Download - Concrete Mix Design Manual

(Fourth Revised Edition)

CONCRETE MIX

DESIGN

N.Pokharel

1

INTRODUCTION 1

AMERICAN CONCRETE INSTITUTE (ACI) METHOD 4

GENERAL 5

LIMITATION ACI METHOD 5

REQUIRED PARAMETERS OF INGREDIENTS 5

EQUIPMENT AND APPARATUS 6

DESIGN GUIDE LINE 7

SUMMARY OF DESIGN PROCEDURE 12

MIX DESIGN DATA SHEET 13

DESIGN STEPS 14

COMPRESSIVE STRENGTH TEST OF SAMPLE 17

GRAPHICAL DETERMINATION OF REQUIRED

W/C RATIO 18

HIGH STRENGTH MIX METHOD 19

GENERAL 20

FEATURE OF DESIGN 20

LIMITATION OF HIGH STRENGTH DESIGN 21

REQUIRED PARAMETERS OF INGREDIENTS 22

DESIGN PROCEDURE 23

EQUIPMENT AND APPARATUS 24

MIX DESIGN DATA SHEET 27

DESIGN STEPS 28

Contents

2

INTRODUCTION

1. American Concrete Institute (ACI)

2. High Strength Mix

Cement concrete is an artificial rock which can be made of required

size, shape, and strength for the structure in construction work. It is the

most widely used construction material and is very hard to find its

substitution . Technologists may select this construction material as their

requirement such as strength, permanance, durability, impermeability, fire-

resistance, abrasion resintance etc. Regarding these required properties of

concrete, it is very important to determine the proportion as well as quality

of its constituents. Determining process of selecting suitable ingredients,

its proportion, producing minimum strength and durability as economically

as possible is called mix design.

In Nepal, still we adopt the arbitrary proportional ratio method in

many organizations of HMG departments, municipalities, private buildings

and other small scaled projects. But most of the large scaled foreign aid

projects can not ignore the necessity of mix design of the concrete for

precise supervision. The arbitrary proportinal method may always not

govern the true proportion of ingredients and cause segregation, bleeding,

uneconomic and weaker or over strength. People are not conscious to hire

Basic concept of mix design prevails on the relationship between

two essential ingredients i.e. aggregates and paste. Paste is not termed as

solution of cement in water, but the suspension of cement particles. Hence

the degree of dilution of paste may affect workability and strength of the

concrete. The more dilute the paste, the greater the spacing between

cement particles and thus the weaker will be ultimate paste structure. It is

therefore helpful to consider more closely the structure of the paste. It is

important that as little paste as possible should be used and here lies the

importance of grading of aggregates. Excess of paste cause high cost,

greater shrinkage, greater susceptibility to percolation of water and

therefore attack by aggressive waters and weathering action. This is

achieved by minimising the voids by well gradation.

There are several methods of mix design to adopt, but here we

describe only two of them in detail which are more effective and viable in

the contest of Nepal. Most of the renowned projects and agencies of Nepal

have been adopting these two mix-design methods widely as per their

requisites of the concrete materials. These methods are -

3

1. Cement:

a) Portland cement, of possibly 53 grade

b) Specific gravity 3.15

2. Fine Aggregate

a) Required size and well-graded and washed.

b) Saturated surface dry condition (SSD)

c) Very less weathering, alluvial (glacier) blueish grey:

Specific gravity 2.65 to 2.67 Absorption 1.0%

d) Less weathering, alluvial deposit (perennial river), yellowish grey:


e) Less weathering, alluvial deposit (stream), pale yellow:


f) Washed crushed rock:


g) Fineness modulus (FM)

coarser 3.1, moderate 2.9, fine 2.6, very fine 2.3

3. coarse Aggregate

a) Required size and well-graded and washed.

b) Saturated surface dry condition (SSD)

c) Alluvial / glacier (fresh deposit):


d) Alluvial / common perennial river (fresh deposit):


e) Alluvial (loose conglomerate):


f) Washed crushed rock (stream),


a technician to conduct the supervision and rely on a head mason who will

be contractor of their private construction. In Terai region of Nepal, most of

these masons have tendency of using more sand with large size coarse

aggregate and less sand with small size aggregate which is absolutely

wrong approach . Due this reason, people find their construction defective

after all.

Regarding these common problems all over the country, it is highly

necessary to follow the technical way of construction wheather it's small or

huge construction. Possibly, it is needed to conduct the test of concrete

materials to obtain true design parameters. Otherwise adopt in design

these parameters for concrete materials, if conducting the test is not

possible. These parameters are here tabulated below according to practice

and records.

4

g) Compacted density (Kg/m3):

Aggregate

Sp.gr. 2.62 - 2.65 2.66 - 2.69

50 mm

16001600

17001750 1800

1650 1400

Crushed rock:

1650 1650

1550

From the above statement, a technical person can easily decide the

nearest true properties of concrete material according to its possession

regarding location, appearance etc. After conforming these data

tentatively, here we can proceed the mix design calculation as per our

requirements. It may give more accurate proportion and workability than

the arbitrary ratio gives. If little bit difference in volume or workability is

found, it may be adjusted very easily.

1850 1750

2.62 - 2.65 2.66 - 2.69 2.70 - 2.72

1450 1500

1700 1550

38 mm 1750

10 mm

20 mm

1450

1800 1600

Screened gravel

5

American Concrete Institute (ACI)

METHOD

6

GENERAL

F

F

F

LIMITATION ACI METHOD

F It is better to design a concrete mix only up to 35 MPa of plastic state.

