multi-parameter study of sulfate attack in bl d d c t m t ......bonakdar, a., and mobasher, b.,...

2010 Concrete Sustainability Conference 1 © National Ready Mixed Concrete Association

Multi-Parameter Study of Sulfate Attack in Bl d d C t M t i lBlended Cement Materials

Aboozar Bonakdar , PhD CandidateBarzin Mobasher, PhD, PE, FACI

School of Sustainable Engineering and the Built EnvironmentDepartment of Civil, Environmental, and Sustainable Engineering

ARIZONA STATE UNIVERSITY

Concrete Sustainability Conference, April 13-15, 2010, Tempe, AZ


Cement & Concrete Technology:Temporal, Spatial, and Scientific Span

Disciplines

• Materials Science• Engineering• Chemistry• Mechanics • Computational Techniques• Manufacturing products and systems

Time

hydration Early age Long termService life

• Manufacturing products and systems• Sustainable development• Technical & non-technical labor poolnanometers to kilometers

(1x10-6 to 1x103 meters)

Space

Seconds to Centuries

(1 to 3x1010 Seconds)

y Early age Performance


Primary Incentives Research Theme

• Sustainability– Shrinking resources– Increasing demand– Globalization– Social justice & technology transfer

• Quality of life– Provide modern, energy efficient, and economical infrastructure for

societies with a growing middle class population

• Economical Development – Conservation of energy, time, resources, & cost– Value added products for infrastructure


Outline

•Overview of Research Group activities

D bilit f t t i bilit i•Durability of concrete as a sustainability issue •Performance based specification, long term performance , economical materials selection, and life cycle cost• Models applicable to a host of transport related problems•Sulfate attack- case study

• Experimental program• Macroscopic expansion, what do ASTM results mean?• Microstructural studies

Transport properties• Transport properties• Mechanical properties

• Modeling• AssumptionsAssumptions• Parametric study and Verification


Concrete in Arizona- Pay Factors, Statistical Process Control

Source: ADOT Database for One ready mix supplier over a course of two years

10000

All concrete classes28 day strength

Over-strength LevelAt $100-$400 per cubic yard, $1.5-6 Billion industry in Arizona

8000

ngth

, psi

4000

6000

Del

iver

ed S

tren

o = 100 cubic yards

2000 4000 6000S ifi d f' i

2000

D

Specified f'c, psi

Laungrungrong, B., Mobasher, B., Montgomery, D., “Development of Rational Pay factors Based on Concrete Compressive strength Data, Arizona Department of Transportation,”, SPR 608, 2008.

B. Laungrungrong, B. Mobasher, D. C. Montgomery, and C. M. Borror, “Hybrid Control Charts for Active Control and Monitoring of Concrete Strength ” ASCE Journal of Materials Engineering Jan 2010


Housing is a human rights issue

• Navajo Nation is 27,000 square miles in the states of AZ, NM, and UT, geographically is the largest Native American reservation in the U.S.

•The Navajo Nation has the highest poverty rate in the U.S. More than 56% of Navajos live below the poverty level

•Unemployment rate is 44 percent, median family income is $11,885, Per capita income is $6,217.

•The population has increased 3.5 times from the 50 000 people in 194050,000 people in 1940.

•Most homes do not have electricity, running water, or telephones.


Aerated Fiber-Reinforced Concrete (AFRC)Block Manufacturing & Construction Methods

Demonstration Home in Town of Guadalupe, AZDesigned by ASU Stardust CenterDesigned by ASU Stardust Center

•Thermal Mass• Airtight, Whole wall coverage•reduce HVAC Equipment•Reduces energy consumption•Fire Resistant, 8” Bearing wall, 4 hour UL fire rating


Properties of AFRC

LVDT-1Actuator

-Energy efficient, Effective R-value, 3.4/in,Fire Pest resistant

LVDT-2

- Fire, Pest resistant- Durable, no autocalve- Acoustical insulation- Energy absorbing- Easy to use


Thermal Insulation of Concrete Homes

Thermal properties (200x200x20 mm plates)(200x200x20 mm plates)

