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    Concrete science and technology

    Bridge between materials science, concrete

    technology, execution and design of concretestructures

    Lecture 10.09.2010

    Mix design

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    September 17, 2010 2

    Cement

    When happiness was a common thing

    Sand Aggregate

    Water

    B25

    B35B45

    Concrete

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    It has becomecomplicated

    Gravel

    Sand

    Cement

    Water

    Slag

    Fly ash

    Silica fume

    FillersSteel FibersPolymer fibersAccelerator

    Retarder

    Stabilizer

    Air entrainer

    Superplasticizer

    Water

    entrainer

    Recycled aggregates

    B15

    B35

    B45

    B55

    B65

    B75

    B85

    B95

    B105

    B120

    B200

    B800

    Light weight Concrete

    Selfcompacting concrete

    Fibre reinforced concrete

    Property defined concrete

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    September 17, 2010 4

    Mix design procedureDutch standard procedure (ordinary concrete mixtures)

    Phases in mix design process1. Choice of materials

    2. Determination of composition of cement paste

    3. Determination of aggregate (sand and gravel)

    4. Check of volumes and mass (uitleveringsberekening)5. Check of chloride content

    fccmfcck

    Pre-phase:

    1. Designer defines required strength (C/B value) and specific mass

    2. Location and environment determine environmental class

    3. Adopted execution method determines consistency

    C-value

    B-value

    B-value

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    September 17, 2010 5

    Mix design procedureDutch standard procedure

    Phases in mix design process

    1. Choice of materials Aspects:

    1. Availability2. Properties of raw materials (chemical, physical, mechanical)3. Price

    2. Determination of composition of cement paste

    1. Strength of the concrete

    2. Norm strength of the cement paste

    3. Water/binder ratio

    4. Air content

    5. Water and cement content

    3. Determination of percentages sand and gravel (Workability!)1. Fuller method

    2. Method of Rengers-Anthonisse (Currently used Dutch mixtures)

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    September 17, 2010 6

    Mix design procedureDutch standard procedure Design criteria

    Strength

    Workability (consistency classes 1, 2, 3,4)

    Particle size distribution aggregate

    Max. particle size aggregate

    Percentage of fine material (< 250 m)

    Amount of water

    Durability

    Specific mass (type of aggregate) Aesthetics (Color)

    Chloride content (check)

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    September 17, 2010 7

    Strength

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    September 17, 2010 8

    Transfer of forces inside skeleton

    matrix

    External loading

    Strength:

    1. Matrix2. Aggregate

    3. Interfacial zone

    Strength

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    September 17, 2010 9

    Norm strength of cement vs. Concrete strength

    External loading

    Strength

    Concrete strength

    Coarse aggregate

    Sand

    Mortar

    Cement paste

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    September 17, 2010 10

    Relation cylinder/cube compressive strength

    C-value

    B-value

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    September 17, 2010 11

    Strength classes ENV 206 and VBT

    ENV 2006 VBT 1996 (Dutch)

    Strength class Char. Cylindercompr. Strength

    [MPa]

    Char. Cubecompr. Strength

    [MPa]

    Strength class Char. Cubecompr. Strength

    [MPa]

    -

    C12/15

    -

    12

    -

    15

    B5

    B15

    5

    15

    C16/20

    C20/25

    16

    20

    20

    25

    -

    B25

    -

    25C25/30

    C30/37

    25

    30

    30

    37

    -

    B35

    -

    35

    C35/45

    C40/50

    35

    40

    45

    50

    B45

    -

    45

    -

    C45/55

    C50/60

    45

    50

    55

    60

    B55

    -

    55

    -

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    September 17, 2010 12

    Concrete strength and norm strength N

    c

    w/c

    bN.a(N)fccm +=

    N = Norm strength of cement

    Norm strength: mortar prisms 160x40x40 mm

    s/c = 3:1, w/c = 0.5

    a = 0.8 (0.75 - 0.85)

    b = 25 (20 - 25)

    c = 45 (40 50)

    fccm

    Strength

    B-value

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    Strength

    class

    Compressive strength (Norm strength)

    N/mm2Begin

    setting

    min.