F

F

REQUIRED PARAMETERS OF INGREDIENTS

A. CEMENT

1. Grade and type as ACI - classification

2. Specific Gravity

B. FINE AGGREGATE

1. Gradation (Sieve Analysis)

2. Fineness Modulus (FM i.e. 2.4 to 3.1preferable)

3. Specific Gravity (SSD Bulk)

4. Absorption

Type-I, non air-entraining (OPC) as per ASTM/C-150, Specific Gravity

of 3.15

Coarse aggregate:- Gradation as per ASTM/C-33, Specific Gravity of

2.68, Absorption of 0.5%.

Fine Aggregate :- Gradation as per ASTM/C-33, Specific Gravity of

2.64, Absorption of 0.7%, FM of 2.8

The American Concrete Institute (ACI) has recommended an efficient

procedure of concrete mix design considering more economical use of

locally avilable materials to produce desirable workability, durability and

strength. The ACI method is able to produce concretes from very stiff to

fluid state workability as it is required in different conditions.The design

tables incorporating the basic relationships between the parameters, are

useful in selecting optimum combinations of the ingredients of non air-

entrained or air-entrained concrete mixes. The following design criteria are

assumed in formulating the design tables:

Though the specific gravity of coarse aggregate is taken 2.68 in this

ACI manual but if it is different see footnote of table-4.

It is important to note that the mix design tables serve as a guide in

selecting proportions and suitable minor adjustments should be

effected in the field for any departures in quality of aggregates and

type of cement used.

Before starting to design a concrete mix, it is very much important to have

all informations about concrete ingredients i.e physical test reports. These

physical parameters may be obtained by own laboratory test or by the

manufacturer. Basicaly for the design mix, the following parameters should

be available in the time.

7

C. COARSE AGGREGATE


2. Dry Rodded Unit Weight


4. Absorption

D. WATER

1. Chemical content(free of salt and alkalies)

2. Turbidity (potable or clear)

EQUIPMENT AND APPARATUS

A. SLUMP TEST 2. Mixer or mixing pan

1. Slump cone 3. Triple beam balance (1 g.)

2. Base plate 4. Scoop

3. Tamping rod 5. Straight edge

4. Graduated scale 6. Tamping rod or

5. Straight edge 7. Vibrator plate

6. Mixer (1 cft.) or 8. Rubber mallet

7. Mixing pan with shovel 9. Weighing containers

8. Scoop 10. Thermometer

9. Triple beam balance (1 g.) C. STRENGTH TEST

10. Weighing containers 1. Compressive St. machine

B. SAMPLE PREPARATION 2. Triple beam balance (1 g.)

1. 6 nos. cylinder or cube mould 3. Rubber sheet

To perform a mix design, the following equipment or apparatuses must be

available in advance:

10

15

20

25

30

35

40

45

50

0.36 0.40 0.44 0.48 0.52 0.56 0.60 0.64 0.68 0.72 0.76 0.80

CY

LIN

DE

R S

TR

EN

GT

H IN

28

DA

YS

(MP

a)

WATER CEMENT RATIO

fig.- 1

RELATIONSHIP OF W/C RATIO TO STRENGTH

Non Air Entarined Mix

Air Entarined Mix

8

DESIGN GUIDE LINE

F

F

Percentage of

recommended average total air content.

F

3.5 3.08.0 7.0 6.0 5.0

112 to 56

56 to 28

4.5 4.0

Drop Table

Revolutions

160

170

175

185

180

190

135

-

150

160

155

165

165 160 145 140 135 120

80 - 100

150 - 180

180 175

190

205

200

215

20 - 50

Maximum Size of Coarse Aggregates (mm)

Air Entrained Concrete

20 25 40 50

0.3 0.2percentage amount of entrapped air in non air entrained concrete.

Approximate

145

160

170

200

210

180

195

205

80 - 100

155

170

180

125

140

-

175

240 230150 - 180

225 215

Table : 1 Approximate Mixing of Water (Kg/m3

of Concrete)

Requirements for Different Slumps and Maximum Size of Aggregates

Slump

(mm)

185

150

0.53 2 1.5 12.5

Non Air Entrained Concrete

10 12.5

205 200 185 16020 - 50

70

3 to 0

-

0.90

0.95

Compacting

Factor

-

0.70

0.75

0.85

Slump

25 - 50

75 - 100

150 - 175

Vebe

(Sec.)

32 to 18

18 to 10

10 to 5

5 to 3

Plastic

Flowing

(mm)

0 - 25

-

-

Extremely dry

Very stiff

Stiff

Stiff plastic

Firstly, to know the water cement ratio of concrete mix, find out it by

coinciding the required designed strength (i.e. minimum required

strength plus strength for safety factor as specified or assumed) to the

appropriate graph line mentioned in figure -1 above.

To know the quantity of water for 1 m3

of fresh concrete made in

screened river gravel, find out that required quantity with regarding the

desirable workability (slump) mentioned in table -1 below. This table

does not entertain crushed aggregate.

The way of inspection and testing of consistency or workability of

concrete may differ as the specification quotes in different projects, so

compare the following consistency as it requires.

