Study of mechanical properties of concrete at elevated temperatures a revieweSAT Journals
Abstract Concrete, the second highest consumed material after water in the world, plays a vital role in the construction field because of the versatility in its use. Developments during the last two decades have shown a marked increase in the number of structures involving the long time heating of concrete. In recognition of its importance, many researchers have attempted to investigate the effect of elevated temperature on mechanical properties of concrete. These researchers, during their investigation, used materials with varying combination and different experimental conditions. These materials include cement, different percentages of admixtures like fly ash, silica fume, metakaolin, finely grounded pumice(FGP), group granulated blast furnace slag(GGBS), polypropylene fibre(PP fibre), palm oil fuel ash(POFA), Portland pozzolana cement(PPC), rice husk ash(RHA), different fine and coarse aggregates, super plasticisers, retarders and the conditions included a temperature range of 28oC to 1200oC . The other conditions that were varied are the shapes and sizes of test specimens, curing methods, curing conditions and test methods. The analysis of these investigations and their results are reviewed and presented in this paper. Key words: concrete, mechanical properties, elevated temperature, admixtures, curing methods
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Study of mechanical properties of concrete at elevated temperatures a revieweSAT Journals
Abstract Concrete, the second highest consumed material after water in the world, plays a vital role in the construction field because of the versatility in its use. Developments during the last two decades have shown a marked increase in the number of structures involving the long time heating of concrete. In recognition of its importance, many researchers have attempted to investigate the effect of elevated temperature on mechanical properties of concrete. These researchers, during their investigation, used materials with varying combination and different experimental conditions. These materials include cement, different percentages of admixtures like fly ash, silica fume, metakaolin, finely grounded pumice(FGP), group granulated blast furnace slag(GGBS), polypropylene fibre(PP fibre), palm oil fuel ash(POFA), Portland pozzolana cement(PPC), rice husk ash(RHA), different fine and coarse aggregates, super plasticisers, retarders and the conditions included a temperature range of 28oC to 1200oC . The other conditions that were varied are the shapes and sizes of test specimens, curing methods, curing conditions and test methods. The analysis of these investigations and their results are reviewed and presented in this paper. Key words: concrete, mechanical properties, elevated temperature, admixtures, curing methods
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Resistance of Fly Ash and Silica Fume Based Glass Fiber Reinforced High-Perfo...RSIS International
Improvements in concrete properties have been achieved by the invention of High- Performance Concrete (HPC). The ductility of HPC can be improved by altering its composition through the addition of glass fibers in the design mix. This paper presents the details of an experimental investigation planned to utilize fly ash and silica fume in the production of Glass fibre reinforced high Performance Concrete. The investigation examines the progressive deterioration of concrete mixtures containing various combinations of fly ash and silica fume based Glass fibre reinforced High-Performance concrete mixes exposed to chloride solution. Acid attack tests have been conducted to measure the durability. Cubes of 100X100X100 mm have been cast, cured and then kept immersed in 5% concentrated solutions of HCl for 30 and 60days and then tested to record the residual compressive strengths produced with the fly ash and silica fume mineral admixtures. The results have been analysed and useful conclusions have been drawn
An equiaxed, submicron grain size distribution was generated in an Al (0.1 wt.% Sc) alloy by
processing through equal channel angular pressing followed by a low temperature pre-
ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350,
400 and 450° C for investigating the thermal stability of the deformation microstructure. It
was found that up to 400° C, the submicron grain structure coarsens slowly and uniformly by
a process of continuous recrystallization.
