Project on Concrete Mix Design for various grades of Concrete
1ANS.
Mix proportioning of M 35 grade concrete using flyash:
I.Stipulations for Proportioning:
a)Grade designation : M35
b)Type of cement : OPC 53 Grade conforming to IS 12269
c)Type of mineral admixture : Flyash conforming to IS 3812(Part 1)
d)Maximum nominal size of aggregate : 20mm
e)Minimum cement content : 340 kg/cum (as per Table 5 of IS 456-2000,exposure condition)
f)Maximum water-cement ratio = 0.45 (as per Table 5 of IS 456-2000,exposure condition)
g)Workability : 100-120mm (Slump value 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 cemenet content : 390 kg/cum
m)Chemical Admixture type : Superplasticizer
II.Test Data For Materials:
a)Cement used : OPC 53 Grade conforming to IS 12269
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 type : Superplasticizer Confirming to IS 9103
f)Specific gravity of
1)Coarse aggregate 20mm : 2.67
2)Fine aggregate : 2.65
g)Water absorption
1)Coarse aggregate : 0.5%
2)Fine aggregate : 1%
h)Free moisture content
1)Coarse aggregate : NILL
2)Fine aggregate : NILL
i)Sieve analysis
1)Coarse aggregate : Conforming to all in aggregates of table 2 of IS 383
2)Fine aggregate : Conforming to Grading Zone I of table 4 of IS 383
III.Target Strength for Mix Proportioning:
1.TARGET MEAN STRENGTH ft=Fck+1.65 x S
=35+(1.65x5)
=43.25 N/MM^2
Where ft = Target average compressive strength at 28 days
Fck=Characteristic compressive strength at 28 days
S=Standard Deviation
From table 1 of IS 10262:2009,Standard deviation S = 5 N/MM^2
IV.Selection of W/C RATIO:
Adopted maximum water-cement ratio = 0.41
For very severe exposure condition of table 5 IS 456-2000
For M35,w/c ratio=0.45
0.41 < 0.45 hence ok
V.Selection of WATER CONTENT
from table 2 IS 10262-2009
FOR 20MM AGGREGATE OF SLUMP VALUE RANGES FROM 25-50MM=186 lit
FOR 20MM,IF SLUMP VALUE IS 100MM = 186+((6/100)X186)=197 lit
IF PLASTICIZER IS USED THEN 20% WILL BE REDUCED=197-((20/100)X197)=158 lit
VI.Calculation of CEMENT CONTENT from table 5 IS 456-2000
w/c=0.41,w=158 lit
cement=158/0.41=385 kg/cum
for very severe exposure condition cement=340 kg/cum
385 > 340 hence ok
Now,to proportion a mix containing flyash the following steps are suggested:
- The percentage of flyash needs to be decided based on project requirement and quality of materials.
- In some cases increase in cementitious material can be warranted, increase in cementitious material content and its percentage may be based on experience and trail(This example is with increase of 10% cementitious material content)
Cementitious material content = 385 x 1.10 = 424 kg/cum
Water content = 158 kg/cum
W/C Ratio = 158/424 = 0.372
Fly ash @ 30% total cementitious material content = 424 x 30% = 127.2 kg/cum
Cement OPC = 424-115 = 309 kg/cum
Saving of cement while using fly ash = 424 – 309 = 115 kg/cum
Flyash being utilized = 127.2 kg/cum
VII.PROPORTION OF VOLUME OF COURSE AGGREGATE AND FINE AGGREGATE CONTENT:
From table 3 IS 10262-2009
Volume of coarse aggregate corresponds to 20mm aggregate and Fine aggregate will be
Zone I for W/C ratio of 0.5 = 0.6
Corrected w/c ratio 0.41=0.63
For pumpable concrete these values are reduced by 10%
volume of coarse aggregate = 0.63 x 0.9 = 0.567
volume of fine aggregate = 1-0.567=0.433
VIII.MIX CALCULATIONS(BY ASSUMING STANDARD VALUES):
a)volume of concrete = 1cum
b)volume of cement = ((mass of cement/specific gravity of cement) x (1/1000))
= ((309/3.15)x(1/1000))
= 0.098cum
c)volume of Flyash = ((mass of water/specific gravity of water) x (1/1000))
= ((127.2/2.2)x(1/1000))
= 0.057cum
d)volume of water = ((mass of water/specific gravity of water) x (1/1000))
= ((158/1)x(1/1000))
= 0.158cum
e)volume of super plastisizer = ((mass of super plasticizer/specific gravity of
super plasticizer) x (1/1000))
= ((7.6/1.145)x(1/1000))
= 0.006cum
f)volume of all aggregates =((a-(b+c+d+e))
=((1-(0.098+0.057+0.158+0.006))
=0.681 cum
g)mass of coarse aggregate=volume of all aggregates x volume of coarse aggregate x x specific gravity of coarse aggregate x 1000
=0.681 x 0.567 x 2.67 x 1000
=1030.95 kg
h)mass of fine aggregate=volume of all aggregates x volume of fine aggregate x
specific gravity of fine aggregate x 1000
=0.681 x 0.433 x 2.65 x 1000
=781.41 kg
IX)CONCRETE MIX PROPORTIONS
CEMENT = 309 KG/CUM
FLY ASH = 127.2 KG/CUM
WATER = 158 LIT/CUM
SUPER PLASTICIZER = 7 KG/CUM
FINE AGGREGATE = 781.41 KG/CUM
COARSE AGGREGATE = 1030.95 KG/CUM
W/C = 0.372
2ANS.
