SMARTER THAN THE AVERAGE ROCK: HOW CARBON FIBER REINFORCED CONCRETE IS THE FUTURE OF INFRASTRUCTURE

earthwhistleUrban and Civil

Nov 25, 2013 (3 years and 8 months ago)

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Conference Session
C9

Paper #
3216

University of Pittsburgh

Swanson School of Engineering

April 13, 2013



1

SMARTER THAN THE AVERAGE ROCK: HOW CARBON FIBER

REINFORCED CONCRETE

IS THE FUTURE OF
AMERICA’S
INFRASTRUCTURE

Sean Kosma (
smk114@pitt.edu
, Vidic 2:00), Alex Veurink (
adv21@pitt.edu
, Bursic 2:00
)
Abstract
--
Carbon Fiber Reinforced Concrete, or CFRC, is a
material with the potential to revolutionize civil e
ngineering.
A high
-
tech
alternative

to traditional concrete, CFRC adds
small, alm
ost weightless carbon fiber filaments to the
mixture of cement, aggregate and water that composes
modern concrete. The addition of these filaments allows
maintenance and repair crews to send an electrical current
through the structure, locating an “electri
cal resistance,”
which could si
gnify a crack or depression.

Due to its unique
ability to electrically pinpoint flaws in aging buildings, we
wi
ll demonstrate, through analyzing research

research, how
CFRC can potentially lead America’s aging infr
astructure
out of the past, while sustaining levels of efficiency for
centuries to come.

The maintenance of traditional concrete, primarily in
bridge structures, poses a huge hassle in the location and
assessment of each imperfection that might arise and harm
the
integrity of a structure. Carbon fiber reinforced concrete
increases the conductivity of the material, allowing crews to
identify stru
ctural flaws within seconds.

CFRC prevents
minor flaws from becoming fatal compromises of the
building’s integrity in the
future. This paper will explain the
development of carbon fibers and precisely how they serve
as an important aggregate in traditional concrete.

Along with analyzing

research, the paper will analyze
the ethical realm of construction and maintenance, with the
perspective of preventing structural catastrophes from
causing death.

CFRC has great potential to become the
future standard of building material with its high e
mphasis
on ensuring

building integrity and people’s

safety. The
objective of this paper is to show how CFRC technology can
improve upon America’s out
-
of
-
date infrastructure and

obtain a certain level of sustainability highly sought after in
the constructio
n realm of civil engineering.

This
sustainability will be presented as the addition of
geopolymers that could be more environmentally friendly,
while it may also increase the standard of living.

A material
like CFRC could

bring about a new renaissance of

A
merican
civil engineering.

Keywords


Civil engineering, Concrete, Conductivity,
Maintenance, Reinforcement, Smart materials, Structure


OUR PURPOSE


Carbon fiber reinforced concrete is the new high
-
tech
building material that will change the concrete and
construction world as we know it. Revolutionizing basic
concrete, a composite of aggregate, cement, and water,
carbon fiber reinforced concrete is a m
aterial with a lot of
potential in the construction and ongoing maintenance of
structures
.
Within the new composition of CFRC, ti
ny,
noncontiguous carbon fibers add increased levels of
electrical conductivity and strength, both of which are highly
desirabl
e trai
ts in the construction industry [1
]
.


Rather than retrofitting the exterior of an existing
concrete structure with preformed sheets of a carbon fiber
reinforced polymer in the hope of strengthening its
crumbling integrity which is sometimes referred
to as carbon
fiber reinforced concrete, this paper will discuss the carbon
fibers as an aggregate to the concrete mixture and the very
useful properties that come of it.


WHAT IS CONCRETE?

Basic c
oncrete is widely used for a variety of structures
ranging f
rom foundations, walls and pavements to roadways,
bridges and dams. Made of a composite of aggregate,
cement, and water, concrete is known for its strength.
Aggregates are often crushed rocks such as limestone or
gravel accompanied by sand. Along with an a
ggregates,
cement, the most common being Portland Cement, is a
compound

composed of the chem
icals tricalcium silicate,
dical
cium silicate, tr
ic
alcium aluminate, and
tetracalcium
aluminoferrite [2
]
, which in the presence of water, enables
the coating and ha
rdening of the aggregates, binding
everything into a uniform, firm mixture when set.

Throughout the technological advancements in materials and
chemicals, different additives have been developed to obtain
certain properties found useful in the constructi
on industry.
Accelerating admixtures decrease the time needed for the
concrete set, while retarding admixtures, often used in the
hot weather, keep the concrete from setting too quickly.
Other admixtures may reduce the amount of water needed in
the concret
e mixture, or they may improve workability.

Engineering these additives is evidence that a once
-
simple
material, concrete, is receiving demands that will lead to
future evolutions in its utilization in construction projects.

