ENGINEERED CEMENTITIOUS COMPOSITES: APPLICATIONS AND IMPACT OF HIGH TENSILE, SELF-HEALING CONCRETE

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S
ession A5


Paper #
3204

University of Pittsburgh

Swanson Scho
ol of Engineering

March 7
, 2013

1

ENGINEERED CEMENTITI
OUS COMPOSITES: APPL
ICATIONS AND
IMPACT OF HIGH TENSI
LE, SELF
-
HEALING CONCRETE


Jayne Marks (jam347@pitt.edu, Vidic 2:00), Jon Conklin

(
jjc105@pitt.edu
, Vidic 2:00
)


Abstract


Engineered Cementitious

Composite, or
ECC
, is
a unique type of cement mixture that was initially developed
by Victor Li at the University of Michigan

in
2001

[
1
]. It
improves upon current concrete mixes and Fiber Reinforced
Concrete

(
FRC
) types due
to
its

unique composition of
low
volume fibers and variable composites
,


that give it a high
tensile strength

and
the
ability to repair itself [2
]. The
concre
te mix was created based mainly
on the interactions
between the microfibers included in the mixture and the
other m
aterials pre
sent (the matrix)
. These interactions
create

flat steady state cracking of the concrete when under
stress

[3]
. This ty
pe of cracking better protects
the concrete
from the introduction of solvents and corrosive elements
while also promoting the reactions th
at cause self
-
healing,
and these properties are what set
Engineered Cementitious
Composite

apart from the concrete currently in use today.
The improvement to concrete
Engineered Cementitious
Composite

displays has many societal appli
cations that can
help i
mprove

the current state of the world’s structures
including longer lasting infrastructure, less repair costs, and
more versatile physical propertie
s of structures it is used in

[4]
.

This paper will discuss experiments performed to test
tensile strength,
compression resistance, and shrinkage of
Engineered Cementitious Composite

concrete based on
variations in the composite make up of
Engineered
Cementitious Composite

that cause it to differ from other
concretes and
Fiber Reinforced Concrete
s in
the
areas
of
ductility, durability, permeability, a
nd other important
properties
. It will also explore the benefits of application to
society and economic advantages while also taking into
account environmental impacts and cost by citing specific
examples of
Engine
ered Cementitious Composite

use in
society today; such as seismic dampening support co
lumns
in skyscrapers of Japan, or dam overlay repair
.


Key
Words


Cement, Concrete,
ECC
,
Engineered

Cementitious Composite, Fiber Reinforced Concrete, Victor
Li


CONCRETE

AS IT STANDS




C
oncrete is the most widely used construction material in
the world [
5
]. Not only is it us
ed on highways and
buildings, concrete

is a vital component of many other
structures necessary for the function of society such as
underground t
ransit, wastewater treatment, marine
structure
s, and bridges.
Every year, the use of concrete for
construction projects globally exceeds 12 billion tons [2]. To
put that into perspective, there are roughly 7 billion people
on t
he planet, averaging out to
1
.7 tons of concrete per
person

used each year

Concrete is

one of the most
prominently used construction resources
, yet the
main types
of concrete in
use

tend to have major issues that hinder their
performance.

Concrete is fundamentally

a mixture of
aggregates and paste. The aggregates are sand and gravel or
crushed

stone; the paste is water and Standard P
ortland
cement.

When
the average person thinks of concrete
,
this
basic
mixture

is

typically

what they are

thinking

of.

H
owever, this p
articular

type
of concrete
has drawbacks that
make it a less than ideal choice for such an important
resource. This traditional concrete may be strong initially,
but it tends to be very brittle and cracks easily under
mecha
ni
cal and environmental loads [5
]
.
T
he cracks that
develop
tend to be very large,
allow
ing

sulfates and
corrosive agents to permeate through and damage any inner
steel structures the concrete may be covering.
In the event
of a catastrophe such as an

earthquake, a damaged section of
concr
ete could be the difference between a building standing
or collapsing.

For this reason, it is necessary to consider an ideal
concrete mixture that woul
d retain the strength of basic
concrete
, while better handling the stresses of the
environment that
these types of structures experience on a
daily basis. This ideal concrete would need to be ductile, or
able to deform under tensile stress, so it would not crack and
crumble under mechanical loads, but it would have to retain
a large tensile

(or bending)

strength. The
concre
te should not
be easily permeated

so
the infrastructure is kept away from
harmful chemicals, and it should also be easily repaired if
damage is sustained.

