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Sustainable Concrete Technology

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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.
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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. 158165
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. 158165
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. 158165
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. 158165
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. 158165
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. 158165
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 2050%. 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. 158165
165
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... . 3.4 Absorption Test Mould. 37 3. 3.5 Pozzolanic Activity Test Mould 37 3.4 Concrete Mixing and Preparation 38 3. 4.1 Mix Proportion 38 3. 4.2 Mixing of Replacements with Cement 41 3.4.3 Casting and Compacting of Fresh Concrete 42 3. 4.4 Curing 43 3. 5 Tests on concrete 43 3. 5 3. 5. 1.2 Destructive Test 45 3. 5.2 Workability Test (Flow Slump Test) 49 3. 5.3 Durability Test 50 3. 5. 3.1 Water Absorption Test 50 3. 5. 3.2 PH Test 52 3. 5.4 Pozzolanic Activity 52 3. 5. 4.1 Mixes of Pozzolanic Activity Index 52 3. 5. 4.2 Results of Pozzolanic Activity Index 53 3.6 Characterization of concrete 56 3. 6.1 X-Ray Diffraction Analysis (XRD) 56 3. 6.2 Scanning Electron Microscope (SEM) 57 3.7 Thermogravimetric Analysis TG-DTG 58 . ...
... Chapter Five: Results And Discussion 4.1 Slump flow for concrete mixes with micro replacements 61 4.2 slump flow for concrete mixes with nano replacements 62 4.3 slump flow for concrete mixes with recycled replacements 63 4.4 Result of compressive strength for concrete mixes with different micro replacements 69 4.5 Result of compressive strength for concrete mixes with different nano replacements 70 4.6 Result of compressive strength for concrete mixes with different recycled replacements 71 4.7 Enhancement % of control in Compressive strength for concrete mixes with 1% of replacement. 72 4.8 Enhancement % of control in Compressive strength for concrete mixes with 2% of replacement 72 4.9 Enhancement % of control in Compressive strength for concrete mixes with 3% of replacement 73 4. 10 Enhancement % of control in Compressive strength for concrete mixes with 4% of replacement 73 4.11 Result of split tensile strength for concrete mixes with different micro replacements 75 4.12 Result of split tensile strength for concrete mixes with different nano replacements 77 ...
... How to develop concrete technology in a sustainable way becomes an urgent issue in the world [3]. Supplementary cementing materials are often added to concrete to make concrete mixtures more economical, reduce permeability, increase strength, or influence other concrete properties [4]. ...
Thesis
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This thesis aims to study the effect of using various types of materials as partial replacement of cement on the properties of high strength concrete. Nano SiO2, Nano CaCO3, micro SiO2, micro CaCO3, recycled silica gel (beads and powder) and limestone were used as replacements, all replacements were used with four different contents of 1%, 2%, 3% and 4% by weight of cement. also binary combination of (Nano SiO2 + Nano CaCO3), (micro CaCO3 + micro SiO2) and (recycled silica gel powder + limestone) were applied to investigate their combined effect. Ten groups of concrete mixes were made by progressive cement replacement (micro silica, micro CaCO3, micro silica+ micro CaCO3, nano silica, nano CaCO3, nano silica, + nano CaCO3, silica gel, crushed silica gel, limestone and crushed silica gel) in addition to control mix without replacement so the total mixes were 41 mixes. Mechanical properties (compressive strength, split tensile strength and flexural strength) were done after 28 days of water curing. Also water absorption test and alkalinity test were carrying out for obtaining the durability properties of concrete specimen, while the workability of all mixes were obtained by applying the slump flow test on fresh concrete. Thermal analysis (TG-Thermogravimetric) and (DTG- Derivative Thermogravimetry) were performed to estimate the CH content for each concrete group. X-ray diffraction and SEM (scanning electron microscope) characterization were achieved to confirm and interpret the results of above tests. Results of compressive strength tests manifested that the mix with 3% Nano silica showed the maximum enhancement 47.55 % at 3% dosage, followed by micro silica 30.75% at 4% dosage, binary nano mix 26.42% at 3% dosage, crushed silica gel and nano CaCO3 18.86% at 4% dosage, binary recycled mix 11.32% at 4% dosage, silica gel and binary micro mix 9.43% at 4% dosage, micro 7.55% at 4% dosage and finally limestone mix 0% at 4% dosage. Approximately same trend for III replacement effect was observed in the results of split tensile strength and flexural strength. Results of water absorption test revealed that all replacements