50Experiment, Tout

Experiment, Tin

30

40

Tem

pera

ture

, 0 C

Simulation, Tin

Experimental and thermal simulation of insulation of concrete walls 0 10 20 30 40

Time, h

20

T


Durability of concrete

• Major concerns: • Life cycle cost• Premature failure and serviceability issues

• Design codes: • Durability- is a black box issue• Main criterion: compressive strength, W/C, empirical tests

P t ti t h i Wh t d t t lt ll ?• Proper testing techniques: What do test results really mean? • Key parameters affecting the durability: multi-scale and multi-variant•Transport mechanisms dominate major durability issues • Alkali silica reaction (ASR), sulfate attack, carbonation, leaching, frost resistance and corrosion•Damage by sulfate attack: building foundations, bridge, piers.

Before sulfate exposure

After sulfate exposure


External Sulfate attack

• Diffusion of sulfate ions into concrete and reaction with cement paste:• Dissolution of portlandite (CH) and decomposition of C-S-H phase • Formation of gypsum and/or ettringite crystals, vol. expansion

263 HSACHHSCAC →++

• Formation of ettringite: topochemical reaction: may cause expansion and cracking of the hardened cement

323623 263 HSACHHSCAC →++• Volume of reaction products >> volume of reactants • Need for better mechanics based models

• Blended cements improve sulfate resistance by reducing the porosity (diffusion) and lt i th h i l ti (l C A)altering the chemical reactions (less C3A)


Experimental program

• Hypothesis: • Can effect of different fly ash compositions be directly related to performance?• How do you measure performance?

•Type I/II portland cement + 7 different fly ashes (class F, C)•Tests: ASTM C 1012, XRD, microstructural studies (SEM/EDS), ionic diffusion (EDS, PIXE), micro-hardness, flexural response, fracture parameters

Cement F1 F2 F3 C1 C2 O

SiO2 21.62 62.93 58.72 56.48 52.16 37.2 41.1S O2 6 6 93 58 56 8 5 6 3

Al2O3 4.06 22.84 24.86 25.61 30.11 20.39 17.37

Fe2O3 3.54 4.01 4.94 3.01 2.71 5.32 3.45

CaO 63.90 2.57 4.56 3.22 8.93 25.91 19.8

M O 1 40 1 64 1 57 1 67 1 37 3 79 1 33MgO 1.40 1.64 1.57 1.67 1.37 3.79 1.33

SO3 2.81 0.14 0.21 0.38 0.51 1.93 10.12

Na2O 0.06 1.46 1.11 1.22 0.51 1.88 0.96

K2O 0.54 1.53 1.11 1.49 1.55 0.45 0.78


Properties of studied fly ashesSEM and XRD for fly ash particles


Expansion (ASTM C 1012)

Specimen size: 1x1x11 in (standard) vs. 0.4x0.4x4 in (modified)

0.1

0 06

0.08

, %

Standard SizePaste with 20% Fly ash

0.04

0.06

Expa

nsio

n,

ControlF1F2F3

0 100 200 300 400 500 6000

0.02 F3C1C2O

Exposure Time, Days

Hypothesis: can smaller specimens be used in order to measure the same material properties for modeling, what does 0.1% expansion mean?


Expansion: modified vs. standard

paste mixture

1”x1”x11”0.24

mm

E i t l D t

.4”x.4”x4”0.16

pans

ion,

% . Experimental Data

Initial Linear FitFinal Linear Fit

1

1.8

Size effect consideration: SA/V0.08

Mod

ified

Exp

11

1R2 = 0.60

5.217.042.0

)/()/( tan ≈=

Modified

dardS

VSAVSA

0

Nor

mal

ized

M 1

Normallization Factor = 2.5

R2 = 0.86

Normalization Factor: 2.5

Bonakdar, A., and Mobasher, B., “Multi-Parameter Study of External Sulfate Attack in Blended Cement Materials ” Construction and Building Materials 24 (2010) 61–70 2009

0 0.03 0.06 0.09Standard Expansion, %

N


Expansion: mortar vs. paste

• Effect of aggregates is undeniable:0.5Experimental Data

standard ASTM size

- Creating ITZ in mortar - Increase of porosity due to ITZ- Higher rate of diffusion - Higher expansion values

0.3

0.4

sion

, %

Experimental DataOverall Exponential Fit

• Developing specifications for every combination of cement-fly ash-aggregate becomes improbable

0.2

orta

r Exp

ans

ln(Y) = 69.46 X - 5.90R2 = 0.52

• Need performance based specifications to address internal mechanisms

• How to address empirically based 0 0 03 0 06 0 09

0

0.1M

“effective transport parameters”?