This paper, however, will delve

into an extremely
exceptional additive known as carbon fiber. Tiny carbon
fibers are added as an aggregate for the cement to wrap
around in the setting process, enabling properties contained
by carbon fiber to be utilized by the whole concrete structure
a
s these fibers weave their way through the structure’s core.

Materials known as geopolymers are being developed to
compliment carbon fiber’s naturally occurring properties.

Sean Kosma

Alex Veurink

2


Role of G
eopolymers


Geopolymers represent a category of admixtures that
improve
the performance of concrete
. These admixtures
could curb such damages

caused by stress from tension or
the flexion, or bending, of structures caused by nature’s
elements

from becoming major problems in the structure’s
integrity
. Geopolymers are formed by t
he alkali activation of
aluminosilicate powder, which consists of high amounts of
silica and alumina. Source materials for these geopolymers
include metakaolin, kaolinite, clays, mica, as well as
industrial byproducts such as fly ash, silica

fume, slag and

ric husk ash. [3
] Traditional concrete simply consists of
crushed rock such as limestone or quartz. A study reported
on in the educational journal
Materials and Structures
outlines how geopolymer concrete, when coupled with
carbon fibers, forms to create
an extremely effective medium
for health
-
mon
itoring concrete

that could become a crucial
instrument in the locating of damages in the structure.

Through the properties of CFRC, this paper will look at how
the presence of these geopolymers will aide in the
detection
of damages.

Geopolymers have also received influences from
biological properties to achieve more environmentally
friendly utilizations. The
Department of Civil Engineering

at
the University of British Columbia published a paper of a
newly engineered polymers made from natural cellulose
fibers that would turn any structure containing such material
into a recyclable,

bio
degradable structure that would be a
pioneer in the sust
ainability side of civil engineering. The
paper than illustrates that
CFRC would be a prime example
for the implementation for such geopolymers for its ability
for damage and deflection sensing abilities. Material as
versatile as a concrete infused with ce
llulose would pioneer
the future of material science as it applies to civil
engineering.


Damages to Regular C
oncrete

Concrete structures meet hazardous elements that
commonly affect the structure’s integrity. Extended use and
weather elements often nega
tively affect the strength of a
structure.

Earthquakes would be an obvious danger to the
structure’s health, while other natural elements could
indirectly affect, many times overlooked by the average
inspector, the integrity of said structure. Take for ins
tance,
snow.

Snow, in itself, may not damage a road or roadway,
however, the accompanying factors may lead to
compromises in the structure. When it snows, for example,
road crews are hard at work laying down salt to prevent any
ice from building up and
eventually causing a car accident.
These salts contain chemicals that are rather harsh to
concrete. A study by the
Department of Geological and
Atmospheric Sciences

at Iowa State University determined
that certain solutions of salts containing magnesium ch
loride
lead to the accelerated deterioration of concrete structures.
The magnesium chloride when coupled with the calcium
silicate hydrates found in most concrete mixtures form
“noncohesive magnesium silicate hydrates” that could cause
crystalline structur
es. These crystalline structures would, in
turn, cause pressures against the concrete structure that could
cause microfractures
on the structures. Microfractures by
themselves are not harmful to a structures durability, but
with these fractures present, wa
ter is more likely to enter
into the structure’s interior.
[4]

The most common of damages is the entrance of water
into the interior of a concrete structure and freezing.
Trapped, freezing water expands and pushes against the
concrete causing major problem
s for its integrity. Major
damages could appear on the exterior in the form of cracks,
visible reinforcing bars, discoloration, or visible sagging of
what
-
should
-
be a straight support beam. Finding major flaws
are not difficult, but the repair must be quic
k and efficient,
as the structure could be severely compromised which might
lead to a dramatic failure. The key to preventing major
damages from causing such failure is to find these damages
while they are still minor, interior flaws.

With the help of
addi
tional carbon fibers and the properties brought into
concrete, damage
assessment will be made a much
more
efficient process.


WHAT IS CARBON FIBER?

Carbon fiber is a material formed by long chains of
carbon atoms, created from “precursor” chemical
compounds modified by chemical engineers for efficiency.
In the past, carbon fiber’s prices have been high due to the
complexity of developing these precurs
or compounds, the
most expensive being polyacrylonitrile, or PAN for short.
Traditionally, carbon fibers were manufactured by
“carbonizing polyacrylonitrile yarn at high temperatures and
then aligning the resultant graphite crystallites by a process
called

hot stretching.”
[3]
With PAN being the most widely
utilized precursor used for the production of carbon fiber,
costs of development are bound to be high. According to the
Oak Ridge National Laboratory, that is about to change.
Scientists at this laborato
ry have, apparently, developed a
new method of forming this polyacrylonitrile yarn. This
could be extremely beneficial to the carbon fiber market.
Currently the price of a pound of solid carbon fiber sells for
around $15 to $20. The scientists of the Oak R
idge
laboratory say, with their new, more efficient production
method, they could easily see prices falling to anywhere
from $5 to $7

per pound

in the near future. This means big
things are to come for the wide range of applications of
carbon fiber, a mate
rial full of useful physical and chemical
properties.