contributed in the reduction of water absorption due to the densification of concrete microstructure, the maximum reduction were observed in silica gel and crushed silica gel and binary mixes. High alkalinity (PH) value was recorded for concrete mixes, a slight dropping in this value was recognized after using replacements, and the maximum drop was found with Nano mixes. Calcium hydroxide (CH) content results depicted the lowest value with nano silica mix followed by binary nano mix and crushed silica gel mix, while other mixes exhibited approximate values but all of them were less than the control mix, this indicated larger amounts of calcium silicate hydrate (CSH) gel formed after employment of replacement which has contributed mainly to improving the strength and durability of concrete. SEM (scanning electron microscope) micrographs displayed the presence of calcium silicate hydrate (CSH), Calcium hydroxide (CH) and Ettringite phases, which are evidence of the completeness of the hydration process, same results were confirmed from the X- ray diffraction analysis. A result of tests showed that silica series mixes (nano silica, micro silica, silica gel and crushed silica gel) had a higher affirmative effect on the properties and durability of high strength concrete than CaCO3 series (nano CaCO3, micro CaCO3, limestone).
... Supplementary cementing materials (SCMs) such as fly ashes, slag cement (ground, granulated blast furnace slag), and silica fume, are often added to concrete to make concrete mixtures for more economical, reduce permeability, increase strength, or influence other concrete properties [25][26][27][28]. Demands and application of SCMs would increase because of decreasing of CO2 emission from cement producing as shown in Figure 10. ...
... Fig. 10. Reduction of CO2 emission by using SCM [28] 6 MATEC Web of Conferences 138, 03008 (2017) DOI: 10.1051/matecconf/201713803008 EACEF 2017 ...
Article
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The enormous amount of concrete production has a serious impact on energy, resources, environment and ecosystem. Therefore, the issue of development of sustainable concrete technology with little impact on the environment is becoming a major issue. In this paper, researches related with sustainable development of concrete are presented in last three decades. FRP has high corrosion resistance and lightweight, thus it can be potential solution for sustainable development of concrete structures as strengthening material or reinforcement instead of steel. Researches and techniques are presented on performance of concrete beam with FRP rebar and enhancing performance of existing concrete structure using FRP strengthening methods. 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. In past 10 years, a great improvement in the recycling technique to produce RCA of which quality is close to natural aggregate, hence the applicability and evaluation of RCA are presented in this paper. This paper includes experimental studies for application of waste glass which could decrease CO2 emission from cement producing. The achievements of these studies are presented in this paper to contribute for sustainable development of concrete infrastructures.
... Currently, researches on sustainable development on concrete have been carried out on the following aspects: extension of "concrete structure and development of low-carbon concrete material and structure [2]. Contemporary mixed cement types also use pozzolan as a cement replacement material or a mineral additive that is inter-ground or mixed with Portland cement. ...
Article
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Cement production uses large quantities of natural resources and contributes to the release of CO2. In order to treat the environmental effects related to cement manufacturing, there is a need to improve alternative binders to make concrete. Accordingly, extensive study is ongoing into the utilization of cement replacements, using many waste materials and industrial. This paper introduces the results of experimental investigations upon the mortar study with the partial cement replacement. Fly ash, silica fume and glass powder were used as a partial replacement, and cement was replaced by 0%, 1%, 1.5%, 3% and 5% of each replacement by the weight. Compressive strength test was conducted upon specimens at the age of 7 and 28 days. Microstructural characteristic of the modified mortar was done through the scanning electron microscope (SEM) vision, and X-ray diffraction (XRD) analysis was carried out for mixes with different replacements. The tests results were compared with the control mix. The results manifested that all replacements present the development of strength; this improvement was less in the early ages and raised at the higher ages in comparison with the control specimens. Microstructural analysis showed the formation of hydration compounds in mortar paste for each replacement. This study concluded that the strength significantly improved by adding 5% of silica fume compared with fly ash and glass powder.