Bonakdar & Mobasher, Journal of Construction and Building Materials, 2009

0 0.03 0.06 0.09Paste Expansion, %


Microstructural studies (SEM/EDS)

Specimen size: 0.4x0.4x0.4 in (used in expansion test)

Formation of ettringite crystals in pores

Bonakdar & Mobasher, Journal of Construction and Building Materials, 2009


Measurement of Other Properties

• Can we get extra information using the same specimens ?

1”1”

1/4”

• Microstructural studies-SEM EDS

or

SEM, EDS

• Transport properties-1D diffusion

2D diffusion

1x1x5”

- 2D diffusion

• Mechanical properties- Strength

Stiffness- Stiffness- Hardness


1-D diffusion using PIXE

12000

16000

20000

unts

1-4-1, w/c=0.7

Position 1Position 2Position 4Position 5Position 6

Si PIXE (Particle Induced X-ray Emission)

4000

8000

12000

Elem

ent C

o Position 6Position 7Position 8

S

AlNaK

Ca

CaTi

400

600

unt

Control (Experiment)Blended (Experiment)Error Function (Fitted)

Concentration of Sulfates (Mortar)0 1 2 3 4 5

Energy, KeV

0Ti

200

400

Sul

fur A

rea

Cou

Control: D = 2.4 x10-11

k = 4.4 x10-8

Blended: D = 1.6 x10-11

k = 2 2 x10 8

Specimen size: 2x2 in cylinders 0 10 20 30 40 50

Specimen Depth, mm.

0

k = 2.2 x10-8


2-D diffusion using EDS

Specimen size: 1x1x0.25 in (used in expansion test) 1”

1”1/4”1.6

1 2 3 4 5

5

4.8

6.4

25 mm

6.4

4

3

2

1.6

4.8

1

Sulfur Content, % (Interpolated Data)

0 8

0.9

11

12Calcium Content, % (Interpolated Data)

0 8

0.9

22

23

Diffusion of sulfur Leaching of calcium

Y, i

n

0.4

0.5

0.6

0.7

0.8

6

7

8

9

10

Y, i

n

0.4

0.5

0.6

0.7

0.8

18

19

20

21

Interpolated contour plots for diff t l t

X, in

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0.1

0.2

0.3

2

3

4

5

X, in

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0.1

0.2

0.3

16

17

18different elements


Mechanical properties

Control (no fly ash) Blended (30% class F fly ash)160

No 1: Control (Mortar)S/C=2.0, W/C=0.5, Curing=1 Month

160

No 2: Blended (Mortar)S/C=2.0, W/C=0.5, Curing=1 Month

Specimen size: 1x1x5 in80

120

l Loa

d, lb

f Before Exposure 3 Months Exposure12 Months Exposure

, , g

80

120

l Loa

d, lb

f Before Exposure 3 Months Exposure12 Months Exposure

, , g

Specimen size: 1x1x5 in(used in expansion test)

40

Flex

ural

40

Flex

ural

0 0.002 0.004 0.006

CMOD, in

00 0.002 0.004 0.006

CMOD, in

0

Ratio: Blended/Control MORElastic Flex.

StiffnessBefore exposure 0.81 1.04

3m exposure 0.85 0.7512m exposure 1.19 2.21


Modeling Steps

• Components of a diffusion reaction-micromechanics based damage model.