Sean Kosma

Alex Veurink

3



Properties of Carbon Fiber


Carbon fiber, with its wide range of extremely useful
properties, has found itself on the forefront of innovation.
One property, in particular, is its unparalleled strengt
h to
weight ratio. This strength comes from the very nature of the
crystalline chemical bonds formed in the “hot stretching”
process. Also aiding in its strength is the intricate patterns
these tiny, carbon fibers are woven into. These patterns
highlight t
he properties of the chemical bonds, producing a
super rigid, super light structure. Often times, these woven
fabrics are placed into resins to form plastics, which increase
the usefulness applicability of the carbon fibers in the
production of numerous ma
terials. Carbon fiber is, also,
relatively flexible due to alignment of the composition of the
atoms. This flexibility is, yet another, key property found
crucial in the application of carbon fiber. No property,
however, has as much applicability to the fi
eld of civil
engineering, as carbon fiber’s electrical conductivity.

Discovered in the 1980s, the development of the then
-
revolutionary material we have come to call carbon fiber in
pitch
-
based development lead to a breakthrough in the field.
Carbon fiber’
s conductivity of electrical currents was a very
significant find according to the scientists in charge. These
pitch
-
based carbon fibers, which are derived from petroleum
or plant matter, tend to have high modulus, as well as high
thermal and electrical co
nductivities. With the combination
of previously discussed properties and breakthroughs in the
production, developers have utilized carbon fiber as a cost
-
effective building block for a wide range of materials and
products.


Applications of Carbon Fiber in

Today’s Industries


Due to its flexibility, carbon fiber has been implemented
into products in which flexibility is crucial. Hockey sticks,
golf clubs, and even Formula 1 cars have used carbon fiber
for the strength it is capable of applying to a structure, while
withstanding

extreme forces of flexion. In some cases,
carbon fiber is even used for the sheer aesthetic purposes as
some believe the weave of the fabric encased in the plastic
resin is somewhat attractive. Carbon fiber’s main application
in the commercial and industr
ial side of things comes from
its strength and flexion, in union with its incredibly
lightweight nature. The same reinforcement carbon fiber
provides for sporting goods and automobiles is being applied
to much more serious areas of discipline such as aeros
pace
travel and the field of construction. Many components of a
satellites’ technology are made of carbon fiber due to its
unmatched strength to weight ratio.

Within the construction industry is where this paper finds
carbon fiber’s superior application.
Innovations lowering the
cost of carbon fiber, along with its desirable properties of
strength, flexibility, and conductivity, give reason to believe
that carbon fiber will reinvent the field of civil engineering
from the foundation up

in the form of a new
ly thought of
carbon fiber aggregate
.

Having seen the useful properties of
carbon fiber and the utilities sought after in concrete, many
believe a carbon fiber aggregate would pose as a realistic
answer to the many needs of developers within the industry.



C
arbon

F
iber

A
ggregate


Carbon fiber aggregate could be
a
n

actual

solution to
many of civil engineering’s problems
. Especially

wit
hin the
practice of maintenance, where many questions and
demands have been unanswered, a carbon fiber aggregate
would truly meet many demands that many
ask of a
traditional concrete structure.

What truly sets it apart stems
from its high electrical conduc
tivity. Electrically conductive
concrete allows structural inspectors to perform
measurements on the material’s resistivity, which can be
used to estimate stress variations, thus i
ndicating a structural
flaw.

[3
]
These innovations will revolutionize many
aspects
of the construction industry.



CARBON FIBER AND CONCRETE
APPLIED



Carbon f
iber reinforced concrete,

through the
components used to make up the mixture, has certain
properties that make it extremely applicable to its use in
construction. Concrete in itself is a highly durable material
known for its ability to even strengthen over time. In
addition to the

durability of concrete, it is extremely popular
to add extra reinforcement throughout the relative center of
structures in the form of reinforcing steel bars often referred
to as “rebar.” Accompanying these already durable
properties of the structure, the

addition of small, lightweight
carbon fibers adds increased electrical conductivity to the
concrete. The fibers, with their small density and lightweight
properties, will also make the weight of the entire structure
that much lighter. Electrical conductiv
ity may not seem like
a desirable trait for concrete structures, but with the
increased levels of conductivity of concrete structures
infused with carbon fibers, damage detection will be made
much less invasive as previous met
hods.

Many of the
properties b
elonging to
CFRC

are

sought after as
revolutionizing the already desirable traits belonging to
concrete.