One

improvement that has been used commercially since
the 1900s is the addition
of small fibers, usually made of
steel or glass, to the concrete mixture. This

addition
increase
s

the
bending strength of the material due to the
flexible nature of the fibers
.
These concretes are known as

Fiber Reinforced Concrete

(
FRC
)
, and while this do
es solve
some of the problems presented by regular concrete,
it was
not until 2001

that an ideal

concrete solut
ion was developed.
This new MIXTURE

incorporates

the strength of regular
concrete with the flexibility of
Fiber Reinforced Concrete
. It
also exhi
bits a rather useful quality that far exceeded the
ability of the other two options. This concrete mixture is
called
Engineered Cementitious Composite (
ECC
)
: the

strong,
flexible
,

and self
-
healing concrete

[3]
.


WHAT IS EN
GINEERED CEMENTITIOUS
COMPOSITE
?

Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

2



According to a research article published by the
University of Michigan Transportation Research Record,

Engineered Cementitious Composite

is “a special type of
high performance fiber reinforced concrete containing a
small amount of short random fi
ber
s micromechanically
designed…

to achieve high damage tolerance under severe
loading and high durability under norma
l service conditions


[5].

It was developed in 200
1

by Dr. Victor Li at the
University of Michigan.
However,
Engineered Cementitious
Composit
e

is no longer confined to the

academic research
laboratory; i
t is finding its way into precast plants,
construction sites, an
d repair and retrofitting jobs

in
countries including Japan,
South
Korea
, Australia,
Switzerland,
Canada,
and the United States

[4
]
. What
makes
Engineered Cementitious Composite

different from
other regular and fiber reinforced concretes are the unique
properties associated with its specially tailored composites.
These properties include a smaller crack width, superior
tensile stre
ngth, significantly higher ductility, self
-
healing
properties, and low fiber volume

[
5
]
.

All of these properties
contribute to improving the safety, strength, and
sustainability o
f the structures it’s implemented into.


CHARACTERISTICS AND PROPERTIES
OF
ENGINEERED CEMENTITIOUS
COMPOSITE



The introduction and

application of
Engineered
Cementitious Composite

would be point
less without the
very
specific

qualities and strengths that it exhibits
. These special
qualities are

based upon its material make up

and
the
interaction
s

with the surrounding environment

it
experiences
.
The

characteristics break

down into the
physical strength and interactions that
Engineered
Cementitious Composite

undergoes, along with the chemical
reactions and properties that allow
the process of self
-
healing to occur. The
se physical

properties
include

remarkable tensile (or bending) strength and ductility, which
allow for one of the more important interactions in the
concrete itself: micro
-
cracking. The process of micro
-
cracking exp
onentially increases the tensile strength and
remains within a low degree of permeability
. This low
permeability
reduce
s the effects associated with

the
absorption of chemicals

which include

the weakening of

any

underlying support structure
s

and erosion of

the concrete
itself

[4
]
. This

increases the lifespan and repair cycle of the
concrete and the structure as a whole
,

while
also
creatin
g the
conditions that allow

specific chemical reactions

to occur

that help to fill in the cracks of the concrete
.


Physical Properties and Stress Interactions of
Engineered Cementitious Composite



Engineered Cementitious Composite concrete exhibits
many natural
,

physical qualities

that

allow it to be

a
pplied in

place of standard fiber reinforced concrete as

a more

dependable,

long
-
term replacement.
These characteristics
include its low permeability

along with high tensile strength,
flexibility
,

and
resistance to corrosion and spalling, or the
fragmentation of the concrete under stress

[3]
.

When stress is introduced

to a sample of
Engineered
Cementitious Composite
, the major transfer of this stress is
through
the formation of micro
-
cracks in response to a
tensile strain. The nature of these cracks is different from
that of the cracks seen on ot
her fiber reinforced
concretes
due to

the fact that flat steady state micro
-
cracks are formed
as opposed to localized Griffith crack propagation

[3]
. The
former of the stress responses is ideal because
when this
type of micro
-
cracking occurs,

it
form
s

multiple
,

uniform
cracks
over a small area, whereas Griffith crack propagation
forms large jagged cracks that are localized and harmful to
the strength and permeability of the concrete. Under th
e
conditions of s
teady state flat crack propagation, a process
known as plasticity occu
rs where the material strength is
higher after the first crack is formed and increases linearly to
the final tensile strength factor. These cracks

in
Engineered
Cementitious Composite

then follow simple formulae of
crack potential and width that allows
Eng
ineered
Cementitious Composite

to form smaller crack widths
.
These equations used to predict things such as crack width,
strength, length, and flexibility

can be found below
.



