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CONCRETE MIX DESIGN

Mrinaljyoti Adhyapok

CONCRETE MIX DESIGN

Major Project Report submitted to

Sikkim Manipal University, Sikkim

Submitted in partial fulfillment of the requirements for the award of

the degree of

Bachelor of Technology

By


Under the guidance of

Mr. Abhranil Adak

DEPARTMENT OF CIVIL ENGINEERING

SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY

MAJITAR, RANGPO, EAST SIKKIM 737136

MAY 2013

© 2013, Mrinaljyoti Adhyapok. All rights reserved.

DECLARATION

I certify that

a. The work contained in this report is original and has been done by me under the guidance

of my supervisor(s).

b. The work has not been submitted to any other Institute for any degree or diploma.

c. I have followed the guidelines provided by the Institute in preparing the report.

d. I have conformed to the norms and guidelines given in the Ethical Code of Conduct of

the Institute.

e. Whenever I have used materials (data, theoretical analysis, figures, and text) from other

sources, I have given due credit to them by citing them in the text of the thesis and giving

their details in the references.


ABSTRACT

In the following pages to follow an attempt is being made to bring forward a brief analysis about

the concrete mix designs of M30 and M40 concrete. Here an effort has been made to find out the

compressive strengths developed by both M30 and M40 concrete not only by its normal mix

design but also through addition of admixtures and fibres.

The theories presented here have been adopted from the study of various standard codes

available for the conduct of civil engineers. Any suggestions and queries regarding correction of

the theories as well as the numerical presentations are welcome.

Close care has been taken to present the design solution calculation to the nearest

possible decimal values and any error or misprint in the calculations may suitably be considered.

CHAPTER 1

INTRODUCTION

1.1 General

The process of selecting suitable ingredients of concrete and determining their relative amounts

with the objective of producing a concrete of the required strength, durability and workability as

economically as possible, is termed the concrete mix design. The proportioning of ingredients of

concrete is governed by the required performance of concrete in two states, namely the plastic

and the hardened state. If the plastic concrete is not workable it cannot be properly placed and

compacted. The property of workability therefore becomes of vital importance.

The compressive strength of hardened concrete which is generally considered to be an

index of other properties depends upon many factors, for example quality and quantity of

cement, water and aggregates, batching and mixing, placing, compaction and curing. The cost of

concrete is made up of the cost of materials, plant and labour. The variation in the cost of

materials arise from the fact that the cement is several times costly than the aggregate, thus the

aim is to produce as lean a mix as possible. From the technical point of view the rich mixes may

lead to high shrinkage and cracking in the structural concrete, and to evolution of high heat of

hydration in mass concrete which may cause cracking.

The actual cost of concrete is related to the cost of materials required for producing a

minimum mean strength called characteristic strength that is specified by the designer of the

structure. This depends on the quality control measures, but there is no doubt that the quality

control adds to the cost of concrete. The extent of quality control is often and economic

compromise, and depends on the size and types of job. The cost of labour depends on the

workability of the mix.

1.2 Scope of present work

The area of work that has been foreseen in this project is the study of strength of compacting

strength of concrete with the use of the aggregates easily available in this area. Focus has been

given only upon the general strength development of concrete mix design.

1.3 Objective of the present investigation

1. Concrete mix design of M30 and M40 concrete ( M30 and M40 has been selected

because through a general study it has been found out that these two mixes are generally

used in the Sikkim region).

2. Test of development of strength by the use of admixture, jute fibre and steel fibre along

with normal design mix of M30 and M40 concrete.

3. Taking all the results of the various design mixes and comparing their compressive

strength and economic possibilities.

CHAPTER 2

2.1 REQUIREMENTS OF CONCRETE MIX DESIGN

The requirements which form the basis of selection and proportioning of mix ingredients are:-

1. The minimum compressive strength required from structural consideration.

2. The adequate workability necessary for full compaction with the compacting equipment

available.

3. Maximum water cement ratio and/or maximum cement content to give adequate

durability for the particular site condition.