CARBON FIBER REINFORCED
CONCRETE PROPERTIES



This material exhibits many properties that are
considered desirable for the purpose of buildings. A few
examples include high
levels of conductivity, extreme
compressive strength, and heightened resistance to chemical
Sean Kosma

Alex Veurink

4


deterioration
. [4
] Classic building c
oncrete tends to exhibit
low amounts of flexibility when it supports a load, leading to
the possibility of cracks forming over time. However, carbon
fiber aggregates increase the material’s flexibility and make
it more able to resist cracking under such he
avy strain.



C
onductivity



Carbon fibers exhibit high amounts of electrical
conductivity as well as low amounts of electrical resistance.
In fact, studies done at Louisiana Tech indicate that the
electrical resistance of ordinary Portland cement (OPC
), or
traditional concrete, greatly exceeded that of GPC, or
concrete reinforced with geopolymers and carbon fiber. The
study tested a specimen of OPC that had been in water for
seven days and a comparable piece of concrete reinforced
with carbon fibers so
aked in water for the same amount of
time. The results indicated that the non
-
reinforced concrete
exhibited 1259.37 ohms of resistance, whereas the
reinforced slab exhibited 533.15 ohms of resistance. Another
test showed an even more astonishing result. Th
is test
consisted of two geopolymer concrete slabs, one with 0%
carbon fiber and the other laced with 0.4% carbon fiber by
weight. These slabs were left dry for 24 hours and kept at 60
degrees C. When measured, the results showed that the slab
without carb
on fibers exhibited 486.98 ohms of resistance.
The specimen with carbon fiber contained a comparably tiny
157.91 ohms of resistance.

This set of collected, when
compared, illustrates

how a carbon fiber aggregate infused
concrete is more favorable for electrical structure
maintenance.

[5]


Since e
lectrical resistance indicates a material’s
op
position to an electric current, and t
he reinforced
specimen exhibited less than half the r
esistance of the
traditional concrete,

than this indicates

that it serves as a
superior medium for electrical structure maintenance. When
geopolymers were added to the data, the results showed an
even lower amount of resistance, with the GPC exhibited
appr
oximately one
-
third of the resistance of
its OPC cousin.
According to a

source from Louisiana Tech, the decreased
electrical resistance in carbon fibers “may be due to increase
in curvature at the compression face, leading to a reduction
in the separation
distance between the electrodes (i.e.,
physical shortening of the conduction path).”

[6]

According
to this quote, the flexibility of the carbon fiber material may
also be responsible for its decreased electrical resistance,
displaying a concept described a
s the “apparent con
ductive
length factor”. [3
] Therefore,
CFRC’s

ability to flex allows it
to serve not only as an exceptional electrical medium, but
also as a material that can sustain excessive physical
disturbances.





C
arbon
F
iber’s

Compressive

S
trength



CFRC
can be used to greatly increase the compressiv
e
strength of concrete columns, which are often found in the
center and around the edges of a structure due to the shapes
ability to bare high amounts of weight
.

It also allows
concrete to be
nd without causing major damage; a property
that traditional concrete lacks for the most part.

Dragos
-
Marian Bontea, D.D.L. Chung and G.C. Lee describe one
aspect of carbon fiber reinforced concrete’s compressive
strength in the journal
Cement and Concrete

Research.
The
results of the experiment displayed how the carbon fibers
would be vital during the detection of any critical
imperfections that could put the structure at risk.



This article describes an experiment that monitors the
resistance in a
piece of carbon fiber reinforced concrete
when stress was applied to it. It showed that the resistance
increased slightly when minor amounts of stress were
applied and then reversed when the stress was taken away.
This indicates that the material has an ab
ility to take strain
and flex in the presence of stress without completely
breaking. In contrast, when the testers applied huge amounts
of stress to the concrete, they detected a larger increase in
resistance that went down slightly when the stress was
rem
oved, but it never fully left. This indicates a breakage.
The ability of carbon fiber reinforced concrete to bend
without taking major damage plays an important role when
used as a building material. Pieces of infrastructure must be
able to sustain many fo
rces such as that of the weight it
bears and the weather.


Prior to the last two decades, research had been put
toward steel
-
based reinforcement, despite it suffering from
excessive weight to the structure. However, the development
of fiber
-
based compo
sites led to the discovery of carbon
-
fiber sheets as a method of increasing the compressive
strength of concrete without too much added weight. Glass
fiber
-
based composites were found to enhance the
compressive strength of concrete up to 100% while certain

composite jackets, such as aramide and carbon
-
fiber
increased that strength up to 200%. The carbon
-
fiber
reinforcing sheets had the greatest effectiveness on concrete
cylinders considered “low” or “medium” strength. Covering
the concrete cylinders with hi
gh
-
strength carbon
-
fiber
laminates increased the compressive stren
gth from 54.6 MPa
to 190 MPa. [7
]

The popularity of retrofitting pre
-
existing
structures with carbon fiber sheets is due to the range of
properties of carbon fiber, many pioneers in the indu
stry are
looking at CFRC as a way to incorporate carbon fiber as a
building is being erected, avoiding the hassle of retrofitting
sheets on the exterior of a structure years down the road.