    Shape

    preser-

    vation

    mm

    Initial strength

    After 28 days

    After 2

    days

    After 7

    days

    32.5

    32.5 R

    --

    > 10

    > 16

    --

    > 32.5

    > 32.5

    < 52.5

    < 52.5

    > 60 < 10

    42.5

    42.5 R

    > 10

    > 20

    --

    --

    > 42.5

    > 42.5

    < 62.5

    < 62.5

    52.5

    52.5 R

    > 20

    > 30

    --

    --

    > 52.5

    > 52.5

    --

    --

    > 45

    Boundary values: strength, begin setting and shape preservation

    Table 2.6

    (Norm strength: mortar prisms 160x40x40 mm, s/c = 3:1, w/c = 0.5)

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    September 17, 2010 14

    Type of

    cement

    code Norm strength N of cement [N/mm2]

    1 day 2 days 3 days 28 days

    Portland

    cement

    CEM I 32.5 R

    CEM I 42.5 R

    CEM I 52.5 R

    10

    19

    29

    17

    30

    39

    25

    35

    44

    48

    58

    63

    Portland-

    flyash

    cementCEM II/B V32.5 R 13 22 25 49

    Blast

    furnace

    slagcement

    CEM III/A 32.5

    CEM III/A 42.5

    CEM III/B 32.5 LH

    CEM III/BA 42.5

    7

    8

    5

    8

    14

    17

    10

    17

    19

    22

    14

    25

    46

    59

    48

    58

    Guide values for mean norm strength N of currently used cements

    Table 10.8

    Strength

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    cw/c

    bN.a(N)fccm +=

    Relationship betweenw/c and compressivestrength of concrete fordifferent strength

    classes (= Normstrengths) of cement

    Compre

    ssivestren

    gth

    [MPa]

    Strength

    Water/cement ratio

    Norm strength cementCompressivestrength

    (N/mm2)

    Strength

    class

    Compressive strength (Norm strength)N/mm2

    Beginsettin

    g

    min.

    Shapepreser

    -vation

    mm

    Initial strength

    Af ter 28 daysAfter 2

    days

    After 7

    days

    32.5

    32.5 R

    --

    > 10

    > 16

    --

    > 32.5

    > 32.5

    < 52.5

    < 52.5

    > 60 < 10

    42.5

    42.5 R

    > 10

    > 20

    --

    --

    > 42.5

    > 42.5

    < 62.5

    < 62.5

    52.5

    52.5 R

    > 20

    > 30

    --

    --

    > 52.5

    > 52.5

    --

    --

    > 45

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    Strength depends on maximum aggregate size

    Biggerparticles result

    in lowerstrength

    (Generally because of

    more intensivemicrocracking)

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    September 17, 2010 17

    Mixture parameters vs. Mixture properties

    Parameter Strength Workability Durability

    Water/cement ratio X

    Type of cement X

    Amount of cement

    Aggregate (Fineness modulus)

    Amount of fines (< 250 m)

    Max. particle diameter aggregate XSlump (experimental)

    Air content

    Water demand

    Curing regime

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    September 17, 2010 18

    Workability

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    September 17, 2010 19

    Workability

    Classification:

    No slump concrete (aardvochtig beton)

    Semi-Plastic (half plastisch)

    Plastic (plastisch)

    Flowable (vloeibaar beton)

    Influencing factors: Particle grading of aggregate (sieve line)

    Maximum particle diameter

    Percentage fine material (< 250 m)

    Amount of water

    (Super)plasticizers

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    September 17, 2010 20

    Consistency / Workability

    Consistency

    Consistency of the concrete determines:

    Plasticity

    Cohesion

    Internal friction

    Stability

    Consistency tests:1. Compacting factor

    2. Vebe test

    3. Slump test

    4. Flow table test

    5. Viscometer

    y stress

    Rateof flow

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    September 17, 2010 21

    Walz vessel

    Consistency

    Consistency of sticky mixtures

    Betoniek, 13/08

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    September 17, 2010 22

    Slump test (consistency 2, 3)

    Consistency Cone of Abrams

    De Rooij

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    Consistency classes (Dutch)

    Class Consistency Compacting

    Factor

    V = (400/400-s)

    Slump test

    mm

    Flow table

    test

    mm

    1 No slump > 1.26 < 40 ---

    2

    Half plastic

    (semi -) 1.25 1.11 50 - 90 150 - 350

    3 Plastic 1.1 1.05 100 - 150 360 - 480

    4 Flowable --- > 160 490 - 600

    Less preferable method

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    September 17, 2010 24

    Particle size of materials

    Material size [m]

    Gravel 4000 - 63000 Sand: Coarse 500 - 4000

    Fine 63 - 200

    Fly ash 1 - 200

    Cement 0.5 100 Silica fume 0.1 0.15

    Particle grading

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    September 17, 2010 25Sand: fine, middle and coarse

    fine

    coarse

    Particle size [mm]

    % passing

    middle

    Particle grading

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    Boundaries for workable mixtures

    Mixtures 0 - 16 mm

    Sieve opening [mm]

    Cum.sieveres

    iduein%(v/v)

    A

    B

    C

    Particle grading

    Fine

    coarse

    0.125 0.250 0,500 1 2 C4 C8 C16

    0

    10

    20

    30

    40

    50

    60

    70

    80

    90

    100

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    Boundaries for workable mixtures

    Fine

    coarse

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    September 17, 2010 28

    Particle grading aggregate

    Fineness modulus (sand and gravel):

    100

    residusievecumulativesumF =s

    Sieves according

    NEN 2560

    Sieve residue (sand)

    per sieve Cumulative

    C4

    2 mm

    1 mm100 m

    150 m

    125 mrest

    5.7

    24.5

    21.326.8

    17.5

    3.3

    0.9

    5.7

    30.2

    51.578.3

    95.8

    99.1

    --

    total 100.0 Fs

    Particle grading

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    September 17, 2010 29

    Amount of sand and gravel in mixtureSand percentage Ps according to Rengers-Anthonisse:

    Ps = 10 Fs + 28 + 0.05 z 0.08 C

    Fs = Fineness modulus of the sand

    z = Slump value [mm]

    C = Cement content [kg/m3]

    Gravel percentage: Pg = 100 - Ps

    Note: Rengers-Anthonisse is applicable for currently used Dutch mixtures

    Particle grading

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    September 17, 2010 30

    Maximum particle size Dmax

    Maximum particle Dmax: largest sieve

    diameter of the coarsest particle group

    Criteria originate from:

    1. Mixing, transport, pouring

    2. Reinforcement layout

    3. Cover on reinforcement

    4. Free space between prestressing ducts

    Particle grading

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    September 17, 2010 31

    Amount of fine material: < 250 m

    Fine material (< 250 m) consists of: Cement Fillers and fine sand Air bubbles (Air entraining agents)

    Minimumamount of fine material is related tomaximumparticle diameter

    Maximum particle Dmax[mm]

    Minimum amount of fine material (< 250 m)per m3 concrete

    [l]

    8

    1631.5

    140

    125115

    Table 10.5

    Particle grading

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    September 17, 2010 32

    Measured air content of fresh

    paste

    % (v/v)

    Effective air content per m3 concrete, to be

    considered as fine material

    [l]

    2

    3

    4

    56

    --

    10

    20

    3040

    Table 10.6 Effective air content, to be considered as fine material

    Air content in concrete

    Air content affects workability, strengthand durability

    1% air results in a strength reduction of about 5%

    Air entraining agent

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    Largest sieve [mm] 8 16 31.5 63

    Grade area A-B A-C A-B A-C A-B A-C A-B A-C

    Consistency 1

    (slump < 40 mm)

    Compaction factor > 1.26175 195 160 180 150 170 140 155

    Consistency 2(slump 50 90 mm) 192 213 180 200 165 185 155 170

    Consistency 3

    Slump 100 150 mm 205 225 195 218 180 200 168 190

    Guide values for water demand W of concrete [kg/m3 concrete]

    Table 10.11

    For consistency 4no guide values are given.