Study on the fire resistant design of reinforced concrete flexural memberseSAT Journals
Abstract The inherent fire resistance property of concrete is one of its benefits. This thesis mainly focuses on fire resistant design of RC flexural member’s viz. beams and slabs using finite element software ANSYS 13. Both thermal and thermo-structural analysis was carried out for various parameters. Thermal analysis is done by taking into concern several parameters viz. aggregate type, cover to the reinforcement, concrete thickness, strength of concrete etc. The results are compared with IS 456:2000 provisions. Thermo-structural analysis is conducted for various support conditions and load ratio. Elements were modeled using SOLID 70 element and LINK 33 element for thermal analysis. For thermo-structural analysis instead of SOLID 70 element, SOLID 65 element was used. The parameters having a paramount influence on fire resistance are support conditions, dimensions of members, action of members under load, cover to the reinforcement, type of aggregates etc. Effect of the parameters on fire resistance is found out. Techniques to develop fire resistance are then found out. Moreover, it is found out that by changing some parameters, better fire resistant design for structural elements can be achieved. Key Words: Thermal analysis, Thermo-structural analysis, SOLID 70, SOLID 65, LINK 33
Corrosion resistance performance of fly ash blended cement concreteseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Done by Electron Group, Ahmed bin Hanbal Independent Secondary school for boys
Concrete : building material made by mixing cement with sand , gravel , water - of material things existing in material form that can be touched, felt or definite.
The presence of salt in soil or groundwater inside the concrete structure is a source of corrosion and cracks, as some salts attack the concrete and begin to fragment it such as sulfates
COMPRESSIVE STRENGTH AND CARBONATION OF SEA WATER CURED BLENDED CONCRETE IAEME Publication
This paper investigates the influence of sea water on pre-cast concrete containing
industrial by-product materials such as fly ash (FA) and silpozz. The mix design is targeted for
M30 grade concrete. Ten concrete mixtures were designed to have the same degree of
workability with water to cementitious material ratio of 0.43. The studied parameters include
the compressive strength of normal water curing (NWC) and sea water curing (SWC) samples
after 28 days of NWC for 7, 28, 90, 180 and 365 days curing period. The carbonation depth of
concrete samples for 28, 90, 180 and 365 days SWC after 28 days of NWC was measured. It
was found that the higher the FA content the higher is the carbonation process occurred. The
percentage increase in compressive strength for blended cement concrete in NWC is better
than the samples in SWC after 28 days of NWC
Microstructure and Abrasive Wear Properties of Chrome Alloy Steel IDES Editor
En 31 steel is widely used for applications like ball bearings and grinding media balls. The sliding wear properties of En 31 steel has been studied in the past, however the data on abrasive wear properties of En 31 steel is limited. En 31 steel was quenched and tempered at different tempering temperatures. Metallographic and hardness studies were carried out on heat treated samples. The hardened and tempered samples were tested using two body abrasive wear testing apparatus. The abrasive medium used in the present investigation was silicon carbide paper. The effect of normal load and sliding distance on wear loss of as received and heat treated specimens tempered at different tempering temperatures was investigated. The abrasive wear resistance of EN 31 steel with different hardness was compared under different test conditions. The worn out samples were observed by Scanning Electron Microscope to study morphology of worn surfaces. The abrasive wear resistance exhibited an increasing trend with increase in hardness and it was rationalized in terms of microstructure and the hardness.
Study Of Mechanical Properties Of High Strength Concrete By Partial Replaceme...dbpublications
Concrete is considered as durable and strong material. Concrete is one of the most popular material used for constructions. The present investigation deals with High strength concrete of M60 by adding fiber material to strengthen the concrete. Partial replacement of OPC with fly ash in percentages of 0%, 5% and10% in various ratios and also add Masterpel777, super plastisizer for workability purpose. Exposure periods of 7, 14 and 28 days on various tests. In this project we have designed M60 grade concrete using Design mix of Department of Environment method of various strengths.
