Challenge

Project on Concrete Mix Design for various grades of Concrete

RRamuverma .Verma12 Jul 2023

Concrete Mix Design of M35 Grade with fly Ash.

A-1 STIPULATIONS FOR PROPORTIONING
a) Grade designation : M35
b) Type of cement :OPC 43 Grade Confirming to IS :8112
c) Type of mineral admixture :Fly ash conforming to IS 38I2 (Part I)
d) Maximum nominal size of aggregate : 20 mm
e) Minimum cement content :320 kg/cum
f) Maximum water-cement ratio :.45
g) Workability : 100 mm
h) Exposure condition :Severe (for reinforced concrete)
j) Method of concrete placing :Pumping
k) Degree ofsupervision : Good
m) Type of aggregate :Crushed angular aggregate
n) Maximum cement (OPC) content :400 kg
p) Chemical admixture type : Superplasticizer conforming to IS 9103

A-2 TEST DATA FOR MATERIALS

a-Cement ( Specific Gravity)-3.15 , Specific Gravity of Fly Ash-2.2

b- Specific Gravity of

Coarse Aggregate- 2.74

Fine Agregate-2.74

Water Apsoption

Coarse Aggregate 0.6

Fine Aggregate:-1

Surface Moisture

Coarse Aggregate -Nill

Fine Aggregate:-Nill

Seive Analysis

Coase Aggregate- Conforming to IS 383

Fine Aggregate - Confirming to IS 383-Zone-2

A-3 TARGET STRENGTH FOR MIX PROPORTIONING

f'ck =fck + 1.65 s
where
f'ck = target average compressive strength at 28 days,
fck = characteristic compressive strength at 28 days, and
s = standard deviation.
From Table I, standard deviation, s =5 N/mm2
Therefore, target strength =35 + 1.65 x 5 =43.25 N/mm2

A·4 SELECTION OF WATER-CEMENT RATIO
From Table 5 of IS 456, maximum water-cement ratio = 0.45.
Based on experience, adopt water-cement ratio as 0.40.
0.40 < 0.45 , hence O.K.
A-5 SELECTION OF WATER CONTENT
From Table 2, maximum water content =186 litre (for 25 to 50 mm slump range)
for 20 mm aggregate
Estimated water content for 100 mm slump =186+6/100 X 186
100
=197 litre
As superplasticizer is used, the water content can be reduced up 20 percent and above.
Based on trials with superplasticizer water content reduction of 29 percent has been achieved. Hence, the
arrived water content =197 x 0.71 =140 litre.

A-6 CALCULATION OF CEMENT AND FLY ASH CONTENT
Water-cement ratio lsee note under 4.1)
Cementitious material (cement + fly ash) content
= 0.40/140 = 350 kg/m

From Table 5 of IS 456, minimum cement
content for 'severe' exposure conditions 320 kg/cum,
350 kg/m3 > 320 kg/m3, hence. O.K.

Now, to proportion a mix containing fly ash the following steps are suggested:

a) Decide the percentage fly ash ,to be used based on project requirement and quality of materials
b) The decision on increase in cementitious material content and its percentage may be based on experience and Trail Mix
NOTE - hence we considerd only 10 % cementitios Material
Water Content

= 350 x 1.10 = 385 kg/m3
= 140 kg/m3
So. water-cement ratio =140/385= .364
Fly ash @ 30% of total cementitious material content= 385 x 30% =115 kg/m3
Cement (OPC) = 385 - 115 =270 kg/m3
Saving ofcement while using fly ash = 350 - 270 = 80 kg/m3, and
Fly ash being utilized = 115 kg/cum

A-7 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate -zone-2
for water-cement ratio of 0.50 =0.60

In the present case water-cement ratio is 0.40. Therefore. volume of coarse aggregate is requ ired (0 be increased
to decrease the line aggregate content. As the water-cement ratio is lower hy 0.10. the proportion 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) ,
Therefore. corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62
NOTE - In case the coarse aggregate is not angular one. then also volume: of coarse aggregate may he required to be increased
suitably. based on experience.
For pumpable concrete these values should be reduced by 10 percent.
Therefore. volume of coarse aggregate =0.62 x 0.9 =0.56.
Volume of fine aggregate content = I - 0.56 = 0.44.