    Higher consistency only by using (super)plasticizers

    Dont add water to achieve consistency 4 Water demand

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    September 17, 2010 34

    Mixture parameters vs. Mixture properties

    Parameter Strength Workability Durability

    Water/cement ratio X X

    Type of cement X

    Amount of cement (X)

    Aggregate (Fineness modulus sand Fs) X

    Amount of fines (< 250 m) X

    Max. particle diameter aggregate X XSlump (experimental) X

    Air content X

    Water demand X

    Curing regime

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    September 17, 2010 35

    DurabilityEnvironmental classes

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    Durability of concrete

    Town of Bellefontaine, State of Ohio, USA, 1891

    50 year concrete pavement

    75 year concrete pavementGeorge Bartholomew

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    September 17, 2010 37

    Oresund Bridge (2000)

    15 mm

    Concrete

    crack

    Photo: Ingenieur 2007

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    September 17, 2010 38

    Durability & Environmental classes

    Rebar corrosion

    Carbonation-induced corrosion

    Chloride-induced corrosion

    ASR Alkali-Silica Reaction

    Sulphate attack (sea water)

    Leaching processes (acid attack)

    Main points of concern:

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    H2O, CO2

    CaCO3

    pH = 7 - 9

    pH = 13

    pH

    Consumption

    of Ca(OH)2

    Rebar corrosion!

    Rebarw

    Carbonationinduced rebar corrosion

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    September 17, 2010 40

    Design lifetime of large infrastructural works:

    100 - 150 years

    Eastern Scheldt storm surge barrier

    Chloride exposure

    Freeze-thaw

    Drying & wetting

    (Micro)cracking

    Risk of corrosion ofreinforcing steel

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    September 17, 2010 41

    Environmental classes (NEN)

    Class Description of environment (Current Dutch code)

    1

    2

    3

    4

    5

    Dry

    Humid

    Humid in combination with de-icing salts

    Sea water

    Aggressive;

    a: weakb: moderate

    c: strong

    d: very strong

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    September 17, 2010 42

    Type of aggressive

    substance

    No weak moderate strong Very

    strong

    pH>6.5 6.5 5.5 5.5 4.5 4.5 4.0 < 4.0

    CO2 (dissolves lime)

    [mg CO2/l] < 15 15-30 30-60 60-100 >100

    Ammonium

    [mg NH4+/l] < 15 15-30 30-60 60-100 >100

    Magnesium

    [mg NH4+/l]

    < 100 100-300 300-1500 1500-3000 >3000

    Sulphates

    [mg SO42-/l]

    < 200 200-600 600-3000 3000-6000 >6000

    Aggresivity of solutions in water

    Table 10.2

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    Environmental classes

    Class Description of environment (European code)

    XO

    XC

    XD

    XS

    XF

    XA

    NO risk of corrosion or attack

    Carbonation initiated corrosion

    Chloride induced corrosion, not from sea water (De-icing)

    Chloride induced corrosion - Sea water

    Freeze-thaw attack, with and without de-icing salts

    ChemicalAttack

    Class Description of environment (Current Dutch code)

    1

    2

    34

    5

    Dry

    Humid

    Humid in combination with de-icing saltsSea water

    Aggressive; a: weak, b: moderate, c: strong, d: very strong

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    Environmental classes NEN-EN 206-1

