spin practical aspects in concrete mix design

7/24/2019 Spin Practical Aspects in Concrete Mix Design

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PRACTICAL ASPECTS IN

CONCRETE MIX DESIGN

Prof. Dubravka Bjegovi, Ph.D.C.E.University of Zagreb, Faculty of Civil Enginering, Department for

Materials

Institut IGH, d.d., Zagreb, Croatia

Assis.prof. Irina Stipanovi Oslakovi, Ph.D.C.E.Institut IGH d.d., Zagreb, Croatia

University of Twente, Faculty of Engineering and Technology,

Construction Management and Engineering Department, Netherlands


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CONCRETE IN EUROPE

Yearly production of concrete in Europe - 750millions m3 (around 4 tonnes per EU citizen)

In the European Union (EU27 countries), totalcement production in 2007 is estimated at 283

million tonnes, representing 10.5% of worldproduction.

Cement production in the EU is dominated bySpain, at over 19% of the EU total, followed by Italy

and Germany.

Natural resources consumation - 9 billion tonnes ofsand and rock and 0.9 billion tonnes of mixing waterannually


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Concrete construction

Concrete construction is

becoming increasingly

complex and the importance

of producing structures thatmeet required performances

or that satisfies their

strength, that are costeffective and durable has

never been higher.


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Concrete mix design

The process of selecting suitable

ingredients of concrete and determining

their relative amounts with the objective ofproducing a concrete of the required,

strength, durability, and workability as

economically as possible, is termed the

concrete mix design.


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CONCRETE building product produced

from:

concrete

con= 2.4 t/m3

cement c= 3 t/m3

aggregate a= 2.65 t/m3

water w= 1 t/m3

chemical and/or mineral

addmixtures
http://upload.wikimedia.org/wikipedia/commons/f/fc/Water_droplet_blue_bg05.jpg


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Concrete mix design

The various factors affecting the mix design

are:

Compressive strength

Workability

Durability

Cost


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It is one of the most importantproperties of concrete and

influences many otherdescribable properties of thehardened concrete.

The mean compressive strengthrequired at a specific age, usually28 days.


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Two states of concrete

The proportioning of ingredient ofconcrete is governed by therequired performance of concretein 2 states:

the plastic and the hardened states.

If the plastic concrete is not

workable, it cannot be properlyplaced and compacted. Theproperty of workability, therefore,becomes of vital importance.


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Workability

The degree of workability required depends on three

factors: the size of the section to be concreted,

the amount of reinforcement, and

the method of compaction to be used.

The desired workability depends on the compactingequipment available at the site.


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Workability

For the narrow and complicated section with

numerous corners or inaccessible parts, the concrete

must have a high workability so that full compaction

can be achieved with a reasonable amount of effort.

This also applies to the embedded steel sections.


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Concrete durability

Concrete durability is one of the most

important considerations in the design

of new structures and when assessing

the condition of existing structures.

Concrete durability: its resistance to

weathering action, chemical attack,

abrasion and other degradation

processes.


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Concrete durability

Different concretes require different degrees

of durability depending on the exposure

environment and the properties desired.


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Concrete durability

Durability of concrete can be addressed by

two approaches:

the prescriptive approach,

the performance based approach.


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Concrete durability

Prescriptive approach

In the prescriptive approach, designers

specify materials, proportions, and

construction methods based on fundamentalprinciples and practices that exhibit

satisfactory performance.


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Concrete durability

Performance based approach

In the performance based approach,

designers identify functional requirements

such as strength, durability, and volumechanges, and rely on concrete producers and

contractors to develop concrete mixtures to

meet those requirements.


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Concrete durability

High strength concrete is generally more

durable than low strength concrete.

In the situations when the high strength is not

necessary but the conditions of exposure are

such that high durability is vital, the durability

requirement will be determined by concrete

penetrability (absorption, diffusion,permeability).

C1

> C2

C1

C2

P

H2O


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Performance specifications

Performance specifications define

performance for a given exposure and life

expectancy, and include tests, which are tied

not only in the laboratory but also to the fieldperformance of concrete.


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Cost of concrete

The cost of

concrete is made

up of the cost of

materials, plant

and labour.