A-8 MIX CALCULATIONS
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m3
b) Volume of cement =Mass of cement *I1/ Specific gravity ofcement*1 000

=270*1/3.15*1000=0.086 cum

c)Volume of fly ash =115*1 /1000*2.2=0.052 cum

d)Volume of water =140*1 /1000*1=0.014 cum

e)Volume of chemical admixture
(superplasticizer) @ 2.0% by mass
of cementitious material) =7*1/1.145*1000=.006 cum

f) volume of Aggregate=(1-b-c-d-e)=(1-.086-.052-.14-.006)=0.716 cum

Mass of Coarse Aggregate- .716*.56*2.74*1000=1099 kg

Mass of Fine Aggregate- .716*.44*2.74*1000=863 kg

A-8 MIX PROPORTIONS FOR TRIAL NUMBER 1
Cement = 270 kg/m'
flyAsh = 115 kg/m'
Water = 140 kg/m'
Fine aggregate = 863 kg/m3
Coarse aggregate = 1099 kg/m3
Chemical admixture = 7 kg/m3
Water-cement ratio =.364

2.0 M50 grade concrete without Fly ash.

2-1 STIPULATIONS FOR PROPORTIONING
a) Grade designation : M50
b) Type of cement :OPC 43 Grade Confirming to IS :8112
c) Maximum nominal size of aggregate : 20 mm
d) Minimum cement content :400 kg/cum( in IS 456 cement content up to m40 so we increase 20 kg cement for every 5kg,cm2 stregth)
e) Maximum water-cement ratio :0.4 ( in Is 456 water cement ratio up to grade m40 oly ,lets we concider same for M50 Also_)
f) Workability : 100 mm
g) Exposure condition :Severe (for reinforced concrete)
h) Method of concrete placing :Pumping
i) Degree ofsupervision : Good
j) Type of aggregate :Crushed angular aggregate
k) Maximum cement (OPC) content :450 kg
l) Chemical admixture type : Superplasticizer conforming to IS 9103

2-2 TEST DATA FOR MATERIALS

a-Cement ( Specific Gravity)-3.15

b- Specific Gravity of

Coarse Aggregate- 2.74

Fine Agregate-2.74

Water Apsoption

Coarse Aggregate 0.6

Fine Aggregate:-1

Surface Moisture

Coarse Aggregate -Nill

Fine Aggregate:-Nill

Seive Analysis

Coase Aggregate- Conforming to IS 383

Fine Aggregate - Confirming to IS 383-Zone-2

2-3 TARGET STRENGTH FOR MIX PROPORTIONING

2·4 SELECTION OF WATER-CEMENT RATIO
From Table 5 of IS 456, maximum water-cement ratio = 0.40
Based on experience, adopt water-cement ratio as 0.35
0.35 < 0.40 , hence O.K.
2-5 SELECTION OF WATER CONTENT
From Table 2, maximum water content =186 litre (for 25 to 50 mm slump range)
for 20 mm aggregate
Estimated water content for 100 mm slump =186+6/100 X 186
100
=197 litre
As superplasticizer is used, the water content can be reduced up 20 percent and above.
Based on trials with superplasticizer water content reduction of 29 percent has been achieved. Hence, the
arrived water content =197 x 0.71 =140 litre.

2-6 CALCULATION OF CEMENT CONTENT

= 140/.325 = 431 kg/m 3

From Table 5 of IS 456, minimum cement
content for 'severe' exposure conditions 400 kg/cum,
431 kg/m3 > 400 kg/m3, hence. O.K.

Now, to proportion a mix containing fly ash the following steps are suggested:

2-7 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate -zone-2
for water-cement ratio of 0.50 =0.60

2-8 MIX CALCULATIONS
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m3
b) Volume of cement =Mass of cement *I1/ Specific gravity ofcement*1 000

=431*1/3.15*1000=0.137 cum

d)Volume of water =140*1 /1000*1=0.014 cum

e)Volume of chemical admixture
(superplasticizer) @ 1.7% by mass
of cementitious material) =7*1/1.145*1000=.006 cum

f) volume of Aggregate=(1-b-d-e)=(1-.137-.14-.006)=0.717 cum

Mass of Coarse Aggregate- .717*.56*2.74*1000=1100 kg

Mass of Fine Aggregate- .717*.44*2.74*1000=864 kg

A-8 MIX PROPORTIONS FOR TRIAL NUMBER 1
Cement = 431 kg/m'
Water = 140 kg/m'
Fine aggregate = 864 kg/m3
Coarse aggregate = 1100 kg/m3
Chemical admixture = 7 kg/m3
Water-cement ratio =.325

End of Design Mix

Project on Concrete Mix Design for various grades of Concrete

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