Resistance of Fly Ash and Silica Fume Based Glass Fiber Reinforced High-Perfo...RSIS International
Improvements in concrete properties have been achieved by the invention of High- Performance Concrete (HPC). The ductility of HPC can be improved by altering its composition through the addition of glass fibers in the design mix. This paper presents the details of an experimental investigation planned to utilize fly ash and silica fume in the production of Glass fibre reinforced high Performance Concrete. The investigation examines the progressive deterioration of concrete mixtures containing various combinations of fly ash and silica fume based Glass fibre reinforced High-Performance concrete mixes exposed to chloride solution. Acid attack tests have been conducted to measure the durability. Cubes of 100X100X100 mm have been cast, cured and then kept immersed in 5% concentrated solutions of HCl for 30 and 60days and then tested to record the residual compressive strengths produced with the fly ash and silica fume mineral admixtures. The results have been analysed and useful conclusions have been drawn
An equiaxed, submicron grain size distribution was generated in an Al (0.1 wt.% Sc) alloy by
processing through equal channel angular pressing followed by a low temperature pre-
ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350,
400 and 450° C for investigating the thermal stability of the deformation microstructure. It
was found that up to 400° C, the submicron grain structure coarsens slowly and uniformly by
a process of continuous recrystallization.
Study on the fire resistant design of reinforced concrete flexural memberseSAT Journals
Abstract The inherent fire resistance property of concrete is one of its benefits. This thesis mainly focuses on fire resistant design of RC flexural member’s viz. beams and slabs using finite element software ANSYS 13. Both thermal and thermo-structural analysis was carried out for various parameters. Thermal analysis is done by taking into concern several parameters viz. aggregate type, cover to the reinforcement, concrete thickness, strength of concrete etc. The results are compared with IS 456:2000 provisions. Thermo-structural analysis is conducted for various support conditions and load ratio. Elements were modeled using SOLID 70 element and LINK 33 element for thermal analysis. For thermo-structural analysis instead of SOLID 70 element, SOLID 65 element was used. The parameters having a paramount influence on fire resistance are support conditions, dimensions of members, action of members under load, cover to the reinforcement, type of aggregates etc. Effect of the parameters on fire resistance is found out. Techniques to develop fire resistance are then found out. Moreover, it is found out that by changing some parameters, better fire resistant design for structural elements can be achieved. Key Words: Thermal analysis, Thermo-structural analysis, SOLID 70, SOLID 65, LINK 33
Corrosion resistance performance of fly ash blended cement concreteseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Done by Electron Group, Ahmed bin Hanbal Independent Secondary school for boys
Concrete : building material made by mixing cement with sand , gravel , water - of material things existing in material form that can be touched, felt or definite.
The presence of salt in soil or groundwater inside the concrete structure is a source of corrosion and cracks, as some salts attack the concrete and begin to fragment it such as sulfates
COMPRESSIVE STRENGTH AND CARBONATION OF SEA WATER CURED BLENDED CONCRETE IAEME Publication
This paper investigates the influence of sea water on pre-cast concrete containing
industrial by-product materials such as fly ash (FA) and silpozz. The mix design is targeted for
M30 grade concrete. Ten concrete mixtures were designed to have the same degree of
workability with water to cementitious material ratio of 0.43. The studied parameters include
the compressive strength of normal water curing (NWC) and sea water curing (SWC) samples
after 28 days of NWC for 7, 28, 90, 180 and 365 days curing period. The carbonation depth of
concrete samples for 28, 90, 180 and 365 days SWC after 28 days of NWC was measured. It
was found that the higher the FA content the higher is the carbonation process occurred. The
percentage increase in compressive strength for blended cement concrete in NWC is better
than the samples in SWC after 28 days of NWC
Microstructure and Abrasive Wear Properties of Chrome Alloy Steel IDES Editor
En 31 steel is widely used for applications like ball bearings and grinding media balls. The sliding wear properties of En 31 steel has been studied in the past, however the data on abrasive wear properties of En 31 steel is limited. En 31 steel was quenched and tempered at different tempering temperatures. Metallographic and hardness studies were carried out on heat treated samples. The hardened and tempered samples were tested using two body abrasive wear testing apparatus. The abrasive medium used in the present investigation was silicon carbide paper. The effect of normal load and sliding distance on wear loss of as received and heat treated specimens tempered at different tempering temperatures was investigated. The abrasive wear resistance of EN 31 steel with different hardness was compared under different test conditions. The worn out samples were observed by Scanning Electron Microscope to study morphology of worn surfaces. The abrasive wear resistance exhibited an increasing trend with increase in hardness and it was rationalized in terms of microstructure and the hardness.