P=(ε
sh
-

e

cp

i
)) (1
)[3]



This equation demonstrates that as the sum of the elastic
tensile strain capacity (
ε
e
), tensile creep strain (
ε
cp
), and
strain capacity (
ε
i
) increase or decrease relative to the
shrinkage strain (
ε
sh
), the cracking potential (P) will increase
or

decrease respectively.




L
ch
=EG
f


t
2

(2)[3]



This equation demonstrates that as the tensile strength (
σ
t
)
increases or decreases relative to the product of the Young’s
modulus (E)
and the fracture energy (
G
f
), the Hillerborg’s
material characteristic length (
L
ch
) will decrease or increase
respectively.



W=L(P/(1
-
L/2
L
ch
) (3)[3]




In equation 3
, crack widt
h (W) is proportional to the
product of the crack length (L) and the crack potential
divided by the crack length minus one divided by the
Hillerborg’s material characteristic length. This relates that a
larger cracking potential will result in a greater cr
ack width
which is shown to be the opposite for Engineered
Cementitious Composites.


Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

3

These equations

also
show

that when cracking potential
(P) is greater than or equal to zero
, a single crack forms in
the conc
rete with a proportional width (W)

and the mat
erial
will have a larger strain capacity as the number of cracks
increases until the strain capacity value reaches an ultimate
tensile strength.
Engineered Cementitious Composite

has a
large strain capacity of about
five percent

(500 times that of
standard

concrete), and an extremely low chance of the
formation of localized fracture damage [3].

The forma
tion of these micro
-
cracks
creates a unique
resistance to the absorption of water and chloride ions which
pose the greatest threat to the underlying structu
re of any
reinforced concrete. Through experimentation and analysis,
it was determined that
Engineered Cementitious Composite

exhibits crack width well under the threshold of permeability
for water and chloride ions under accelerated corrosion
testing. Whe
n compared to that of norm
al concrete over a 14
week

freeze thaw cycl
e
, the traditional concrete was
deteriorated at such a rapid rate
,

that it was removed from
testing after five

weeks.

T
he
Engineered Cementitious
Composite

sample went on to complete the
14 weeks with
no degradation of the surface or strength. Similarly
,

a 26
week test of
Engineered Cementitious Composite

was
conducted in a high temperature
and alkaline environment,
which, when complete,
showed that the
Engineered
Cementitious Composite

dropped in tensile strain from 4.5%
to 2.75%. While this seems to show a significant degradation
in the concrete, similar traditional concrete
s are still 250
times weaker

in comparison

[6]
.

Material makeup of
Engineered Cementitious Composite

also plays a part in the properties of strength and
micromechanical interactio
ns. The introduction of certain
composites

to the mix of
Engineered Cementitious
Composite

results in a greater c
ompressive and tensile
strength,

while also increasing the bond
strength between the
underlying structure and the concrete

[4]
.
The increase in
compressive and tensile strength means that
Engineered
Cementitious Composite

is able to experience large axially
directed pushing forces and lateral stretching or pulling
forc
es

without showing serious deformation or sharp breaks
.
This ductility is similar to that seen in metals. The flexibility
of the material can

be seen in F
igure 1 below.


FIGURE 1


Engineered Cementitious Composite
’s flexibility
exemplified [
7
]


This has b
een experimented on multiple times and has
reached a point of customization to the project that would
allow a longer period between repairs than is already
expected for similar applications of
Engineered
Cementitious Composite
. One such experiment consiste
d of
the addition and substitution of different proportion of glass
beads to
specifically
form a lightweight, coarse
aggregate
that would lower the density in a uniform manner.
This

customized, lightweight

version of
Engineered Cementitious
Composite

showed significant improvement in
tensile and
compressive
strength,

w
hile allowing
for a product that
provided 40 MPa (mega
-
Pascal) of compressive strength and
4MPa of tensile strength on average

(much higher than other
concretes)

[8
]
. However,
the cost an
d practi
cality of certain
mixtures is regarded as

a serious factor to consider wh
en
application of
Engineered Cementitious Composite

is
compar
e
d

to that of standard fiber reinforced concretes.
Along with this same experiment, a sample that had a
density of

.93 g/cm
3
, less than that of water, was deemed
acceptable for application in seismic dampeners with a
tensile strength of 2.85MPa and a compressive strength of
28.1MPa

[8
]
. T
his relationship shows that at
a certain point
,

the relationship between density
and the strength of
Engineered Cementitious Composite

will drop to a point that
resembles the compressive strength of standard concrete
while retaining the tensile properties that makeup the major
benefits of the application of
Engineered Cementitious
Comp
osite
.