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Concrete service life

Concrete ingredients, their proportioning,

interactions between them, placing and curing

practices, and the service environment

determine the ultimate durability and servicelife of the concrete.


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Variables in the concrete mix

proportioning -1

The actual cement strength is not necessarily the

one expressed by the grade of cement.

There are now a variety of supplementary

cementitious materials like fly ash, ggbs, microsilica and metakaolin.

The supplementary cementitious materials not

only influence the strength of concrete, but also

the water demand, workability and the ability to

retain workability of the mix!


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Variables in the concrete mix

proportioning -2

Admixtures continue to evolve, each generation ofthese bringing in greater complexity in theinterplay of the constituents of concrete.

The transportation and placing methods havetheir own demand on the properties of freshconcrete at different stages.

Designers (both structural and concrete mix) have

the confidence, (sometimes a need) to use 56days or even 90 days strength as against 28 daysstrength.


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Information for materials -1

For the concrete mix proportioning the

following information for available materials

will be useful:

Sieve analyses of fine and coarse aggregates.

Unit weight of coarse aggregate.

Bulk specific gravities and absorption of

aggregates. Mixing-water requirements of concrete developed

from experience with available aggregates.


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Information for materials -2

Relationship between strength and water-cement

ratio or ratio of water-to-cement plus other

cementitious materials.

Specific gravity of Portland cement and othercementitious materials, if used.

Optimum combination of coarse aggregates to

meet the maximum density grading for mass

concrete.


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Examples:(prescriptive approach)

Simple one

Complex one


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EXAMPLES

based on EN norms related to concrete structures:

EUROCODES and EN 206-1

1. CONCRETE REINFORCED ROOF PLATE

2. PRESTRESSED BEAM IN BRIDGE


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1. REINFORCED CONCRETE ROOF PLATE


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Basic data about structural element

Concrete mix design has to be done for reinforced

concrete roof plate situated in the appartement

house

From structure design:

plate height is 20 cm, and surface area 135 m2.

1. REINFORCED CONCRETE ROOF PLATE


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STEPS IN QA/QC PROCEDURES

GEOMETRICAL

CHARACTERISTICS

STRENGTH WORKABILITYADDITIONAL

REQUIREMENTS

CO

S

TPOURINGCONCRETE

QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)

CONTROL AFTER

POURING

DURABILITY


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Requirements for concrete are

defined in structural design project

ENVIRONMENTAL CLASSES

Corrosion induced by carbonation

XC1

Dry or

permanentlywet

Concrete in structures with low RH or dry air

Concrete permanently submerged

XC2 Humid, rarely dryConcrete surface exposed to long-term contact with water

Most foundations

XC3 Moderate wet Concrete in structures with moderate to high RH of airOuter concrete protected from rain

XC4

Changing dry

and wet

conditions

Concrete surface in contact with water but different from

XC2

Plate is in the environment class XC1


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DURABILITY CONDITION Recommended limit values for concrete mix design for XC1

Exposure

class

Max w/c

ratio

Minconcrete

strength

class

Min. amount of

cement (kg/m3)

Min air

content (%)

Other

requirements

Degradation process: Carbonation

XC 1 0,65 C25/30 260 -

XC 2 0,60 C30/37 280 -

XC 3 0,55 C30/37 280 -

XC 4 0,50 C30/37 300 -

Requirements for concrete mix design based on durability


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GEOMETRICAL

PARAMETERS

WORKABILITYADDITIONAL

REQUIREMENTS

CO

S

TPOURING

CONTROL AFTER POURING

DURABILITY STRENGTH


QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)

IDENTITY TEST


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CONCRETE STRENGTH

Concrete must be of at least compressivestrength class C25/30.

Testing according HRN EN 12390-3

Requirements for concrete mix design based on structural design project


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CEMENT

For construction of concrete plate following cementmay be used:

cement for general purpose, strength class 32,5.

It has to satisfy specifiations given in HRN EN 197-1.