Tixier & Mobasher, ASCE, Materials Journal, 2002


Diffusion/Reaction Based Model

U Plane of symmetryU

Calcium Aluminates

U0 U0U0 U0

Sulfates,U

at t>0

at t=0

0 L0

ConcentrationProfile

0 L0

HSAC26H HS3C A C HSAC16H 2CSH HSACCH HSAC 14H HS3C AHC

323623

32362124

32362134

⇒++

⇒++

+⇒++

3236 HSACSqCA ⇒+ettringitesummarize

XX

Tixier & Mobasher, ASCE, Materials Journal, 2002

CA = C4AH13 (monosulfate and residual C3A combined)q = equivalent stoichiometric coefficient

323623


Transport properties

• Durability-related phenomena: one or more transport mechanisms: movement of water and chemicals in to or out of concrete

• Ionic diffusion: predominant transport mechanism in most cases• Ionic diffusion: predominant transport mechanism in most cases

• Sulfate attack: ionic diffusion + chemical reaction

)()( 2 txCtxC ∂∂ )(}),,(),,({),,(222

CtyxCtyxCtyxC ∂∂∂

Concentration Contour - with reaction

45

50

0.9

1

)(),(),(:1 20 CRx

txCDt

txCD +∂

∂=∂

∂− )(}),,(),,({),,(:2 220 CRy

tyxCx

tyxCDt

tyxCD +∂

∂+∂

∂=∂

∂−

80

90

100Concentration Profile - with reaction

without reactionwith reaction

1D Solution using error

Y-D

epth

, mm

20

25

30

35

40

0.4

0.5

0.6

0.7

0.8

40

50

60

70

80

C/C

0, %

with reaction

D=10-12 (m2/s)

using error function

X-Depth, mm

0 10 20 30 40 50

0

5

10

15

0

0.1

0.2

0.3

0 5 10 15 20 25 30 35 40 45 500

10

20

30

40

k=10-8 (1/s) 2D Solution using series


Volumetric Changes & Damage Evolution

• The result of reaction between sulfates and C3A is formation of delayed ettringite which has a lot more water molecules and consequent volume change.

M ( / l ) ( / 3)

32623 263 HSACHHSCAC →++

Mi (g/mole) ρi(g/cm3) ai

C3A 270 3.04 3

Gypsum 138 2.32 1

Ettringite 710 1.75 3

∑∑ ±==Δi i

ii

ii

MaVVρ.

r)

Da

Stress-Strain CurveDegraded SlopeDamage Functionft

reactedreacted SVV .Δ=Δ

reactedVt Δ== )(εε ensi

le S

tress

(σr

amage Function

E' = E0 (1- ω) E'

E

specimenVV V

t)(εε

Tixier & Mobasher, ASCE, Materials Journal, 2002T il St i ( )

Te (ω)

'E' decreasing nq

dxx ])(1.[)( 0 −=σσ

u(x)

d


Parametric study

Effect of reaction term(on the concentration)

Effect of diffusion term(on the stiffness and expansion)

20000

25000

MPa

Modulus of Elasticity

0.08

0.1

Expansion

D1=10-12 D2=10-13 D3=10-140.6

0.8

1

/U0

0 5 10 15 20 25

without reaction (k=0)

D = 5x10-13 m2/s

10000

15000

of E

last

icity

, M0 04

0.06

Expansion,

w/c = 0.4E0/E1 = 75%k = 10-7

D1 10 2 3

'D' decreasing0

0.2

0.4U/

1 month

12 months

0 8

1

5000

10000M

odul

us

0.02

0.04 %k = 10

D1=10-12 D2=10-13 D3=10-14

0.2

0.4

0.6

0.8

U/U

0 with reaction (k=10-7)

D = 5x10-13 m2/s

12 months

0 100 200 300 400

Exposure Time, Days

0 00 5 10 15 20 25

X, mm

01 month


Parametric study

Effect of W/C ratio(on the expansion values)

Effect of C3A content(on the expansion values)

0.3

0.4

W/C = 0.8 (Experiment)W/C = 0.8 (Model)W/C = 0.6 (Experiment)W/C = 0.6 (Model)W/C = 0.45 (Experiment)W/C = 0 45 (Model)