Mix proportioning of M 50 grade concrete using flyash:
I.Stipulations for Proportioning:
a)Grade designation : M50
b)Type of cement : OPC 43 Grade conforming to IS 8112
c)Maximum nominal size of aggregate : 20mm
d)Minimum cement content : 360 kg/cum
e)Maximum water-cement ratio = 0.35
f)Workability : 50-75mm (Slump value 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 cemenet content : 450 kg/cum
l)Chemical Admixture type : Superplasticizer
II.Test Data For Materials:
a)Cement used : OPC 43 Grade conforming to IS 8112
b)Specific gravity of cement : 3.12
- c) Chemical Admixture type : Superplasticizer Confirming to IS 9103
d)Specific gravity of
1)Coarse aggregate 20mm : 2.74
2)Fine aggregate : 2.56
e)Water absorption
1)Coarse aggregate : 0.5%
2)Fine aggregate : 1%
f)Free moisture content
1)Coarse aggregate : NILL
2)Fine aggregate : NILL
g)Sieve analysis
1)Coarse aggregate : Conforming to all in aggregates of table 2 of IS 383
2)Fine aggregate : Conforming to Grading Zone I of table 4 of IS 383
III.Target Strength for Mix Proportioning:
1.TARGET MEAN STRENGTH ft=Fck+1.65 x S
=50+(1.65x5)
=58.25 N/MM^2
Where ft = Target average compressive strength at 28 days
Fck=Characteristic compressive strength at 28 days
S=Standard Deviation
From table 1 of IS 10262:2009,Standard deviation S = 5 N/MM^2
IV.Selection of W/C RATIO:
Adopted maximum water-cement ratio = 0.35
From table 5 IS 456-2000
V.Selection of WATER CONTENT
from table 2 IS 10262-2009
FOR 20MM AGGREGATE OF SLUMP VALUE RANGES FROM 25-50MM=186 lit
FOR 20MM,IF SLUMP VALUE IS 100MM = 186+((6/100)X186)=197 lit
IF PLASTICIZER IS USED THEN 20% WILL BE REDUCED=197-((20/100)X197)=158 lit
VI.Calculation of CEMENT CONTENT from table 5 IS 456-2000
w/c=0.35,w=158 lit
cement=158/0.35=451 kg/cum
for extreme exposure condition cement=360 kg/cum
451 > 360 hence ok
VII.PROPORTION OF VOLUME OF COURSE AGGREGATE AND FINE AGGREGATE CONTENT:
From table 3 IS 10262-2009
Volume of coarse aggregate corresponds to 20mm aggregate and Fine aggregate will be
Zone II for W/C ratio of 0.5 = 0.62
Corrected w/c ratio 0.35=0.65
For pumpable concrete these values are reduced by 10%
volume of coarse aggregate = 0.65 x 0.9 = 0.585
volume of fine aggregate = 1-0.585=0.415
VIII.MIX CALCULATIONS(BY ASSUMING STANDARD VALUES):
a)volume of concrete = 1cum
b)volume of cement = ((mass of cement/specific gravity of cement) x (1/1000))
= ((451/3.12)x(1/1000))
= 0.144cum
d)volume of water = ((mass of water/specific gravity of water) x (1/1000))
= ((158/1)x(1/1000))
= 0.158cum
e)volume of super plastisizer = ((mass of super plasticizer/specific gravity of
super plasticizer) x (1/1000))
= ((8.2/1.145)x(1/1000))
= 0.007cum
f)volume of all aggregates =((a-(b+c+d+e))
=((1-(0.144+0.158+0.007))
=0.691 cum
g)mass of coarse aggregate=volume of all aggregates x volume of coarse aggregate x x specific gravity of coarse aggregate x 1000
=0.691 x 0.585 x 2.74 x 1000
=1152.48 kg
h)mass of fine aggregate=volume of all aggregates x volume of fine aggregate x
specific gravity of fine aggregate x 1000
=0.691 x 0.415 x 2.56 x 1000
=763.86 kg
IX)CONCRETE MIX PROPORTIONS
CEMENT = 451 KG/CUM
WATER = 158 LIT/CUM
SUPER PLASTICIZER = 8.2 KG/CUM
FINE AGGREGATE = 763.86 KG/CUM
COARSE AGGREGATE = 1152.48 KG/CUM
W/C = 0.35