Before using cement in the concrete production, it isnecessary to prove (certify) cements declaredproperties



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STRENGTH REQUIREMENTS

C25/30

fc,m >fck + (6 do 12) N/mm2

fc,m > 30 + 8 = 38 N/mm2

forfc,m = 38 N/mm2 cement class 32,5

From the diagram w/c ratio can beread and it is recommended to use:

w/c 0,55

Requirements for concrete mix design based on cements strength and

type

w/c

fc(MPa)


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ADDITIONAL

REQUIREMENTS

CO

S

TPOURING

QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)


STRENGTH WORKABILITY

GEOMETRICAL

PARAMETERS



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CONCRETE COVER Nominal concrete cover depth (cnom) is determined

from:c

nom

=cmin

+ c (mm)where:

cmin minimum concrete cover depth depending onenvironment class and i requirements for adhesionproperties

c allowed deviation (tolerance) in concrete coverdepth

Nominal concrete cover depth is cnomje 20 mm.


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AGGREGATE It is chosen to use natural river aggregate due to the source and

proved quality

Has to be certified and tested according HRN EN 12620.

Requirement Property

Class SI20 Shape index

Class LA35 Course aggregate resistance to grinding

Class FNR Frost resistance

< 0,06 % Chlorides content

AS0,2 Maximum sulpfate content dissolved in acid

1% Total suplhate content



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CHOICE OF CONCRETE ADMIXTURES

Concrete will be produced without admixtures

DETERMINATION OF PORE AMOUNT IN CONCRETE

(assumed values for design procedure)

Max grain size (mm) The amount of air in

non-aerated concrete

(%)

The amount of entrained

air - pores (%)

32-63 0,4 2-3

16-32 1,5 3-5

8-16 2,5 5-7

4-8 3 7-10

Requirements for concrete mix design based on maximum grain size Dmax


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GEOMETRICAL

PARAMETERS

ADDITIONAL

REQUIREMENTS

CO

S

TPOURING

QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)


WORKABILITY


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WORKABILITY REQUIREMENTS SLUMP VALUES

Structure type Transport type Slump (mm)

Not reinforced or weak

reinforced concrete foundations Straps, special containers 10 - 50

Reinforced foundations, walls,

plates, columnsPumps, container on crane 60 - 120

Heavily reinforced columns and

beamsPumps, container on crane 80 - 160

Industrial floors, roads Straps, trucks 10 - 50

Concreting under water Pumps, tubes 120 - 180

Mass concrete Straps, trucks, sylobus 10 - 50

Anchoring pouring, casting

plates of machinesContainers 130 - 200



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Water amount for 1m3 of fresh concrete (l)

Curve Crushed aggregate River aggregate

S1 S2 S3 S1 S2 S3

A63 120 145 160 95 125 140

A32 130 155 175 105 135 150

A16 140 170 190 120 155 175

A8 155 190 210 150 185 205

B63 135 160 180 115 145 165

B32 140 175 195 130 165 185

B16 150 185 205 140 180 200

B8 175 205 225 170 200 220

C63 145 180 200 135 175 190

C32 165 200 220 160 195 215

C16 185 215 235 175 205 225

C8 200 230 250 185 215 235

Workabillity condition

Choice of demanded

amouont of water

for achieving slump

class S2

Requirements for concrete mix design based on workability


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CO

S

TPOURINGIDENTITY CONTROL



REQUIREMENTS


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CO

S



GEOMETRICAL

PROPERTIES

DURABILITY WORKABILITYADDITIONAL

REQUIREMENTSDURABILITY

CONCRETE MIX DEISGN


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CONCRETE MIX DESIGN

SELECTED VALUESType of cement

Cement

CEM I 32,5

Type of aggregateNatural river

aggregate

Max grain size (mm) 16

Pores (%) 2,5

w/c ratio

Strength condition

Durability condition

0,55

0,65

Selected 0,55

Amount of water for 1 m3 concrete ( l ) 155

Amount of

cement (kg)

Lowest amount of cement durability condition:

Amount of cement from w/c strength condition:

260

281,8

Selected amount of cement: 282

Concrete mix design


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Concrete mix design

Calculated values

Component mass

(kg/m3)Cement 282,0

Water 155,0

w/c = 0,55 -

Air 2,5 % -

Aggregate 1924,0

TOTAL 2361,0

1000Vmmmm

z

d

d

ZPSz

a

c

c

w

w


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CALCULATION OF TOTAL CONCRETE

NEEDED Plate dimensions:

Depth 20 cm

Surface 135 m2

Needed concrete total volume:

Vbet = 0,2 x 135 = 27 m3

Needed amount of each component: Cement: 7614 kg

Water: 4185 l

Aggregate: 51945 kg


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CO

S



GEOMETRICAL

PROPERTIES




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Quality control for determination of

concrete mix design

Quality control during production of concrete

at the concrete plant

Qulity control at site before pouring concrete identity control testing

QUALITY CONTROL AT THE SITE


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Testing of fresh concrete properties

workability - slump

pore amount

temperature


IDENTITY TESTING



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Sampling in order to make control of

hardenet concrete propestries:

Identity of compressive strength


IDENTITY TESTING



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Program for sampling for test on hardened concretein order to prove identity of compressive strengthand other required properties

Criteria: Certified production of concrete Uncertified production of concrete

Property Number of samples

Compressive strength 3 samples


IDENTITY TESTING


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C

O

S



GEOMETRICAL

PROPERTIES




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CO

S

TPOURING

QUALITY CONTROL

AT THE SITE

(IDENTITY TEST)


GEOMETRICAL

CHARACTERISTICS




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Concrete mix design for 2 prestressed beams inlongitudinal direction, freely supported on ends, fortrain bridge

Data from structure design project Beam height 130 cm,

width 420 cm,

length 24,60 m,

span 23,00 m.

Beam cross section


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Reinforcement

Beam is heavily reinforced, and

post-tensioned prestressed in

longitudinal direction

Grouting of tendons after

prestressing.


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GEOMETRICAL

CHARACTERISTICS


REQUIREMENTS

CO

S

TPOURINGCONCRETE

QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)

CONTROL AFTER

POURING

DURABILITY


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Exposure classes


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Corrosion caused by carbonation

XC1Dry or permanently

wet

Reinforced and prestressed concrete surfaces inside enclosed structures except areas of structures

with high humidity

Reinforced and prestressed concrete surfaces permanently submerged in non-aggressive water

XC2 Wet, rarely dry Reinforced and prestressed concrete completely buried in soil, foundations

XC3 Moderate humidity

External reinforced and prestressed concrete surfaces sheltered from, or exposed to, direct rain

Reinforced and prestressed concrete surfaces subject to high humidity (e.g. poorly ventilated

bathrooms, kitchens)

XC4Moderate humidity

or cyclic wet and

dry

Reinforced and prestressed concrete surfaces exposed to alternate wetting and

drying

Interior concrete surfaces of pedestrian subways not subject to de-icing salts,

voided superstructures or cellular abutments

Reinforced or prestressed concrete beneath waterproofing

Corrosion caused by freezing/thawing with or without de-icing salts

XF1Moderate water

saturation without

de-icing agent

Vertical concrete surfaces such as faades and columns exposed to rain and freezing

Non-vertical concrete surfaces not highly saturated, but exposed to freezing and to

rain or water

XF2

Moderate water

saturation with de-icing

agent

Concrete surfaces such as parts of bridges, which would otherwise be classified as XF1, but which

are exposed to de-icing salts either directly or as spray or run-off

XF3High water saturation

without de-icing agent

Horizontal concrete surfaces, such as parts of buildings, where water accumulates and which are

exposed to freezing

Concrete surfaces subjected to frequent splashing with water and exposed to freezing

XF4

High water saturation

with de-icing agent or

sea water

Horizontal concrete surfaces, such as roads and

pavements, exposed to freezing and to de-icing salts either

directly or as spray or run-off

Concrete surfaces subjected to frequent splashing withwater containing de-icing agents and exposed to freezing


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DURABILITY REQUIREMENTS

Recommended limit values for concrete composition for

clasess XC4 and XF1

Environ-

ment class

Max wc

ration

Min

strength

Min. amount of

cement (kg/m3)

Min air

content (%)

Additional

requirements

XC 4 0,50 C30/37 300 -

XF 1 0,55 C30/37 300 -

Aggregate

according

HRN EN 12620 hasto be frost resistant

Requirements for concrete mix design based on durability


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GEOMETRICAL

PARAMETERS


REQUIREMENTS

CO

S

TPOURING


DURABILITY STRENGTH


QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)

IDENTITY TEST


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Compressive strength class

(testing acc. HRN EN 12390-3) C35/45

Average concrete tensile strength fctm

(testing acc. HRN EN 12390-6)3,2 N/mm2

Static modulus of elasticity (Ecm)

(acc. HRN U.M1.025)

33500 N/mm2

Minimum compressive strength needed for prestressing

calculated on final force of prestressing (at the age of

concrete of 30 days tested on concrete cylinder)34 N/mm2

MECHANICAL PROPERTIES OF CONCRETE:

STRENGTH AND MODULUS OF ELASTICITY



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CEMENT

It is possible to use:

cement for general purpose, Strength class 42,5,

With the condition of low hydration heat (sign LH).