... CIS = Commonwealth of Independent States. RoW = Rest of World[41]. ...
Article
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Fully decarbonizing global industry is essential to achieving climate stabilization, and reaching net zero greenhouse gas emissions by 2050–2070 is necessary to limit global warming to 2 °C. This paper assembles and evaluates technical and policy interventions, both on the supply side and on the demand side. It identifies measures that, employed together, can achieve net zero industrial emissions in the required timeframe. Key supply-side technologies include energy efficiency (especially at the system level), carbon capture, electrification, and zero-carbon hydrogen as a heat source and chemical feedstock. There are also promising technologies specific to each of the three top-emitting industries: cement, iron & steel, and chemicals & plastics. These include cement admixtures and alternative chemistries, several technological routes for zero-carbon steelmaking, and novel chemical catalysts and separation technologies. Crucial demand-side approaches include material-efficient design, reductions in material waste, substituting low-carbon for high-carbon materials, and circular economy interventions (such as improving product longevity, reusability, ease of refurbishment, and recyclability). Strategic, well-designed policy can accelerate innovation and provide incentives for technology deployment. High-value policies include carbon pricing with border adjustments or other price signals; robust government support for research, development, and deployment; and energy efficiency or emissions standards. These core policies should be supported by labeling and government procurement of low-carbon products, data collection and disclosure requirements, and recycling incentives. In implementing these policies, care must be taken to ensure a just transition for displaced workers and affected communities. Similarly, decarbonization must complement the human and economic development of low- and middle-income countries.
... As reported in the literature, glass particle in concrete showed quite good mechanical properties, such as compressive strength, flexural strength, and modulus of elasticity [6]. With these mechanical properties, the concrete with the glass particle is appropriate for the use of the concrete pavement of highway [7]. ...
Article
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Abstract— The curing method becomes important to be considered in applying the Reactive Powder Concrete (RPC) in the field. Currently, the application of RPC in the field can be simulated with the method of steam curing at 90oC that resulted in compressive strength of 102 MPa. This study used some methods of curing included the method of steam curing at 90oC to investigate mechanical behavior of RPC such as compressive, flexural, and splitting tensile strengths. The objective of this research is to obtain the method of in-situ curing which reasonable good in results of the mechanical behavior of RPC. There were 4 types of curing method in this study, namely the steam curing method of 90oC for 8 hours in laboratory (C1), the water curing in laboratory (C2), the in-situ steam curing with flowed steam of 3 hours per day for 7 days (C3), and the in-situ wet curing (C4). This study showed that the compressive, flexural, and splitting tensile strengths of the RPC with in-situ curing method of type C3 compared with the RPC with curing method type C1 have the different of 10.6%, 19.0%, and 13.3%, respectively. The in-situ curing method of type C3 is better than the in-situ curing method of type C4 in term of the strengths. Keywords— in-situ curing method; mechanical behavior; Reactive Powder Concrete; steam curing.
... Using 20% of waste glass powder to substitute the cement content in the concrete and with 28 days of water curing, the compressive strength of 36 MPa can be reached. The concrete is suitable for the application in concrete pavement of highway [3]. ...
Article
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A development of Reactive Powder Concrete (RPC) currently is the use of quartz powder as a stabilizing agent with the content to cement ratio of 30% and steam curing method in an autoclave temperature of 250ºC which produced a high compressive strength of 180 MPa. That RPC can be generated due to one reason for using the technique of steam curing in an autoclave in the laboratory. This study proposes in-situ curing method in order the curing can be applied in the field and with a reasonable compressive strength results of RPC. As the benchmarks in this study are the curing methods in laboratory that are steam curing of 90°C for 8 hours (C1), and water curing for 28 days (C2). For the in-situ curing methods that are covering with tarpaulins and flowed steam of 3 hours per day for 7 days (C3), covering with wet sacks for 28 days (C4), and covering with wet sacks for 28 days for specimen with unwashed sand as fine aggregate (C5). The comparison of compressive strength of the specimens in this study showed compressive strength of RPC with in-situ steam curing (101.64 MPa) close to the compressive strength of RPC with steam curing in the laboratory with 8.2% of different. While in-situ wet curing compared with the water curing in laboratory has the different of 3.4%. These results indicated that the proposed in-situ curing methods are reasonable good in term of the compressive strength that can be achieved.