28 to 14

14 to 7

7

-

Table : 2 Comparison of Consistency Measurements by Various Methods

Consistency

Description

9

F

0.53 #

Exposure Condition *

The exposure condition of structure may be affected by the climatic

condition, chemicals in contact (such as sulphate, salt, water etc) or

air. It means that durability of concrete should be considered as its

exposure condition that governs the strength of concrete (required w/c

ratio will be selected from the table-3 below).

Table : 3 Maximum Permissible Water Cement Ratios for Different Types

of Structures and Degrees of Exposure

Type of structuresAt the water line or with in

the range of fluctuating

water level or spray

Severe wide range in

temperature, or frequent

alternations of freezing and

thawing (air entrained concrete

only)

In

air

At the water line or with in

the range of fluctuating

water level or spray

In fresh

water

In sea water or

in contact with

sulphates1

Mild temperature rarely below

freezing, or rainy, or aid.

In sea water or

in contact with

sulphates1

In fresh

water

In

air

1 Soil or ground water containing sulphate concentrations of more than 3.2%.

**When sulphate resisting cement (as per ACI type-V) is used, maximum water/cement ratio may be increased

by 0.13 litres per bag.

# Water/cement ratio should be selected on basis of strength workability requirements.

0.39

Concrete which will later be protected by

enclosure or backfill what which may be

exposed to freezing and thawing for

several years before such protection is

offered. 0.53 - - # - -

# - #

*Air entrained concrete concrete should be used under all conditions involving severe exposure and may be

used under mild exposure conditions to improve workability of the mixture.

Concrete protected from weather,

interiors of buildings, concrete below

ground. - - -

0.44

Concrete slabs laid on the ground. -- - -

Concrete deposited by tremie under

water - 0.44 0.44

0.44**Exterior portions of heavy (mass)

sections. 0.57 0.48 0.44 # 0.53 0.44**

- 0.44

0.53 0.48

# 0.53

0.390.44

Thin sections, such as railings, curbs,

sills, ledges, ornamental or architectural

concrete, reinforced piles, pipes and all

sections with less than 25 mm. Concrete

cover reinforcing.Moderate sections, such as retaining

walls, abutments, piers, girders, beams. 0.53 0.48 0.44**

0.48

10

F

Where,

VA = apparent vol. of solid particles per unit volume of concrete

g1 = used specific gravityVD = Vol. of dry rodded agg. per unit volume of concrete

F

for example:

VC = f x VA = 1.15 x 0.62 = 0.71

Where,

VC = corrected vol. of aggregate in per unit vol. of stiff concrete

f = multiplying factor from table-5 (next page)

VA = apparent vol. of solid particles per unit volume of concrete from table-4

0.65 0.63

0.6620 0.60 0.58

0.5912.5 0.53 0.51

0.5010 0.44 0.42

Table : 4 Volume of Dry Rodded Coarse Aggregates per Unit

Volume of Concrete (V D ) only for Plastic Consistency

Maximum Size of

Coarse Aggregate 2.60 3.00 3.202.802.40

Fineness Modulus (FM) of Sand

Find out the volume of aggregate for per unit volume of concrete with

respect to the fineness modulus of sand and nominal maximum size of

aggregate. The value not given in following table will be determined by

interpolation of given value which are only for the particular aggregate

with specific gravity of 2.68. If our specific gravity is different then, see

the note of table 4.

0.70 0.68

50 0.76 0.72 0.70

0.74 0.72

0.74

40

To determine the exact volume of coarse aggregate in per unit volume

of concrete in non-plastic consistency (i.e. in stiff condition), select the

appropriate multiplying factor (f) listed below to the volume mentioned

in table-4. For example, see note# of table-5 in next page.

0.77

0.83

Note: The volume of dry rodded coarse aggregate recommended in above table, applies to the aggregate of the

given specific gravity g which in this case is 2.68. If the aggregate used has a specific gravity g 1 , the volume of

coarse aggregates specified in the table should be multiplied by the ratio (g 1 /g ) to account for gross apparent

volume (VA) of solid particles. i.e. V A = g 1 /2.68xV D

0.75 0.73

150 0.85

0.71

0.76

0.78

0.81 0.7970

25

0.46

0.55

0.62

0.67

0.48

0.57

0.64

0.69

0.81 0.790.87

If it is to prepare a concrete mix with a slump (0 - 25 mm) and 20 mm aggregate in a

sand with FM 2.8 then the corrected volume of coarse aggregate per unit volume of

11

F

10 12 20 25 40

177 168 158 148 137

188 182 168 158 148

196 192 177 168 158

206 196 182 177 162

226 217 203 192 177

240 226 212 203 188

3.0 2.5 2.0 1.5 1.0

158 148 137 133 123

168 158 148 137 133

177 168 158 148 137

182 177 162 152 143

203 192 177 168 158

212 203 188 177 168

8.0 7.0 6.0 5.0 4.5

Percentage of approximate amount of entrapped air in non-air - entrained concrete,

Air-Entrained Concrete

78

83

88

106

0.91

0.95

Stiff plastic 92

Plastic

Flowing

75 - 100

150 - 175

100

-

0.70

0.75

0.85

Non - Air-Entrained Concrete

Workability

-

112 - 56

56 - 28

28 - 14

14 - 7

7

-

18 to 10

10 to 5

5 to 3

3 to 0

Factors for Maximum Size of Coarse Aggregate (mm)

1.09

1

11

12.5

1.7

Water, Kg. Per m3 for

indicated maximum size

of C. A. (mm)

Relative

Water

content

(%)

1.06

1

1

40

1.3

1.25

1.21.15

25

1.4

1.25

1.15

Consistence

1

1.45

1.3

10

1.9

1.6

1.35

20

1.45

1.3

1.08 1.06

Drop

Table Revolutions

Compacting

Factor

Fluid

1

0.97

Plastic (Reference)

0.98

1.04

Table : 6 Approximate Mixing of Water (Kg/m3 of Concrete) Required for

Different Consistencies and Maximum Size of Aggregates *

Stiff

Very stiff

Extremely dry

Extremely dry

1

-

Slump

(mm)

Vebe,

(sec.)