Study Of Mechanical Properties Of High Strength Concrete By Partial Replaceme...dbpublications
Concrete is considered as durable and strong material. Concrete is one of the most popular material used for constructions. The present investigation deals with High strength concrete of M60 by adding fiber material to strengthen the concrete. Partial replacement of OPC with fly ash in percentages of 0%, 5% and10% in various ratios and also add Masterpel777, super plastisizer for workability purpose. Exposure periods of 7, 14 and 28 days on various tests. In this project we have designed M60 grade concrete using Design mix of Department of Environment method of various strengths.
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An Experimental Investigation on Effect of Elevated Temperatures on M35 grade...IJERD Editor
In the event of sudden fire break out, the concrete elements such as columns, beams etc. are
subjected to extreme temperatures. The assessment of their performance after fire becomes necessary to decide
upon its fitness and required repair measures. Hence, it is important to understand the changes in the concrete
properties due to its exposure to extreme temperatures. It is important to know the effect of elevated temperature
on the properties of concrete. In this project thesis work experimental investigation is carried out to study the
effects of elevated temperatures on the compressive strength of normal concrete and on concrete by partial
replacement of cement with various percentages of fly ash. In the present study a concrete mix M35 and is taken.
In the normal concrete, cement is replaced with (0, 5, 10, 15, 20 and 25%) fly ash.The compressive strength of
concrete with various percentages of fly ash (0%to 25%) are subjected to temperatures (400 to 6000C), for
different time periods (30 and 60min) which were tested for 28 days and 56 days of curing. The samples are
cured in water and later exposed to various temperatures with various time periods. After heating the samples in
electrical furnace to the desired temperatures .They are allowed to cool to the room temperatures and tested
under compression. The average of the readings obtained is recorded and presented in various tables. This study
shows that the compressive strength of fly ash (0%to 10%) concrete is more than the normal concrete at room
temperatures and elevated temperatures and also compared to compressive strength of fly ash (15%to 25%)
concrete.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This research aims to study the problems of the rotary kiln of al Kufa cement plant.
The heating process of the furnace starts by burning a certain amount of wood near the
fuel outlet inside the rotary kiln to provide the initial combustion process of the heating
oil at (80-100°C). Then the front fan of the furnace is operated while the heating
process is continuing for 24 hours. The most important problems that appear during
the use of the rotary kiln were: mechanical wear, thermal wear and chemical wear.
These problems have been diagnosed and taking the necessary treatments to reduce
them, whereas the operational limits must e observed during the operation. When
mechanical, thermal or chemical problems occur they will result high torque furnace
that causes the risk of the main vehicles of the rotary kiln
An Experimental Study on Structural Grade Concrete Using Multi Mineral Admixt...IJERD Editor
Supplementary cementitious material (SCM) such as fly ash, ground granulated blast furnace slag
sand silica fume are extensively used in construction. A partial replacement of cement by mineral admixtures
such as, fly ash, GGBFS, silica fume (SF) in concrete mixes would help to overcome these problems and lead to
improvement in the durability of concrete. In this thesis of work, an attempt has been made to study the
mechanical properties of structural grade concrete using ternary blend.
A EXPERIMENTAL STUDY ON SELF COMPACTING CONCRETE WHEN SUBJECTED TO ELEVATED TEMPERATURE
To achieve the SCC mix for M40 grade
To obtain optimum Percentage Replacement of cement by GGBS, FLYASH, Micro cement
To find the Mechanical Properties of SCC when subjected to elevated temperature
To draw the conclusions after conducting the Tests.