    Class Description of environment

    XO

    X0

    NO risk of corrosion or attack

    Concrete without reinforcement, except classes XF and XA concrete with

    reinforcement: very dry environment

    XC

    XC1

    XC2

    XC3

    XC4

    Carbonation initiated corrosion

    Dry of constant wet

    Wet, rarely dry

    Intermediate moisture condition

    Alternating wet and dry

    XDXD1

    XD2

    XD3

    Chloride induced corrosion, not from sea water (De-icing)Dry of constant wet

    Wet, rarely dry

    Alternating wet and dry

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    Environmental classesEnvironmental classes Houses and buildingsHouses and buildings

    Facade

    Cellar wallBalcony

    Cellar wall Cellar deck

    Cellar f loor

    Floors, walls (inside)

    Fresh water

    E i t l l NEN EN 206 1

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    Environmental classes NEN-EN 206-1

    Class Description of environment

    XS

    XS1

    XS2

    XS3

    Chloride induced corrosion - Sea water

    Salt containing air

    Constant under water

    Tidal zone, splash zone

    XF

    XF1

    XF2XF3

    XF4

    Freeze-thaw attack, with and without de-icing salts

    Non-saturated water, without de-icing salt

    Non-saturated water, with de-icing saltSaturated water, without de-icing salt

    Saturated water, with de-icing salt or sea water

    XA

    XA1

    XA2

    XA3

    ChemicalAttack

    Weak aggressive environment

    Moderate aggressive environment

    Severe aggressive environment

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    Environmental classes Houses and buildings

    Coastal area

    Facade

    Cellar wall

    Floors, walls (inside)

    Cellar floor slab

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    Environmental classes Industrial buildings (XA)

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    Environmental classes

    Industrial buildings and infrastructural works (XA, XF)

    D bilit it i

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    September 17, 2010 50

    Durability criteria

    Consequences for mix design

    2. Water/cement (binder) ratio

    General: Denser cement paste gives higher durability

    1. Type of cement

    3. Cement content

    4. Curing (Give it a week)

    Prevent early evaporation

    Better curing gives higher degree of hydration

    Keep temperature low

    Environmental classes (NEN)

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    Environmental classes (NEN)

    Class Description of environment (Current Dutch code)

    1

    2

    3

    4

    5

    Dry

    Humid

    Humid in combination with de-icing salts

    Sea water

    Aggressive;

    a: weak

    b: moderate

    c: strong

    d: very strong

    Criteria for concrete mixtures for different environmental classes

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    Microlab Faculty of Civil Engineering and Geosciences

    Environmental class

    1 2 3 4 5a 5b 5c,d

    +aea +aea

    W/c (w/b)

    Plain

    Reinforced

    Prestressed

    --

    0.65

    0.60

    0.70

    0.55

    0.55

    0.55

    0.55

    0.55

    0.45

    0.45

    0.45

    0.55

    0.55

    0.55

    0.45

    0.45

    0.45

    0.55

    0.55

    0.55

    0.50

    0.50

    0.50

    0.45

    0.45

    0.45

    Min. cement/ binder

    [kg/m3]

    Plain

    Reinf. & prestress

    Grading A-B

    Grading A-C

    Discontineous

    150

    260

    260

    260

    200

    280

    280

    280

    280

    280

    300

    300

    280

    280

    300

    300

    280

    280

    300

    300

    300

    300

    300

    300

    300

    300

    300

    300

    Table 10.3 aea = air entraining agent

    Criteria for concrete mixtures for different environmental classes

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    Environmental class

    1 2 3 4 5a 5b 5c,d

    +aea +aea

    Min. air content

    [%] for aggr. Diam.