4. Maximum cement content to avoid shrinkage, cracking due to temperature cycle in mass

concrete.

2.2 FACTORS AFFECTING THE CHOICE OF MIX PROPORTION

1. Compressive strength

2. Workability

3. Durability

4. Maximum nominal size of aggregate

5. Grading and type of aggregate

6. Quality control

2.3 FACTORS TO BE CONSIDERED FOR MIX DESIGN

1. The grade designation giving the characteristic strength requirement of concrete.

2. The type of cement influences the rate of development of compressive strength of

concrete.

3. Maximum nominal size of aggregates to be used in concrete may be as large as possible

within the limits prescribed by IS 456-2000.

4. The cement content is to be limited from shrinkage, cracking and creep.

5. The workability of concrete for satisfactory placing and compaction is related to size and

shape of section, quantity and spacing of reinforcement and technique used for transportation,

placing and compaction.

2.4 METHODOLOGY AND PROCEDURE

Before performing the design calculations we have to perform the following standard tests.

1. Test for specific gravity of cement, fine aggregate and coarse aggregate.

2. Test for water absorption of coarse and fine aggregate.

3. Test for free moisture of coarse and fine aggregate.

4. Sieve analysis.

5. Compacting factor test.

2.4.1 Test for specific gravity of cement, fine aggregate and coarse aggregate

2.4.1.1 Test for specific gravity of cement

Apparatus: Specific gravity bottle, weighing balance

Procedure: Weigh a clean and dry specific gravity bottle with its stopper (w1). Place a sample of

cement upto half of a flask and weigh its stopper (w2). Add kerosene to the cement in the flask

till the graduated mark. Mix thoroughly with glass rod to remove entrapped air. Dry the outside

and weigh (w3). Empty the flask, clean it and refilled with clean kerosene up till the graduated

mark. Wipe dry the outside and weigh (w4).

Calculation:

Table 2.1: Showing values for calculating average specific gravity of cement

Weights Sample 1 Sample 2 Sample 3

Empty weight of

bottle, W1

0.031 0.030 0.030

Weight of bottle +

cement, W2

0.048 0.046 0.045

Weight of bottle +

cement + kerosene,

W3

0.083 0.082 0.082

Weight of bottle +

kerosene, W4

0.072 0.072 0.072

*weights are in kg(kilogram)

𝑆𝑝. 𝐺 =𝑊2−𝑊1

(𝑊4−𝑊1)−(𝑊3−𝑊2)= 3.0997

= 3.1

2.4.1.2 Test for specific gravity of fine aggregate

Apparatus: Specific gravity bottle, weighing balance

Procedure: Weigh a clean and dry specific gravity bottle with its stopper (w1). Place a sample of

sand upto half of a flask and weigh its stopper (w2). Add water to the sand in the flask till the

graduated mark. Mix thoroughly with glass rod to remove entrapped air. Dry the outside and

weigh (w3). Empty the flask, clean it and refilled with clean water up till the graduated mark.

Wipe dry the outside and weigh (w4).

Calculation:

Table 2.2: Showing values for calculating average specific gravity of sand


Empty weight of

bottle, W1

0.063 0.065 0.066

Weight of bottle

+ sand, W2

0.15 0.139 0.142

Weight of bottle

+ sand + water,

W3

0.24 0.236 0.232

Weight of bottle

+ water, W4

0.186 0.188 0.185



(𝑊4−𝑊1)−(𝑊3−𝑊2)= 2.68

= 2.68

2.4.1.3 Test for specific gravity of coarse aggregate

Apparatus: conical flask, weighing balance

Procedure: Weigh a clean and dry conical flask with its stopper (w1). Place a sample of coarse

aggregate upto half of a flask and weigh its stopper (w2). Add water to conical flask in the flask

till the graduated mark. Mix thoroughly with glass rod to remove entrapped air. Dry the outside

and weigh (w3). Empty the flask, clean it and refilled with clean water up till the graduated

mark. Wipe dry the outside and weigh (w4).