Stiff plastic

-

0 - 25

25 - 50

Very Stiff

Stiff

Table:5 Factor ( f ) to Applied to the Volume of Coarse Aggregate

Calculated on the Basis of Table:4, for Mixes of Consistence Other than

Plastic

32 to 18

To know the quantity of water for 1 m3

of fresh concrete made in

crushed aggregate, find out that required quantity with regarding the

desirable workability (slump) mentioned in table -6 below. This table

does not entertain the aggregate produced by screened river gravel.

Extremely dry - 32 to 18 112 - 56 - 78

Stiff 0 - 25 10 to 5 28 - 14

Very Stiff - 18 to 10 56 - 28 0.70 83

0.75 88

0.85 92

0.91 100

Stiff plastic 25 - 50

Plastic 75 - 100 3 to 0 7

5 to 3 14 - 7

0.95 106Recommended average total air content, percent (%)

Flowing 150 - 175 - -

* These quantities of mixing water are use in computing factors for trial batches. They are for reasonably well-

shaped angular coarse aggregates graded within limits of accepted specifications. If more water is required

than shown, the cement factor, estimated from these quantities, should be increased to maintain desired water-

cement ratio, except as otherwise indicated by laboratory tests for strength.

12

F

Table : 7 Zone of Limit of Concrete Aggregate as adpoted by ACI

(ASTM:C-33)

The aggregates to be used in concrete mix should fall with in the zone

of limit envelope for each NMSA mentioned below.

4.75~25 9.5~25

95 ~ 100

37.5~90

0~5 2.36~9.5 4.75~12.5 4.75~19 9.5~19

0 ~ 5

4.75~50 25~50 37.5~63

0.15

2.36

1.18

0.6

0.3

0.6

0.3

0.15

100

Sieve

Size (mm)

9.5

4.75

0 ~ 5

9.5

4.75

2.36

1.18

2 ~ 10

100

90 ~ 100

40 ~ 85

10 ~ 40

0 ~ 15

Sieve

Size (mm)

100

90

75

63

50

37.5

25

19

12.5

12.5~25 4.75~37.5

80 ~ 100

50 ~ 85

25 ~ 60

10 ~ 30

100

100

90 ~ 100

40 ~ 70

100

85 ~ 100

10 ~ 30

0 ~ 10

0 ~ 5

0 ~ 15 0 ~ 10

0 ~ 5

20 ~ 55

100

90 ~ 100

20 ~ 55

100

90 ~ 100

100

0 ~ 15

0 ~ 5

100

95 ~ 100

25 ~ 60

0 ~ 10

0 ~ 5

0 ~ 5

90 ~ 100

20 ~ 55

0 ~ 10

95 ~ 100

35 ~ 70

0 ~ 5

90

75

19~37.5

63

50

37.5

25

19

12.5

10 ~ 30

0 ~ 5

100

0 ~ 5

0 ~ 15

100

90 ~ 100

20 ~ 55

100

95 ~ 100

100

90 ~ 100

35 ~ 70

0 ~ 15

0 ~ 510 ~ 30

35 ~ 70

0 ~ 15

0 ~ 5

100

90 ~ 100

25 ~ 60

100

90 ~ 100

0 ~ 5

0 ~ 15

35 ~ 70

13

F

FM = 284.40 /100 = 2.84

SUMMARY OF DESIGN PROCEDURE

F

F

F

F

F

F

F

F

F

F

F

% of Retained

Now prepare three sample after varying W/C ratio with 5% more & 5%

less but keeping the quantity of water same in two of them.

Test these three sample in specified time and plot graph strength vs

W/C ratio. Here it is determined the actual W/C ratio required for min.

design strength graphically.

% of

Passing

Similarly, multiplying the dry rodded density to volume required as per

table-4, find out the quantity of coarse aggregate required.

Determine the min. design strength including safety factor for site.

25 to 60

10 to 30

2 to 10

Find the fineness modulus (FM) of sand from the sieve analysis report

prepared in laboratory same as demonstrated in table-7 below.

Now calucate the absolute volume of concrete by using the respective

specific gravity of materials excluding sand.

Find out the W/C ratio as per strength consideration using fig.-1 or as

per durability in exposer consideration table-3, whichever is lower.

Determine the quantity of water required and percentage of air

entraining using table-1 or table-6 as the coarse aggregate is used.

Find out the volume of coarse aggregate using table-4 and table-5,

with respect to FM value as well as specific gravity of sand.Thus find out the quantity of cement having value of W/C ratio and

water required for 1 m3 of concrete.

50 to 85

6.414.2

Table : 8 Example , Determination of Fineness Modulus of Fine Aggregate

(Sand) from Sieve Analysis Report

ACI Specification

Limit (ASTM:C-

33)

95 to 100

80 to 100

% cum.

