Advancements in Predictive Modeling for Concrete · PDF filePredictive Modeling for Concrete Structures Matt Miltenberger, ... Burj Dubai (Dubai, UAE) 24 ... Depth Into Concrete (Inches)

1

Advancements in Predictive Modeling for

Concrete Structures

Matt Miltenberger, P. E.

Applications

• Parking Structures• Marine Structures• Bridges / Pavements• Foundations• Coastal Buildings

2

Need for Predictive Models

Issues to Consider for Modeling

History of Predictive Models

Discussions of Various Predictive Models

Case Studies

Agenda

• Asset management

• Protection system selection

• Preventative maintenance programs

• Due diligence for leases and sales of properties.

• Comparision of restoration options


3

Where you don’t need predictive models...





Case Studies

Agenda

4

Service Life Expectations

Concrete Properties

Exposure Conditions

Costs

Predictive

Model

Inputs

Primary Considerations

What isService Life ?

…Time to collapse

…Time to major repair

…Time to ANY repair

5

Complicating Issues for Modeling

Initial Protection

Subsequent Protection

Climate (T & RH)

Reinforcing System

Wet / Dry Conditions

Exposure Zones

Transport Properties

Surface Treatments

Cracking Effects

Multiple DegradationTraffic Patterns

Variation in Concrete Properties

Curing Effects

• Concrete Properties (Transport)

• Exposure Conditions

• Existing Protection Systems

• Past Protection Systems

• Level of Contamination

• Physical Degradation

• Cracking (Micro and Macro)

• Degradation Mechanisms (Corrosion, ASR, DEF, Sulfate Attack, etc.)

Common Modeling Inputs / Considerations

6





Case Studies

Agenda

• Experience Models

• Tutti Models

• Diffusion-Based Models

• Multiple Transport / Degradation Models

History of Service Life Models

Primarily all models were designed for new construction and not for existing concrete structures.

7

Experience Models (<1980’s)Pros Cons

� Easily understood� Statistical

approach� Fact-based� Identifies trends� “Reality Check”� Basis for generic

comparison

� Inconsistent data � No scientific basis

for evaluating new technology

� Assumes static technology and environment

� Difficult to support claims on specific projects

Pros:

• Time is always beneficial.

Cons:

• Service expectations exceed expertise

• Many technologies are relatively new

• Concrete and reinforcing chemistries have

changed over last 30 years dramatically

• Difficulty in supporting claims of performance

• Case Studies

Experience Model

8

Pros:

• Very Simplistic

• Conceptually and directionally good

• Applicable mostly to singular degradation

Cons:

• Too simplistic

• Doesn’t have the mechanism for quantification

Tutti Model

Time

Det

erio

ratio

n

Chl

orid

e-In

duce

dC

orro

sion

Tutti Model (1980’s)

PropagationPeriod

CorrosionInitiation

AcceleratingDamage

Chloride IngressDet

erio

ratio

n

DamageInitiation

Transport Phase Damage Propagation

9

Tutti Model - 1980’sPros Cons

� Very simplistic� Conceptual / Intuitive� Fact-based� Bi-linear approach� Simple calculation

� Too simplistic� Poor quantification� Educated guess� Assumes static

technology and environment

• Builds on Tutti model

• Standard test method

• Single transport mechanism

• Applicable to saturated environments

• Not applicable for many structures

Diffusion-Based Models

10

Time

Det

erio

ratio

n

Chl

orid

e-In

duce

dC

orro

sion

Modified Tutti Diagram Model

CorrosionInitiation

AcceleratingDamage

Chloride Ingress

Diffusion

ASTM C 1556 Bulk Diffusion Test

11

Depth (mm)

0,0

2,0

4,0

6,0

8,0

10,0

0 5 10 15 20

Chl

orid

eC

onte

nt (

g/kg

)

ExperimentalExperimentalBest fit to dataBest fit to data

ASTM C1586 Bulk Diffusion Test

XX XX

12

XX XXDe = X De = 10X

0

5

10

15

20

25

30

Depth Increment

Chl

orid

e C

onte

nt P

CY Exposed

Protected

Exposure conditions influence test resultEffective diffusion is not a true property!

XX XX

Diffusion is NOT the primary transport mechanism for:• cyclic wet/dry environments• evaporative environments • structures with coatings and sealers

13

Diffusion-Based Models (1990’s)Pros Cons

� Improvement over bi-linear calculation

� Empirical-based� Captures non-

linear behavior� Standard tests

available� Widely accepted

� Testing required� Assumes static

technology and environment

� Invalid model assumptions

� Model easily misused� Single transport

mechanism





Case Studies

Agenda

14

Life-365 TM

Life-365 Service Life Prediction Model TM

for Reinforced Concrete Exposed to Chlorides

Version 1.1

Life-365 Service Life Prediction Model and Life-365are trademarks of the Silica Fume Association.