Chemical Interactions of Self
-
Healing
Engineered
Cementitious Composite



While the durability of
Engineered Cementitious
Composite

is due

to a low permeability and diffusion rate,
along with a high tensile and compressive st
rength, the long
lifespan

is also due to a chemical proc
ess of self
-
healing that
occurs inside

the micro
-
cracks

of the concrete
. Duri
ng the
early stages of cracking

(
fewer than

fifty micrometers)
,

the
concrete will engage automatically

in a self
-
healing reaction
Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

4

that will

mechanically fill in the micro
-
cracks. It takes place

directly in the crack and

under a multitude of environmental
conditions ranging from freezing
-
thawing cycles to chloride
submersion

which allows the self
-
healing to be dependable
in real life applicatio
ns
. This process

of self
-
healing

stems
from the carbonation of the calcium in
the
cement matrix,
but only occurs in the presence of specific acidity levels of
the water and calcium ion concentration at the crack surface.
As water moves more slowly through
cracks of a smaller
width
, as opposed to quickly through larger cracks in regular
Fiber Reinforced Concrete
s
, pH levels will rise as carbonate
precipitation occurs.

This reacti
on is shown in equation
number 4

below

[3]
.


Ca2
+

+ HCO
3
-

<=> CaCO
3
+H
+
(7.5<pH
water

>8)


(4
)[
3
]


As the water
,

which contains carbon dioxide
,

penetrates
the pores of hardened cement paste

even deeper
, it dissolves
additional calcium ions f
rom the calcium hydroxide
. This
then raises the pH value of the solution

even more tow
ards
the ideal pH

creating a more favorable environment for the
self
-
healing process.
The formation of
CaCO
3

is the
compound that will ultimately fill in the micro
-
cracks in
which the reaction is occurring.
[
3
]


Experimentation has shown that a sample of
En
gineered
Cementitious Composite

put under tensile strain and then
subject to three wet dry cycles, will successfully fill a one
hundred micrometer crack with calcium carbonate crystals.
Additional testing in this experiment also showed that the
introductio
n of fly ash

to the
Engineered Cementitious
Composite

mixture

would decrease average crack width to
around ten micrometers, thus promoting a quicker and more
filled self
-
healing sample

[
9
]
.
The results of this experime
nt
can be seen in Figure 2
.


FIGURE 2


Engineered Cementitious Composite

a) before healing and
b) after healing [
9
]


The process
of self
-
healing that

Engineered Cementitious
Composite

under
goes during this time has little effect on the
t
ensile strength of the concrete:

lowering the overall strength
from 4.5% to 3%, a value well beyond that of standard fiber
reinforced concrete

[3]
. Along with this
,

the introduction of

additives such as
fl
y ash

(an industrial waste resulting from
coal
-
fired thermoelectric power
generation
)

to
Engineered
Cementitious Composite

would allow it to be applied to

situation
s

where a more consistent self
-
h
ealing process
would
be observed.
Certain
other
additives

create different

customized

properties of
Engineered Cementitious
Composite
,

including the ability to be
sprayed

as a
much
lighter

material
, high
er

tensile strength,
or
high
er

compressive strength
. These various forms of
Engineered
Cementitious Composite

make it much mo
re applicable to
various commercial

needs.


APPLICATIONS OF EN
GINEERED
CEMENTITIOUS COMPOSITE AND ITS
AFFECTS ON SOCIETY



The many positive qualities of
Engineered Cementitious
Composite

have been repeatedly exemplified in a laboratory
setting, but the superior physical characteristics also pose
many benefits to society through application. Engineered
Cemen
titious Composites pave the way

for many possible
improvements to the current stand
ing of concrete, and in
some cases,
Engineered Cementitious Composite

has alr
eady
been
implemented in construction projects
.
These
cases
exhibit structures that

are more resilient and less susceptible
to damages
. Because sustainability is the capacity to e
ndure,
t
he

more durable and longer lasting structures associated
with the use of Engineered Cementitious Composite
contribute not only to the sustainability of the world’s
infrastructure, but also to a reduction in maintenance and
repair costs, a better en
vironmental impact, and an overall
improvement of the safety of structures constructed with
concrete.



