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158
Civil Engineering Dimension, Vol. 17, No. 3, December 2015 (Special Edition), 158-165 CED 2015, 17(3), DOI: 10.9744/CED 17.3.158-165
ISSN 1410-9530 print / ISSN 1979-570X online
Sustainable Concrete Technology
Sim, J.1* and Lee, K.H.1
Abstract: The growing concern over global warming and significant ecological changes requires sustainable
development in all fields of science and technology. Concrete not only consumes huge amount of energy and
natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that
such large amount of concrete production has put significant impact on the energy, resource, environment,
and ecology of the society. Hence, how to develop the concrete technology in a sustainable way has become a
significant issue. In this paper, some of Korean researches for sustainable development of concrete are
presented. These are sustainable strengthening for deteriorated concrete structure, sustainable reinforcement
of new concrete structure, sustainable concrete using recycled aggregate and supplementary cementing
materials and finally application of each technique to precast concrete.
Keywords: Sustainable development; FRP strengthening; recycled aggregate; industrial by-product; FRP
reinforcement.
Introduction
Sustainable development is the organizing principle
for sustaining finite resources necessary to provide
for the needs of future generations of life on the
earth. It is a process that envisions a desirable future
state for human societies in which living conditions
and resource-use continue to meet human needs
without undermining the "integrity, stability and
beauty" of natural biotic systems [1].
The concept of sustainable development is derived
most strongly from the 1987 Brundtland Report. In
1987, the United Nations World Commission on
Environment and Development released the report
‘Our Common Future’, commonly called the
Brundtland Report. This report included what is now
one of the most widely recognized definitions of
sustainable development [1].
“Sustainable development is development that
meets the needs of the present without
compromising the ability of future generations
to meet their own needs. It contains within it
two key concepts:
* The concept of 'needs', in particular, the
essential needs of the world's poor, to which
overriding priority should be given; and
* The idea of limitations imposed by the state of
technology and social organization on the
environment's ability to meet present and
future needs.”
Concrete is the widely used construction material.
The principal binder of concrete is cement, which was
produced 4.3 billion tonnes in 2014 and global
1Department of Civil and Environmental Engineering, Hanyang
University, SOUTH KOREA.
*Corresponding author; Email: jssim@hanyang.ac.kr
production of cement has steadily increased, as
shown in Figures 1 and 2 [2]. The production of cement
is a major contributor to greenhouse gas emissions.
Thus, concrete industry significantly impacts the
ecology of our planet. How to develop concrete
technology in a sustainable way becomes an urgent
issue in the world even in Korea. Green house gases
is major factor to global climate change. Korea is the
9th largest producer of green house gases, which is
1.75% of global CO2 emissions in 2014, as shown in
Figure 3 [3].
Currently, researches on sustainable development on
concrete have been carried out on following aspects:
extension of service life of concrete structure and
development of low-carbon concrete material and
structure. In this paper, therefore, some sustainable
concrete technologies, which have proceeded in
Korea, are presented by following three categories:
strengthening technique of existing concrete struc-
ture, sustainable concrete, and sustainable reinforce-
ment.
Figure 1. World Cement Production 2014, by Region and
Main Countries (%) [2]
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
159
Figure 2. The 10 Largest CO2 Emitters 2014 [3]
Figure 3. World Cement Production by Region – Evolution
2001~2014 (index: 2001=100) [2]
Strengthening Technique of Existing
Concrete Structure
Deterioration by damage or aging of concrete
structure causes declining of performance and dura-
bility. Deteriorated concrete structure needs streng-
thening, rehabilitation, reconstruction, or demolition
to secure safety and serviceability of structure.
The strengthening is one of ways to extend a service
life of concrete structure with minimum environ-
mental, social and economic effects. For streng-
thening of concrete structure, steel plate has widely
been used as conventional strengthening material.
