Project on Concrete Mix Design for various grades of Concrete
Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash
Ans] Aim=Mix design for M35 grade concrete
procedure:
Step 1:-
Stipulations for proportionig:-
a] Grade of mix = M35
b] Type of admixture = Fly ash
c] Type of cement = OPC (Ordinary Portland Cement)
d] Workability = 100mm slump value of pumpable concrete
e] Maximum cement content = 450kg/mm^³
f] Minimum cement content = 320kg/mm^³
g] Aggregate maximum nominal size = 200mm
h] Placing in method of concrete = Pumping
i] Maximum water-cement ratio = 0.45 ,Table:5 IS 456-2000,based on exposure condition
j] Type of chemical admixture = super platicizer
k] Exposure condition = reinforced concrete
l] Supervision of degree = Good
m] Type of aggregate = Crushed angular aggregate
Step 2:-
Test data for materials:-
a] Test of cement = OPC(OrdinaryPortlandCement) 43grade confirming to IS8112
b] Free surface moisture
Fine aggregate = Nil
Coarse aagregate = Nil
c] Specific gravity of cement = 3.15
d] Specific gravity of fly ash = 2.2
e] Specific gravity of =
Coarse aggregate = 2.74
Fine aggregate = 2.74
f] Water obsorption =
Coarse aggregate = 0.5%
Fine aggragate = 1%
g] Fly ash = conforming to IS3812
h] Chemical admixture = Superplasticizer conforming to IS 9103
i] seive analysis
Coarse aggregate:-
IS Analysis of % of
Seive coarse aggregate different
Size(mm) Fraction fraction
l ll l ll Combined
20 100 100 60 40 100 Table2 of IS 383
10 0 71.2 0 28.5 28.5
4.75 9.4 3.7 3.7
2.36 0
Fine aggregate :-Conforming to grading zone 1 of table 4 IS 383
Step 3:-
To find target mean strength for mix proportioning
The target mean strength f'ck = fck+1.65s s = Standard deviation
= 35+1.65X5 fck = Characterstic of compressive strength
= 43.25N/mm²
Step 4:-
Selection of water- cement ratio
Maximum water-cement ratio = o.45 (for severe condition,from table 5 IS 456-2000)
On experience water-cement ratio = 0.4
0.4<0.45 Here OK
Step:- 5
Calculation of water content
Maximum water content for 20mm aggregate = 186 liters for 25mm to 50mm slump range
(Table 2 IS 1026:2009)
For 100mm slump, = 186+(6/100)X186
= 197 liters
As superplasticizer is used,the water content is reduced upto 30%
Based on trials water content reduction of 29% is achieved with plasticizern
Here arrived water content = 197X0.71 = 140 liters
Step:- 6
Calculation of cement content
Water-cement ratio = 0.4
Cementatious material (Cement + flyash ) = 140/0.4 = 350kg/m³
In table 5 IS 456-2000, the cement content for severe exposure = 320kg/m³
350kgmm³>320kgm³
Here Ok
To proportion the mix containing fly ash the following steps are suggested:-
a] The percentage of fly ash need to be decided based on project requirement and quality of materials
b] In some cases incrase in cementatious materials can be warrned increase in cementatious material content and its
percentage may be based on experience and trial
In tnis increase of 10% cementatious material cantent is considered
Cementatious material content = 350X1.1 = 385kg/m³
Water content = 140kg/m³
So,Water-cement ratio = 140/385=0.364
Fly ash at 30% total cementatious material content = 35-30%=115kg/m³
Cement (OPC) = 385-115 = 270kg/m³
Saving of cement while using flyash = 350-270 = 80kg/m³
Fly ash beign utilized = 115kg/m³
Step:- 7
Proportion of volume of coarse aggregate and fine aggregate contet
From table 3 IS 1026:2009, volume of coarse aggregate corresponding to 20mm size of aggregate and fine aggregate
(Zone 1) for water -cement ratio = 0.6
In present case the water-cement ratio is = 0.4
Therefore the volume of coarse aggregate needs to be increased to decreased the fine aggregate content