Cost/Benefit Analysis


When comparing costs of Eng
ineered Cementitious
Composite
and regular concrete, it is important to not only
look at the initial m
anufacturing cost of the product, but to
also consider the cost over the span of the concrete’s
lifetime. If the initial costs are compared, regular concrete
does exhibit a lower starting value (ab
out three times

less

than
Engineered Cementitious Composite
), but this initial
benefit

comes at the price of quality

[7
]
.

The prices may

differ in favor of regular concrete, but the long term
financial benefits are substantial enough to drive the market
in favor of
Engineered Cementitious Composite
. The reason
for

the gap in startup price arises from the composition of
Engineered Cementitious Composite
. Unlike regular cement,
Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

5

Engineered Cementitious Composite

contains tiny fibers that
drive up the price of production, and whi
le other
Fiber
Reinforced Concrete
’s use

steel fibers,

Engineered
Cementitious Composite

typically uses more expensive

poly
-
vinyl alcohol (
PVA
)

fibers.

These are fibers made from
poly
-
vinyl alcohol or a type of plastic [3].

These PVA fibers
are more expensive to use, but they weigh considerably
less
than the steel or glass fibers used in ordinary Fiber
Reinforced Concrete

Similarly,
Engineered Cementitious
Composite

has an extremely low fiber volume compared
with other
Fiber Reinforced Concrete
. Both of these factors
reduce

the weight

of Engineer
ed Cementitious Composite
compare to other Fiber Reinforced Concrete, and because it
is typical to price concrete based on mass, it is possible that
using Engineered Cementitious Composite could be cheaper
than Fiber Reinforce Concrete. However both are st
ill
considerably more expensive than basic concrete which
includes no fibers
.
In order to lower the cost of Engineered
Cementitious composite, the
expensive cement that is used
in
the mixture to make the paste component of the concrete

can easily be replac
ed with a less expensive alternative such
as fly ash
. This substitution would
cause no drastic changes
in function

[
10,
2
]
. The
practice

of adding fly ash has
already been implemented and has been shown to include
benefits other than cost reduction such as

less environmental
pollution.

The cost of manufacturing Engineered
Cementitious Composite may be high, but in the long term,
the concrete proves to help reduce expenses.


The main long term financial benefit of using
Engineered
Cementitious Composite

is t
he reduction of the maintenance
costs when compared to regular concrete. Because
Engineered Cementitious Composite

is much more sturdy,
less brittle, more flexible, and self
-
healing, it requires repairs
less frequently than other concretes. The brittle nat
ure of
regular concretes leads to “repeated cycles of short
-
term
repair scenarios which result in increased consumption of
r
epair materials and fuels”[10
]. Dr. Victor Li stated that “a
bridge built with traditional concrete will average $350,000
a year in
maintenance, user, and environmental costs

its so
called “life
-
cycle cost”

over 60 years. The

same bridge, if
built with [
Engineered Cementitious Composite
], ought to
have a 50% lower life
-
cycle cost. That would add up to a
savings of $11 million, potenti
ally justifying the much
h
igher initial price tag.”[7
].
Similarly, structures in better
condition mean less financial repercussions for those using
them. Currently 32% of US major roads are in p
oor or
mediocre condition [2
]. Driving on these
roads costs
drivers
an average of $22 extra per driver in vehicle operating costs
each year totaling $41.5 billion. The implementation of
Engineered Cementitious Composite

would save money in
t
he long term
, and that compensates for any discrepancy
between initial manu
facturing costs of
Engineered
Cementitious Composite
,
Fiber Reinforced Concrete
, and

regular

concrete.


Practical Applications of
Engineered Cementitious
Composite



The superiority of
Engineered Cementitious Composite

not only financially, but in over
all quality and performance,
has caused
the beginnings of implementation to the
commercial concrete business
.
Engineered Cementitious
Composite

has been used in
a
skyscraper in Japan, a mall

in
Canada
,
and a bridge in Michigan. In the specific case of the
bridge,
Engineered Cementitious Composite

was used as a
link slab to connect portions

of the bridge deck

as seen in
Figure 3
.