    D = 63 mm

    D = 31.5 mm

    D = 16 mmD = 8 mm

    --

    --

    ----

    --

    --

    ----

    3.0

    3.5

    4.05.0

    --

    --

    ----

    3.0

    3.5

    4.05.0

    --

    --

    ----

    --

    --

    ----

    --

    --

    ----

    --

    --

    ----

    Type of cement Sulphate

    resistant

    BFSC

    Sulphate resistant

    cement

    Table 10.3 (cont.)

    aea = air entraining agent (luchtbelvormer)

    Mixture parameters vs Mixture properties

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    Mixture parameters vs. Mixture properties

    Parameter Strength Workability Durability

    Water/cement ratio X X X

    Type of cement X X

    Amount of cement (X) X

    Aggregate (Fineness modulus) X X

    Amount of fines (< 250 m) X

    Max. particle diameter aggregate X X X

    Slump (experimental) X

    Air content X X

    Water demand X

    Curing regime X

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    Mix design

    Mixture for specified environment

    Example

    Mix design - Example

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    Mix design - Example

    Project: Infrastructure construction Mass concrete

    Environmental class 2 (Dutch code)

    Materials: Sand and gravel given (see table)

    Mix design - Example

    Grading sand and gravel (in stock)

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    Grading sand and gravel (in stock)

    Sieve according NEN2560

    Cumulative sieve residue [%]

    sand gravel

    C 31.5

    C16

    C8

    C4

    2 mm

    1 mm

    500 m

    250 m

    125 m

    --

    --

    --

    3

    9

    28

    60

    94

    100

    --

    28

    70

    94

    100

    100

    100

    100

    100Fineness modulus F 2.94 6.92

    Mix design - Example

    6% sand < 250 m

    Mix design

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    Mix design

    The unknowns are:

    Concrete strength

    Type of cement

    w/c

    Amount of water

    Amount of cement

    Amount of air

    Amount of sand

    Amount of gravel

    Air?

    Water?

    Cement?

    Sand?

    Gravel? workability

    durability

    Mix design - Considerations

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    Mix design Considerations

    Mass concrete: Low heat cementCEM III/B (Slag: 66-80%)

    Required strength: B25 (= C20/25)

    fcck= 25 MPafccm = 32 MPa

    Pouring with container: Consistency class 2

    Mix design - Example

    Class Consistency Compacting

    Factor

    V = (400/400-s)

    Slump test

    z

    mm

    Flow table

    test

    mm

    1 No slump > 1.26 < 40 ---

    2Half plastic

    (semi -)1.25 1.11 50 - 90 150 - 350

    3 Plastic 1.1 1.05 100 - 150 360 - 480

    4 Flowable --- > 160 490 - 600

    Slump z = 50 90 mm

    z = 70 mm

    Mix design

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    Mix design

    The unknowns are:

    Concrete strength B25

    Type of cement CEMIII-B

    w/c .

    Amount of water .

    Amount of cement .

    Amount of air .

    Amount of sand .

    Amount of gravel .

    Air?

    Water?

    Cement?

    Sand?

    Gravel?

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    Mix design - Example

    Strength

    Mix design - Example

    Guide values for mean norm strength N of currently used cements

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    Type of

    cement

    code Norm strength N of cement [N/mm2]

    1 day 2 days 3 days 28 days

    Portland

    cement

    CEM I 32.5 R

    CEM I 42.5 R

    CEM I 52.5 R

    10

    19

    29

    17

    30

    39

    25

    35

    44

    48

    58

    63

    Portland-

    flyashcement CEM II/B V32.5 R 13 22 25 49

    Blast

    furnace

    slag

    cement

    CEM III/A 32.5

    CEM III/A 42.5

    CEM III/B 32.5 LHCEM III/BA 42.5

    7

    8

    58

    14

    17

    1017

    19

    22

    1425

    46

    59

    4858

    Table 10.8

    Mix design - Example

    Concrete strength and Norm strength N

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    Concrete strength and Norm strength N

    c

    w/c

    bN.a(N)fccm +=

    N = Norm strength of cement = 48 MPa (for CEM III/B)

    a = 0.8; b = 25; c = 45

    Required w/c = 0.65

    (Note: Norm strength refers to mortars with w/c=0.5)

    fccm

    Mix design - Example

    Check whether w/c is OK in view of durability requirements!! (Table 10.3)

    a = 0.8 (0.75 - 0.85)

    b = 25 (20 - 25)

    c = 45 (40 50)

    Mix design

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    Mix design

    The unknowns are:

    Concrete strength B25

    Type of cement CEMIII-B

    w/c 0.65

    Amount of water .

