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 with fly ash

Step:-1

I. STIPULATIONS FOR PROPORTIONING OF M35 GRADE CONCRETE

A	Grade Designation	M35
B	Type of Cement	OPC 43	IS 8112 to conforming grade
C	Type of Admixture	Fly ash	IS 3812 (part 1)to conforming grade
D	Maximum Nominal Size of Aggregate	20mm
E	Minimum Cement Content	320kg	From Table no 5 Of Is 456:2000 based on Exposure Condition
F	Maximum Water Cement ratio	0.45	From Table no 5 Of Is 456:2000 based on Exposure Condition

G	Workability	100mm	Slump Value for pumpable concrete
H	Exposure Condition	Sever	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	450 kg/cum
M	Chemical admixture type	Superplasticizer

Step:-2

TEST DATA FOR MATERIALS

A	Cement used	OPC 43	IS 8112 to conforming grade
B	Specific gravity of cement	3.15
C	Fly ash		IS 3812 (part 1)to conforming grade
D	Specific gravity of Fly ash	2.2
E	Chemical admixture	Superplasticizer	IS 9103 to conforming
F	Specific gravity of . Coarse aggregate . Fine aggregate	2.74 2.74
G	Water absorption . Coarse aggregate . Fine aggregate	0.5% 1.0%
H	Free Surface Moisture . Coarse aggregate . Fine aggregate	Nil Nil

F) Seive analysis

. Coarse aggregates:

Is Seive Analysis of % of Remark

Size Coarse different

mm aggregate fraction fraction

I II I II Combined

20 100 100 60 40 100

10 0 71.20 0 28.50 28.50

4.75 9.40 3.70 3.70

2.36 0 Is 383 Of conforming

to table no 2

. Fine aggregate :- Conforming to grading Zone 1 of Table 4 IS 383.

Step:-3

TARGET STRENGTH FOR MIX PROPORTIONS OF M35 GRADE CONCRETE

Formula of Target Mean strength F'ck=Fck+1.65*s

Given:-

Characteristic Compressive strength Fck= 35 N/Sqmm

Standard deviation S= 5 N/Sqmm From given bleow Is 10262:2009

F'ck= 35+1.65*5

F'ck= 43.25 N/Sqmm

Step:-4

SELECTION OF WATER-CEMENT RATIO

Maximum W/C ratio = 0.45 ( for sever condition, from table 5 of IS 456-2000)

On experience W/C ratio = 0.40

0.40<0.45, Hence OK.

Step:-5

SELECTION OF WATER CONTENT

Maximum water content for 20mm aggregate =186 litres (Table 2 of IS 1026:2009) for 25mm to 50mm slump range

For 100 mm slump,= 186+(6/100)*186 =197 litres

As superplaticizer is used, the water content is reduced upto 30%

Based on trials water content reduction of 29% is achieved with plasticizer

Hence arrived water content = 197*0.71 = 140 litres

Step:6

Calculation of cement content

Water- cement ratio = 0.4

Cementatious material (Cement +flyash ) = 140/0.4 =350 kg/cum

In table 5 of IS 456-2000, the cement content for severe exposure =320 kg/cum

350 kg/cum> 320kg/cum

Hence OK.

To proportion the mix containing flyash the following steps are suggested

a. The percentage of flyash need to be decided based on project requirement and qualityof materials.

b. In some cases increase in cementatious materials can be warrned. Increase in cementatious material content and its percentage may be based on experience and trial.

In this increase of 10% cementatious material content is considered.

Cementatious material content = 350*1.1 =385kg/cum

Water content = 140kg/cum

So, water- cement ratio = 140/385 =0.364

Fly ash at 30% total cementatious material content = 35-30% = 115kg/cum

Cement (OPC) =385-115 = 270kg/cum

Saving of cement while using flyash = 350-270=80kg/cum

Fly ash beign utilized = 115kg/cum

Step: 7

Proportion of volume of coarse aggregate and fine aggregate content

From table 3 of IS 1026:2009,volume of coarse aggregate corresponding to 20 mm size aggregate and fine
aggregate (Zone 1) for water- cement ratio = 0.60

In present case the water - cement ratio is 0.40

Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.

As the water- cement ratio is lowered by 0.1 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)

Hence the corrected value ofcoarse aggregate for the water-cemnt ratio = 0.62

(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)

For pumpable concrete, these are reduced by 10%

Volume of coarse aggregate = 0.62*0.9 = 0.558

Volume of fine aggregate = 1-0.558 =0.442

Step :8

Mix calculations

Mix calculation per unit volume of concrete:

a. Volume of concrete = 1 m^3.

b. Volume of cement = (Mass of cement / Specific gravity of cement) *1/1000

= (270/3.15 )*1/1000 =0,086 m²

c. Volume of flyash = (Mass of flyash / Specific gravity of flyash)*1/1000

=(115/2.2) 1/1000 = 0.052m²

d. Volume of water = (Mass of water / Specific gravity of water)*1/1000

= (140/1)*1/1000 =0.140 m3

e. Volume of chemical admixture = (Mass of admixture / specific gravity of admixture)*1/1000