As the water- cement ratio is lowered by 0.1, the propotion of volume of coarse aggregate is increased by 0.02 (at the rate
of +/- 0.01 for every +/- 0.05 change in water-cement ratio)
Here the corrected value of coarse aggregate for the water-cement ratio = 0.64
For pumpable concrete, thesd are reduced by10%
Volume of coarse aggregate = 0.64X0.9 = 0.576
Volume of fine aggregate = 1-0.576 = 0.424
Step 8:-
Mix calculations
Mix calculation per unit volume of concrete :-
a] Volume of concrete = 1m³
b] Volume of cement = (Mass of cement/specific gravity of cement0 X1/100
= (270/3.15)X1/1000 = 0.086m³
c]Volume of flyash = (Mass of flyash/Specific gravity of flash)X1/100
= (115/2.2)X1/1000
= 0.052m³
d] Volume of water = (Mass of water/Specific gravity of water)X1/1000
= (140/1)X1/1000
= 0.140m³
e] Volume of chemical admixture = (mass of admixture/Specific gravity of admixture )X1/1000
= (7.6/1.14)X1/1000 = 0.006m³
f] Volume of aggregate (Fine and coarse ) = a-(b+c+d+e)
= 1-(0.086+0.052+0.140+0.006) = 0.716m³
g] Mass of coase aggregate = fXVolume of coarse aggregate X Specific gravity of coarse aggregate X 1000
0.716 X 0.576 X 2.74X1000 = 1130kgm³
h] mass of fine aggregate = f X Volume of fine aggregate X Specific gravity of fine aggregate X 1000
= 0.716 X 0.424 X 2.74 X 1000 = 831kg/m³
Step 9:-
Mix proportion
Cement = 270kg/m³
Flyash = 115kg/m³
Water = 140kgm³
Fine aggregate = 831kg/m³
Coarse aggregate = 130kg/m³
Chemical admixture = 7kgm³
Water-Cement ratio = 0.364
Mix ratio 1:2.15:2.94
Step 10:-
The slump shall be measurd and the water content and dosage of admixture shall be adjusted for achieving the required
slump on trial
The mix proportion shall be reworked for the actual water content and checked for durability requirements
Step 11:-
Two (or) more trialss having variation of 10% of water-cement ratio in clause 10(step 10) shall be carried out and a graph
between three water-cement ratios and corresponding strengths shall be plotted to work out the mix proportions for field trials. However durability shall be met
RESULT :-
The mix design for M35 grade of concrete with flyash is 1:2.15:2.94
M50 grade of concrete without flyash
Aim:- Mix design for M50 grade of concrete without flyash
Step 1:- Stipulation for concrete design mix
a] Grade of concrete : M50
b] Type of cement : Ordinary Portland Cement(OPC) 53Grade
c] Maximum water-Cement ratio :- o.45 (Table-5 IS456:2000 Exposure condition)
d] Maximum nominal size of aggregate :- 20mm
e] Minimum cement content :- 320kg/m³(Table-5 IS 456:2000 Exposure condition)
f] Exposura condition :- Severe (For Reinforced concrete)
g] Degree of supervision :- Good
h] Workability :- 100mm (Slump value for pumpable concrete
i] Method of concrete placing :- Pumping
j] Type of aggregate :- Crushed angular aggregates
k] Chemical admixture type :- Super plasticizer
l] Maximum cement content:- 450kg/m³
Step-2 :-
Test data for materials
a] Used of cement :- OPC 53grade (Conforming IS 12269-1987)
b] Chemical admixture :- Super Plasticizer (Conforming to IS 9103
c] Water absorption of coarse aggregate :- 0.5%
d] Specific gravity of cement :- 3.15
e] Specific gravity of fine agregate :- 2.64
f] Specific gravity of coarse aggregate :- 2.74
g] Water absorption of fine aggregate :- 1.0%
h] Sieve analysis of
fine aggregate :- Conforming to grading zone ll of Table-4 of IS 383
coarse aggregate :- Conforming to Table-2 of IS 383
i] Free surface moisture
fine aggregate :- Nil
Coarse aggregate :- Nil
Step-3 :-
Target strength for mix proportioning
f'ck = fck+1.65s Here s = Standered deviation
Where
f'ck = target average compressive strength at 28days
fck = characteristics compressive strength at 28days & 50+1.65X5 = 58.25N/mm²
From Table l of IS 10262:2009,Standered deviation (s) = 5N/mm²
