The FutureThe Future

FORWARD

Material properties, such as Material properties, such as

corrosion resistance, fire corrosion resistance, fire

resistance and durability resistance and durability

are being continuously are being continuously

improved and exploited. improved and exploited.

These inherent qualities of These inherent qualities of

precast prestressed precast prestressed

concrete and its concrete and its

considerable design considerable design

flexibility also make it ideal flexibility also make it ideal

for a wide variety of other for a wide variety of other

applications: poles, piles, applications: poles, piles,

culverts, storage tanks, culverts, storage tanks,

retaining walls, sound retaining walls, sound

barriers and even barriers and even

railroad tiesrailroad ties..

THE FUTURE

FORWARDBACK

The benefits of High The benefits of High

Performance Concrete are Performance Concrete are

already beginning to be already beginning to be

applied. These include applied. These include

reduced initial construction reduced initial construction

costs that result from costs that result from

wider girder spacing and wider girder spacing and

longer spans as well as longer spans as well as

reduced long-term costs reduced long-term costs

due to fewer replacements due to fewer replacements

and fewer repairs. High and fewer repairs. High

Performance Concrete is Performance Concrete is

being increasingly being increasingly

specified for the nation’s specified for the nation’s

bridges and structures. bridges and structures.

THE FUTURE

FORWARDBACK

One form of HPC is high One form of HPC is high

strength concrete. A strength concrete. A

strength of 14,000 psi was strength of 14,000 psi was

specified here for the specified here for the

beams of the Louetta beams of the Louetta

Road Bridge, a Road Bridge, a

demonstration project, demonstration project,

located in Houston, Texas. located in Houston, Texas.

High strength concrete High strength concrete

was also used in this was also used in this

bridge for the stay-in-bridge for the stay-in-

place deck panels, the place deck panels, the

cast-in-place concrete cast-in-place concrete

deck and precast deck and precast

segmental piers.segmental piers.

THE FUTURE

FORWARDBACK

The Giles Road Bridge in The Giles Road Bridge in Sarpy County, Nebraska also Sarpy County, Nebraska also was constructed using High was constructed using High Strength Concrete. Strength Concrete. Completed in 1996, it is Completed in 1996, it is another example of a bridge another example of a bridge with 12,000 to 14,000 psi with 12,000 to 14,000 psi concrete girders and a 5,000 concrete girders and a 5,000 to 8,000 psi concrete deck. to 8,000 psi concrete deck. The Federal Highway The Federal Highway Administration, together with Administration, together with PCI and several states, PCI and several states, continues to promote the use continues to promote the use of High Performance of High Performance Concrete in bridge Concrete in bridge applications. For the precast applications. For the precast industry, High Performance industry, High Performance Concrete often involves Concrete often involves higher than average higher than average compressive strength. compressive strength.

THE FUTURE

FORWARDBACK

However, other factors, such However, other factors, such

as low permeability and as low permeability and

resistance to freeze-thaw – resistance to freeze-thaw –

not just strength – may be not just strength – may be

features of High Performance features of High Performance

Concrete depending on the Concrete depending on the

geographic location of the geographic location of the

bridge and the component for bridge and the component for

which it is used. Lightweight which it is used. Lightweight

aggregate concrete with aggregate concrete with

strengths in the 7,000 to strengths in the 7,000 to

10,000 psi range is also being 10,000 psi range is also being

used on some newer bridges. used on some newer bridges.

Lightweight concrete provides Lightweight concrete provides

reduced dead-loads and reduced dead-loads and

seismic forces. seismic forces.

THE FUTURE

FORWARDBACK

Strands of larger diameters Strands of larger diameters and higher strengths are and higher strengths are becoming more common as becoming more common as higher strength concretes higher strength concretes are used and the demand for are used and the demand for higher tensile force higher tensile force increases. When 0.6 inch increases. When 0.6 inch diameter strands are used in diameter strands are used in conjunction with high conjunction with high strength concrete, in the strength concrete, in the 10,000 to 12,000 psi range, 10,000 to 12,000 psi range, standard I-beams and other standard I-beams and other products are able to reach products are able to reach significantly longer spans significantly longer spans never thought possible never thought possible before. Even larger and before. Even larger and stronger strand are on the stronger strand are on the horizon. Corrosion-resistant horizon. Corrosion-resistant steels and coatings promise steels and coatings promise unlimited durability.unlimited durability.

Corrosion-resistant coatingsStainless-cladCorrosion-resistant steel

0.7"?