The behavior of hybrid reinforced concrete after heat resistanceIJERA Editor
This study is trying to provide the behavior of concrete when additional fibers are added under the effect of
evaluated temperatures. Three types of polypropylene fibers are used with different length respectively 3 mm, 6
mm and 12 mm and two types of steel fibers are used of length respectively of 3cm and 5 cm. Hybrid specimens
of concrete are prepared by using two different combinations: 0.5% steel fibers in combination with 0.2%
polypropylene fibers by the volume of concrete; and 0.25% of steel fibers in combination with 0.1%
polypropylene fibers by the volume of concrete. The specimens were subject to different temperatures. An
electric furnace was used to heat the specimens up to 200 0C, 400 0C and 600 0C. The mass loss and compressive
strength were determined by using twelve different mixtures.
Corrosion resistance performance of fly ash blended cement concreteseSAT Journals
Abstract Durability of reinforced concrete with respect to corrosion of reinforcement is one of the major aspects to be considered in the management of civil infrastructure systems. An accelerated laboratory test method developed at SERC where the concrete specimen containing rebar is subjected to polarization under a constant voltage in a sodium chloride solution. It is found that the current response with time follows that of a typical service life model indicating depassivation and corrosion propagation. Index terms- Materials, cement, super plasticizer, workability, compressive strength etc.
MECHANICAL PROPERTIES OF HIGH VOLUME FLY ASH CONCRETE SUBJECTED TO ELEVATED ...Umer Farooq
Fly ash is a finely divided waste product resulting from the combustion of pulverized coal in power plants.
It contains large amounts of silica, alumina and small amount of unburned carbon, which pollutes environment.
It is grey in colour and alkaline in nature.
The particle size ranges between 5-120 microns
Effect of silica fume on the strength of cement mortareSAT Journals
Abstract
The replacement of sand/cement by certain percentage of silica fumes, resulted in the improvement in compressive strength of the mortar. Silica fumes to the highly pozzolanic materials because it consists essentially of silica in non- crystalline form with a high specific surface. It is used to improve the mechanical properties of the concrete. The main objective of this paper is to study the effect of silica fume on the compressive strength of mortar. Three proportions of mixes viz mix 1:3, mix 1:4 and mix 1:6 with different percentages of silica fumes replacement with sand/cement were used. The maximum increase in strength at the age of 28 days when sand is replaced by 15% of silica fume has been observed as 40% and in case of cement replaced with 15% of silica fume, the observed increase in compressive strength of mortar comes out to be 28%.
A quantitative cost analysis shows that with the replacement of cement and sand by silica fume, the in cost is more when sand is replaced and it is less when cement is replaced.
Keywords: pozzolanic, silica fumes, non- crystalline, compressive strength
1.
Abstract—Concrete is found to undergo degradation when
subjected to elevated temperatures and loose substantial amount of its
strength. The loss of strength in concrete is mainly attributed to
decomposition of C-S-H and release of physically and chemically
bound water, which begins when the exposure temperature exceeds
100°C. When such a concrete comes in contact with moisture, the
cement paste is found rehydrate and considerable amount of strength
lost is found to recover. This paper presents results of an
experimental program carried out to investigate the effect of recuring
on strength gain of OPC concrete specimens subjected to elevated
temperatures from 200°C to 800°C, which were subjected to
retention time of two hours and four hours at the designated
temperature. Strength recoveries for concrete subjected to 7
designated elevated temperatures are compared. It is found that the
efficacy of recuring as a measure of strength recovery reduces with
increase in exposure temperature.
Keywords—Elevated Temperature, Recuring, Strength Recovery,
Compressive strength.
I. INTRODUCTION
ONCRETE is a very popular construction material and it
finds its application in almost all the civil engineering
disciplines. It’s characteristics such as mouldability and high
compressive strength has made it a versatile building material.
Concrete offers good resistance to heat because of its low
conductivity and incombustible nature and further, no toxic
fumes are emitted from concrete surface when it is heated.