Steel, however, has presented weakness as streng-
thening material due to increasing of self-weight,
corrosion, and limit of application. Using of FRP
(Fiber Reinforced Polymer), therefore, as streng-
thening material is increasing. In these days, it is
due to advantages of FRP such as high tensile
strength, corrosion resistance, and lightweight.
Figure 4 shows strengthening methods with steel
and FRP.
Figure 4. Strengthening of Concrete Structure with Steel
and FRP
There are various types of FRP which are produced
such as plate, sheet and rod type. Materials, like
carbon, glass, aramid, basalt, bamboo, and plastic,
are used for fiber of FRP product, which are shown
in Figure 5.
Figure 5. Types of Fibers for FRP [4-8]
Externally Bonded Reinforcement (EBR)
Steel plate bonding and column jacketing are the
conventional methods of external strengthening.
Steel plates bonded to the tension zones of concrete
members have shown to be increasing the flexural
capacity of the members [9]. This conventional
method has been used over the world to strengthen
bridges and buildings. However, the corrosion of
steel plates, deterioration of the bond between steel
and concrete, installation difficulties such as neces-
sity of heavy equipment in installing have been
identified as major drawbacks of these techniques.
As a result researchers investigated FRP streng-
thening as an alternative to this method [10].
There are a number of applications of FRP as the
strengthening material of reinforced concrete struc-
ture. The externally bonded reinforcement (EBR) is
typical strengthening method using FRP. Figure 6
shows how to apply EBR to concrete structures. FRP
plates or strips can be bonded to the external surface
of concrete members thus increasing the flexural
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
160
or/and shear strength of the members. FRP fabrics
or sheets can be wrapped around reinforced concrete
columns thus increasing the confinement and the
axial strength. Furthermore it increases the flexural,
shear and torsion strengths and improves the
ductility [10].
Figure 6. Externally Bonded FRP Systems [11,12]
Near Surface Mounted (NSM) Method
The externally bonded reinforcement has showed
several drawbacks which are early debonding of FRP
and not fully showing tensile characteristic of FRP
strengthening material [13]. Therefore, embedding of
strengthening material, Near Surface Mounted
(NSM) method, which is shown in Figure 7, was
suggested to supplement such drawbacks of exter-
nally bonded reinforcement. The NSM method could
improve bonding performance between structural
member and strengthening material by embedding
FRP strengthening material so it could effectively
not only transfer stress but also prevent early
debonding. Consequently, tensile property of FRP
reinforcement can be expected to be effectively
shown [14].
Figure 7. Near Surface Mounted (NSM) Strengthen-
ing Method [5]
Sustainable Concrete
Recycled Aggregate
In the last decade, amount of construction waste has
been considerably increased due to the demolition of
old structures, re-construction of buildings, improve-
ment of the living standard, etc. Also, the reserves of
natural aggregate for construction become depleted
rapidly. Social and environmental pressures, there-
fore, on the construction wastes drive greater signi-
ficance on the recycling of the waste. The application
of recycled concrete aggregate (RCA) has sometimes
been limited in the practice and remained in the low-
valued purposes only such as road base materials.
Primary reasons may include negative under-
standings of concrete engineers on the quality and
performance of RCA and concrete using RCA, as well
as unstable supply of waste to the recycling facilities
leading to unpredictable deliveries of final RCA. In
the past the recycling technique was not satisfactory
to produce a good quality RCA with appropriate
economic efficiency. There has been, however, a
great improvement in the recycling technique to
produce RCA of which quality is close to natural
aggregate [15].
There were some techniques how to produce recycled
aggregate with high quality, including (1) mecha-
nical grinding which is shown in Figure 8 [15]; (2)
heating and grinding (Figure 9) [16], and (3) acid
treatment [17]. In this paper, study on recylced
aggregate with acid treatment is presented.
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
161
Figure 9. Process of Aggregate Refining by Heating and
Grinding Method [16]
Recycled Aggregate with Acid Treatment
Natural aggregate was used for production of control
mix. The maximum size of natural coarse aggregate
was 25 mm and in addition to well-graded natural
fine aggregate was used for experimentation. Recy-
cled aggregates was used with same condition as
natural aggregate. Recycled aggregates were, how-
ever, contained impurities like bonded mortar.