FIGURE 3


Section of Michigan bridge replaced by
Engineered
Cementitious
Composite

[6]


Bridges experience necessary movement such as
expansion and contraction due to temperature, vehicle loads,
and settlement. It must be able to withstand all of these
stresses, while also exhibiting good riding quality and
minimal noise. Norma
lly, sections of the bridge deck are
connected using mechanical expansion joints, however
,

these metal joints can easily fall into disrepair and begin to
deteriorate the bridge
structure itself. In the case of the
bridge in Michigan, the four

span simply s
upporte
d steel
girder bridge with a nine
-
inch

thick reinforced concrete deck
constructed in 1976 underwent construction to replace the
deck and include an
Engineered Cementitious Composite

slab. This was the initial implementation of Engineered
Cementitiou
s Composite. Two days after patching, the
Engineered Cementitious Composite

showed no visible
cracking, yet the concrete patch had a clearly visible crack
approximately 300mm wide. Ten months after patching, the
maximum
Engineered Cementitious Composite

c
rack width
was 50μm while the section of concrete was described as
“severely deteriorating.
” Five winters
after installation, the
concrete needed re
-
repaired, but the
Engineered
Cementitious Composite

still only showed small cracks

[10
].
The reason for thi
s difference in performance is due to the
flexibility of the
Engineered Cementitious Composite
. It is
better able to handle the thermal expansion and contraction
of the bridge. Also, the micro
-
cracks that do develop are
either self
-
healed or small enough t
o not affect the
functioning of the bridge.

Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

6

This unique outperformance is the case for all examples
of
Engineered Cementitious Composite

application. Because
it can be cast, extruded (pushed through a die of desired
shape and cross sectional area), or spr
ayed
,

and has unique
self
-
healing capabilities,
Engineered Cementitious
Composite

is a good choice for a long lasting repair material.
In an experiment involving damaged concrete beams that
were repaired with
Engineered Cementitious Composite
, it
was found that
Engineered Cementitious Composite

actually
increased the tensile strength of the beam to levels higher
than the original, undamaged beam [
11
].
This can be seen in
F
igure
4

below.


FIGURE
4


Regular concrete beam (left) compared to
Engineered
Cementitious Composite

beam

(right) during a strength
loading experiment [
4
]


Alt
hough
Engineered Cementitious Composite

has a
higher price than regular concrete, using even small amounts
to repair beams, dam
s, bridges, and other construction
pr
ojects

or to coat undamaged structures is an investment in
the sta
bility of the structure
. This
creates a more sustainable

building material,

reduces
the price of repairs and

the
amount of materials used for repairs
, and he
lps to lower the
negative impact
on the environment


Sustainability and
Environmental Impact of Engineered
Cementit
i
ous Composites




“Cement is responsible for 3% of global greenhouse gas
emissions
.” Every time 1 ton of cement is produced, 1 ton
of CO
2

is released as well

[2
]
. When
structures like roads are
built with regular cement, they need to be repaired more
frequently. This uses more cement which releases more
greenhouse gases into the atmosphere. While a road is being
repaired, the traffic in that area increases due to
constru
ctions and road closings. This congestion leads to
inc
reased fuel use and emissions [
2
]. Using
Engineered
Cementitious Composite

can help to slightly decrease this
environmental
impact

which improves the overall
sustainability of the project
. Figures
5

and
6

compare
Engineered Cementitious Composite
, concrete made only
from Portland

cement
, and hot mixed asphalt (HMA)

on
important environment
al statistics.


FIGURE
5


Energy use for regular concrete,
Engineered Cementitious
Composite
, and HMA (hot mix a
sphalt) compared [
2
]


FIGURE
6


Carbon Dioxide production due to concrete,
Engineered
Cementitious Composite
, and

HMA

(
hot mix asphalt
compared
)

[
2
]


The
se figures demonstrate the decrease in energy use and
CO
2

emissions that can be achieved by using Engineered
Cementitious Composite, however, there is still room for
improvement.

The
current accepted mixture of
Engineered
Cementitious Composite

includes a significant amount of
cement so the adverse environmental effects associated with
this material are still present in
Engineered Cementitious
Composite
. However, by substituting this with industrial
waste such as sands, kiln dust, and fly ash,
t
he
environmental effects of the cement production would be
reduced while also disposing of waste.
“70% of
Engineered
Cementitious Composite
’s composites may be replaced
without reducing critical mechanical performance
characteristics
[10
].”
Also, as stated

previously, the fly ash
would not only lessen the negative environmental impacts of
Engineered Cementitious Composite

manufacturing, it may
also help to facilitate self
-
healing reactions better than in
regular
Engineered Cementitious Composite

mixtures.