Cement has to satisfy specifications accordingnorms HRN EN 197-1 and HRN EN 197-3.

Need to be certified


Beam:

height 130

cm,

width 420

cm,

length

24,60 m


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Strength conditions

C35/45

fc,m > fck + (6 do 12) N/mm2

fc,m > 45 + 10 = 55 N/mm2

forfc,m = 55 N/mm2 and class of

cement 42,5 From diagram read value is:

w/c ratio of 0,45

Requirements for concrete mix design based on

concrete strength required and chosen cement

w/c

fc(MPa)


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structural design project

CONCRETE COVER Nominal concrete cover depth (cnom) is determined

from:

cnom=cmin + c (mm)where: cmin minimum concrete cover depth depending on

environment class and i requirements for adhesionproperties

c allowed deviation (tolerance) in concrete cover depth

cnom = 55 mm for ordinary steel reinforcement

cnom = 105 mm for prestressing steel


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AGGREGATE It is chosen to use crashed aggregate due to the source and provedquality

Has to be certified and tested according HRN EN 12620.

Requirement PropertyClass SI20 Shape index

Class LA35 Course aggregate resistance to grinding

0,075 % Volume stability shrinkaeg due to drying

Class F1 Frost resistance

< 0,03 % Chlorides content

AS0,2 Maximum sulpfate content dissolved in acid

1% Total suplhate content



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MAXIMUM GRAIN SIZE Maximum grain size Dmax may not be greater than:

1) concrete cover depth cnom2) 1/4 of beam height

3) 0,8 horizontal distance of reinforcing bars minimum sistance is 90mm accroding the project

cnom concrete cover depth = 50 mm

d plate height = 20 cm

a horizontal distance between reinforcing bars = 125 mm

1) Dmax c = 550 mm

2) Dmax 1/4d = 1/3250 = 62,5 mm

3) Dmax 0,8a = 0,890 = 72 mm

Selected:

Dmax=32 mm


d


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CHOICE OF CONCRETE ADMIXTURES

Concrete will be produced wit admixture AIR ENTRAINING

AGENT in order to ensure frost resistance of concrete

DETERMINATION OF PORE AMOUNT IN CONCRETE

(assumed values for design procedure)Max grain size (mm) The amount of air in

non-aerated concrete

(%)

The amount of

entrained air - pores

(%)

32-63 0,4 2-3

16-32 1,5 3-5

8-16 2,5 5-7

4-8 3 7-10

Requirements for concrete mix design based on maximum grain size Dmax


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Choice of concrete admixtures and requirements

Pore content in fresh concrete (testing acc.HRN EN 12350-7): Tested mix 2,5% of the value in the control mix

Total content of air should be 4-6% of volume

Pores in hardened concrete (testing acc. HRNEN 480-11): Air spacing ratio in tested mix has to be 0,200 mm

Compressive strenght at 28th day(teseted acc. HRN EN 12350-3):

Tested mix 75% of control mix



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GEOMETRICAL

PARAMETERS

ADDITIONAL

REQUIREMENTS

C

O

S

TPOURING

QUALITY CONTROL

AT THE SITE (BEFORE

POURING CONCRETE)


WORKABILITY


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Class of workability

slump 80 -160 mm selected S3 (100-150 mm)

Slump class(mm)

Vebe class(s)

Compactionclass

Spread class(mm)

S1 10 - 40 V0 31 C0 1,46 F1 340

S2 50 - 90 V1 30 - 21 C1 1,45 - 1,26 F2 350 - 410

S3 100 - 150 V2 20 - 11 C2 1,25 - 1,11 F3 420 - 480

S4 160 - 210 V3 10 - 6 C3 1,10 - 1,04 F4 490 - 550

S5 220 V4 5 - 3 C4 < 1,04 F5 560 - 620

- - - - - - F6 630



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Water amount for 1m3 of fresh concrete (l)