Retained

0.0

8.5

Mass of

Retained

(gms)

0.0

60.0

-

100.0

91.5

63.1

20.6

2.8

-

97.2

100.0

42.6

3.5

2.820.0

200.0

300.0

100.0

25.0

36.9

0.0

8.5

28.4

79.4

93.6

No # 8 2.36

No # 16

No # 30 0.60

No # 50 0.30

Sieve Size

BS mm

No # 100 0.15

Pan

1.18

No # 4 4.75

TOTAL 705 284.4

Collect the all the properties of concrete materials by conducting

necessary tests.

Then subtracting that absolute volume in 1 m3

volume, the remaining

value will be determined as the volume of sand which is converted in

weight by using the specific gravity of sand.

14

Mix Design Data Sheet

TRIAL MIX TM-….… A

Project A1

Location A2

Structure A3

Member A4

Concrete Class A5

Type and Brand of Cement A6

Source of Fine Aggregate A7

Type of Coarse Aggregate A8

Source of Coarse Aggregate A9

Specific Gravity of Cement A10

Specific Gravity of Fine Aggregate A11

Fineness Modulus (FM) of F.A. (as determined in table-7) A12

Nominal Max. Size of Coarse Aggregate (mm) A13

Specific Gravity of Coarse Aggregate A14

Rodded Unit Weight of Coarse Aggregate (Kg/m3) A15

Minimum Cylinder Strength Required # (MPa) A16

Percentage of Safety Factor Specified (%) A17

Net Design Cylinder Strength (MPa) A18

Water Cement Ratio (wc1) - [whichever is lower below] A20

Strength Consideration (fig.-1) or Durability Consideration (table-2 )

Desirable Workability (Slump) (mm) A21

*Required Weight of Water (table-1or 6) (Kg/m3) A22

*Entrained Air in Concrete (table-1 or 6) (%) A23

(* If the coarse aggregate is crushed rock i.e angular shape, use table-6)

Volume of Coarse Aggregate Required (table-4) A24

TRIAL MIX TM-….… B

Water Cement Ratio (wc2) - [10% more than specified] A25

TRIAL MIX TM-….… C

Water Cement Ratio (wc3) - [10% lesser than specified] A26

A16 + (A17/100)xA16

( # If cube strength is required, select 80% of cylinder strength above i.e Cube Strenght = 1.2 x Cyl. Strength )

A20 + 0.10 x A20

A20 - 0.10 x A20

15

Design Steps


Weight of water Required (Kg/m3) B1

Weight of Coarse Aggregate Required (Kg/m3) B2

Weight of Cement Required (Kg/m3) B3

Solid Volume of Cement in Concrete (cc) B4

Solid Volume of Water in Concrete (cc) B5

Solid Volume of Coarse Aggregate in Concrete (cc) B6

Volume of Entrained Air in Concrete (cc) B7

Total Volume of Ingredients (except F. Agg.) (cc) B8

Required Volume of Fine Aggregate in Concrete (cc) B9

Weight of Fine Aggregate Required (Kg/m3) B10

ESTIMATED BATCH QUANTITY

Cement (Kg)

Water (Kg)

Fine Aggregate (Kg)

Coarse Aggregate (Kg)

Density of Fresh Concrete (Kg/m3)

0.007 x B1

For 1 m3

VolumeIngredients

NOTE: Here, check the slump of this TRIAL-A. If the desirable slump range is not obtained,

recalculate by increasing or decreasing the weight of water by 5% again and again until the slump is

maintained but keeping the W/C ratio same. After maintaining the desirable slump, prepare six nos. of

sample (cylinder or else) for strength test and then proceed to TRIAL -B.

0.04 x B2B2

0.04 x B10B10

B3+B1+B10+B2

0.007 x B2

0.007 x B10

40 Litres for Lab.

Sample

B1

7 Litres for Slump

Test 0.007 x B3

0.04 x B1

0.04 x B3B3

B3 x 1000 / A10

A23 /100 x 1000000

B4+ B5+ B6+ B7

1000000 - B8

B9 x A11 /1000

B2 x 1000 / A14

A24 x A15

A22

B1 / A20

B1 x 1000

16

Design Steps


Weight of water Required (Kg/m3) C1

Weight of Coarse Aggregate Required (Kg/m3) C2

Weight of Cement Required (Kg/m3) C3

Solid Volume of Cement in Concrete (cc) C4

Solid Volume of Water in Concrete (cc) C5

Solid Volume of Coarse Aggregate in Concrete (cc) C6

Volume of Entrained Air in Concrete (cc) C7

Total Volume of Ingredients (except F. Agg.) (cc) C8

Required Volume of Fine Aggregate in Concrete (cc) C9

Weight of Fine Aggregate Required (Kg/m3) C10


Cement (Kg)

Water (Kg)

Fine Aggregate (Kg)



Note: Prepare minimum 6 nos. of samples (cube or cylinder). 3 nos for 7 days and 3 nos. for 28 days.