This ability to drastically increase the compressive
strength
of concrete makes carbon fiber a more
-
than suitable
candidate for a building material. In the case of bridges,
which much sustain multiple tons of cars and other
automobiles every day, this compressive strength would
allow the material to bend slightly and

uphold the force
Sean Kosma

Alex Veurink

5


applied to it as opposed to not bending and cracking instead.
Such cracks could prove fatal flaws in the future and should
definitely
be avoided if possible.




C
arbon

F
iber’s

C
hemical

P
roperties



A report from PCI Journal says that,

“Precast concrete
products are susceptible to degradation as a result of sulfate
attack, freeze
-
thaw cycling, alkali
-
silica reaction, and
corrosion of embedded reinforcing bars, if present.” This
shows that concrete has many chemical susceptibilities
with
out carbon fiber reinforcement. Fiber
-
based
reinforcement exhibits chemical properties that can limit
such deterioration of structures. In the presence of chlorides,
steel tends to corrode. However, carbon
-
fibers have been
found to bind with those chloride
s thus reducing the amount
of chlorides that could jeopardize the inte
grity of the steel
underneath.


Carbon fibers also exhibit useful chemical properties that
reduce the severity of cracking in concrete. The report from
PCI Journal

says, “Fiber rein
forcement improves crack
resistance, increases the surface roughness of cracks, and
promotes multiple
-
crack development, thereby significantly
reducing the permeability of concrete in service. In case of
stresses and stress
-
induced cracks, results have sho
wn that
cracks dramatically increase the permeability of plain
concrete, while the permeability of fiber
-
reinforced concrete
remains far below that of plain concrete under service
conditions.”
[4
] The testing was performed when water was
introduced to plai
n concrete and then applied to fiber
reinforced concrete. The testing showed that although fiber
reinforcement did not prevent crack development, it
certainly lowered the severity of the cracks created and
lowered the chances of cracks becoming fatal flaws

in a
structure. The fibers lowered the concrete’s permeability to
water, thus allowing less water to go through the concrete
and weaken its stability. This property would prove most
useful for bridges that span bodies of water. The submerged
supports of b
ridges would have less chances of failing if
fiber reinforcement were introduced.


I
mportance

of

C
arbon

F
iber

P
roperties



These previously discussed properties of carbon fiber
could

prove useful in
the construction of buildings, as

well
as the maintenance of roads and bridges. The higher
conductivity of carbon fibers allows a

much

stronger electric
current to pass through the structure and provides the
primary method through which inspectors gauge its
condition. Without a higher con
ductivity, using electrical
currents to locate imperfections would prove obsolete.
Carbon fiber reinforcement also adds compressive strength
to the structure. This allows structures to sustain a greater
amount of bending without causing cracks to form, add
ing
greater certainty that fatal flaws won’t form. Finally, carbon
fiber exhibits useful chemical properties such as resistance
to corrosion from chlorides which prove dangerous to steel
structures. It also has a great role in decreasing concrete’s
suscept
ibility to water damage, thus making fiber
reinforcement a great candidate for bridge
-
building.


DAMAGE ASSESSMENT


C
urrent Method of Damage

A
ssessment



Current methods to examining a structure for minor
damages within the interior of a structure
involve [
5
] a
technique of detecting the change in flexibility of a s
tructure.
The method includes the measurement of a
vibration
, due to
a natural frequency,

dispersed throughout the structure that,
however helpful it may be in detecting minor flaws, may
also cause minor flaws to turn into bigger problems within
the structure. This means the detection process is damaging.
This is where the infusion of carbon fibers could come to the
rescue of structures meeting elements that cause gradual
deterioration.
[6]


U
tilizing Carbon Fiber Reinforced Concrete in Damage
Assessment



With the ever
-
dropping price of carbon
fibers
, this once
-
costly material is finding its way into many facets of
everyday life.

However, its application to the construction
industry utilizes some of its previously little used properties,
namely its significant electrical conductivity. This
conductivity allows building inspectors to pass an electrical
current “i” through the struct
ure much more easil
y than
through normal concrete
[6]
.

They could use this method to
find imperfections in the structure much faster than with
visual inspection. The electric current would send back data
of areas of high resistance, which would indicate a
bend in
the “circuit” and therefore indicate some sort of imperfection
in the structure (crack, bend, etc.) This area of high
resistance

(R)

would be signified by a change in voltage

(V)
over the current (i)
. These quantities would be related via the
equation:

R=







(1)[
7
]


The units of resistance are “ohms,” sign
ified by the G
reek
letter Omega,
Ω
.