Because of all these characteristics concrete can be rated as
the best building material as far as resistance to elevated
temperature is concerned
The concrete basically consists of two phases, the aggregate
phase and the hardened cement paste phase. There is a thermal
incompatibility between the aggregate phase and hardened
paste phase which initializes the cracking process when the
concrete is heated [1]. The cement paste begins to the
dehydrate at about 110°C [2] and as the temperature rises
above 300°C there will be subsequent decomposition of
Ca(OH)2 and the calcium silicate hydrates as the temperature
progresses above 600°C [3].
The tendency of aggregates is to expand due to high
temperature before disintegration. This differential thermal
expansion between aggregates and cement paste leads to
Shree Laxmi Prashant, Asst Prof., is with the Department of Civil
Engineering, MIT Manipal, Udupi 576104 (e-mail:
shrilaxmi.civil@gmail.com).
Subhash C. Yaragal and K. S. Babu Narayan are Professors with the
Department of Civil Engineering, National Institute of Technology Karnataka,
Surathkal, Srinivasnagar-575025, Mangalore, India (e-mail:
subhashyaragal@yahoo.com, shrilalisuta@gmail.com).
surface crazing which further leads to deeper cracking [4].
Aggregate stability has a major influence on performance of
concrete at elevated temperature and the deterioration [5], [6].
The differential thermal expansion combined with
decomposition of CSH gel leads to deterioration of ITZ, which
is one of the major causes of deterioration of concrete strength
[7], [8].
Whenever structural concrete is subjected to elevated
temperatures its effects can be visualized in the form of
surface cracking, spalling, and disintegration that render the
concrete structure unserviceable. The damaged concrete
surface is usually repaired by removing the weak layers of
concrete (or where the cement paste has lost significant
amount of binding property) and their replacement with fresh
concrete. But studies conducted by [8], indicate any thermally
damaged concrete has the tendency to recover the lost strength
by rehydration whenever the concrete is exposed to moist
environment. In their studies they found the concrete to
recover almost 80% of its original strength in the span of
about 12 months. Studies on similar lines were carried out by
[9], wherein the thermally deteriorated concrete were
subjected to air and water curing. It was found that if the
thermally exposed concrete is given constant moisture supply
the concrete rehydrates itself to recover the strength and
durability.
The strength deterioration of concrete is attributed to the
coarsening of pore structure and opening of the capillaries,
due to dehydration of the gel, that were initially filled by the
hydration products. When moisture is supplied to such
concrete partial rehydration of cement paste will take place
and the capillaries created due the elevated temperature
exposure will be refilled by rehydration process [10]. This
rehydration is expected to result in regain of certain amount of
its lost original strength. The compressive strength of certain
cement pastes does not reduce much even up to 500°C or
higher [11]. This paper presents the results of the effect of 7,
14, 28 and 56 days of water recuring of thermally deteriorated
OPC concrete cubes (100 mm) on their compressive strength.
II.EXPERIMENTAL METHODOLOGY
Ordinary Portland Cement 43 grade with brand name ACC
was used for preparing the concrete specimens. The chemical
composition of the cement is given in Table I. River sand
conforming to zone 3 (I.S 383-1970 grading requirements)
with specific gravity 2.65 was used. Coarse aggregates with
specific gravity 2.77 satisfying I.S 383-1970 [12] grading
requirements for graded aggregates were used. The mix
proportion is given in Table II.