    Amount of cement . Amount of air .

    Amount of sand .

    Amount of gravel .

    Air?

    Water?

    Cement?

    Sand?

    Gravel?

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    Mix design - Example

    Strength

    Mix design - Example

    Strength gives first indication about w/c (w/c = 0.65)

    Is this w/c also OK for durability?

    Criteria for concrete mixtures for different environmental classes

    Table 10 3

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    Environmental class

    1 2 3 4 5a 5b 5c,d

    +aea +aea

    W/c (w/b)Plain

    Reinforced

    Prestressed

    --

    0.65

    0.60

    0.70

    0.55

    0.55

    0.55

    0.55

    0.55

    0.45

    0.45

    0.45

    0.55

    0.55

    0.55

    0.45

    0.45

    0.45

    0.55

    0.55

    0.55

    0.50

    0.50

    0.50

    0.45

    0.45

    0.45

    Min. cement/binder [kg/m3]

    (Plain concrete)

    Reinf. & prestress

    Grading A-B Grading A-C

    Discontineous

    150

    260

    260

    260

    200

    280

    280

    280

    280

    280

    300

    300

    280

    280

    300

    300

    280

    280

    300

    300

    300

    300

    300

    300

    300

    300

    300

    300

    Table 10.3

    aea = air entraining agent

    Concrete strength and Norm strength N

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    g g

    c

    w/c

    bN.a(N)fccm +=

    N = Norm strength of cement = 48 MPa (for CEM III/B)

    a = 0.8; b = 25; c = 45

    (Note: Norm strength refers to mortars with w/c=0.5)

    Required w/c = 0.65

    For Env.Class 2 (table 10.3) w/c = 0.55

    For sake of safety: w/c = 0.53

    fccm

    Mix design - Example

    Mix design

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    Mix design

    The unknowns are:

    Concrete strength B25

    Type of cement CEMIII-B

    w/c 0.65 0.53

    Amount of water .

    Amount of cement . Amount of air .

    Amount of sand .

    Amount of gravel .

    Air?

    Water?

    Cement?

    Sand?

    Gravel?

    Air content and water demand

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    Air content: No requirements

    Assume: Va< 2%, e.g. 1%

    Then no effect on strength!

    Water demand: Depends on aggregate grading!

    (Table 10.11)

    Mix design - Example

    Guide values for water demand W of concrete [kg/m3 concrete]

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    Largest sieve [mm] 8 16 31.5 63

    Grade area A-B A-C A-B A-C A-B A-C A-B A-C

    Consistency 1(slump < 40 mm)

    Compaction factor > 1.26175 195 160 180 150 170 140 155

    Consistency 2

    (slump 50 90 mm) 192 213 180 200 165 185 155 170

    Consistency 3

    Slump 100 150 mm205 225 195 218 180 200 168 190

    Table 10.11

    For consistency 4no guide values are given.

    Higher consistency only by using (super)plasticizers

    Dont add water to achieve consistency 4

    Air content and water demand

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    Air content: No requirements

    Assume: Va< 2%, e.g. 1%

    Then no effect on strength!