Figure 1

that displays the mechanism used
to find imperfections on a small scale:










Sean Kosma

Alex Veurink

6


FIGURE 1


Small scale measurement device of electric
current through
beam of carbon fiber reinforced concrete [1]



The picture displays a CFRC beam attached to two
copper electrodes on either end. The electrodes send the
current through the beam, using the beam as the electrical
medium. A voltage probe
and a current probe are attached as
well to measure both those values respectively. An
illustrated version of the setup is pictured above. The data
from both probes is relayed back to a computer that then
computes the resistance with the gathered values.

T
he
resistance should be relatively steady throughout the beam
assuming an absence of imperfections. The computer then
shows at what part of the beam (if any) a sudden increase of
resistance happens. This would then indicate a possible
imperfection.

[8]


AP
PLICATIONS OF CARBON FIBER

REINFORCED CONCRETE



Today, carbon fibers have a large importance in the
aerospace, sporting goods and automobile industries.
However, it has the potential to play a vital role in an
industry that almost every citizen of a somewhat developed
country must rely on; infrastructur
e. Carbon fiber exhibits
many chemical and physical properties that make it a viable
candidate as a building material. Its various properties allow
it to be easily inspected, resistant to water damage and
corrosion as well as having a significant amount of

compressive strength compared to regular concrete. It can
therefore be applied to numerous types of infrastructure
inc
luding bridges and skyscrapers.


A
pplication

t
o

B
ridges



In the instance of bridges,
CFRC

can play an extremely
important role. Concrete and steel bridges must be kept in
the utmost condition since vehicles cross over it that carry
important goods to a thriving economy as well as ordinary
citizens. Often times, bridges serve the purpose of spa
nning
an otherwise impassable obstacle, such as a gorge or a body
of water. These bridges must be able to sustain the heavy
loads that cross over it as well as have the ability to survive
sometimes
-
harsh weather conditions.
CFRC

can help with
almost all th
e conditions bridges must be able to sustain
themselves through. Like all pieces of infrastructure, bridges
require maintenance. Traditionally, the inspection of bridges
required workers to climb down on the structure and
physically examine every inch of t
he structure. Using
electrical currents to inspect for areas of electrical resistance
allows civil engineers the ability to quickly identify an
imperfection and not waste as much time examining every
inch of the bridge. Bridge supports, depending on the de
sign
of the structure, are sometimes submerged in water. Carbon
fiber reinforcement gives concrete increased water
resistance, allowing those structures to remain at their
optimal condition for longer periods of time. Carbon fiber
reinforcement also greatl
y increases the compressive
streng
th of concrete; to over 200%. [9
] This will allow
bridges to sustain heavier loads without causing cracks to
form.


A
pplication to

Buildings



Another type of infrastructure that
CFRC

has great
potential to improve in
cludes skyscrapers. Skyscrapers reach
high into the sky, so they must uniquely be able to handle
high, upper
-
altitude winds and have the ability to sustain
their own enormous weight.
CFRC

can help make
skyscrapers safer and much easier to maintain. Using c
arbon
fiber
-
infused aggregate in the building’s structure can help
make the structure lighter. This will help take some of the
burden off the lower floors of the skyscraper, which must be
able to sustain their own weight and that of the floors above.
Also,

since skyscrapers consists of so much structural
material, the fast speed of inspection associated with CFRC
makes inspection of the entire building that much faster

[10]
.


IMPORTANCE



The future of modern society depends greatly on the
integrity of its infrastructure. In a world that builds and
Sean Kosma

Alex Veurink

7


moves at an ever faster rate, infrastructure plays a central
role in making sure that world functions correctly. Today,
everything depends on tr
ansportation. Business leaders from
China need to fly to America in order to make a deal.
Engineers need to drive to work everyday in order to
complete projects for their company. Without a modern
infrastructure, modern society would be impossible.
Therefo
re, a modern infrastructure requires the most modern
means to maintain it.
CFRC

plays a vital role in maintaining
that infrastructure. As more cars pass over a bridge
everyday, the most efficient means to make sure that bridge
stays stable must be used. CF
RC can become those means.
CFRC

not only plays a functional role in the maintenance of
infrastructure, it also plays an ethical one. An engineer
charged with the maintenance of a certain bridge has not
only a functional duty but a moral duty to keep that b
ridge
intact. If he fails at his job, he puts people’s lives at stake.
Using
CFRC

in that bridge’s design helps ensure that he
completes his job with the utmost efficiency.