C1 / A25

C3 x 1000 / A10

A23 /100 x 1000000

C9 x A11 /1000

0.04 x C1

A22

IngredientsFor 1 m

3

Volume

7 Litres for Slump

Test

40 Litres for Lab.

Sample

C3 0.007 x C3 0.04 x C3

C4+ C5+ C6+ C7

1000000 - C8

C1 x 1000

C2 x 1000 / A14

A24 x A15

C10 0.007 x C10 0.04 x C10

C1 0.007 x C1

C3+C1+C10+C2

C2 0.007 x C2 0.04 x C2

17

Design Steps


Weight of water Required (Kg/m3) D1

Weight of Coarse Aggregate Required (Kg/m3) D2

Weight of Cement Required (Kg/m3) D3

Solid Volume of Cement in Concrete (cc) D4

Solid Volume of Water in Concrete (cc) D5

Solid Volume of Coarse Aggregate in Concrete (cc) D6

Volume of Entrained Air in Concrete (cc) D7

Total Volume of Ingredients (except F. Agg.) (cc) D8

Required Volume of Fine Aggregate in Concrete (cc) D9

Weight of Fine Aggregate Required (Kg/m3) D10


Cement (Kg)

Water (Kg)

Fine Aggregate (Kg)



Note: Prepare minimum 6 nos. of samples (cube or cylinder). 3 nos for 7 days and 3 nos. for 28 days.

D2 0.007 x D2 0.04 x D2

D4+ D5+ D6+ D7

1000000 - D8

D9 x A11 /1000

IngredientsFor 1 m

3

Volume

7 Litres for Slump

Test

D3+D1+D10+D2

D10 0.007 x D10 0.04 x D10

D1 0.007 x D1 0.04 x D1

40 Litres for Lab.

Sample

A22

A24 x A15

D1 / A26

D3 x 1000 / A10

D1 x 1000

D2 x 1000 / A14

A23 /100 x 1000000

D3 0.007 x D3 0.04 x D3

18

Compressive Strength Test of Sample


"

"

"

"

"


"

"

"

"

"


"

"

"

"

" " s6 = p6 / a

W/C

Rat

io

Compressive

Load (N)

p1

p2

p3

p4

p5

p6

X28=(S1+S2+S3)/35 28 " s5 = p5 / a

6 28

4 28 " s4 = p4 / a

3 7 "

Age of

Sample

(day) W/C

Rat

io

Compressive

Load (N)

s3 = p3 / a

Sectional

Area

(mm2)

Compressive

Strength (Mpa)

28 p6

s4 = p4 / a

s2 = p2 / a

7 "

7

Age of

Sample

(day)

p4

p5

Sectional

Area

(mm2)

p2 "

" s6 = p6 / a

1 7

6

Remarks

1 7 a s1 = p1 / a

X7=(S1+S2+S3)/32

Sample

No.

s2 = p2 / a

X28=(S1+S2+S3)/3

4 28 "

Average

Strength (Mpa)

5 28 " s5 = p5 / a

p3

Average

Strength (Mpa)Remarks

X7=(S1+S2+S3)/3

3 7 " s3 = p3 / a

Sample

No.

" s6 = p6 / ap6

X28=(S1+S2+S3)/3

2

Compressive

Strength (Mpa)

p1 a s1 = p1 / a

p4 " s4 = p4 / a

p3

" s5 = p5 / ap5

2

Sample

No.

Age of

Sample

(day) W/C

Rat

io

Compressive

Load (N)

7 p1

7 p2

Remarks

"

1

X7=(S1+S2+S3)/3

Sectional

Area

(mm2)

Compressive

Strength (Mpa)

" s3 = p3 / a

a

5

6

7

28

28

28

3

4

s1 = p1 / a

Average

Strength (Mpa)

s2 = p2 / a

19

Graphical Determination of Required W/C Ratio

Summary of Designed Mix




TRIAL MIX TM-11, B

TRIAL MIX TM-11, A

TRIAL MIX TM-11, C

Mix Design W/C Ratio7 Days Strength

(Mpa)

28 Days Strength

(Mpa)

as per design

Remarks

W/C2 w/c=5% more

W/C Ratio7 Days Strength

(Mpa)

28 Days Strength

(Mpa)

W/C1

18 25 w/c=5% more

Remarks

Example: A tipical required value of W/C ratio (as shown in fig.-2) for

minimum design strength is determined by the observed data as

demontrated below.

W/C3 w/c=5% less

Mix Design

0.52 21 30 as per design

0.48 27 39 w/c=5% less

0.56

10

15

20

25

30

35

40

45

50

0.560.520.48

Com

pre

ssiv

e S

tre

ngth

(M

Pa)

W/C Ratio Fig.- 2

Determination of Actual W/C Ratio

Design Strength

Req

uire

d W

/C R

atio

Example: For Design Str. = 32 Mpa Requires W/C Ratio = 0.51

20

High Strength Mix METHOD

21

GENERAL

FEATURE DESIGN

F

F

F

In general, only a natural sand is needed for use of fine aggregate

because high strength are rarely obtained with crushed rock fine

aggregate.

Crushed aggregate (possibly granite) is more preferred than that use

of irregular gravel coarse aggregate for strength assurance.

Low workability is introduced instead of high degree of workability.

This high strength concrete mix design has been developed by B. W.

Shacklock and H. C. Erntroy in 1954. For designing concrete mix of low

and medium grade compressive strength i.e. up to 35 MPa, it is assumed

the strength of fully compacted concrete at a required age to be dependent

only on the w/c ratio of the mix. However, compressive strength of high-

strength mix above 35 MPa is mainly influenced by the properties of

aggregates in addition to that of w/c ratio. The methods of mix design used

for medium grade concrete cannot therefore, govern to lead to an accurate

estimate of the required mix proportions for high strength concrete under

all circumstances.