    Water demand (Table 10.11)Consistency class 2

    Dmax < 32 mm

    Grading lines A-B

    Vw = 165 l/m3

    Mix design - Example

    Cement content and paste volume

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    Mix design - Example

    Cement content C:

    W/C = 0.53

    Vw = 165 l/m3 = 165 kg/m3

    Note: Environmental Class 2 (Table 10.3): C> 280 kg/m3: OK

    C = 311 kg/m3

    Criteria for concrete mixtures for different environmental classes

    Table 10.3

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    Environmental class

    1 2 3 4 5a 5b 5c,d

    +aea +aea

    W/c (w/b)

    Plain

    Reinforced

    Prestressed

    --

    0.65

    0.60

    0.70

    0.55

    0.55

    0.55

    0.55

    0.55

    0.45

    0.45

    0.45

    0.55

    0.55

    0.55

    0.45

    0.45

    0.45

    0.55

    0.55

    0.55

    0.50

    0.50

    0.50

    0.45

    0.45

    0.45

    Min. cement/ binder

    [kg/m3]

    Plain

    Reinf. & prestress

    Grading A-B

    Grading A-C

    Discontineous

    150

    260

    260

    260

    200

    280

    280

    280

    280

    280

    300

    300

    280

    280

    300

    300

    280

    280

    300

    300

    300

    300

    300

    300

    300

    300

    300

    300

    aea = air entraining agent

    Mix design

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    The unknowns are:

    Concrete strength B25

    Type of cement CEMIII-B

    w/c 0.65 0.53

    Amount of water 165 l.

    Amount of cement 311 kg/m3

    Amount of air 10 l (=1%)

    Amount of sand .

    Amount of gravel .

    Air?

    Water?

    Cement?

    Sand?

    Gravel?

    Cement content and paste volume

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    Mix design - Example

    Cement content C:

    W/C = 0.53

    Vw = 165 l/m3 = 165 kg/m3

    Note: Environmental Class 2 (Table 10.3): C> 280 kg/m3: OK

    C = 311 kg/m3

    Cement paste volume:

    Slag cement: C = 311 kg/m3 (311/2950) = 0.102 m3

    Water: Vw= 165 kg/m3 = 0.165 m3

    Air: Va = 1% = 0.010 m3

    Cement paste volume Vcp = 0.280 m3

    Sand + coarse aggregate V = 0.720 m3

    Amount of sand and gravel

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    Sand percentage Ps according to Rengers-Anthonisse:

    Ps = 10 Fs + 28 + 0.05 z 0.08 C

    Fs = 2.94 (Fineness modulus of sand)

    z = 70 mm (Slump value between 50 and 90 mm)

    C = 311 kg/m3 (Cement content)

    Ps = 10 2.94 + 28 + 0.05 70 0.08 311

    Ps = 36%

    Gravel percentage: Pg = 100 36 = 64%

    Mix design - Example

    Check amount of fine material < 250 m

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    Fine material (< 250 m) consists of Cement (0.102 l)

    Fillers and fine sand (see sieve analysis: 6% of sand)

    Air bubbles (Air entraining agents) (--)

    Maximum particle Dmax

    [mm]

    Minimum amount of f ine material ( 115 l OK

    Mix design - Example

    Sieve according NEN2560

    Cumulative sieve residue [%]

    sand gravel

    C 31.5

    C16

    C8

    C4

    2 mm

    1 mm

    500 m250 m

    125 m

    --

    --

    --

    3

    9

    28

    6094

    100

    --

    28

    70

    94

    100

    100

    100100

    100

    Fineness modulus F 2.94 6.92

    Mix design

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    The unknowns are:

    Concrete strength B25

    Type of cement CEMIII-B w/c 0.65 0.53

    Amount of water 165 l.

    Amount of cement 311 kg/m3

    Amount of air 10 l (=1%)

    Amount of sand 260 l.

    Amount of gravel 460 l.

    Air?

    Water?

    Cement?

    Sand?

    Gravel?

    Mix design Summary

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    RequirementsStrength B25

    Environmental class 2

    Consistency class 2

    Mixture composition

    W/c 0.53

    Cement 311 kg/m3

    Water 165 kg/m3

    Air 10 l

    Sand 36% of 720 l = 260 l

    Gravel 64% of 720 l = 460 l

    Mix design - Example

    In case of new types of mixtures: Always test mixtures!!