Therefore, it was proposed to remove the bonded
mortar by acid (HCl) treatment so that its effect on
compressive strength of concrete studied [17].
The compression test indicates that an increasing
trend of compressive strength in the early age of the
concrete specimens. However, it shows that strength
of recycled aggregate specimens is lower as compared
to natural aggregate specimens. Since the cement,
mortar attached to the recycled aggregate is the
major factor that weakens the mechanical behavior
of concrete. Therefore, removal of attached mortar is
necessary to improve their quality. Figure 10 shows a
graphical representation of variation of compressive
strength decreasing of each batch was analyzed. The
main cause of the poorer quality of recycled aggre-
gate is due to bonded mortar content that resulted in
porous, high absorptive and cracks during the
crushing of the concrete waste. Different concentra-
tion of hydrochloric acid has been used in this study
to remove the bonded mortar content effectively. It
shows that water absorption of the RCA has signi-
ficantly reduced [17].
NA = Natural Aggregate; RA = Recycled Aggregate
Figure 10. Comparison of Compressive Strength [17]
Figure 8. Production Process of Recycled Aggregate [15]
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
162
Concrete with Waste Glass Powder
Supplementary cementing materials (SCMs) contri-
bute to the properties of hardened concrete through
hydraulic or pozzolanic activity. Typical examples
are fly ashes, slag cement (ground, granulated blast-
furnace slag), and silica fume. These can be used
individually with portland or blended cement or in
different combinations. Supplementary cementing
materials are often added to concrete to make
concrete mixtures more economical, reduce permea-
bility, increase strength, or influence other concrete
properties [18]. Demands and application of SCMs
would increase due to decreasing of CO2 emission
from cement producing as Figure 11 describing.
Figure 11. Using of SCM for Decreasing of CO2 Emission
Fly ash, the most commonly used pozzolan in con-
crete, is a by-product of thermal power generating
stations. Commercially available fly ash is a finely
divided residue that results from the combustion of
pulverized coal and is carried from the combustion
chamber of the furnace by exhaust gases.
Slag Cement, formerly referred to as ground
granulated blast-furnace slag, is a glassy, granular
material formed when molten iron blast-furnace slag
is rapidly chilled - typically by water sprays or
immersion in water - and subsequently ground to
cement fineness. Slag cement is hydraulic and can be
added to cement as an SCM.
Silica fume, also called condensed silica fume or
microsilica, is a finely divided residue resulting from
the production of elemental silicon or ferro-silicon
alloys that is carried from the furnace by the exhaust
gases. Silica fume, with or without fly ash or slag, is
often used to make high-strength concrete.
Glass waste has an increasing importance as a new
source of pozzolanic addition for the production of
sustainable blended cements. Glass chemical compo-
sition and average fineness are very important
parameters in view of physical and mechanical
performances expected in the relevant binder [19].
Furthermore, recycling waste glass is an economical
and eco-friendly source by a substitute for concrete
and admixture. This study aims at evaluation of
physical performances (i.e. flexural and compressive
strength) of concrete depending on the ratio of waste
glass ground granulated and fly ash to recycle it out
of industrial by-products which is generated from
domestic and international industry [20].
Using the following substitution ratios of waste glass
powder (5, 10, 20, and 30%) and fly ash (10%) to
evaluate the application of waste glass powder. For
comparison, a concrete mixture containing 20% fly
ash as cement replacement was adopted as a control
mixture, which is extensively used for concrete
pavement on highways in Korea. Compressive
strength test was performed on 100 × 200 mm con-
crete cylinders according to ASTM C39. Strength of
specimen was measured at 7 and 28 days after water
curing temperature of 20 ± 2. Flexural strength
test was performed using prismatic shape 150 × 150
× 550 mm. Flexural strength test was performed
according to 4-point flexural test method after water
curing temperature of 20 ± 2. Test results are
presented at Figure 12 [21].