Because
sustainability is the
ability of a process,
method, or structure to endure over time and to support the
endurance of society, the reduction of negative
Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

7

environmental impacts, the increase in the life
-
span of
structures using Engineered Cementitious

Composite, and
the decrease in the amount of resources needed to repair
these structures all show that Engineered Cementitious
Composite is a sustainable alternative to regular concrete
Using
Engineered Cementitious Composite

as a commercial
replacement f
or cement and
Fiber Reinforced Concrete
s
would lessen the environmental footprint of the cement
industry through not only the reduction of emissions during
manufacturing, but also through the reduction of repair
materials necessary to keep structural condi
tions safe.


The Ethics Behind
Engineered Cementitious Composite



The most important aspect of any new building material is
its safety. If
Engineered Cementitious Composite

was not
safe
, all of the previously stated characteristics would be
irrelevant.

In the American Society of Civil Engineers

(ASCE)

code of ethics, Canon #1 states that “engineers shall
hold paramount the safety, health and welfare of the public”
[
12
]. When using concrete, especially for load bearing
structures such as buildings and b
ridges, it is absolutely
essential that the concrete be able to hold up the weight of
that structure. If the concrete cracks and crumbles under
stress lower than the stress expected to be experienced
during use, the possibility of structural failure could
result.
This can cause increased repair costs, malfunctions of
essential societal systems like dams and water treatment
plants, injury, or even death. Engineered Cementitious
Concrete has been experimentally proven multiple times to
perform exceptionally w
ell under many different types of
loads, stresses, strains, and forces. The strain capacity for
Engineered Cementitious Composite

is high enough to be
deemed safe for public use. Similarly,
Engineered
Cementitious Composite

is able to withstand damage caus
ed
by factors experienced in society such as varying weather
conditions, wear, friction and grinding, corrosion, and many
other environmental elements.
Engineered Cementitious
Composite

has an exceptionally long lifetime, and is able to
not only withstand
these conditions (as proven by multiple
freeze
-
thaw, wet
-
dry tests mentioned above), in the case of
weather patterns, precipitation actually increases
Engineered
Cementitious Composite
’s ability to function. The water
better facilitates the self
-
healing pr
ocesses creating a
stronger concrete structure.

In the code of ethics from the American Society of Civil
Engineers, it is also stated in Canon #1, part D that
“Engineers should seek opportunities to be of constructive
service in civic affairs and work for

the advancement of the
safety, health and well
-
being of their communities…” [
12
].
The use of Engineered Cementitious Composite rather than
regular concrete would not only be a viable replacement, it
would be a definite advancement of the current cement
te
chnology. It is becoming clear that
Engineered
Cementitious Composite

is a better alternative to regular
concrete. For all aspects of safety involved in the use of
cement and concrete,
Engineered Cementitious Composite

meets the requirements set by the
Ame
rican Society of Civil
Engineers

code of ethics and exceeds the performance of the
current material majority.



RECOUNTING ENGINEERING
CEMENTITOUS COMPOSITE


Concrete is an extremely vital component of today’s

society and

is used
in

many different structur
es that are
critical to the
function

of

the world
.
Due to the

strong yet
comparably
brittle nature of current
Fiber Reinforced
Concrete
, very little can be done in terms of high tensile
strains and load bearing applications.
Engineered
Cementitious
Composite

solves these problems and provides
even greater advantages in application through its distinctive
and unique properties of
self
-
healing,
high
ductility, and
tensile strength that is 500 times that of standard concrete
s
.
Application on the co
mmerc
ial level benefits many
, based
on the fact that the standard life cycle of repair is increased
dramatically
, the
superior
strength of the concrete can
possibly increase the structural integrity
of the projects it’s
used in
, and
average
maintenance

time and

cost as a whole

is
decreased
. This not only improves safety
,

but also cuts down
on

materials used for maintenance which decreas
e negative
environmental impact
.

The init
ial starting cost may propose
a deterrent to the use of
Engineered Cementitious
Composi
te
,
however
the
long term savings from

its
application
,

will out

weight the initial expense
.
Experimentation with
Engineered Cementitious Composite

is ongoing,

and the fields of applica
tion are forever
expanding for E
ngineered Cementitious
C
omposite. The
s
eemingly unbelievable characteristics of this bendable, self
-
repairing concrete are being proven more and more
applicable to society as testing an
d application continues,
and in
the future
,

it should be expected that
Engineered
Cementitious Composite

becom
es
more prevalent in
commercial concrete projects
.



REFERENCES


[1]

Li
-
li Kan, Hui
-
sheng Shi
.