Calculation:

Table 2.3: Showing values for calculating average specific gravity of coarse aggregate


Empty weight of

bottle, W1

0.171 0.187 0.172

Weight of bottle +

coarse aggregate,

W2

0.426 0.431 0.43

Weight of bottle +

coarse aggregate +

water, W3

0.818 0.831 0.823

Weight of bottle +

water, W4

0.656 0.681 0.663



(𝑊4−𝑊1)−(𝑊3−𝑊2)= 2.653

= 2.65

2.4.2 Test for water absorption of coarse and fine aggregate

2.4.2.1 Test for water absorption of coarse aggregate

Apparatus: Beaker of size 1000 ml, weighing balance

Procedure: Weigh a dry empty beaker (w1). Now put clean coarse aggregate into the beaker till

1/3 rd. its depth. Now add 500 ml water into the beaker. Keep it until air bubble disappears.

Weigh it (w3). Now drain the water from the beaker. Keep the weighted aggregates on a dry

sheet of paper for surface drying for 10-15 minutes. Now weigh the aggregate along with the

beaker (w4). Now keep the aggregates in an oven at 110 degrees for 24 hours and weigh it again

(w5).

W1=0.177 Kg.

W2=0.604 Kg

W3=0.930 Kg

W4=0.430 Kg

W5=0.427 Kg

Water absorption of coarse aggregate = W5 W4

W4

=0.430 0.427

0.427

= 0.7025%

2.4.2.2 Test for water absorption of fine aggregate

Apparatus: Beaker of size 1000 ml, weighing balance

Procedure: Weigh a dry empty beaker (w1). Now put clean sand into the beaker till 1/3 rd. its

depth. Now add 500 ml water into the beaker. Keep it until air bubble disappears. Weigh it (w3).

Now drain the water from the beaker. Keep the weighted aggregates on a dry sheet of paper for

surface drying for 10-15 minutes. Now weigh the aggregate along with the beaker (w4). Now

keep the aggregates in an oven at 110 degrees for 24 hours and weigh it again (w5).

W1=0.177 Kg.

W2=0.477 Kg

W3=0.977 Kg

W4=0.303 Kg

W5=0.300 Kg

Water absorption of fine aggregate = W5 W4

W4

= 0.303 0.300

0.300

= 1%

2.4.3 Test for free moisture of coarse and fine aggregate.

2.4.3.1 Test for free moisture of coarse aggregate

Apparatus: Three equal size aluminum boxes, oven for drying, weighing balance.

Procedure: To test the average moisture content of coarse aggregate three equal samples of

coarse aggregate are taken and placed in previously weighed aluminum container (w1) and the

weight of the container after putting the aggregates is also taken (w2).Now the containers are

placed in a previously heated oven at 110 degree Celsius for 24 hours. After this the weight of

the containers are again measured (w3). The average difference between the normally exposed

aggregate and the dried aggregate gives us the free moisture content of coarse aggregate.

Calculation:

Table 2.4: Showing values for calculating average free moisture of coarse aggregate


Empty weight of

aluminium box, W1

0.006 0.006 0.007

Weight of aluminium box

+ coarse aggregate, W2

0.082 0.096 0.09


with coarse aggregate after

24 hr oven drying, W3

0.082 0.096 0.09

Therefore, the free moisture for coarse aggregate = W2−W3

W3 = 0

2.4.3.2 Test for free moisture of fine aggregate

Apparatus: Three equal size aluminum boxes, oven for drying, weighing balance.

Procedure: For fine aggregates the procedure to be followed is just the same as that of the coarse

aggregates, only that it should be kept in mind that the fine aggregate should be from readily

accessible portion of the aggregate storage site (else retention of moisture may lead into different

values if taken from beneath and lower portion of the aggregate dump).