Figure 12. Compressive and Flexural Strength Results
using Fly Ash (FA) and Waste Glass (WG) Powder [21]
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
163
The Results can be Summarized as Follows: [21]
Compressive strength tests shows gradual decrease
of the strength as the additives of waste glass
powder increased. With the waste glass powder of
5%, however; the strength shows the highest
strength up to 102% compared with that of OPC.
As a result of the flexural strength tests all mixed
cases except for the waste glass powder mixture of
30%, exceeds the designed and mix flexural strength
of 4.5MPa and of 5.4MPa, respectively. According to
the compressive strength test, the higher the mix
rate of glass powder, the lower the resultant flexural
strength.
Sustainable Reinforcement
Inevitably, traditional concrete structures with steel
reinforcing bars gradually deteriorate, because of
either external loading or severe environmental
conditions, such as alkali reactions, de-icing salt, and
freeze-thaw cycles. Degradation or deterioration in
reinforced concrete members can lead to other
serious structural damage, eventually causing
structural failure. The most effective way to prevent
corrosion is to use a reinforcing material that does
not corrode [22]. Many studies have focused on
developing new reinforcing materials, such as fibre-
reinforced polymers (FRPs), to solve the funda-
mental problems of steel rebar [23,24]. In reinforced-
concrete construction, FRP rebar is generally
composed of organic fibres such as carbon and glass
fibre or inorganic fibres such as aramid fibre, which
are bonded together using a polymer resin such as
polyester, vinyl-ester, or epoxy. Glass FRP (GFRP)
constitutes the majority of FRP/polymer matrix
composites because of its wide range of properties
and lower cost. Commercial GFRP rebar is manu-
factured using a pultrusion process, which is suitable
for the construction industry on account of its fast
speed of operation, good quality, and relatively low-
equipment cost. However, GFRP rebar, which is just
pultruded, has plain surface. It will be not able to
have enough bond capacity for reinforcement of
concrete structure. The surface structures of GFRP
rebar, therefore, used to enhance bonds with
concrete are usually classified into one of three
categories: braided patterns, sand-coated or deform-
ed [25].
GFRP Rebar with Ribs Containing Milled
Glass Fibers
The bond of FRP rebar with shallow continuous
fibers and rough particles depends primarily on
chemical adhesion and friction. In contrast, the bond
of FRP rebar with deformations like lugs or ribs
depends primarily on the mechanical interaction
with the surrounding concrete. The FRP rebar with
ribs have been proved to be available on reinfor-
cements in concrete structures by a number of
experimental studies. The surface structure of C-bar,
which is a representative ribbed GFRP rebar, is
made with several of sheet molded compound (SMC).
The use of SMC enables manufacturers to form
curved shape of the rebars. It should be noted that
SMC, which is composed of a resin, fibers, and
calcium carbonate, has good formability and
strength. A mixture of epoxy resin and milled glass
fibers was tested and evaluated as a surface
structure of GFRP rebars to enhance the bond with
the concrete in this study. The milled glass fibers
were produced by grinding the fiber glass into a
powder form of cotton-like appearance, resulting in
initial placing in fresh liquid epoxy. The milled glass
fibers were utilized as a reinforcing material in order
to improve formability and strength of the matrix in
surface structure of GFRP rebar [25].
The glass fiber used is commercially available in the
E-Glass formulation, which is the most widely used
general purpose form of composite reinforcements.
The milled glass fiber is one that is hammer-milled
strands into small lengths. They are usually used to
improve thermal properties and dimensional sta-
bility in the injection molding processes. The milled
glass fibers used in this study were manufactured by
a special order of the authors not commercially
available in Korea. The surface structure analogous
to the ribs of ordinary steel rebar was considered as
shown in Figure 13. The rib height and spacing were
preliminary determined by using best performing
value of relative rib area and spacing-to-height ratio
theory that was originally used for ordinary steel
rebars. The spacing and height of a rib were finally
determined to be 6 mm and 1.3 mm, respectively
[25].