Taget mean strength = 58.25N/mm²
Step-4:-
Selection of Water-Cement ratio
The maximum Water-Cement ratio to design M50grade of concrete can be found from Table-5 ofIS 456-2000 for severe exposure
Maximum W/C ratio = 0.45
Based on experience adopted water cement ratio = 0.44
o.44
Adopted W/C ratio = 0.44
Step-5:-
Election of water content
From Table-2 of IS 10262:2009 maximum water
content for 20mm aggregate = 186liters (for 25 to 50mm slump range)
Clause 4.2 suggeste increasing of 3% of water
content for every extra 25mm slump from 50mm = 186+(6/100)X186 = 197liters
slump so 6% is to be added to it
Estimated water content for 100mm slump
(Note: If superplasticizer is used the water content can be reduced up to 20% & above)
Based on trials with superplasticizer water content
reduction of 20% has been achieved hence the = 197X0.8 = 158liters
arrived water content
Water required 158 litres
Step-6:-
Calculation of cement required
Adopeted W/c ratio = 0.44
Cement content = 158/0.44 = 359kg/m³
From Table -5 of IS 456, Minimum cement content
for severe exposure conditions = 320kg/m³
359kg/m³>320kg/m³ Hence OK
Cement required is 359kg/m³
Step-7:-
Volume of coarse aggregate & fine aggregate content
From Table-3 of (IS 10262:2009) volume of coarse aggregate
corresponding to 20mm size of aggregate & fine aggregate (Zone ll) = 0.62
for Water-Cement ratio of 0.50
In the present case Water-Cement ratio is o.44 therefore, volume of coarse aggregate is required to be increased to decreased
the fine aggregate content. As the Water-Cement retio is lower by 0.06. The propotion of volume of coarse aggregate is
incresed by 0.02 (At the rate of -/+ 0.01 for every = 0.05 change in Water-Cement ratio)
Therefore, corrected proportion of volume of coarse aggregate
for the Water-Cement ratio of 0.44 = 0.632
For pumpable concrete these values should be reduced up
to 10%. Therefore, volume of coarse aggregate = 0.632X0.9 = 0.568
Volume of fine aagregate content = 1-0.576 = 0.431
Volume of fine aggregate and coarse aggregate is 0.431 and 0.568 respectively
Step-8:-
Mix calculations
The mix calculations per unit volume of conrete shall be as follows
a] Volume of concrete = 1m³
b] Volume of cement = [Mass of cement ]/Specific gravity of cement]X1/1000
= (359/3.15)X(1/1000) = 0.114m³
c] Volume of water = [Mass of water]/[Specific gravity of water] X 1/1000
= (359/3.15)X(1/1000) = 0.158m³
d] Volume of chemical admixture = [Mass of admixture]/[Specific gravity of admixture]X1/1000
= (7.6/1.145)X(1/1000) = o.oo6m³
e] Volume of all in aggregate = [a-(b+c+d)
= [1-(0.114+0.158+0.006)]= 0.722m³
f] Mass of coarse aggregate = e X Volume of coarse aggregate X Specific gravity of fine aggregate X 1000
= 0.722X0.568X2.74X1000 = 1123kg/m³
g] Mass of fine aggregate = e x volume of fine aggregate X specific gravity of fine aggregate X 1000
= 0.722X0.431X2.64X1000 = 821kg/m³
Step-9:-
Mix proportion
Cement = 359kg/m³
Water = 158kg/m³
Fine aggregate = 821kg/m³
Coarse aggregate 20mm = 1123kg/m³
Chemical admixture = 7.18kg/m³
Water-Cement ratio = 0.44
Mix proportion by weight = 1:2.28:3.12
Step-10:-
The slump shall be measured, the water content and dosage of admixture shall be adjusted for adcheving the required slump
on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements
Step-11:-
Two more trials having variaton of 10% of Water-Cement ratio shall be carries out and a graph between three Water-Cment
Ratios and corresponding strength shall be plotted to work out the mix proportions be the ginven target for field trials
RESULT:-
Mix proportion by weight of M50 grade of concrete without fly ash is 1:2.28:3.12 and its water_Cement ratio was found to be 0.44