Calculation:

Table 2.5: Showing values for calculating average free moisture of fine aggregate


Empty weight of

aluminium box, W1

0.006 0.006 0.007


+ fine aggregate, W2

0.094 0.093 0.094


with fine aggregate after

24 hr oven drying, W3

0.093 0.092 0.093

Therefore, the free moisture for fine aggregate = W2−W3

W3 = 1.0752%

2.4.4 Sieve analysis

Apparatus: sieve sizes of 4.56mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron

Calculation:

Table 2.6: Showing values of sieve analysis

Sieve Weight

of

Sieve

Sieve +

retained

FA

Weight

of FA

retained

% retained %

cumulative

retained

% finer

4.75mm 0.377 0.45 0.073 3.65 3.65 96.35

2.36mm 0.33 0.389 0.059 2.95 6.6 93.4

1.18mm 0.334 0.622 0.288 14.4 21 79

600 micron 0.32 0.818 0.498 24.9 45.9 54.1

300 micron 0.291 1.158 0.867 43.55 89.25 10.75

150 micron 0.289 0.462 0.173 8.65 97.9 2.1

*weights are in kg (kilogram)

*FA = fine aggregate

Fineness modulus =264.3

100= 2.643

From the graph,

D10=0.28 mm

Cu = D60

D10 =

0.78

0.28 =2.78

Cc =D30

2

D60 x D10 =

0.382

0.78 x 0.28 = 0.66

From IS code 383-1970, it is of grading zone II.

2.4.5 Compacting factor test

COMPACTING FACTOR

Compacting factor of fresh concrete is done to determine the workability of fresh concrete by

compacting factor test as per IS: 1199 – 1959. The apparatus used is Compacting factor

apparatus.

Procedure to determine workability of fresh concrete by compacting factor test

0

20

40

60

80

100

120

4.75 2.36 1.18 0.6 0.3 0.15

% F

INE

R

SIEVE SIZE

GRAIN SIZE DISTRIBUTION CURVE

1. The sample of concrete is placed in the upper hopper up to the brim.

2. The trap-door is opened so that the concrete falls into the lower hopper.

3. The trap-door of the lower hopper is opened and the concrete is allowed to fall into the

cylinder.

4. The excess concrete remaining above the top level of the cylinder is then cut off with the

help of plane blades.

5. The concrete in the cylinder is weighed. This is known as weight of partially compacted

concrete.

6. The cylinder is filled with a fresh sample of concrete and vibrated to obtain full

compaction. The concrete in the cylinder is weighed again. This weight is known as the

weight of fully compacted concrete.

Compacting factor = (Weight of partially compacted concrete)/(Weight of fully compacted

concrete)

2.5 REQUIREMENT OF MIX DESIGN OF M30 AND M40

The IS 456-2000 has designated fixed mix proportions for concrete like M10, M15, M20

and M25 to be respectively of the ratios 1:3:6, 1:2:4, 1:1.5:3 and 1:1:2 respectively. But there is

no design mix proportion fix for M30 and above. Hence depending upon the aggregates available

and their zoning, type of cement used, condition to which the concrete is to be exposed we

develop mix design for concrete M30 and above based on calculations (in reference to Indian

Standard Codes IS 10262-1984).

CHAPTER 3

DESIGN MIX CALCULATION FOR M30 CONCRETE

3.1 STIPULATIONS FOR PROPORTIONING

1. Maximum size of aggregate = 20 mm

2. Workability compacting factor = 0.90

3. Quality control = good

4. Type of exposure = mild

5. Characteristics compressive strength required in the field at

28 days = 30 N/mm2

3.2 TEST DATA FOR MATERIALS

1. Cement used = Ordinary Portland Cement (OPC 53 GRADE)

2. Specific gravity of cement = 3.1

3. Specific gravity of coarse aggregate = 2.65

4. Specific gravity of fine aggregate = 2.68

5. Water absorption of coarse aggregate = 0.7025%

6. Water absorption of fine aggregate = 1%

7. Free moisture of coarse aggregate = nil

8. Free moisture of fine aggregate = 1.0752

9. From sieve analysis and IS 383-1970, grading zone II

3.3 CALCULATION

3.3.1 Target mean strength of Mix design

f f t Sck ck

Where,

fck

= Target average compressive strength at 28 days.

fck

= Compressive strength at 28 days.