Curve Crushed

aggregate

River aggregate

S1 S2 S3 S1 S2 S3

A63 120 145 160 95 125 140

A32 130 155 175 105 135 150

A16 140 170 190 120 155 175

A8 155 190 210 150 185 205

B63 135 160 180 115 145 165

B32 140 175 195 130 165 185

B16 150 185 205 140 180 200

B8 175 205 225 170 200 220

C63 145 180 200 135 175 190

C32 165 200 220 160 195 215

C16 185 215 235 175 205 225

C8 200 230 250 185 215 235

Workabillity condition

Choice of demanded

amouont of water

for achieving slump

class S3

Requirements for concrete mix design based on workability


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CO

S




REQUIREMENTS


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Special conditions by the construction of structuralelement

Due to large dimensions of this beam (130x420cm) it can be expected a high temperature in themiddle of cross section due to the heat hydrationdevelopment.

It is recommended to:

use cement of low hydration heat during mix design preliminary testing of heat development during hydration on

concrete for the prestressed beam

Requirements for concrete mix design based on structure design project


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Special conditions by the construction of structural element

Due to the post-tensioning of tendons it is necessary to determine:

Shrinkage of concrete (HRN U.M1.029) and

Creep coefficient of concrete (HRN U.M1.027).

Basic deformation of shrinkage cs (mm/m)

- At the age of t1 = 30 days cs(t1, ts) = -0,8410-5

- At the age of t = 30000 days cs(t, ts) = -20,3910-5

Creep coefficient (t, t0)

- At the age of t1 = 30 days (t1, t0) = 0,423

- At the age of t = 30000 days (t, t0) = 1,610

Design values of shrinkage and creep

Requirements for concrete mix design based on structure design project

f


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Requirements for concrete

Additional requirements for fresh concrete

Cement of low hydration: sign LH

Hydration heat: 270 J/g

Temperature of fresh concrete: 5-25 C

Pore content in fresh concrete: 4%


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Additional requirements for hardened concrete

Freezing thawing test (frost resistance): 100 cycles

Tensile strength: 3,2 N/mm2

Static modulus of elasticity: 33500 N/mm2

Maximum shrinkage at the age of t1 = 30 days:

cs(t1, ts)= -0,8410-5 mm/m

Maximum creep coefficient at the age t1

= 30 days:

(t1, t0) = 0,423

Requirements for concrete


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CO

S



GEOMETRICAL

PROPERTIES



CONCRETE MIX DEISGN

CONCRETE MIX DESIGN


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CONCRETE MIX DESIGN

recommended and selected values

Type of cement PC, low hydration cement CEM I 42,5 LH

Aggregate type Drobljeni agregat

Maximum grain size (mm) 32

Admixture aerant

Air content (%) 4

w/c ratio

Strength requirement

Durability risk - frost (XF1)

Durability risk - carbonation (XC4)

0,45

0,55

0,50

Selected 0,45

Amount of water on 1 m3 of concrete ( l ) 195

Cement

amount (kg)

Lowest amount of cement durability condition:

Amount of cement from w/c strength condition:

300

433,3

Selected value of cements:: 433

CALCULATION OF


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CONCRETE MIX DESIGN

COMPONENT MASS

(kg/m3)

Cement 433,0

Water 195,0

w/c = 0,45 -

Air entrainer 0,5% onmc~2,0

Air 4 % -

Agreggate 1708,0

TOTAL 2338,0

1000Vmmmmz

d

d

ZPSz

a

c

c

w

w


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CALCULATION OF TOTAL CONCRETE

NEEDED Beam dimensions:

Beam length 24,6 m

Cross section surface 5,76 m2

Concrete needed for 2 beams:

Vbet = 24,6 x 5,76 x 2 = 283,4 m3

Needed amount of each component:

Cement: 122.712 kg

Water: 55.263 l

Agreggate: 484.025 kg

Air entraining agent: 615 kg


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C

O

S

TPOORINGIDENTITY TESTING

CONTROL AFTER POORING

GEOMETRICAL

PROPERTIES



Quality control for determination of


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Qua ty co t o o dete at o o

concrete mix design

Quality control during production of concrete

at the concrete plant

Quality control at site before pouring concrete

identity control testing



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Testing of fresh concrete properties

workability - slump

pore amount

temperature


IDENTITY TESTING



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Quality control of hardened concreteidentity tests of:


Tensile strength by splitting

Static modulus of elasticity

Freezing/thawing

Shrinkage Creep


IDENTITY TESTING



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Program for sampling concreteproperty Broj i uestalost uzimanja uzoraka

Compressive strengthAt least 1 sample on a day of concreting

At least 1 sample on each 100 m3 poored concrete

Tensile strength At least 1 sample on a day of concretingAt least 1 sample on each 200 m3 poored concrete

Static modulus of

elasticity

3 samples for compressive strength determination

3 samples for static modulus of elasticity

Freezing thawing

resistance15 samples

Shrinkage At least 3 samples

Creep

3 samples for deformations due to shrinkage

3 samples for compressive strength

3 samples for meausirng total deformations under a constant load


IDENTITY TESTING



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CRITERIA FOR COMPRESSIVE STRENGTH

Number of tested samples for

declared amount of concrete

production

Criteria 1 Criteria 2

Average from n results (fcm)

(N/mm2)Each single result (f

ci) (N/mm2)

2-4 fck + 1 fck - 4

Number of tested

samples, n, forthe assesment of

strength in the

group


Average from n results

(fcm) (N/mm2)

Each single result (fci)

(N/mm2)

Initial 3 fck + 4 fck - 4

Continuous Not less than 15 fck +1,48 fck - 4

For uncertified concrete production

For certified production of concrete


IDENTITY TESTING



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CRITERIA FOR TENSILE STRENGTH

Production

Number of tested

samples, n, for

the assesment of

strength


Average from n

results (ftm)

(N/mm2)

Each single result

(fti) (N/mm2)

Initial 3 fck + 0,5 fck 0,5

Continuous Not less than 15 fck + 1,48 fck 0,5


IDENTITY TESTING



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CRITERIA

PROPERTY CRITERIA

Freezing / thawing resistance Loss of compressive strength after 100

cycles has to be less than 25%

Modulus of elasticity 33.500 N/mm2

Maximum shrinkage at t1 = 30days (cs(t1, ts)) -0,8410-5 mm/m

Maximum creep at t1 = 30 days

((t1, t0)) 0,423


IDENTITY TESTING

REQUIRED PROPERTIES


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REQUIRED PROPERTIES

FOR THE GROUTTESTING

PROPERTYMETHOD

HRN EN 445DESCRIPTION CRITERIA

HRN EN 447

Fluidity / flowability Cone method Time needed for flow of 1L of grout

through the cone 25 s

Bleeding Gauge glass The amount of bleeded water after 3

hours

-1%; < +5%

Compressive

strentghprisms

On prisms 4x4x16 cm, after 28 days> 30 MPa


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CO

S

TPOORING

QUALITY CONTROL

AT THE SITE

(IDENTITY TEST)

QUALITY CONTROL

AFTER POORING

GEOMETRICAL

CHARACTERISTICS




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CO

S

TPOORING

QUALITY CONTROL

AT THE SITE

(IDENTITY TEST)

CONTROL AFTER POORING

GEOMETRICAL

CHARACTERISTICS



SUMMARY 1


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SUMMARY- 1

Durability of concrete in 21st century: carefully selected materials

control and optimization of their properties

reduction of varaiblity in mixing, transport,placement and curing of concrete

performance-based specifications to control in-situ concrete

real-time monitoring, NDT evaluation understanding reaction between concrete and its

environment

SUMMARY 2


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SUMMARY - 2

It is surely within the capability of the modernday IT systems to capture all these variables in

a complicated mix design software.

However, the trial mix would not necessarilyfollow the predicted results as the numbers of

independent variables contributing to the

single outcome are too many!

SUMMARY 3


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SUMMARY -3

The journey from the calculated mixproportion to the final proportion would

require judgment and experience, and

laboratory trials.


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Thank you

foryour attention!

spin practical aspects in concrete mix design

Documents