session 4 reference values for durability design dr. paul j. tikalsky, p.e., faci the pennsylvania...

Session 4 Reference Values for Durability Design

Dr. Paul J. Tikalsky, P.E., FACIThe Pennsylvania State University

USA

Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

Defining Durability

Detailed Knowledge Structural Requirements Environment Material Science Deterioration Mechanisms


Structural Requirements

Define the precise design functionCompression, Tension, Shear, Combined?Stiffness? Brace? Load Sharing?

Define the structural design RV

Define the long term and short term behavioral requirements of the structure

Define the desired design life


Define the Environment

Concentrations of chemical and gases

Wet/Dry cycles

Freeze/Thaw cycles

Physical loadings AbrasionFluid contact and velocity

Vibrations/Repeated cycles


Level of Chemical Exposure

Chemical ExposureSulfate concentration (0-5% SO4

-2)Chloride concentration (0-3 kg/m3)Carbon dioxide or monoxide concentrationAcid concentration and type Other chemical concentrations


Creating Reference Values

Reference Values for Durability depend on multiple variablesDesired years of serviceAcceptability or Consequences of deterioration

(nuclear power plant or retail space)Compounding exposure conditionsTime of testing or evaluation


Material Science Models

Appropriate models must exist for the prediction of deterioration

Time based models that progress with predictably changing exposure conditions


Chloride Diffusion Model

C C erfxD tx t oc

( , )

1

2

C(x,t) = chloride concentrationt = timex = depthCo = surface chloride concentrationDc = chloride diffusion constanterf = Error Function

Chloride Concentration and Diffusion Constant

0

1

2

3

4

5

6

7

0 5 10 15 20 25 30 35 40 45 50

Time

Cl C

on

ce

ntr

ati

on

(#

/cy

)

0.05 in^2/yr

0.07 in^2/yr

0.09 in^2/yr

0.11 in^2/yr

0.13 in^2/yr

0.25 in^2/yr

x = 2, Co = 9.0

Threshold


Chloride Concentration vs Time

0

1

2

3

4

5

6

7

0 10 20 30 40 50Time

Cl C

on

cen

trat

ion

(kg

/m3 )

Dc = 45 mm2/yr, x = 75mm, Co = 2.4 kg/m3

Dc = 83 mm2/yr, x = 50 mm, Co = 6 kg/m3

0.9 kg/m3 Threshold


Subsidence Cracking Model

pey

ey

15 05

1

. .

p = probability of settlement cracking

y = 1.37 - 0.023x1 - 0.56x2 + 0.011x3

x1 = concrete cover, mm

x2 = concrete cover / bar size

x3 = concrete slump, mm


Permeability

K C = permeability coefficient

Q = rate of flow

H/L = ratio of head of fluid to percolation length

A = cross section area under pressure

AL

HKQ C


Chloride Penetration

Test Method: AASHTO T277 (Coulombs passed in 6 hours)


56- Day Chloride Ion Permeability (AASHTO T 277)

0

1500

3000

4500

6000

PC100/

AQ

PC97SF3/

AQ

PC100

PC100/

IP

PC70FA30

PC97SF3

PC70FA27

SF3

PC65BS35

PC65FA30

SF5

PC55BS42

SF3

To

tal C

ha

rge

Pa

ss

ed

(C

ou

lom

bs

)


Yes. Specify CP-

Grade 3 Yes

Will the member be saturated

completely during

freezing?

No. Specify CP-

Grade 2

Yes

Is the member

exposed in a potentially

moist environment?

No. Specify CP- Grade 1

CP

Chloride Penetration Durability

Is the concrete exposed to

chloride salts or soluble

sulfate environments

? No. CP grade should not be specified.

Test

Method HPC Grade 1 HPC Grade 2 HPC Grade 3

CP

Chloride

penetration,

Coulombs

AASHTO

T 277 4000X 2000X 800>X

Ex: Defining Permeability Performance


Yes. Specify SH-Grade 3 Y

es

Is the member

designed to be watertight or crack free?

No. Specify SH-Grade 2

Yes

Is the member

constructed without joints?

No. Specify SH- Grade 1

SH

Shrinkage

Is the concrete

exposed to moisture,

chloride salts or soluble

sulfate environments

? No. SH grade should not be specified.

Test

Method Grade 1 Grade 2 Grade 3

SH

Shrinkage

(microstrain)

ASTM

C 157 800X 500X 200X

Ex: Defining Shrinkage Performance


Yes. Specify AS -

Grade 3 Yes

Will the member be

saturated during freezing?

No. Specify AS -

Grade 2

Yes

Is the concrete

exposed to moisture?

No. Specify AS - Grade 1

AS

Alkali Silica

Reaction Durability

Does the concrete contain reactive

aggregates?

No. AS grade should not be specified.

Test

Methods

Grade 1

Grade 2

Grade 3

AASHTO

T 303

X<0.10%

At 14 Days

X<0.10%

At 14 Days

X<0.10%

At 14 Days AS

Alkali-silica

reaction ASTM C

441

X>50%

Reduction in

Expansion

At 56 Days

X>60%

Reduction

in Expansion

At 56 Days

X>70%

Reduction in

Expansion

At 56 days

Ex: Defining ASR Performance


Yes. Specify SU -

Grade 3 Yes

Is the member

exposed to wet-dry cycles?

No. Specify SU -

Grade 2

Yes

Is the member

exposed to more than

0.20 percent soluble

sulfates? No. Specify SU - Grade 1

SU

Sulfate Resistance

Is the concrete

exposed to more than

0.10 percent soluble

sulfates? No. SU grade should not be specified.

Test Method

Grade 1 Grade 2 Grade 3

SU Sulfate

resistance

(expansion)

ASTM

C 1012

X<0.10%

@ 6 months

X<0.10%

@ 12 months

X<0.10%

@18 months

Ex: Defining Sulfate Performance


Models and Design Decisions

Do models exist to predict durability based performance?

Are the models based on materials science?

How can tests at the time of construction be verified by field performance?


Combined Effects

Many durability problems are a result of multiple distress mechanisms.

How can a more holistic model be developed and implemented? (e.g. “Life 365”)


Prof. Paul J. Tikalsky, P.E., FACIPenn State University

Transportation Infrastructure Lab. 3127 Research Drive

State College, PA 16801 [email protected]

Chloride Concentration and Cover Depth

0

1

2

3

4

5

6

0 10 20 30 40 50 60

Time

Cl C

once

ntra

tion

(#/c

y)

1.5 in.

2 in.

2.5 in.

3 in.

3.5 in.

4 in.

Co = 9.0, Dc = 0.09

Threshold

session 4 reference values for durability design dr. paul j. tikalsky, p.e., faci the pennsylvania...

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