S = Standard deviation.

t = tolerance factor (5% results are expected to fall)

From IS 10262-1982,

a) Value of t = 1.65 (1 in 20) and

b) Value of S = 6 (M30 good quality concrete)

Therefore, f f t Sck ck

= (30 + 1.65×6) N/mm2

=39.9 N/mm2

3.3.2 Selection of water cement ratio

3.3.3.1 Water cement ratio = 0.37

3.3.3.2 Maximum water cement ratio not to be exceed = 0.45

3.3.3 Selection of water sand content

3.3.3.1 Water cement for per cubic meter of aggregate is 186 kg.

3.3.3.2 Sand= 35% (of total aggregate volume).

TABLE 3.1: Correction adjustment factor

Change of condition Adjustment required

Water content

%

% sand in TA

1) Decrease in water cement ratio by 0.23 0 -4.6%

2) Increase in compacting factor by 0.10 +3.0% 0

3) For sand conforming zone II of table 4

of IS 383-1970

No adjustment required

TOTAL (in %) +3.0% -4.6%

Therefore sand content as % of total aggregate by absolute volume = (35-4.6) % =30.4%

Water content = 186 + (3/100) ×186

=191.58 kg

3.3.4 Determination of cement content

Water cement ratio = 0.37

Water content = 191.58 kg

Cement required = (191.58/0.37) Kg/m3

= 517.78 Kg/m3

3.3.5 Determination of coarse and fine aggregate

3.3.5.1 For fine aggregate

V= [W+(C/sc) + (1/ρ) × (fa/sfa)]

Nominal maximum size of aggregate = 20 mm

Entrapped air = 2%

V=0.98, W=191.58 kg/m3, C=517.78 kg/m3, Sc=3.1, ρ=0.304, Sfa=2.68

Putting the values in the equation we obtain fa is equal to 506.26 kg/m3

3.3.5.2 For coarse aggregate

V= [W+(C/Sc) + {1/(1-ρ)}×(ca/Sca)]

V=0.98, W=191.58 kg/m3, C=517.78 kg/m3, Sc=3.1, ρ=0.304, Sca=2.65


Entrapped air = 2%

Putting the values in the equation we obtain ca is equal to 1159.07 kg/m3

Therefore for M30 mix design

Concrete = water: cement: fine aggregate: coarse aggregate

= 0.37: 1.0: 0.98: 2.29

CHAPTER 4

DESIGN MIX CALCULATION FOR M30 CONCRETE USING

ADMIXTURE

4.1 Stipulations for proportioning

1. Grade designation = M30

2. Type of cement = OPC 53 grade conforming to IS 8112

3. Maximum nominal size of aggregate = 20 mm


5. Type of exposure = severe

4.2 Test data

1. cement used = OPC

2. specific gravity of cement = 3.1

3. chemical admixture = Rheobuild 1100 i

4. specific gravity of coarse aggregate = 2.65

5. specific gravity of fine aggregate = 2.68

6. water absorption of coarse aggregate = nil

7. water absorption of fine aggregate = 1.0752%

8. from sieve analysis and IS 383-1970 grading zone II

4.3 Calculation


f f t Sck ck

Where fck


fck




From IS 10262-2009,


b) Value of S = 5.0 (M30 good quality concrete)