Shree Laxmi Prashant, Subhash C. Yaragal, K. S. Babu Narayan
Recurring as a Means of Partial Strength Recovery
of Concrete Subjected to Elevated Temperatures
C
World Academy of Science, Engineering and Technology
International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering Vol:9, No:3, 2015
270International Scholarly and Scientific Research & Innovation 9(3) 2015
InternationalScienceIndexVol:9,No:3,2015waset.org/Publication/10000795
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CHEMICAL COM
Soluble Silica (%
Alumina (%)
Iron Oxide (%
Lime (%)
Magnesium (%
Insoluble Residue
hur (Sulphur Triox
Loss On Ignition
Chloride Content
TA
MIX P
ment Fine A
1 1
e was mixed
f size 100mm
crete cubes w
ater. The co
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0°C to 800°C
uild up during
me gradient
flattens grad
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residual stren
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Fig. 1 Time
TABLE I
MPOSITION OF CEM
%)
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xide) (%)
(%)
t (%)
ABLE II
PROPORTION
Aggregate
1.198
in a concret
m x 100mm
were demoulde
oncrete cubes
electric oven
C at an inter
test was as s
steepens up
dually above
ature was rea
mperature for
steady state
mens were left
eached room t
tested to ev
evated temper
n immersed in
estructive testi
y to evaluate th
ngth after recu
ete at ambient
temperature cu
MENT
21.6
5
3.7
63.1
0.8
1.8
2.1
2
0.01
Coarse Aggreg
2.23
10mm
0.877
20
2
te mixer and
x 100mm. A
ed and cured
s were subjec
n target temp
rval of 100°C
shown in Fig.
p to 400°C
400°C is at
ached the spe
duration of 2
. The furnac
t in the furnac
temperature. O
valuate the s
ratures. The na
n water for r
ing was done
he strength ga
uring was co
t temperature.
urve
gate
0mm
.046
poured
After 24
for 28
cted to
perature
C. The
1. The
around
rate of
ecimens
2 hrs in
ce was
ce until
One set
strength
aturally
recuring
for one
ain after
mpared
alo
sub
sur
rep
ch
to
tar
co
the
ed
cra
de
res
str
exp
co
sub
co
30
res
an
Af
co
str
de
7 a
am
reg
50
cal
tem
its
the
the
fill
I
A.Visual Obs
Fig. 2 shows
ong with the
bjected to ele
rface cracking
ported by prev
hanged from n
grey (700°C-
rget temperat
ncrete subjec
e surface of
dges. However
acking after
terioration on
sulting into su
B.Strength D
Fig. 3 shows
rength ratio,
posure to ele
nditions) due
bsequent reco
ncrete subjec
00°C retained
spectively. Af
nd 300°C expo
fter 56 days
ncrete recove
rength respect
The concret
terioration of
and 14 days,
mbient strengt
gained 83%
00°C and abov
lcium hydroxi
mperature of 5
ambient stren
e cement pas
ereby creating
led by new hy
III. RESULTS
servations
s the surface
e concrete a
evated temper
g. Changes re
vious research
normal (at amb
800°C). Colo
ture. Fig. 2
cted to 800°C
the cubes, bu
r no spalling
700°C and
n bond betwe
ubstantial loss
Fig. 2 Concret
Deterioration a
s the deterior
which is the
evated temper
e to elevated
overy with con
cted to an ele
about 92 and
fter recuring f
osed concrete
of recuring,
ered almost
ively.
te exposed
25% of its am
concrete rega
th. After 56
of its ambien
ve the cement
ide and the C
500°C and abo
ngth since aft
ste loses its i
g large voids
ydration produ
S AND DISCUSS
e of concrete
at room tem
rature showed
eported here
hers [3], [11].
bient conditio
or changes are
also shows
C. Cracks are
ut were more
of edges has
800°C expo
een cement p
of strength.
e exposed to 80
and Recovery
ration of stre
ratio of reta
atures to the
d temperature
ntinuing recur
evated temper
d 81 % of the
for 7 days th
is about 94 an
the 200°C a
95% and 85
to 400°C
mbient strengt
ained about 7
days of recu
nt strength. T
t paste hydrati
SH deteriorat
ove the recov
fter exposure t
interlayer wat
s which are v
ucts. Partial f
SIONS
exposed to
mperature. Co
d colour chan
are similar to
. The concrete
ons) to pink (4
found to dep
severe crack
distributed a
e pronounced
taken place.