THE FUTURE

FORWARDBACK

Nonmetallic reinforcement Nonmetallic reinforcement

such as glass, carbon and such as glass, carbon and

aramid fiber composites aramid fiber composites

will be increasingly used will be increasingly used

for special applications. A for special applications. A

recent demonstration recent demonstration

project has shown the project has shown the

compatibility of carbon compatibility of carbon

fiber strands for fiber strands for

prestressing a bridge prestressing a bridge

girder. Both, internally girder. Both, internally

bonded prestressing and bonded prestressing and

external unbonded external unbonded

prestressing systems are prestressing systems are

used.used.

THE FUTURE

FORWARDBACK

Synthetic, organic and Synthetic, organic and

steel fibers have been steel fibers have been

shown to improve shown to improve

toughness and shrinkage toughness and shrinkage

cracking. Recent cracking. Recent

developments in high developments in high

performance fiber-performance fiber-

reinforced concrete hold reinforced concrete hold

promise in terms of promise in terms of

performance and cost-performance and cost-

effectiveness.effectiveness.

THE FUTURE

FORWARDBACK

THE FUTURE

FORWARDBACK

Deg

ree o

f C

orr

osio

n

Time

I

Initiation Propagation(corrosion)

Critical chloride threshold

Migration of chlorides, H20 and O2 into the concrete, no corrosion and no damage to

concrete

Corrosion of the steel reinforcement and

cracking and/or spalling of concrete

Reinforcing steel corrosionReinforcing steel corrosion

THE FUTURE

FORWARDBACK

Corrosion mechanism Corrosion mechanism of steelof steel

Corrosion Mechanisms Can be Corrosion Mechanisms Can be Minimized By Avoiding Microgalvanic Minimized By Avoiding Microgalvanic

Cell Formation Present in Conventional Cell Formation Present in Conventional and Micro-Alloyed Steelsand Micro-Alloyed Steels

THE FUTURE

FORWARDBACK

MMFX is not a stainless MMFX is not a stainless

steel but Step 1 of its steel but Step 1 of its

production adds production adds

chromium and reduces chromium and reduces

the carbon content.the carbon content.

Benefits of adding Benefits of adding

chromium to reduce the chromium to reduce the

steel’s corrosion rate.steel’s corrosion rate.

THE FUTURE

FORWARDBACK

MMFX approach to MMFX approach to altering the micro-altering the micro-structure of the steel: structure of the steel: Produce a Produce a Microcomposite Steel Microcomposite Steel that Eliminates that Eliminates Formation of Formation of Microstructural Galvanic Microstructural Galvanic CellsCells

~ 0 .1m

Prior Prior AustenitAustenite Grain e Grain BoundarBoundar

yy 2 –2 –Dislocated Dislocated

LathsLaths(Martensit(Martensit

e)e)

1 – Untransformed Nano1 – Untransformed NanoSheets of AusteniteSheets of Austenite

1

2

2

2

2

2

1

1

1

1

The Second Step The Second Step

to Achieving to Achieving

Microstructure Microstructure

SteelSteel

THE FUTURE

FORWARDBACK

Reinforcement

Type

Low

Cost installation

High

Cost installation

Chloride Threshold

(lb/yd3)

Propagation (years)

Black Steel $0.38 $0.53 1 6

Epoxy Coated Steel $0.50 $0.66 1 20

Stainless Steel $2.75 $2.91 20 12

MMFX 2 Steel (4 X) $0.70 $0.85 4 12

MMFX 2 Steel (6 X) $0.70 $0.85 6 12

THE FUTURE

FORWARDBACK

Reinforcement TypeReinforcement Type Installation Installation CostCost

InitialInitialCostCost($/ft($/ft22))

Time to Time to Initiation Initiation (Years)(Years)

Time to Time to First First

RepairRepair(Years)(Years)

Total Life Total Life Cycle Cycle Cost Cost ($/ft($/ft22))

MMFX 2 Steel (4 X)MMFX 2 Steel (4 X) HIGHHIGH $15.01$15.01 9090 >100>100 $15.01$15.01

MMFX 2 Steel (6 X)MMFX 2 Steel (6 X) HIGHHIGH $15.01$15.01 >100>100 >100>100 $15.01$15.01

Epoxy Coated SteelEpoxy Coated Steel HIGHHIGH $14.93$14.93 4444 6464 $19.02$19.02

Black SteelBlack Steel HIGHHIGH $14.42$14.42 4444 5050 $21.31$21.31

Stainless SteelStainless Steel HIGHHIGH $23.75$23.75 >100>100 >100>100 $23.75$23.75

Self Consolidating Self Consolidating

concrete is an extremely concrete is an extremely

cohesive and flowable cohesive and flowable

material capable of being material capable of being

placed without vibration. placed without vibration.