Figure 13. Schematic of the Proposed GFRP bar [26]
Comparison of FRP Rebars by Pull-out Test
This pull-out test is designed to evaluate bonding
capacity of the proposed GFRP rebar with 50% of
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
164
milled glass fibers and to be compared with other
types of bars. The rebars tested herein have an
approximately same diameter which is equivalent to
No. 3 steel rebar. The specimens are designated
according to their surface patterns: the proposed
deformed GFRP rebar [PDGR]; the sand-coated
GFRP rebar [SCR]; and the surface-braided GFRP
rebar [SBR] of which surface is braided with glass
fibers. In addition, an ordinary steel rebar is
included and designated as [DS].
Table 1 describes the mechanical properties of rebars
used in pull-out test. The bond strength (σb) was
calculated in MPa according to the following
formula:
(1)
where, P is the pullout load in N, lb is the embedded
length in mm, and db is the nominal bar diameter in
mm [26].
Applicability of a mixture with epoxy resin and
milled glass fibers on a surface structure of GFRP
rebar to enhance bond with concrete has been
examined by several tests in this study. The mixture
is successfully applied and shaped onto the GFRP
composite bars when the amounts of milled fibers in
the surface deformations are within 20–50%. The
bond strength of the GFRP rebar to concrete
increases with the amount of the milled glass fibers
and is better than that of other commercial GFRP
rebars in Korea, and only 10% less than that of the
ordinary steel rebar. However, the amounts of the
milled glass fibers in surface deformations have no
significant effect on long-term durability of the
GFRP rebar [26].
All of the three specimens for each variable failed in
the mode of pullout and the average maximum bond
strength is shown in Figure 14. The average
maximum bond strengths of the GFRP rebars vary
from 56% to 90% of that of the steel bar specimen.
The bond strength of the SCR specimens is
insignificantly low as compared to other types of
GFRP rebar. This low bond strength is particularly
due to low frictional resistance between the core and
the surface structure. The bond strength of SBR is
approximately 31% greater than that of SCR, and
the proposed GFRP bar, PDGR, developed only 10%
less bond strength than the steel rebar, DS. From
the test results, it can be concluded that the proposed
GFRP rebar, which has ribs made of the mixture of
the milled glass fiber and the epoxy, can provide
sufficient bond strength to concrete [26].
Table 1. Summary and Mechanical Properties of Bars in
Pull-out Test
An example of a
column heading
Nominal
diameter
Ultimate
strength
(MPa)
Elastic
modulus
(MPa)
DS
9.5
660
200
PDGR
10.3
592
44.5
SBR
10.7
910
53.5
SCR
10.3
1000
34.8
Figure 14. Results of Pull-out Test [26]
Summary
In this paper, scientific strategies for sustainable
development of concrete in Korea, has been intro-
duced as follows;
• Appropriate strengthening for deteriorated con-
crete structures with FRP,
• Recycling of construction wastes as coarse and
fine aggregate by advanced producing process,
• Using industrial by-products as supplementary
cementing materials,
• Fundamental prevention of reinforcement corro-
sion by using FRP rebar, and
These technologies could be applied to precast
concrete to pursue sustainable development of con-
crete. Advantages of precast concrete with recycled
aggregate are cost down on producing of precast
concrete and enhancing of awareness on concrete
using recycled aggregate. In addition, using of indus-
trial by-product on precast concrete can enhance
performance and durability of precast concrete pro-
ducts.
The achievements of these studies have contributed
to sustainable development of concrete material and
infrastructure, and further researches on their sus-
tainable development features are positively neces-
sary.
Sim, J. et al. / Sustainable Concrete Technology / CED, Vol. 17, No. 3, December 2015, pp. 158–165
165
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