Therefore f f t Sck ck

= (30 + 1.65×5.0) N/mm2

=38.25 N/mm2

4.4 Selection of water cement ratio


4.5 Selection of water content

From table 2 of IS 10262-2009, maximum water content = 186 litre

Estimated water content for 100 mm slump = 186+ (6/100) ×186

= 197.16 litre

As admixture is used the water content can be reduced up to 20% and above

Therefore the arrived water content = (197×0.8) = 157.728 litre

4.6 Calculation of cement content


Cement content = (157.728/0.45) = 350.5 kg/m3

From IS 456-2000, minimum cement content for severe condition = 320 kg/m3

350.5 kg/m3 > 320 kg/m3, hence ok

4.7 Preparation of volume of coarse aggregate and fine aggregate content

From table 3 of IS 10262-2009, volume of coarse aggregate corresponding to 20 mm size

aggregate and fine aggregate (zone 2) for water cement ratio of 0.50 = 0.62

In the present case water cement ratio is 0.45. Therefore volume of coarse aggregate is

required to increase and to decrease the fine aggregate content. As the water cement ratio is

down by 0.05, the proportion of volume of coarse aggregate is increased by 0.01.

Corrected proportion of volume of coarse aggregate for water cement ratio 0.45 = 0.63

Therefore volume of fine aggregate = (1- 0.63) = 0.37

4.8 Mix calculation

The mix calculation per unit volume of concrete shall be as follows

A. Volume of concrete = 1 m3

B. Volume of cement = (350.5/3.1)×(1/1000) = 0.1135 m3

C. Volume of water = (157.728)×(1/1000) = 0.1581 m3

D. Volume of chemical admixture (0.8%) = mass of chemicaladmixture

specificgravityof admixture×

1

1000

= 2.804

1.185×

1

1000

= 0.00236 m3

Therefore,

Volume of all in aggregate = [A-(B+C+D)]

= [1-(0.128+0.158+0.00236)] m3

= 0.72614 m3

Mass of coarse aggregate = (0.72614×0.64×2.65×1000) kg

= 1212.29 kg

Mass of fine aggregate = (0.72614×0.36×2.68×1000) kg

= 720.04 kg

Therefore,

Concrete = water: cement: admixture: fine aggregate: coarse aggregate

= 157.728: 350.5: 2.804: 720.04: 1212.29

= 0.45: 1: 0.008: 2.05: 3.458

CHAPTER 5

DESIGN MIX CALCULATION FOR M30 CONCRETE USING JUTE

FIBRE







5.2 Test data



3. fibre used = jute fibre of diameter 1 mm






5.3 Calculation


f f t Sck ck

Where fck


fck




From IS 10262-1982,




= (30 + 1.65×5.0) N/mm2

=38.25 N/mm2

5.4 Selection of water cement ratio


5.5 Selection of water content



= 197.16 litre

5.6 Calculation of cement content


Cement content = (197.16./0.45) = 438.13 kg/m3


438.13 kg/m3 > 320 kg/m3, hence ok

5.7 Preparation of volume of coarse aggregate and fine aggregate content







Therefore, volume of fine aggregate = (1- 0.63) = 0.37

5.8 Mix calculation


A) Volume of concrete = 1 m3

B) Volume of cement = (438.13/3.1)×(1/1000) = 0.141 m3

C) Volume of water = (197.16)×(1/1000) = 0.197 m3

D) Volume of jute fibre (0.4%) = massof jute fibre

specificgravityof fibre×

1

1000

= 1.7525

1.5×

1

1000

= 0.00168 m3

Therefore,


= [1-(0.141+0.197+0.00168)] m3

= 0.66 m3


= 1101.87 kg


= 654.456 kg

Therefore,

Concrete = water: cement: jute fibre: fine aggregate: coarse aggregate

= 197.16: 438.13: 1.7525: 654.456: 1101.87

= 0.45: 1: 0.004: 1.49: 2.52

CHAPTER 6

DESIGN MIX CALCULATION FOR M40 CONCRETE

6.1 STIPULATIONS FOR PROPORTIONING

1. Maximum size of aggregate = 20 mm

2. Workability compacting factor = 0.90


4. Type of exposure = mild

5. Characteristics compressive strength required in the field at 28 days = 30 N/mm2

6.2 TEST DATA FOR MATERIALS

1. Cement used = Ordinary Portland Cement (OPC 53 GRADE)




5. Water absorption of coarse aggregate = 0.7025%

6. Water absorption of fine aggregate = 1%

7. Free moisture of coarse aggregate = nil

8. Free moisture of fine aggregate = 1.0752

9. From sieve analysis and IS 383-1970, grading zone II

6.3 CALCULATION


f f t Sck ck

Where fck


fck




From IS 10262-1982,




= (40 + 1.65×6.6) N/mm2

=50.89 N/mm2


1) Water cement ratio = 0.3

2) Maximum water cement ratio not to be exceed = 0.40

6.3.3 Selection of water sand content

Water cement for per cubic meter of aggregate is 180 kg.