It can be placed very fast It can be placed very fast

at a very dramatic at a very dramatic

reduction in noise.reduction in noise.

THE FUTURE

FORWARDBACK

The cohesion of the fresh The cohesion of the fresh

concrete and no negative concrete and no negative

effects from vibration will effects from vibration will

result in a more result in a more

homogeneous surface homogeneous surface

layer. This reduces layer. This reduces

permeability, increases permeability, increases

resistance to chloride resistance to chloride

ingress, carbonation and ingress, carbonation and

other chemical attackother chemical attack

THE FUTURE

FORWARDBACK

Another development has Another development has been the use of precast deck been the use of precast deck panels. Used as stay-in-place panels. Used as stay-in-place forms, the panels reduce forms, the panels reduce labor for field placement of labor for field placement of reinforcing steel and reinforcing steel and concrete for bridge decks, concrete for bridge decks, resulting in considerable resulting in considerable savings. The panels become savings. The panels become composite with the field-composite with the field-placed concrete for live placed concrete for live loads. They’re made of high-loads. They’re made of high-quality, plant-produced quality, plant-produced concrete and contain the concrete and contain the primary tensile primary tensile reinforcement between reinforcement between beams. They remain crack-beams. They remain crack-free, protecting this free, protecting this important reinforcing steel.important reinforcing steel.

THE FUTURE

FORWARDBACK

Full-depth precast deck Full-depth precast deck

panels promise to provide panels promise to provide

the solution for extended the solution for extended

closings due to deck closings due to deck

replacement. The technique replacement. The technique

applies to new construction applies to new construction

as well. Precast highway as well. Precast highway

paving panels are being paving panels are being

demonstrated in Texas to demonstrated in Texas to

speed lane widenings and speed lane widenings and

reduce traffic closures and reduce traffic closures and

detours. Refined materials detours. Refined materials

and methods are making and methods are making

these solution an exciting these solution an exciting

new part of the designers new part of the designers

tool box.tool box.

THE FUTURE

FORWARDBACK

Another innovation is the Another innovation is the

development of development of

horizontally curved horizontally curved

precast concrete bridges precast concrete bridges

which is creating exciting which is creating exciting

new options in new options in

contemporary bridge contemporary bridge

designs. This technique designs. This technique

involves post-tensioning involves post-tensioning

precast elements together precast elements together

in the plants before in the plants before

shipment or in the field shipment or in the field

after erection.after erection.

THE FUTURE

FORWARDBACK

THE FUTURE

Spliced girders give Prestressed concrete girders the ability to reach further and longer

FORWARDBACK

And yet another solution And yet another solution

for curved structures is for curved structures is

segmental construction. segmental construction.

Working together with the Working together with the

American Segmental American Segmental

Bridge Institute (ASBI) and Bridge Institute (ASBI) and

the AASHTO Bridge the AASHTO Bridge

Subcommittee, PCI has Subcommittee, PCI has

endorsed a family of endorsed a family of

standard shapes for standard shapes for

segmental bridges that is segmental bridges that is

intended to reduce the intended to reduce the

cost of segmental bridges cost of segmental bridges

for smaller structures such for smaller structures such

as urban grade as urban grade

separations. separations.

THE FUTURE

FORWARDBACK

Prestressed concrete got Prestressed concrete got

its start as the original its start as the original

composite material and composite material and

further developments by further developments by

the industry and its the industry and its

suppliers have continued suppliers have continued

to refine the performance to refine the performance

of the product for the of the product for the

bridge market.bridge market.

THE FUTURE

FORWARDBACK

Today, it still gives the Today, it still gives the

public extremely good public extremely good

value for its money. The value for its money. The

reputation of the precast reputation of the precast

prestressed concrete prestressed concrete

industry has been built on industry has been built on

the strength, imagination, the strength, imagination,

consistency and integrity consistency and integrity

of its people and products of its people and products

alike. In the future, it will alike. In the future, it will

continue to be the continue to be the

solution of choice.solution of choice.

THE FUTURE

FORWARDBACK

Thank You for Your

Attention

BACK