The methods of high strength design-mix has been developed on the basis

of these following features:

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70

CO

MP

RE

SS

IVE

ST

RE

NG

TH

(M

Pa)

REFERENCE NUMBER

Fig.1

IRREGULAR GRAVEL COARSE AGGREGATE WITH NATURAL SAND AND ORDINARY PORTLAND CEMENT

22

F

F

LIMITATION OF HIGH STRENGTH DESIGN

F

F

F Graphical tables are used instead of analytical formulas or so on.

F

Combined grading of total aggregates may be assumed to be constant

with 30% passing in No. #4 sieve (4.75 mm size sieve).

No concrete of plastic consistency is suggested to design but only stiff

mix is preferred to get high strength.

Nominal maximum size of aggregate(NMSA) is taken only up to 20

mm. Maximum.

These graphs used (to find out the Reference Number) in this method

are obtained from the aggregates containing 30% of material passing

through the 4.75 mm sieve. If other grading are used, suitable

adjustment have to be made as shown in fig. - 7.

An arbitrary reference number is determined from a graph connecting

average design strength and reference number which is needed to

know the required water cement ratio (w/c) for the particular strength.

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70

CO

MP

RE

SS

IVE

ST

RE

NG

TH

(M

Pa)

REFERENCE NUMBER

Fig. 2

CRUSHED GRANITE COARSE AGGREGATE WITH NATURAL SAND AND ORDINARY PORTLAND CEMENT

23

REQUIRED PARAMETERS OF INGREDIENTS

A. CEMENT

1. Grade and type

2. Specific Gravity

B. FINE AGGREGATE



3. Absorption

C. COARSE AGGREGATE



3. Absorption

As usual for designing a concrete mix, it is very much important to be

known all information about concrete ingredients i.e. physical test reports.

These physical parameters may be obtained by own laboratory - test or by

the manufacturer. Basically for the high strength design mix, the following

parameters should be available in the time.

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70

CO

MP

RE

SS

IVE

ST

RE

NG

TH

(M

Pa)

REFERENCE NUMBER

Fig. 3

IRREGULAR GRAVEL COARSE AGGREGATE WITH NATURAL SAND AND RAPID HARDENING PORTLAND CEMENT

24

D. WATER

1. Chemical content(free of salt and alkalis)

2. Turbidity (potable or clear)

DESIGN PROCEDURE

F

F

F

F

F

Find out the arbitrary reference number according to necessity and

availability of concrete materials using fig. 1, 2, 3, 4.

Determine the water/cement ratio (w/c) in terms of reference number

using fig. 5, 6.

Knowing the type of aggregate, size of aggregate, degree of workability

and water cement ratio (w/c), find the aggregate/cement ratio using

table- 1 or table- 2.

Plot the gradation (percentage passing) of available materials i.e. fine

aggregate and coarse aggregate as shown in fig. 7 and then determine

the required fine aggregate/total aggregate ratio connecting with 30%

passing line.

Estimate the average design strength using standard deviation or as it

is specified for the special job.

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70

CO

MP

RE

SS

IVE

ST

RE

NG

TH

(M

Pa

)

REFERENCE NUMBER

Fig. 4

CRUSHED GRANITE COARSE AGGREGATE WITH NATURAL SAND AND RAPID HARDENING PORTLAND CEMENT

25

EQUIPMENT AND APPARATUS

For preparing the sample following euipments are needed:

1. 6 nos. Cylinder or Cube Mould 4. Scoop 7. Rubber Mallet

2. Mixer or Mixing Pan 5. Straight Edge 8. Tamping Rod or Vibrator

3. Triple Beam Balance (1 g.) 6.Thermometer 9. Weighing Containers

To find out the strength of specimens following equipment are needed :

1. Compressive Strength Machine

2. Triple Beam Balance (1 g.)

3. Rubber Sheet (Filler)

To perform a mix design, no special equipment or apparatus is required

more than it requires for normal mix design except a special vibrating

machine is needed to compact the stiff concrete-sample. For the stiff

concrete no hand-mixing is suggested to come true reporting results and

hence is always preferred laboratory mixer to mix vigorously.

0.30

0.32

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0.48

0.50

0 10 20 30 40 50 60 70

WA

TE

R/C

EM

EN

T R

AT

IO

REFERENCE NUMBER

Fig. 5

20 mm. AGGREGATE Degree of Workability

26

3.0 2.4 3.3 2.9

3.8 2.5 3.2 4.0 2.6 3.6 2.3

4.5 3.0 2.5 3.9 2.6 4.6 3.2 2.6 4.2 2.8 2.3

5.2 3.5 3.0 2.5 4.6 3.1 2.6 5.2 3.6 3.1 2.6 4.7 3.2 2.7 2.3

4.0 3.4 2.9 5.2 3.5 3.0 2.5 4.1 3.5 2.9 5.2 3.6 3.0 2.6

4.4 3.8 3.2 3.9 3.3 2.7 4.5 3.8 3.2 4.0 3.3 2.9

4.9 4.1 3.5 4.3 3.6 3.0 4.9 4.2 3.5 4.4 3.6 3.1

5.3 4.5 3.8 4.7 3.9 3.3 5.3 4.5 3.7 4.8 3.9 3.3

4.8 4.1 5.1 4.2 3.6 4.8 4.0 5.1 4.2 3.6

5.2 4.4 5.4 4.5 3.8 5.1 4.2 5.5 4.5 3.8

5.5 4.7 4.8 4.0 5.4 4.5 4.7 4.0

* Natural sand used in combination with both types of coarse aggregates.