Used with permission

Modified Tutti Model

Time

Det

erio

ratio

n

Chl

orid

e-In

duce

dC

orro

sion

CorrosionInitiation

AcceleratingDamage

Chloride Ingress

Life 365

PropagationPeriod Fixed

ChlorideBuild-up &Diffusion

15

Key Build-up Cs(wt. %/yr) (%)

< 0.02 0.2

0.04 to 0.08 0.6

0.08 to 0.12 0.8

> 0.12 1.0

No data available

0.02 to 0.04 0.4

Values are for Parking Structures

Environmental Characterization

Pros:• Applicable for new construction• Graphic user interface – easy to use• Database-driven selection of defaults• User selected concrete mixture and treatments• Allows user to input tested values• Addresses time & temperature-dependant behavior• Addresses sealers and membranes

Cons:• Easily manipulated• Not applicable for existing structures• Not applicable for evaporative transport

Life 365 ModelR

16

• Finite Element Model Architecture

• Coupled Multiple Transport Mechanisms – Diffusion

– Advection

– Electrical Coupling

• Simultaneous Chemical Reactions

• Tracks 9 Ionic Species in/out of Concrete (Including OH/Cl)

• Tracks 9 Solid Phases Forming and Dissolving in Concrete

• Converted to 2-Dimensional (for crack modeling)

• Validated

STADIUM ModelR

17

Consortium (SUMMA)

VTRC QDOT

LOGO

Laboratory Testing – Durability Parameters

20 V

NaCl +NaOHNaCl +NaOH NaOHNaOH

ASTM C642 - Porosity

18

Solid phases after 70 years (Type I)

0

20

40

60

80

100

120

140

160

0 40 80 120 160 200Position (mm)

So

lid p

hase

co

nten

t (g

/kg)

Calcium Hydroxide

AfmCSH

Brucite

Friedel's salt Ettringite

Tim e to Corrosion 60 years (Type I)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 20 40 60 80 100 120 140 160 180 200

Thickness (mm)

Tot

al C

hlor

ide

[g/k

g]Service Life Prediction

Software

0

100

200

300

400

500

600

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50

Distance from the exposed surface (m)

Con

cent

ratio

n (m

mol

/L)

Cl OH

Na

KCa

SO4

STADIUM Output STADIUM Output ExamplesExamples

19

0.45 Type V concrete slab exposed to 2500 ppm of su lfateSolid phases after 80 years

0

20

40

60

80

100

120

140

160

0,00 0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08 0,09 0,10

Position in the slab (m)

Sol

id p

hase

con

tent

(g/k

g)

Gypsum

C-S-H

Portlandite

Ettringite

Monosulfates

STADIUM Output STADIUM Output ExamplesExamples

Testing of Existing Structures

Exposure ProfilingExposure ProfilingDeterioration AnalysisDeterioration Analysis““SurfaceSurface--CreteCrete”” TransportTransport

Initial Pore Solution ChemistryInitial Pore Solution ChemistryInitial Solid PhasesInitial Solid Phases

Ionic TransportIonic TransportMoisture TransportMoisture TransportPorosityPorosity

Exposed Surface

20

Time

Det

erio

ratio

n

XX

X – Known by evaluations

Predictive Modeling

Time

Det

erio

ratio

n

XX


STADIUM Predictions

Predictive Modeling

21

Time

Det

erio

ratio

n

XX


STADIUM Option Analysis

Predictive Modeling

Time

Det

erio

ratio

n

Cor

rosi

on

ASR

Sulfate Attack

DEF

Deterioration Mechanisms

22

Time

Det

erio

ratio

n

Cor

rosi

on

ASR

Com

bine

d

Sulfate Attack

DEF

Deterioration Mechanisms

Pros:

• Validated and industry supported model

• Flexible to capture real world complexities

• Useful for both new and existing concrete

• Useful for both cracked and uncracked concrete

Cons:

• More testing of existing properties and conditions

• More complicated and incremental cost

Multiple Transport / Degradation Model

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There are no simple answers to complex situations!

Allow good science to lead toward better business solutions.

• World’s Tallest Building

Burj Dubai (Dubai, UAE)

24

Artist’s Sketch

U.S. Navy - Modular Hybrid Pier

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Where Can These Advance Modeling Tools Be Used ?

• Condition Assessments

• General Maintenance Programs

• Budgeting / Justification / Prioritization

• Construction Variance Resolution

• Due Diligence Tool – (Assign Future Maintenance/Repair Costs )

• Baseline Conditions for Leasors/Leasees





Case Studies

Agenda

26

Artist’s Sketch

U.S. Navy - Modular Hybrid Pier

Concrete Porosity (ASTM C642)

Tests were conducted on both lightweight and normal weight concrete. (56, 120, 270, and 365 days moist curing).