In the 1950’s, the United States initiated the construction
of the interstate
highway system. Much of America’s
infrastructure was erected as a result of that project in the
following few decades. Today, many of those decades
-
old
bridges and roads have reached the end of their lives and are
falling into disrepair. This offers
CFRC

a

chance to implant
itself on the new pieces of infrastructure that must be erected
to replace or reinforce the old ones. According to the
International Energy Agency, there are 850 milli
on cars on
the road today. [11
] Civil engineers have a moral duty to
e
nsure these drivers have a safe and functional infrastructure
that enables them to carry out their day
-
to
-
day liv
es.


As engineers are obligated to look after the welfare of the
citizens and the lives they lead, within the last decade,
increasing care for the environment has been brought to the
forefront of many people’s stances. Through innovation of
CFRC and geopolymers

discussed earlier,
the sustainability
of civil structures has been at the leading edge of many
arguments dealt with in the expansion of America’s
infrastructure.


Sustainability in

America’s Infrastructure



As sustainability was defined in the 1987
Brundtland
Report by “satisfying the needs of the present generation
without compromising the ability of future generations to
meet their own needs,” this paper’s discussion of CFRC and
the properties contained in the material is a very applicable
subject
for sustainability to be found.

[12]

The very principle
of damage detection with the help of CFRC properties leads
to an easier means of maintaining civil structures for
generations to come. With the additional electrical
conductivity, maintenance crew
s wo
uld no longer have to
the exterior faces of the structures, possibly putting their life
at risk, in the search of possible cracks. Sustainability, in this
sense, would lead to safer working conditions and sustained
health to civil structures, thus leading
to safer everyday
encounters with the population who utilize these structures
to further
their lives.


Sustainability, in the other sense of the word, has been an
increasingly stressed area of importance in recent years.
With many believing the environ
ment is worse off now than
it has ever been, environmentally
-
friendly materials are
highly sought after.
As discussed in a paper by the
Department of Civil Engineering

at the University of British
Columbia, a newly developed geopolymers that, when
coupled with CFRC, could
create a smart material capable
detecting microfractures within the structure. This
geopolymers, biologically influenced by cellulose, is also
capable

of being recycled, and due to the very properties of
cellulose, found in plant cell walls, is biodegradable. The
university’s work portrays how the current state of the
concrete infrastructure found in countries, such as America,
is a highly applicable ar
ea to apply such a “
sustainable, bio
-
inspired fiber reinforced concrete for both new construction
and repairs.” With sustainability at the forefront of
innovation, such materials will be prominent within civil
structures of the future.

[13]


CONCLUSION


CFRC

is an exceptionally
unique material that has the
potential to set a whole new standard for building materials.
As time goes on, humans make more and more discoveries
about themselves and the world they live in. This leads to a
society that demands suc
h discovery at a faster and faster
rate. As people rush to complete their daily tasks, they
require a better and better infrastructure that can sustain the
amount of travel that takes place in this modern world. The
strength of infrastructure depends not o
nly on how much
money is invested in it, but also what kind of material that
money is spent on. CFRC exhibits properties that make it
vital to any civil engineer who wishes to utilize the most
innovative material on the market.

Along with the very
properti
es housed in a carbon fiber,
CFRC seems to be a
super
-
efficient means of achieving sustained levels within
civil structures to be built down the road. Geopolymers,
developed with the properties of CFRC in mind, are
becoming sustainable in themselves, due t
o biological
influences.

It ensures greater durability and greater safety
than traditional concrete once did. It provides a pathway
through the ongoing development of civil engineering and
will ensure a brighter future for all who benefit from its
utiliza
tion.


REFERENCES


[1] P. Chen. (July, 1996) “Carbon Fiber Reinforced Concrete
as an Intrinsically Smart Concrete for Damage Assessment
during Static and Dynamic Loading.”
ACI Materials
Journal.

(Online Journal). <

http://wings.buffalo.edu
/academic/department/eng/mae/cmrl
Sean Kosma

Alex Veurink

8


/Carbon%20fiber%20reinforced%20concrete%20as%20an%
20intrinsically%20smart%20concrete%20for%20damage%2
0assessment%20during%20static%20and%20dynamic%20l
oading.pdf
>

[2]
A. Barron. “Chemical Composition of Portland Cement.”
Aca
demic Press: Connexions.

(Online Article). <

http://cnx.org/content/m16445/latest/
>

[
3
] S. Vaidya, and E. Allouche. (2011, October). “Strain
sensing of carbon fiber reinforced geopolymer concrete.”
Materials and Structures.
(Online Article).
<http://link.s
pringer.com/article/10.1617%2Fs11527
-
011
-
9711
-
3>.

[
4
] S. Blazewicz, J. Piekarczyk, and W. Piekarczyk. (2011,
May). "Compression Strength of Concrete Cylinders
Reinforced with Carbon Fiber Laminate."

Construction and
Building Materials

25.5. (Online
Article).
Http://go.galegroup.com/ps/i.do?action=interpret&id=GAL
E%7CA252446569&v=2.1&u=upitt_main&it=r&p=AONE
&sw=w&authCo
unt=1
.