Article
Geopolymer concrete can be the future of the conventional concrete and it can be used as replacement agent instead of conventional concrete in construction work along with that the GPC is eco friendly in nature as it does not emits CO2 in atmosphere so it is helpful to reduce the Greenhouse effect. The material used for the manufacturing of GPC are Binder’s and Actuators. Birder’s are obtained from the thermal power plant also known as fly ash and actuator consist of the sodium silicate and sodium hydroxide, calcium chloride, sodium thiocyanate, potassium thiocyanate, etc. By combing these acceleration and Binder’s with other concrete material the process of Geopolymeration starts. The objective of these study is to give a detailed review on the geopolymer concrete mix design, compressive behavior, flexural and split tensile behavior and chemical acid resistance when immersed in sopheric acid and nitric acid by using various research paper and the test result difference of conventional concrete and geopolymer concrete. Based on that a review is prepared.
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Urban cities in Malaysia are highly vulnerable to flash floods due to improper drainage system and the impermeable road surface. The Pervious Concrete (PC) Pavement for urban water management indicates the implementation of this system shows promising results to reduce flash flood volume and among the mitigation that can be applied is by adopting the permeable pavement systems. This was based on a case study of Sponge City in China. Since the properties normally consist of coarse aggregate only / or less fine aggregate to fill in the void structure. Regardless of the high advantage of these systems to reduce the flooding impact, this permeable pavement is known for its lower strength. Due to this fact, it is rare and impossible for this permeable pavement to be utilized at the main road and highway. Whereas, currently in Malaysia, the permeable concrete is only accustomed to light traffic loadings such as walkways and car park. This paper was discussing the way to improve the strength properties of PC pavements with a focus on sustainable development.
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In this study, the effects of ash and slag on the physical and mechanical properties of the concrete were investigated experimentally, and the change in the cost of concrete was examined. For this purpose, concrete samples containing a series of standard concrete, 3 series of ash and 2 series of slag were poured. As a result of the study, ash and slag generally increased the beginning and ending of setting times. It was observed that both pozzolan materials increased the workability of fresh concrete and decreased the hydratation heat.In concrete compressive strength, it was observed that the ash and slag replacement decreased the strength at early ages and caused a higher concrete strength at older ages
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This paper presents experimental results obtained from direct pull-out tests of commonly used and a new type of glass fibre-reinforced polymer (GFRP) rebar. The new GFRP rebar, developed by the authors, has a surface structure composed of milled glass fibres and epoxy resin, and its appearance resembles that of ordinary steel rebar. The effects of surface type and increased amounts of milled glass fibres in each rib on bonding with concrete were investigated to characterize the bond performance of the new type of GFRP rebar. The results indicated that the new type of GFRP rebar performed better with a higher bond strength to concrete compared with other tested types of GFRP rebar. Moreover, the rib bearing resistance and energy absorption appeared to increase with increased milled glass fibre in the ribs, which dominated the overall bond behaviour.
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Epoxy-coated bars are used in nearly all types of structures where corrosion may cause deterioration. Bridge decks and parking garages are especially susceptible to salt-induced damage. For satisfactory structural performance, bond between concrete and steel is essential, and the effect of coatings that might decrease bond should be considered in designs. In this study, 21 beams with lap splices in a constant moment region were tested in nine groups and the bond strength of epoxy-coated bars was compared to that of uncoated bars. Variables were bar size, concrete strength, casting position, and coating thickness.
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Sustainable cements containing 25 wt% of different types of recycled glass have been investigated as a supplementary cementing material in order to highlight the role of glass chemical composition during the hardening process. Glass formers, stabilizers and modifiers regulate the glass dissolution in the alkaline environment during cement hydration. As a consequence, pozzolanic reaction and/or alkali–silica reaction are strictly related to the glass chemical composition. The mechanical and microstructure characterizations of mortar samples containing glass blended cements and un-reactive aggregates allow to determine which oxides in the glass have to be carefully monitored to avoid deleterious reactions.
