IMPLEMENTING NEW MATERIALS - Texas A&M University · IMPLEMENTING NEW MATERIALS ... –AASHTO LRFD Bridge Design ... •CM (4.0 –7.9% Cr) •CS (8.0 –10.9% Cr) [see SP to Item

2017 Transportation Short Course October 9 - 11

IMPLEMENTING NEW MATERIALSCorrosion Resistant Reinforcement


Table of contents

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3

4 - 8

9 - 25

Steel Corrosion

TxDOT Corrosion Protection Measures

Corrosion Resistant Reinforcement Materials

1

2

3


Steel Corrosion

Carbon steel (black steel)

– Fresh concrete is a high-alkaline

environment (pH > 13)

– Rebar won’t oxidize as long as

pH > 10 or 11

– Moisture, Oxygen, and Chlorides

arrive and pH

– Rebar corrodes

– Rust occupies 6 - 7 times more

volume than the steel it replaces

– Tension cracks develop

– Faster access for more chlorides

3



4

http://ftp.dot.state.tx.us/pub/txdot-info/library/pubs/bus/bridge/district_corrosion.pdf

“TxDOT Corrosion”



Increased Clear Cover for Bridge Slabs

5

Substructures: case-by-case basis

typically increase to 2½"

no more than 3 - 3½"

Top Clear Cover is now 2.5” for Standard Deck Slabs

and Standard Composite Concrete Slabs (statewide).



High Performance Concrete (HPC) for Bridge Slabs & Rails

6

High Performance Low Permeability

(Class F Fly Ash)



Air Entrainment for Bridge Slab & Rails

7

limited application because air entrainment

negatively Impacts the use of Class F Fly Ash

(TxDOT Research Project 0-5207)

relieves pore

pressures from

freezing /thawing

exposure



Epoxy Coated Reinforcement for Bridge Slabs & Rails

8

...or other types of

corrosion-resistant

reinforcement...

...EXCEPT - stainless steel is usually reserved

for coastal / saltwater applications



9

Carbon Steel

Galvanized*

Epoxy Coated

(ECR)

Fiber Reinforced

Polymer (FRP)

Stainless Steel

Dual CoatedLow Carbon, Chromium

Performance

Co

st

~

Research Project 0-6952

Synthesis of Alternate

Reinforcements for Enhanced

Corrosion Resistance in TxDOT Bridges



Epoxy Coated

– Developed in 1970s

– ASTM A775 (coated before fabrication)

• green

– ASTM A934 (coated after fabrication)

• grey or purple -- no bending after coating!

– Useful for Deck Reinforcing

– Holidays

10

Bar

Sizes

Coating Thickness

(mils)

#3 - #5 7 – 12

#6 - #18 7 - 16

[1 mil = 0.001 inch]

CRSI [2015]


Item 440 – Reinforcement for Concrete

11



Hot Dip Galvanized Reinforcement

– ASTM A767

• Class I

– Heavier coating (5 – 6 mils)

• Class II

– Thinner, more ductile coating

(3.4 mils)

– Bend bars BEFORE hot-dipping

– Useful for Deck Reinforcing

– Domestic Availability

12

...steel reinforcing bars with

protective zinc coatings applied

by immersing the properly

prepared reinforcing bars into a

molten bath of zinc.



13



Continuous Hot-Dip Galvanized Reinforcement

– ASTM A1094

• The process of uninterrupted passage of long lengths of steel products through a molten bath of zinc or zinc-alloy

– Thinner, better-adhering than A767

• Addition of Aluminum

• 2-mil Thickness


– Bend AFTER Galvanizing

– Useful for Deck Reinforcing, or General Usage as Corrosion-Resistant Reinforcement

14



15

...coming soon!



Dual Coated

– ASTM A1055

– Step 1: Metalizing

• Continuous HDG (ASTM A1094)

– Step 2: Fusion Bonding

• Apply outer epoxy powder coating

– Domestic Availability Issues

– Deck Reinforcing, or General Usage as Corrosion-Resistant Reinforcement

16

CRSI [2015]



Glass Fiber-Reinforced Polymer (GFRP)

– Glass Fibers Carry Load

– Polymer Resin Protects Fibers

– AASHTO LRFD Bridge Design

Specifications for GFRP-Reinforced

Concrete Bridge Decks and Traffic

Railings (2009)

• 2nd Edition Currently in the Works

• Will Include Empirical Deck Design

for GFRP

– Canadian Highway Bridge Design Code

– IGFRP

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Glass Fiber-Reinforced Polymer (GFRP)

