ,to 20mm size aggregate & fine aggregate
(Zone 1)for w/c ratio =0.6
Present case w/c ratio is 0.40
Therefore volume of coarse aggregate needs to be increased to decrease the fine aggregate content
As w/c ratio is lower by 0.10,the proportion of volume of coarse aggregate is increased by 0.02
(at the rate of -/+ 0.01 for every + or - 0.05 change in w/c ratio )
Therefore corrected volume of coarse aggregate for w/c ratio of 0.40=0.62
(Note : if coarse aggregate is not of angular type then also the volume of coarse aggregate may be required to be increased suitably based on experience required to be increased suitably )
For pumpable concrete these values are reduced by 10%
Therefore volume of coarse aggregate =0.62×0.9
=0.56
Volume of fine aggregate =1-0.56
=0.44
vol of CA=0.56 ,vol of FA =0.44
Step 8 Mix calculation :
a)volume of concrete =1m^3
b)volume of cement =
mass of cement /specific gravity of cement ×1/1000
=271/3.15×1/1000
=0.086m^3
c)volume of fly ash =
Mass of fly ash /specific gravity of fly ash ×1/1000
=115/2.2×1/1000
=0.052m^3
d)volume of water =mass of water /specific gravity of water ×1/1000
=158/1×1/1000
=0.158m^3
e)volume of chemical admixture =
mass of admixture /specific gravity of admixture ×1/1000
=7/1.145×1/1000
=0.007m^3
f) volume of FA & CA= (a-(b+c+d+e))
=(1-(0.086+0.052+0.158+0.007))
=0.697 m^3
g)Mass of coarse aggregate
=f×vol of CA × specfic gravity of CA
=0.697×0.56×2.74×1000
=1069kg/m^3
h) Mass of fine aggregate
=f× vol of FA ×spwcific gravity of FA×1000
=0.697×0.44×2.74×1000
=840kg/m^3
1) Cement=271 kg/m^3
2)fly ash =115 kg/m^3
3)water =158 kg/m^3
4)fine aggregate =840 kg/m^3
5)coarse aggregate =1069kg/m^3
6)chemical admixture=7 kg/m^3
7)w/c ratio =0.409
MIX RATIO=1:3:3.94
STEP 9: The slump shall be measured & the water content & dosage of admixture shall be adjusted for achieving the required slump on trial .The mix proportion shall be reworked for the actual water content & checked for durability requirements .
Step 10: Two more trails having variation of 10% of w/c ratio in clause x shall be carried out & graph between three water cement ratios & corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials .However ,durability shall be met .
RESULTS
Mix proportion by weight of M35 grade concrete with fly ash is 1:3:3.94 & its w/c ratio is found to be 0.4
2)CONCRETE MIX DESIGN FOR M50 GRADE CONCRETE WITHOUT FLY ASH
Aim:
To calculate concrete mix design for M50 grade concrete without fly ash
INTRODUCTION:
concrete mix design is the method of finding the precise proportion of cement ,sand & aggregate for concrete to achieve the target strength in structures .
OBJECTIVE:
The objective of the project is to produce a mix design M50 grade concrete with fly ash .The mix will be prepared as per IS method.