[5]

D. Bontea, D. D. L. Chung, and G. C. Lee. (2000, May).
“Damage in carbon fiber
-
reinforced concrete, monitored by
electrical resistance measurement.”
Cement and Concrete
Research.

Vol. 30, Issue 4. 651
-
59. (Online Article)

http://www.sciencedirect.com/science/article/pii/S00088846
00002040

[
6
] D. Zhang, Q. Wang, and S. Xu. (2007, September).
"Experimental Study on Electric Properties of Carbon
Fiber
Reinforced Concrete."

Journal of Wuhan University of
Technology
-
Mater. Sci. Ed

22.3 (2007): 546
-
50.

EBSCO
.
(Online Report).

<http://link.springer.com/content/pdf/10.1007%2Fs11595
-
006
-
3546
-
8>.

[
7
] D. Warner. (2012, November 30) "CORRECTED
-
UPDATE 3
-
NJ
Bridge Collapse Derails Freight Train;
Chemical Leaks."

Reuters
. (Online Article).

[
8
] P. Chen and D. D. L. Chung. (2005, September 27).
"Carbon
-
Fiber
-
Reinforced Concrete as an Intrinsically Smart
Concrete for Damage Assessment during Dynamic
Loading."
Journal of the American Ceramic Society

78.3.
(Online Article).
<http://onlinelibrary.wiley.com/doi/10.1111/j.1151
-
2916.1995.tb08254.x/abstract>.

[
9
]

D. Bontea, D. D. L. Chung, and G. C. Lee. (2000, May).
“Damage in carbon fiber
-
reinforced concrete, monito
red by
electrical resistance measurement.”
Cement and Concrete
Research.

Vol. 30, Issue 4. 651
-
59. (Online Article)

http://www.sciencedirect.com/science/article/pii/S000888
46
00002040

[
10
]
N. Banthia, V. Bindiganavile, J. Jones, and J. Novak. (
Summer 2012). “Fiber
-
reinforced concrete in precast
concrete applications: Research leads to innovative
products”
PCI Journal.

(Online Journal).
<
http://www.pci.org/view_file.cfm?file=JL
-
12
-
SUMMER
-
7.pdf
>

[
11
]

F. Vossoughi. (March 2004). "Electrical Resistivity of
Carbon Fiber Reinforced Concrete".
Department of Civil
Engineering
, University of California
-
Berkeley.
(Online
Article). <

http://www.ce.berkeley.edu/~paulmont/241/Reports_04/Car
bon_fiber_rep.pdf
>.

[12]Report of the World Commission

on Environment and
De
velopment. “Our Common Future.”
United Nations.

(International Report) <

http://conspect.nl/pdf/Our_Common_Future
-
Brundtland_Report_1987.pdf
>

[13] N.
Banthia. “Fiber Reinforced Concrete for Sustainable
and Intelligent Infrastructure.”
University of British
Columbia
.
(Online Report). <
http://sbeidco.enset
-
oran.dz/Papers/270_Paper.pdf
>


AD
DITIONAL RESOURCES


P. Chen and D. D. L. Chung. (1993, May 17). "Carbon fiber
reinforced concrete as an electrical contact material for
smart structures."
State University of New York at Buffalo.

(Research
Publication).<
http://wings.buffalo.edu/academic/department/
eng/mae/cmrl/Carbon%20fiber%20reinforced%20concrete%
20as%20an%20electrical%20contact.pdf>.


K. Naito, Y. Tanaka, J. Yang and Y. Kagawa. (2007,
November 1). “Tensile Properties of ultrahigh strength
PAN
-
based, ul
trahigh modulus pitch
-
based and high
ductility pitch
-
based carbon fibers.”

National Institute for
Materials Science, Composites and Coatings Center,
Composite Materials Group. University of California,
Department of Materials Science and Engineering. The
U
niversity of Tokyo, Research Center for Advanced Science
and Technology.
(Online Article).
http://www.sciencedirect.com/science/article/pii/S00086223
07005751

ACKNOWLEDGEMENTS

We

would like to take this time to give thanks to the
many people who helped me co
mplete this assignment. First,
we

would like to give thanks to Beth Bateman Newborg for
pointing all of us in the right direction for this assignment.
Withou
t her help, we would

have bee
n lost. Also, we

would
like to thank the engineering program here at the University
of Pittsburgh for enabling us to write paper
, and having u
s
learn

about our intended discipline of engineering. This
really helps us obtain a d
ecent scope of the work we may be
entailed to do when we graduate.
We would like to also
thank Nichole Faina for meeting with us to clear up the
Sean Kosma

Alex Veurink

9


numerous questions we had during the writing process.
Thanks to everyone
.