– One Huge Benefit

• Galvanic Corrosion Not Possible

(no expansive corrosion product)

– Points to Consider

• Low Compressive Strength, Modulus

• Long-term Tensile Capacity

• Elastic through Failure

• Bends Must Be Incorporated during

Bar Manufacture

• Empirical Deck Design Not Yet

Applicable

18

Concrete Exposure

Condition

Environmental

Reduction Factor, CE

not exposed to

earth and weather0.80

exposed to earth

and weather0.70

Table 2.6.1.2-1

See also:

Gooranorimi et al. (2016)

FRP Reinforcement for Concrete:

Performance Assessment and

New Construction

Vol I: Sierrita De La Cruz Creek Bridge

AASHTO LRFD Bridge Design

Specifications for GFRP-Reinforced

Concrete Bridge Decks and Traffic

Railings (2009)



19



Low Carbon, Chromium Steel

– ASTM A1035

– High Yield Strength

• Available Grades are 100, 120

– Alloys based on Chromium Content

• CL (2.0 – 3.9% Cr)

• CM (4.0 – 7.9% Cr)

• CS (8.0 – 10.9% Cr) [see SP to Item 440]

– No Special Handling Requirements

– 4 < f’c < 12 ksi


20

Chromium (Cr) %

Co

rro

sio

n

Re

sis

tan

ce

– Useful for Deck Reinforcing,

or for General Usage as

Corrosion-Resistant

Reinforcement

CL CM CS SS



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22

Stainless Steel Reinforcement

– ASTM A955

• “CR” or “SS” markings indicate compliance

– Austenitic

• Usual choice for reinforcing steel

• Chromium and Nickel

– Non-magnetic

– Duplex

• Superior strength and corrosion resistance

• Austenite and Ferrite

– Magnetic

These alloys are all available as

reinforcing bars in the US and

permitted in TxDOT Standard

Specifications. Specify all allowable

alloys in plan specifications.

UNS

DesignationType Cr %

Austenitic

S31653 316LN 16.0 – 18.0

S24100 XM-28 16.5 – 19.0

Duplex (Austenitic – Ferritic)

S31803 2205 21.0 – 23.0

S32304* 2304 21.5 – 24.5

* ASTM A240



Stainless Steel Reinforcement

– Solid Stainless Steel (preferred)

• Can be shipped, handled, and bent without damage

• Deck Reinforcing, or General Usage as Corrosion-Resistant Reinforcement

• Useful in Corrosive Coastal Environments

– TxDOT Does Not Permit the Use of Stainless Steel-Clad Carbon Steel

• Fusing process is expensive

• Bar ends require coating

• Limited Domestic Availability

23



This is size 20 font

24



25


Questions?


Additional References

Concrete Reinforcing Steel Institute – CRSI [2012], “Frequently Asked Questions (FAQ) about

Stainless Steel Reinforcing Bars,” CRSI Technical Note ETN-M-2-12, Schaumburg, IL, 8 pp.

Concrete Reinforcing Steel Institute – CRSI [2013], “Specialty & Corrosion-Resistant Steel

Reinforcement: Product Guide,” 28 pp.


Dual-Coated Steel Reinforcing Bars,” CRSI Technical Note ETN-M-7-15, Schaumburg, IL, 5 pp.


Low-Carbon, Chromium ASTM A1035 Type CS, CM and CL Steel Reinforcing Bar”, CRSI Technical

Note ETN-M-11-17, Schaumburg, IL, 6 pp.


Epoxy-Coated Steel Reinforcing Bars,” CRSI Technical Note ETN-M-6-15, Schaumburg, IL, 5 pp.

Concrete Reinforcing Steel Institute – CRSI [2016], “Frequently Asked Questions (Faq) about

Hot-Dip Galvanized Reinforcing Bars,” CRSI Technical Note ETN-M-10-16, Schaumburg, IL, 6 pp.

Gooranorimi et al. [2016], “FRP Reinforcement for Concrete: Performance Assessment and New

Construction, Volume I: Sierrita De La Cruz Creek Bridge,” Final Report, RECAST UTC

#00042134-04-103A, 36 pp.

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28

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IMPLEMENTING NEW MATERIALS - Texas A&M University · IMPLEMENTING NEW MATERIALS ... –AASHTO LRFD Bridge Design ... •CM (4.0 –7.9% Cr) •CS (8.0 –10.9% Cr) [see SP to Item