Table 7 – ASTM C642 Test Results (Absorption)

Manufacturer Type of Concrete

Absorption (after immersion %)

Absorption (after boiling %)

56 d* 120 d* 56 d* 120 d*

Light Weight 9.21 9.34 9.84 9.72 Coreslab Normal 5.14 4.19 5.46 4.47

Light Weight 12.2 12.0 12.8 12.6 Bellingham Normal 6.32 6.10 6.78 6.67

Light Weight 4.68 4.41 4.99 4.60 Clark Pacific

Normal 4.03 4.40 4.16 4.37

* Moist Curing Period

Concrete A

Concrete B

Concrete C

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Ion Migration Test (ASTM C 1202 Modified)

0

50

100

150

200

250

0 50 100 150 200 250 300

Time (hours)

Cur

rent

(m

A)

Disc A

Disc B

20 V

NaCl +NaOHNaCl +NaOH NaOHNaOH

05

101520

253035

4045

0 100 200 300 400

Duration of curing period (days)

DO

H -E

-12

(m2 /s

)

Producer A

Producer B

Producer C

Ionic diffusion coefficients

28

Pore Solution Testing

Test developed and validated at Purdue University (Dr. Sidney Diamond)

Moisture Transmission Test Moisture Transmission Test (ASTM E 96) (ASTM E 96)

Salt Solution

Water Container

ConcreteSample

To Scale

0

10

20

30

40

0 200 400 600 800

Time (hours)

Moi

stur

e up

take

(g)

58% R.H.58% R.H.

81% R.H.81% R.H.

Concrete samples cured for 56 and 365 days

29

Immersion Tests

Testing seawater exposure from one dimension for va rious periods of time.

Ion Content (ppm)

Chloride 17100 Sodium 8620 Sulfate 2820

Magnesium 1180 Potassium 684 Calcium 404

Seawater Composition

Concrete Samples

Saline Solution Wax Coating

Container Cover

Chloride Ion Determination and Profiling

ASTM C1152 Method. Chloride profiles were obtained by milling thin layers from surface.

30

00

22

44

66

88

1010

1212

00 55 1010 1515 2020 2525

Tot

al c

hlor

ides

(g/

kg)

Tot

al c

hlor

ides

(g/

kg) ExperimentalExperimental

Numerical Numerical simsim..

0

2

4

6

8

10

12

0 5 10 15 20 25

Depth (mm)

Chloride immersion tests

Producer C – Curing 56 days

40 days40 daysof immersion of immersion

120 days120 daysof immersionof immersion

ExperimentalExperimentalNumerical Numerical simsim..

Chloride immersion tests

Producer C – Curing 365 days

0,0

2,0

4,0

6,0

8,0

10,0

0 5 10 15 20Depth (mm)

Chl

orid

eC

once

ntra

tion

(g/k

g)

ExperimentalExperimental

0 5 10 15 20

ExperimentalExperimentalNumerical Numerical simsim.. Numerical Numerical simsim..



31

0

20

40

60

80

100

120

140

0 20 40 60 80 100

Years

[Cl- ]/[

OH

- ]

Time Dependent Cl / OH at Depth of 25mm

Corrosion Initiation

• Wharf crane rail beams had variances in concrete cover.

• Resolution process:

– Assess the degree of cover variance.

– Quantify exposure levels.

– Evaluate as-designed service life expectation.

– Evaluate as-built service life expectations.

– Provide repair designs as needed.

Port of San Diego (San Diego, CA)(Construction Variance)

View Along Wharf Cover Measurements

32

Chloride Evolution - Concrete without XYPEX

0.0

0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30 35 40 45

Years

Chl

orid

e C

once

ntra

tion,

g/k

g

¾ in. 1 in. 2 in. 2½ in. Threshold

“As-Built” without Xypex

33

“As-Built” with XypexChloride Evolution - Concrete with XYPEX

0

0.5

1

1.5

2

2.5

0 5 10 15 20 25 30 35 40 45

Years

Chl

orid

e c

once

ntra

tion,

g/k

g


“As-Specified” without XypexChloride Evolution - Concrete UV

0.0

0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30 35 40 45

Years

Chl

orid

e C

once

ntra

tion,

g/k

g


34

35

36

STADIUM Predictive Results

0

5

10

15

20

0 1 2 3 4 5

Depth Into Concrete (Inches)

Chl

orid

e Io

n C

onte

nt (

PC

Y)

Corrosion ThresholdThreshold

RebarRebarYEAR 0


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 2

No Treatment

Single Sealer Application

Periodic Sealer Application

Traffic Bearing Membrane

37


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 4

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 6

No Treatment




38


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 8

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 10

No Treatment




39


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 12

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 14

No Treatment




40


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 16

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 18

No Treatment




41


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)

Corrosion ThresholdCorrosion Threshold

RebarRebarYEAR 20

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 22

No Treatment




42


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 24

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 26

No Treatment




43


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 28

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 30

No Treatment




44


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 32

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 34

No Treatment




45


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 36

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 38

No Treatment




46


0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarYEAR 40

No Treatment





0

5

10

15

20

0 1 2 3 4 5


Chl

orid

e Io

n C

onte

nt (

PC

Y)


RebarRebarRecap

No Treatment




Yr 10

47

(269)384-9980(269)384-9981 Fax

Matthew Miltenberger, P.E. [email protected]

www.tourneyconsulting.com

Documents

Advancements in Predictive Modeling for Concrete · PDF filePredictive Modeling for Concrete Structures Matt Miltenberger, ... Burj Dubai (Dubai, UAE) 24 ... Depth Into Concrete (Inches)