PROCEDURE:
Step 1:stipulations
A)Grade designation:M50
B)Type of cement :opc 53 grade conforming to IS 8112
C)Maximum nominal size of aggregate :20mm
D)Minimum cement content :320kg/m^3(from table 5 of IS 456:2000 Exposure condition )
E)Maximum w/c ratio:0.45(from table 5 of IS 456:2000 -exposure condition )
F)workability :100mm(slump test for pumpable concrete )
G)Exposure condition : Extreme (for reinforced concrete )
H)Method of concrete placing:pumping
I)Degree of supervision :Good
J)Type of aggregate :crushed angular aggregate
K)Maximum cement content :450kg/m^3
L)chemical admixture type :super plasticizer
Step 2:Test data for materials
A)cement used :opc 53 grade conforming to IS 8112
B)specific gravity of cement :3.15
C)chemical admixture :super plasticizer conforming to IS 9103
D)specific gravity of coarse aggregate :2.74
Specific gravity of fine aggregate :2.74
D)water absorption
Coarse aggregate :0.5%
Fine aggregate :1.0%
F)free surface moisture
Coarse aggregate :nil
Fine aggregate :nil
G)sieve analysis
Coarse aggregate :conforming to table 2 of IS 383
Fine aggregate :conforming to grading zone 1 of table 4 of IS 383
step 3:Target strength for mix proportioing
F'ck=fck+1.65s
From table of IS 10262:2009 standard deviation
s=5 N/mm^2
=50+(1.65×5)
Target strength =58.25 N/mm^2
Step 4:selection of w/c ratio:
from table 5 od IS456:2000 for very severe exposure ,max w/c ratio=0.44
Based on experience adopt w/c ratio as 0.44
0.44<0.45 hence ok
step 5: selection of water content
Table 2 of IS 10269:2009 max water content for 20mm aggregate :186lit for 25mm to 50mm slump range
Estimated water content for 10mm slump =186+6/100×186
=197lit
As super plasticizer is used ,the water content can be reduced up to 30%
Based on trails water content reduction 20% is achieved with plasticizer
Hence the arrived water content =197×(100-20)%
=197×80%
water content =158lit
step 6 :calculation of cement content
w/c ratio=0.4
158/0.44=359 kg/m^3
From table 5 of IS 456 minimum content for very severe exposure condition =351 kg/m^3
359kg/m^3 > 320 kg/m^3 hence ok
Step 7: Proportion of volume of course & fine aggregate content :
From table 3 of IS 10262:2009 ,volume of coarse aggregate ,to 20mm size aggregate & fine aggregate
(Zone 2)for w/c ratio =0.62
Present case w/c ratio is 0.40
Therefore volume of coarse aggregate needs to be increased to decrease the fine aggregate content
As w/c ratio is lower by 0.10,the proportion of volume of coarse aggregate is increased by 0.02
(at the rate of -/+ 0.01 for every + or - 0.05 change in w/c ratio )
Therefore corrected volume of coarse aggregate for w/c ratio of 0.40=0.62
(Note : if coarse aggregate is not of angular type then also the volume of coarse aggregate may be required to be increased suitably based on experience required to be increased suitably )
For pumpable concrete these values are reduced by 10%
Therefore volume of coarse aggregate =0.62×0.9
=0.56
Volume of fine aggregate =1-0.56
=0.44
vol of CA=0.56 ,vol of FA =0.44
Step 8 Mix calculation :
a)volume of concrete =1m^3
b)volume of cement =
mass of cement /specific gravity of cement ×1/1000
=359/3.15×1/1000
=0.113m^3
c)volume of water =mass of water /specific gravity of water ×1/1000
=158/1×1/1000
=0.158m^3
d)volume of chemical admixture =
mass of admixture /specific gravity of admixture ×1/1000
=7.6/1.145×1/1000
=0.006m^3
f) volume of FA & CA= (a-(b+c+d)
=(1-(0.113++0.158+0.006))
=0.723m^3
g)Mass of coarse aggregate
=f×vol of CA × specific gravity of CA
=0.723×0.56×2.74×1000
=1109kg/m^3
h) Mass of fine aggregate
=f× vol of FA ×specific gravity of FA×1000
=0.723×0.44×2.74×1000
=871kg/m^3
1) Cement=359kg/m^3
2)water =158 kg/m^3
3)fine aggregate =871 kg/m^3
4)coarse aggregate =1109kg/m^3
5)chemical admixture=7.6kg/m^3
6)w/c ratio =0.4
MIX RATIO=1:2.42:3.08
STEP 9: The slump shall be measured & the water content & dosage of admixture shall be adjusted for achieving the required slump on trial .The mix proportion shall be reworked for the actual water content & checked for durability requirements .
Step 10: Two more trails having variation of 10% of w/c ratio in clause x shall be carried out & graph between three water cement ratios & corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials .However ,durability shall be met .
RESULTS
Mix proportion by weight of M35 grade concrete with fly ash is 1:2.42:3.08 & its w/c ratio is found to be 0.4