Sand= 25% (of total aggregate volume).

TABLE 6.1: Correction adjustment factor

Change of condition Adjustment required

Water content

%

% sand in total

aggregate

1) Decrease in water cement ratio by

0.05

0 -1.0%

2) Increase in compacting factor by

0.10

+3.0% 0

3) For sand conforming zone II of

table 4 of IS 383-1970

No adjustment required

TOTAL (in %) +3.0% -1.0%

Therefore sand content as % of total aggregate by absolute volume = (25-1) % =24%

Water content = 180 + (3/100) ×180 = 185.4 kg

6.3.3.1 Determination of cement content


Water content = 185.4 kg

Cement required = (185.4/0.3) Kg/m3

= 618 Kg/m3

6.3.3.2 Determination of coarse and fine aggregate

I) For fine aggregate

V= [W+(C/sc) + (1/ρ) × (fa/sfa)]


Entrapped air = 2%

V=0.98, W=185.4 kg/m3, C=618 kg/m3, Sc=3.1, ρ=0.24, Sfa=2.68

Putting the values in the equation we obtain fa is equal to 382.861 kg/m3

II) For coarse aggregate

V= [W+(C/Sc) + {1/(1-ρ)}×(ca/Sca)]

V=0.98, W=185.4 kg/m3, C=618 kg/m3, Sc=3.1, ρ=0.24, Sca=2.65


Entrapped air = 2%

Putting the values in the equation we obtain ca is equal to 1198.861 kg/m3.