+ EL = Extremely Low VL = Very Low L = Low M = Medium

0.46

0.48

Wat

er C

emen

t Rat

io (

by w

eigh

t)

0.34

0.36

0.50

Crushed GraniteIrregular Gravel

Degree of

Workability +

Type & Size

of C. A. *

EL VL L EL VL L M

20 mm Size 10 mm Size 20 mm Size

M EL VL

10 mm Size

L ML MEL VL

0.44

0.38

0.40

0.42

0.30

Table- 1: Aggregate / cement ratio (by weight) required to give four

degrees of workability with different water cement ratios using Ordinary

Portland cement

0.32

0.30

0.32

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0.48

0.50

10 20 30 40 50 60 70

WA

TE

R/C

EM

EN

T R

AT

IO

REFERENCE NUMBER

Fig. 6

10 mm. AGGREGATE Degree of Workability

27

2.6 2.9 2.5

3.4 2.2 2.8 3.6 2.4 3.2

4.1 2.7 2.3 3.5 2.4 4.3 2.9 2.4 3.9 2.5

4.8 3.2 2.8 2.3 4.2 2.9 2.4 4.9 3.4 2.9 2.4 4.5 3.0 2.5

5.5 3.7 3.2 2.7 4.9 3.3 2.8 2.3 5.5 3.9 3.3 2.7 5.0 3.4 2.9 2.4

4.2 3.6 3.0 3.7 3.0 2.6 4.2 3.6 3.0 5.5 3.8 3.2 2.7

4.6 4.0 3.4 4.1 3.5 2.9 4.7 4.0 3.3 4.2 3.5 3.0

5.0 4.3 3.7 4.5 3.8 3.2 5.1 4.3 3.6 4.6 3.8 3.2

5.5 4.7 4.0 4.9 4.1 3.5 5.5 4.6 3.9 5.0 4.1 3.4

5.0 4.3 5.2 4.4 3.7 4.9 4.1 5.3 4.4 3.7

* Natural sand used in combination with both types of coarse aggregates.

+ EL = Extremely Low VL = Very Low L = Low M = Medium

0.36

LEL VL L M M ELEL

Type & Size

of C. A. *Irregular Gravel Crushed Granite

20 mm Size 10 mm Size 20 mm Size 10 mm Size

M

Table- 2: Aggregate / cement ratio (by weight) required to give four

degrees of workability with different water cement ratios using Rapid

Hardening Portland cement

Degree of

Workability +EL VL L VL LM VL

Wat

er C

emen

t Rat

io (

by w

eigh

t)

0.46

0.48

0.50

0.38

0.40

0.42

0.44

0.32

0.34

Line of 30% Passing

Required R

atio

= 2

4%

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Pe

rce

nta

ge

Pa

ss

ing

of

C. A

.

10 mm 4.75 mm

2.36 mm

1.18 mm

0.60 mm

0.30 mm

0.15 mm

Pe

rce

nta

ge

Pa

ss

ing

of F

. A.

10 mm

20 mm

4.75 mm

2.36 mm

28

Mix Design Data Sheet

TRIAL MIX: TM - …. A

Project A0

Location A1

Structure A2

Member A3

Concrete Class A4

Type and Brand of Cement A5

Source of Fine Aggregate A6

Type of Coarse Aggregate A7

Source of Coarse Aggregate A8

Specific Gravity of Cement A9

Specific Gravity of Fine Aggregate A10

Specific Gravity of Coarse Aggregate A11

Nominal Max. Size of Coarse Aggregate (mm) A12

Minimum Cylinder Strength Required # (MPa) A13

(# If cube strength is required, select 80% of cylinder strength above)

Additional Strength for Safety Factor (MPa) A14

Average Design Cylinder Strength (MPa) A15

Arbitrary Reference Number (from fig. 1, 2, 3 or 4) A16

Degree of Workability (as required) A17

Water Cement Ratio (from fig. 5 or 6) A18

Total Aggregate to Cement Ratio (from table 1 or 2) A19

% of Fine Aggregate to Total Aggregate (from fig. 7) A20

A13+A14

29

Design Steps

TRIAL MIX: TM - A

A : Mix Proportion by Weight (with reference to cement)

1 Cement B1

2 Water B2

3 Fine Aggregate B3

4 Coarse Aggregate B4

B : Absolute Volume (for 1 m3)

1 Cement B5

2 Water B6

3 Fine Aggregate B7

4 Coarse Aggregate B8

B9

\ Required Weight of -

Cement B10

Water B11

Fine Aggregate B12

Coarse Aggregate B13

C : Batching for

CEMENT

WATER

FINE AGGREGATE

COARSE AGGREGATE

Materials Unit 1 m3 Volume

* Lab.Sample

for 40 Lit. Vol.

A18

A20/(100x A19)

{1-(A20/100)}x A19

B1/A9

B4/A11

* Note : Estimated quantity 40 liters is for 6 nos. of cylindrical moulds

(size dia. 15 cm & ht. 30 cm.). If it is to prepare 6 nos. of 15x15x15 cm.

cubical moulds, take 25 liters volume for laboratory sample.

0.04xB12

0.04xB13

B12

B13Kg

Kg

1000/B9

B3xB10

A18

B2xB10

B5+B6+B7+B8

B3/A10

1

B4xB10

Density of Fresh Concrete (Kg/m3) B10+B11+B12+B13

B10

B11

0.04xB10

0.04xB11

Kg

Kg

30