=(7.6/1.14)*1/1000 =0.006 m³

f. Volume of aggregate (Fine and coarse) = a- (b+c+d+e)

= 1-(0.086+0.052+0.140+0.006) =0.716 m³

g. Mass of coarse aggregate = f* Volume of coarse aggregate * Specific gravity of coarse aggregate *1000

= 0.716*0.558*2.74*1000 =1095kg/cum

h. Mass of fine aggregate = f* Volume of fine aggregate* Specific gravity of fine aggreate*1000

= 0.716*0.442*2.74*1000= 867 kg/cum

Step :9

Mix proportion

Cement = 270 kg/cum

Fly ash = 115 kg/cum

Water = 140k kg/cum

Fine aggregate = 867 kg/cum

Coarse aggregate = 1095 kg/cum

Chemical admixture = 7kg/cum

Water-cement ratio=0.364

Mix ratio 1:2.25: 2.84

Step: 10

The slump shall be measured and the water content and dosage of admixyure shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for the actual water content and checkedd for durability requirements.

Step :11

Two or more trials 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 the given target strength for feild trials .However durability shall be met.

Result: The mix design for M 35 grade of concrete with flyash is 1:2.25: 2.84

Ans:- Aim:- Mix Design for M50 grade concrete without Fly ash

Stipulations for Concrete Mix Design

• Grade designation : M 50
• Type of cement : OPC 43 IS 8112 to conforming grade
• Maximum nominal size of aggregate : 20 mm
• Minimum cement content : 360 kg/cum (From Table no 5 Of Is 456:2000 based on Exposure Condition)
• Maximum water-cement ratio : 0.45 (From Table no 5 Of Is 456:2000 based on Exposure Condition)
• Workability : 100 mm (slump)
• Exposure condition : Extreme (for reinforced concrete)
• Type of aggregate : Crushed angular aggregate
• Maximum cement content : 450 kg/cum

Procedure for Concrete Mix Design of M 50 Concrete

1 Target Strength for Mix Proportioning

f_target = f_ck + 1.65 x s

f'ck= Target mean Strength at 28 days.

f_ck = Compressive Strength at 28 days.

s= stands for Standard Deviation

According to the table 1 of IS: 10262-2009,

standard deviation, s = 5.0 N/mm²

Therefore, target strength = 50 + 1.65 x 5.0 = 58.25 N/sqmm.

2 Selection of Water/Cement Ratio

From Table 5 of IS: 456-2000,

Maximum water-cement ratio = 0.40 ( Assume)

Lower the water cement ratio better the workability

0.40<0.45

Water cement ratio = 0.40

Minimum cement content = 360 kg/cum

3 Selection of Water Content

From Table 2 of IS: 456,

maximum water content =186 litres

Slump range from 25 to 50mm

As superplasticizers 20% reduced

= 186 X 80/100=148.80 (100-20)

Water content =149 litres 149 kg

4 Calculation of Cement Content

Water content = 149 kg

Water-cement ratio = 0.40

Cement content = W/0.40

= 149/0.40 = 372.5 kg/cum

From Table 5 of IS456, minimum cement content for ‘Extreme exposure’ condition = 360 kg/cum

372.5 kg/cum > 360 kg/cum, hence, O.K.

5 Proportion of Volume of Coarse Aggregate and Fine Aggregate Content

From Table 3 of IS: 10262,

volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for a water-cement ratio of 0.60

Water cement ratio =0.40

(+/-0.01 For every +/- 0.005)

So, volume of coarse aggregate =0.62

Volume of fine aggregate =1-0.62=0.38

6. Mix Calculations

a) Volume of concrete = 1m³

b) Volume of cement = (Mass of Cement/ Its Specific Gravity ) X (1/1000)

= (372.5/3.12) X (1/1000)

= 0.12 Cum

c) Volume of Water = (Mass of water/specific gravity of water) X (1/1000)

= (149/1) X (1/1000)

= 0.15 Cum

d) Volume of Superplasticizer = (Mass of Superplasticizer / Specific gravity of admixture) X (1/1000)

= (7.45/1.145) X (1/1000) That is Mass of Superplasticizer =2% of weight of cement

= 0.006 Cum

e) Volume of all aggregate = (a – (b + c + d))

= 1 – (0.12 + 0.15+0.006)

= 0.72 Cum

f) Mass of coarse aggregate = Volume of All Aggregate X Volume of Coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000

=0.72 x 0.62 x 2.74 x 1000

=1223.14 kg/cum

g) Mass of fine aggregate = Volume of all aggregate X volume of fine aggregate X Specific gravity of fine aggregate X 1000

= 0.72 x 0.38 x 2.74 x 1000

= 749.66 kg/cum

7 Concrete Mix Proportions

• Cement = 372.50 kg/cum
• Water = 149 kg/cum
• Fine aggregates = 749.66 kg/cum
• Coarse aggregate =1223.14 kg/cum
• Chemical Admixture=7.45kg/cum
• W/c = 0.40

Trial Mix Ratio= 1 : 2.01 : 3.28