Therefore, for M40 mix design,

Concrete = water: cement: fine aggregate: coarse aggregate

= 0.3: 1.0: 0.62: 1.939

CHAPTER 7

DESIGN MIX CALCULATION FOR M40 CONCRETE USING

ADMIXTURE







7.2 Test data



3. chemical admixture = Rheobuild 1100 i






7.3 Calculation


f f t Sck ck

Where fck


fck




From IS 10262-2009,




= (40 + 1.65×5.0) N/mm2

=48.25 N/mm2



Based on assumption from IS 10262-2009 water cement ration is taken to be

= 0.40

0.40<0.45, hence ok

7.3.3 Selection of water content



= 197 litre

As admixture is used the water content can be reduced up to 20% and above

Therefore the arrived water content = (197×0.8) = 157.6 litre

7.3.4 Calculation of cement content


Cement content = (157.6/0.4) = 397 kg/m3


350 kg/m3 > 320 kg/m3, hence ok

7.3.5 Preparation of volume of coarse aggregate and fine aggregate content








7.3.6 Mix calculation



B. Volume of cement = (397/3.1)×(1/1000) = 0.128 m3


D. Volume of chemical admixture (0.8%) = mass of chemicaladmixture

specificgravityof admixture×

1

1000

= 3.176

1.185×

1

1000

= 0.00268 m3

Therefore,


= [1-(0.128+0.158+0.00268)] m3

= 0.71132 m3


= 1206.30 kg


= 686.28 kg

Therefore,

Concrete = water: cement: admixture: fine aggregate: coarse aggregate

= 157.6: 397: 3.176: 686.28: 1206.30

= 0.40: 1: 0.008: 1.72: 3.038

CHAPTER 8

DESIGN MIX CALCULATION FOR M30 CONCRETE USING JUTE

FIBRE







8.2 Test data

1. Cement used = OPC


3. Fibre used = jute fibre of diameter 1 mm



6. Water absorption of coarse aggregate = nil

7. Water absorption of fine aggregate = 1.0752%

8. From sieve analysis and IS 383-1970 grading zone II

8.3 Calculation


f f t Sck ck

Where fck


fck




From IS 10262-1982,




= (40 + 1.65×5.0) N/mm2

=48.25 N/mm2



Based on experience = 0.40

0.40<0.45, hence ok




= 197 litre



Cement content = (197/0.4) = 492.5 kg/m3


492.5 kg/m3 > 320 kg/m3, hence ok













C. Volume of water = (197)×(1/1000) = 0.197 m3

D. Volume of jute fibre (0.4%) = massof jute fibre


1

1000

= 1.985

1.5×

1

1000

= 0.00132 m3

Therefore,


= [1-(0.158+0.197+0.00132)] m3

= 0.64368 m3


= 1091.68 kg


= 621.02 kg

Therefore,


= 197: 492.5: 1.985: 621.02: 1091.68

= 0.4: 1: 0.004: 1.26: 2.216

CHAPTER 9

DESIGN MIX CALCULATION FOR M30 CONCRETE USING STEEL

FIBRE







9.2 Test data

1. Cement used = OPC


3. Fibre used = steel fibre of diameter 0.1-0.5 mm



6. Water absorption of coarse aggregate = nil

7. Water absorption of fine aggregate = 1.0752%

8. From sieve analysis and IS 383-1970 grading zone II

9. Specific gravity of steel = 7.86

9.3 Calculation


f f t Sck ck

Where fck


fck




From IS 10262-1982,




= (30 + 1.65×5.0) N/mm2

=38.25 N/mm2






= 197.16 litre



Cement content = (197.16./0.45) = 438.13 kg/m3


438.13 kg/m3 > 320 kg/m3, hence ok














D. Volume of steel fibre (1%) = massof steel fibre


1

1000

= 4.3873

7.86×

1

1000

= 0.00055 m3

Therefore,


= [1-(0.141+0.197+0.00055)] m3

= 0.66 m3


= 1101.87 kg


= 654.456 kg

Therefore,


= 197.16: 438.13: 4.3873: 654.456: 1101.87

= 0.45: 1: 0.01: 1.49:

CHAPTER 10

RESULTS and ANALYSIS:

After the note down of all the results of the compressive strengths developed by the

various types of design mixes the following results were obtained:

TABLE 10.1: Compressive strength developed by normal mix:

Compressive strength

developed: M30 M40

After 7 days of casting 20 N/mm2 26 N/mm2 After 28 days of casting 29 N/mm2 38 N/mm2

TABLE 10.2: Compressive strength developed after adding admixture:


developed: M30 M40

After 7 days of casting 21 N/mm2 28 N/mm2 After 28 days of casting 33 42

TABLE 10.3: Compressive strength developed after adding jute fibre:


developed: M30 M40

After 7 days of casting 19 N/mm2 26 N/mm2 After 28 days of casting 29.8 N/mm2 41 N/mm2

TABLE 10.4: Compressive strength developed by adding steel fibre:


developed: M30

After 7 days of casting 27 N/mm2 After 28 days of casting 36 N/mm2

CHAPTER 11

CONCLUSION AND FUTURE SCOPE OF STUDY:

A complete study of such a vast topic in such a short duration of 4 months was to look for a

needle in a hay stack. Hence keeping in mind the priorities only a single design mix for each

category could be developed.

In the near future attempts will be taken to design various mixes of the same category

like:

M30, M40 as well as M50 concrete with addition of different types of admixture as well as

different percentage of the same admixture will be tested for the development of strength,

setting time etc.

Also, Different fibres with various proportions will tested and various other design mixes

possible will be tried out so as to make out a bigger picture of the concrete mix design scenario

and its economic possibilities and difficulties in the real world industry.

References

1) IS 10262-1982 (reaffirmed 1999) for nominal mix design.

2) IS 10262-2009 for design mix using admixture

3) IS 456-2000

4) IS 383-1970 for zoning and grading

5) IS 269-1976