Ouyang et al. Data(1988)

0.3

0.4

C3A = 8.8% (Experiment)C3A = 8.8% (Model)C3A = 7.0% (Experiment)C3A = 7.0% (Model)

Ouyang et al. Data(1988)

0.2

xpan

sion

, %

W/C = 0.45 (Model)

S/C = 4E0/E1 = 80%α = 75% W/C = 0.6

W/C = 0.8D = 7.5x10-12

k = 4.0x10-7

0.2

0 3

pans

ion,

%

C3A = 4.3% (Experiment)C3A = 4.3%(Model)

D = 5x10-12

k = 1-1.5x10-7

W/C = 0.6S/C 0

C3A = 8.8%

0.1

Ex α 5%

C3A = 5%ft = 1.7-2.0 MPa

W/C = 0.45D = 5x10-12

k = 2 5x10-7

D = 6x10-12

k = 3.0x10-7

0.1

ExS/C = 4.0α = 80%ft = 2 MPa

7.0%

0 40 80 120

Exposure Time, %

0k = 2.5x10-7

0 100 200 300

Exposure Time, %

04.3%


Model Verification

Prediction of modulus of elasticity Prediction of expansion

40

50

Pa

Ferraris et al. Data(2006)

0.25

0.3Ferraris et al. Data(2006)

S/C = 2.75W/C = 0.485C3A = 5%

30

40

f Ela

stic

ity, G

P

SF:D = 1x10-13

k = 1x10-7

0.15

0.2

ansi

on, %

ControlD = 2x10-12

k = 2.5x10-7

FA_F(Class F flyash):D = 7x10-13

k = 1.5x10-7

10

20

Mod

ulus

o

Control (Experiment)Control (Model)SF (Experiment)SF (Model)

ControlD = 2x10-12

k = 2.5x10-7

w/c = 0.485C3A = 5% 0.05

0.1Exp

a

Control (Experiment)Control (Model)FA_F (Experiment)FA_F (Model)SF (Experiment)SF (Model)SF (Silica fume):

D = 1x10-13

k = 1x10-7

0 100 200 300 400 500

Exposure Time, Days

00 100 200 300 400 500

Exposure Time, %

0


Model Verification

Prediction of expansion (current study)

0.1 5E-007

Effect of D and k in modeling

0.08

%

Control (Experiment)Control (Model)30% Flyash (Experiment)30% Flyash (Model)

Control: D 8x10 13

4E-007

3 /(m

ole.

s)

Ouyang Data (OPC)Sahamaran Data (OPC)Current Study (OPC)Ferraris Data (Blended)Sahamaran Data (Blended)Current Study (Blended)

0.04

0.06

Exp

ansi

on, %

30% Class F: D=4x10-13

E0/E1 = 0.5

Control: D=8x10-13

E0/E1 = 0.45

2E-007

3E-007

f Rea

ctio

n, m

3 Current Study (Blended)

Zone 1: Fly ash BlendedZone 2: OPC

0

0.02

Current Study: Expansion of Pastes

W/C = 0.4α = 70%k = 1x10-7

ft = 2 MPa1E-007

Rat

e of

Zone 1 Zone 2

0 100 200 300 400 500 600Exposure Time, Days

01E-014 1E-013 1E-012 1E-011

Coeffidient of Diffusion, m2/s


Conclusions

• Effect of various fly ashes on the sulfate resistance of concrete was studied using traditional and developed test methods .

• ASTM C1012 test method using 1x1x11 inch specimens can take up to 12 months for results. Using modeling, smaller size specimens accelerates the reactions and provides results in much shorter titimes.

• Supplementary tests were performed in order to obtain the diffusivity (D) and reactivity (k) of sulfate ions in 1-D and 2-D cases using characterization techniques.

• Flexural tests were performed on exposed samples which showed quantitative measurements of the damage evolution from sulfate q gattack.


Conclusions

• A predictive model is presented based on cement chemistry, concrete physics and solid mechanics.

• Key factors in modeling are: C3A content and reactivity, internal porosity and ionic diffusivity.