Article
The overall objective of this paper is to establish the structural behavior of reinforced concrete (RC) beams strengthened with externally bonded carbon-fiber-reinforced plastic (CFRP) sheets. Four beams, three with bonded CFRP plates on the tension face, and two of which were provided with carefully designed external anchorages at the ends of the plates and along the span, were tested under four-point bending over a span of 4.8 m. The tests were carried out under displacement control. The beams were extensively instrumented to monitor strains, deflection, and curvature over the entire spectrum of loading to total failure, and to determine the structural response to load of the composite beams. The results show that bonding a CFRP plate on the tension face of a RC beam, without consideration of the end-anchorage stresses and the bond slip between the plate and the concrete substrate, can lead to significant degradation in the structural response of the plated beam. Carefully designed external anchorages, on the other hand, can lead to preservation of composite action to almost the failure load, increases in load capacity of up to 70%, substantial regain of structural ductility, and the transformation of a brittle failure to a more ductile failure.
Article
Surface deformations of GFRP rebars are important in developing mechanical anchorage. The mixture of epoxy resin and milled glass fibers is considered as an alternative for surface structure of GFRP rebar to enhance the bond with the concrete. In order to investigate the applicability of the surface structure, manufacturing, material tests, pullout tests and shear tests were conducted. The mixture was successfully applied and shaped onto the GFRP rebars when the milled fibers were mixed to be within 20–50wt% of the mixture. The bond performance was enhanced by adding as much milled glass fibers as possible but up to a workable range. When the milled glass fiber content was 50%, the upper limit of mix ratio, bond strength to concrete was only 10% less than that of the ordinary steel rebar. In addition, under an accelerated alkalinity condition, the amounts of mixed milled glass fibers in surface deformations have a minor effect on the durability of the proposed GFRP rebar.
Article
While at present mostly recycled into road subbase, the amount of demolished concrete in Japan is expected to increase rapidly and exceed the demand for road subbase in the near future. To promote the recycling of concrete, a technology to produce high-quality recycled aggregate has been developed. This technology employs the heating and rubbing method. In order to investigate a future concrete recycling system, first of all, a specific model considering indices of economic activity is established to forecast the amount of demolished concrete in the future. Furthermore, an input-output table is extended by a detailed description of concrete-related industries such as construction, aggregate, cement, and ready-mixed concrete, and several concrete recycling processes have been added.The linear programming model connected to the input-output table assumes that the technology will be introduced in 2020. A subsidy for high-quality recycled aggregate and a carbon tax are found to be effective ways to promote the early introduction of the technology. This series of analysis can be widely used in other countries for investigating suitable recycling systems focusing on the cement and concrete industry as well as the applicability of each individual concrete recycling technology.
Article
Many solid industrial by-products such as siliceous and aluminous materials (fly ash, silica fume, slags, etc.) as well as some natural pozzolanic materials (volcanic tuffs, diatomaceous earth, etc.) may be characterized as supplementary cementing materials (SCM) as they exhibit cementitious and/or pozzolanic properties. Due to plenty of these materials and their large variations on physical and chemical composition, the development of a general design for their use in concrete is required. In this work, the concept of an efficiency factor is applied as a measure of the relative performance of SCM compared with Portland cement. Artificial materials of various compositions and some natural pozzolans were studied. Compressive strength and accelerated chloride penetration tests were performed. With regard to these characteristics, efficiency factors for these materials were calculated. A mix design strategy to fulfil any requirements for concrete strength and service lifetime was developed and it enables concrete performance to be accurately predicted.
Article
Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members.
Climate Change Performance Index, Germanwatch and Climate Action Network Europe
  • J Burck
  • F Marten
  • C Bals
Burck, J., Marten, F., and Bals, C., Climate Change Performance Index, Germanwatch and Climate Action Network Europe, 2014.
The Development of Structural Adhesive for Three Original uses in South Africa
  • C J Fleming
  • G E M King
Fleming, C.J. and King, G.E.M., The Development of Structural Adhesive for Three Original uses in South Africa, RILEM International Symposium, Synthetic Resins in Building Construction, Paris, 1967, pp.75-92.