Bonded Repair of R/C Bridge Components using FRP Wrapping – McDade Road Bridge over US 40

Peter Chang Bala Balaguru

March 23, 2010

University of Maryland

High Strength CompositesFiber Reinforced Polymers(FRP)• Fibers: carbon, glass

• Matrix: organic polymers

• Applications: aerospace, ship building, automobiles, rail cars, Concrete structures

Common Tow Reinforcements

Common Fabric Reinforcements

Advantages of FRP

• High Strength

• Low unit weight

• High specific strength

• Corrosion resistance

• Used for more than 40 years

Major Disadvantage

• Low resistance to high temperature (fire)• Fire hazard in transportation structures,

31% as compared to 37% flooding and 8% earthquake

• Restricted use in buildings• Restricted use in tunnels• Coef. of thermal expansion >> concrete• Some high temp matrix is highly toxic

Applications of Inorganic Polymer in Civil Infrastructure

• Durable and fire resistant

• Strengthening; bricks, concrete, reinforced concrete

• Protective and graffiti resistant coatings

• Sandwich panels

Appearance of Inorganic FRP Compared to Organic FRP

Organic FRP Inorganic FRP

Superior Properties of Geopolymer

• First:– Sets at room temperature; non toxic.

• Second:– higher heat tolerance.

• Third:– Geopolymers resist all organic solvents (and

are only affected by strong hydrochloric acid).

Features of the Inorganic Matrix

• Polysialate (“Geopolymer”)

• Aluminosilicate

• Water-based, non-toxic, durable

• Curing temperature: 20, 80, 150°C

• Resists temperatures as high as 1000°C

• Protects carbon from oxidation

Alumino-silicates as Binder

Polycondensation into poly(sialate) and poly(sialate-siloxo)

three dimensional macromolecular edifice

Research in Coating Technology

Making heat-resistant Geopolymer Composite

Application of Technology for Bridge Protection

Geopolymer Protective Coating

2-year Old Test Patch

Surface Coating of Concrete

Uncoated surface Coated surface

Close-up of Coated Concrete

Durability Tests: As Coating Material

• WET-DRY EXPOSURE (0, 50, and 100 cycles)• SCALING EXPOSURE (50cycles)

Samples Reinforced with:• 2 and 4% discrete carbon fibers • 1, 2, and 3 carbon tows • 1 and 2 layers of carbon fabric

Wet – Dry Durability

0.0

5.0

10.0

15.0

20.0

25.0

27.0 19.7 18.2Silica/Alumina Ratio

In-P

lane

She

ar S

tren

gth

(MP

a)

Before Cycling

After Cycling

Peak Load of Samples after Wet-dry Exposure

0

1

2

3

4

5

6

CON 2%FIB 4%FIB 1TOW 2TOW 3TOW 1LAY

Pe

ak L

oad

(kN

)

0 cycles 50cycles 100 cycles

Peak Load of Samples after Scaling Exposure

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

CON00 2FIB00 4FIB00 1TOW00 2TOW00 3TOW00 1LAY00 2LAY00

Pea

k Lo

ad (k

N)

0 cycles 50cycles

Typical Sample Prior to Test

• Balsa wood core with inorganic carbon fiber facings

• Smooth & glossy• Sample dimensions:

– 4 inches wide

– 4 inches long

– ¼” inch thick

OSU Test on Composite

Sample After Fire Testing

• Facings visibly charred from intense heat

• Rough surface with minor cracking

• Sample dimensions change, including weight

Failure Pattern

• No delamination

• No build-up of shear strain at the interface

• Strain in fiber comparable to organic matrix

Crack Patterns from Flexure Test

PC

2IO-1

3IO-1

4IO-2

5IO-2

2O-1

3O-2

4O-1

Thank you.pchang@umd.edu

(301) 405-1957

www.cee.umd.edu