• Input parameters are compatible with experimental data.

• Effects of degradation, specimen size, curing duration, and material ingredients can be verified using the modelingredients can be verified using the model.

• SULFATE2 computer program can be downloaded on the link to the web site is as follows: http://ciks cbt nist gov/~bentz/phpct/cmml htmlhttp://ciks.cbt.nist.gov/~bentz/phpct/cmml.html


Acknowledgement

• Work Conducted under support from ADOT Project SRR-633 Economical Concrete Design, (Christ Dimitroplos,633 Economical Concrete Design, (Christ Dimitroplos, Program manager). Support of Salt River Materials Group, SRMG, (Jeff Hearne) for the experimental portions of the project is greatly appreciated. p j g y pp


ASR Reaction Products

Control: swelling gels fly ash Blended: safer gels

Bonakdar, Mobasher, Dey, Roy (2010), ACI Materials Journal, V. 107, No.


Chemical Composition vs. Expansion

0.2

0.25

14 Days28 Days0.2

0.2514 Days28 Days

0.1

0.15

xpan

sion

, % Y = 0.094 (Ceq/Seq) - 0.129R2 = 85%

0.1

0.15

xpan

sion

, %

Y = 0 114 (C /S ) - 0 077

0

0.05

Ex

Y = 0.081 (Ceq/Seq) - 0.139R2 = 89%

0

0.05

Ex

Y = 0.099 (Ceq/Seq) - 0.096R2 = 81%

Y = 0.114 (Ceq/Seq) - 0.077

R2 = 75%

eqsimplified

eq

C CaO( )S SiO Al O

=+2 2 3 )37605890(01

)700.0595.0905.0(0.6)( 322

OFeOAlSiOSOOKONaCaO

SC

MLeq

+++++=

1 1.5 2 2.5 3 3.5 4Total Ceq/Seq Ratio (ML)

01 1.5 2 2.5 3 3.5 4

Total Ceq/Seq Ratio

0

eqS SiO Al O+2 2 3

• One can use this fitted equation to estimate the optimum Ceq/Seq ratio for a required expansionlimitNote: ML formula includes molar equivalents and reaction factors (Malvar and Lenke , 2006)

)376.0589.0(0.1 32322 OFeOAlSiOSeq ++

Bonakdar, Mobasher, Dey, Roy (2010), ACI Materials Journal, V. 107, No.


Effect of Fiber-Reinforcement

Flexural properties on 150x150x450 mm prisms

time =0 minCOD=0.0 mmfR=0.00 MPa




time =24 minCOD=18 mmfR=0.13 MPa


Full-Scale Testing of AFRC

Shear wall test results

Note: Фs.Vn: factored shear capacity, Vu: un-factored shear capacity, Фs.Vu: factored service loadload

60

80

Shear Wall Test (2.4x2.4x0.2 m setup)

60

80

Shear Wall Test (2.4x2.4x0.2 m setup)

φs.Vn = 68.7 kN

40

She

ar L

oad,

kN

40

She

ar L

oad,

kN

φs.Vu = 34.3 kN

Vu = 54.9 kN

0 1 2 3 40

20

S

0 4 8 12 160

20

S

0 1 2 3 4

LVDT-1, mm0 4 8 12 16

LVDT-1, mm

magnified


AAC vs. AFRC

AAC (plain, autoclaved) AFRC (fiber-reinforced, non-autoclaved)

600

f

Flexural Response for AFRC Beams (6x6x18 in)

600

f

Flexural Response for AAC Beams (6x6x18 in)

200

400

exur

al L

oad,

lbf

AFRC - Samples 1-4

200

400

exur

al L

oad,

lbf

AAC - Samples 1-4

0

200Fle

Average σR = 77 psi

0

200Fle

Average σR = 93 psi

0 0.05 0.1 0.15 0.2 0.25 0.3

CMOD, in

00 0.004 0.008 0.012 0.016 0.02

CMOD, in

0

Note the difference between scales on X-axis

multi-parameter study of sulfate attack in bl d d c t m t ......bonakdar, a., and mobasher, b.,...

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