(2012)
.

“Investigation of Self
-
Healing Behavior of Engineered Cementitious
Composites(
Engineered Cementitious Composite
)
.

Construction and Building Materials
.
(Online Journal)
.

http://www.highbeam.com/doc/1G1
-
284323187.html

[2]

V. Li, M. Lepech, S. Wang, M. Weimann, G. Keoleian
.

(2007)
.

“Development of Green Engineered Cementitious
Composites For Sus
tainable Infrastructure Systems
.

International Workshop on Sustainable Development and
Concrete Technology
.

(Online Article)
.

http://www.intrans.iastate.edu/publications/_documents/conf
erence
-
proceedings
-
workshops/sustainable
-
dev
-
workshop/ligr
een.pdf

[3]

M. Li & V.C Li. (2006)
.

“Behavior of
Engineered
Jayne Marks

Jon Conklin

University of Pittsburgh

Sw
anso
n School of Engineering

March 7
, 2013

8

Cementitious Composite
/Concrete Layered Repair System
Und
er Drying Shrinkage Conditions.”

Journal of
Restoration of Buildings and Monument.

(Online Article).
http://hdl.handle.net/2027.42/84732 pg. 143
-
160



[4]

V. Li
.

(2003)
.

“On Engineered Cementitious Composites
(
Engineered Cementitious Composite
): A review of the
Material and Its Applications
.

Journal of Advanced
Concrete
Technology.

(Online
Journal)
.
https://www.jstage.jst.go.jp/article/jact/1/3/1_3_215
/_article


[5]

M. Sahmaran, V. Li
.

(2005)
.

“Engineered Cementitious
Composites: Can Composites Be Accepted as Crack
-
Free
Concrete?”
University of Michigan Transportation
Research
Record
.

(Online Article)
.

http://deepblue.lib.umich.edu/bitstream/handle/2027.42/941
98/sahmaran
-
trb
-
crackfree
Engineered Cementiti
ous
Composite
.pdf?sequence=1

[6] E. Yang, J. Yu
.

(2010)
.

“Microstructure of self
-
healed
PVA Engineered cementitious composites under wet
-
dry
cycles”
Institute of Materials, Minerals and Mining
.

(Online
Article).
http://web.ebscohost.com/ehost/delivery?sid=c8a87
805
-
c532/article

[7]
A. Vander
-
Broek. (November 2, 2009) “Self
-
Healing
Concrete”.
Forbes
. (print article). pg. 46.

[
8
]

S.Wang, V. Li
.

(2005)
.

“Lightweight Engineered
Cementitious Composites (
Engineered Cementitious
Composite
.
)”

Advanced Materials Council
.

(Online Article)
.

http://www.advancedmaterialscouncil.org/prepare/uploaded
_docs/material_id_387_pub/shuxinLW
Engineered
Cementitious Composite
.pdf

[9
]

V. Li
.

(2003)
.

“On Engineered Cementitious Composites
(
Engineered Cementitious Composite
): A review of the
Material and Its
Applications
.

Journal of Advanced
Concrete Technology
. (Online
Journal)
.h
ttps://www.jstage.jst.go.jp/article/jact/1/3/1_3_215
/_article

[10
]

M. Lepech, V. Li
.

(2006)
.

“Sustainable pavement
Overlays Using Engineered Cementitious Composites
.

International J
ournal of Pavement Research and
Technology
.

(Online Article)
.

http://trid.trb.org/view.aspx?id=987336


[11]

A.M. Anwar, K. Hattori, H. Ogata, M. Ashraf &M.
Mandula. (2009). “Engineered Cementitious Composites for
Repair of Initially Cracked Concrete Beams
.”
Asian Journal
of Applied Sciences. (
Online Journal).
http://scialert.net/fulltext/?doi=ajaps.2009.223.231


[12]American Society of Civil Engineers.

(September 2,
1914). “Code of Ethics of the American Society of Civil
Engineers.”
American Society of Civil Engineers.
(Code of
Ethics)
http://www.asce.org/Leadership
-
an
d
-
Management/Ethics/Code
-
of
-
Ethics/


ACKNOWLEDGEMENTS



We would like to acknowledge and thank Dr. Vidic,
Nancy Ko
e
rbel, Dr. Budny, Beth
Bateman
-
Newborg, the
librarians who speak to our class about sources, Ms. Galle,

John

Broscious

and
Benjamin

Hunter

our chairs, and
Agatha

Carlin

our co
-
chair
.