osure signifi
aste and aggr
00°C
ength (Expres
ained strength
strength at am
e exposure a
ring till 56 day
rature of 200°
eir ambient st
e strength of
nd 83% respec
and 300°C ex
5% of its am
suffered st
h. After recur
77% and 79%
urring, concre
The temperat
ion products s
es. For the ex
ery is below 7
to 500°C and
ter and bond
very difficult
filling ability o
800°C
oncrete
ge and
o those
e color
400°C)
end on
king of
ll over
at the
Severe
es the
regates
ssed as
h after
mbient
and its
ys. The
°C and
trength
200°C
ctively.
xposed
mbient
trength
ring for
% of its
ete had
ture of
such as
xposure
75% of
d above
d water
t to be
of new
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271International Scholarly and Scientific Research & Innovation 9(3) 2015
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3. hydration products will help in partial recovery of lost
strength.
Fig. 3 Strength improvement through recuring for concrete subjected
to heating for 2 hrs
Fig. 4 Strength improvement through recuring for concrete subjected
to heating for 4 hrs
Concrete exposed to 600°C experienced large deterioration
of strength and the residual strength is only about 50%. After
recuring the concrete regained 18% of its ambient strength in
just 7 days. At the end of 56 days of recuring the residual
strength recovered is 66% of its ambient strength. Similarly
for 700°C and 800°C the concrete had suffered severe strength
loss, on recuring recovered 61% and 52% of its ambient
strength.
Fig. 4 shows the effect of recuring for the thermally
deteriorated concrete exposed to heating for 4 hrs. For the
concrete exposed to 400°C the gain in strength was observed
but comparatively slower as compared to the concrete exposed
to 2 hr heating. For the exposure temperatures of 500°C and
600°C the strength recovery was not very appreciable, while
the concrete specimen exposed to 700°C and 800°C were
damaged to an extent that they lost their integrity and hence
could not be recured.
The concrete with exposure duration of 3hr and 4hr
recovered about 21 and 34% of the lost strength respectively
after recuring for 56 days.
IV. CONCLUSIONS
1. Recuring is the most economical and easiest technique to
recover the strength lost as a result of elevated
temperature exposure. Concrete regains its lost strength
because if constant supply of moisture to the dehydrated
cement paste.
2. For lower temperature substantial amount of strength is
recovered after recuring, for higher temperatures (above
400°C) all the lost strength cannot be recovered because
the new hydration products formed as a result of recuring,
fill the voids and cracks formed as a result of elevated
temperature exposure partially.
3. The rate of strength gain is faster during the initial 7 days
of recuirng and later slows down.
4. Recuring capacity of the dehydrated cement paste
decreases with the increase in exposure duration.
5. The technique of recuring is significant as it could reduce
the expenses required for repair and rehabilation of
thermally deteriorated concrete and conserve resources.
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[1] J P olliver, J C Maso, B Bourdette. “Interfacial Transition Zone in
Concrete”. Advanced cement based materials vol.2, pp.30-38, 1995.
[2] Y. Xu, Y.L. Wong, C.S. Poon, M. Anson. “Influence of PFA on
cracking of concrete and cement paste after exposure to high
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2003.
[3] Khoury G A, Majrona C E, Pasavento F Shrefler B A. “Modeling of
heated concrete”. Magazine of Concrete Research, 54 vol 77 pp.101,
2002.
[4] Arioz O. “Effects of elevated temperatures on properties of concrete”
Fire Safety Journal vol 42, pp. 516-522, 2007.
[5] B. Georgali, P. E. Tsakiridis. Microstructure of fire-damaged concrete.
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[6] D Campbell Allen,P M Desai. Influence of aggregate on behavior of
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[7] S C Chakrabarti, K N Sharma and Abha Mittal, ‘Residual strength in
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[8] Chi-Sun Poon, Salman Azhar, Mike Anson, Yuk-Lung Wong, “Strength
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[9] C. Alonso, L. Fernandez. “Dehydration and rehydration processes of
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[10] Gabriel A. Khoury and Patrick J. E. Sullivan, ‘Research at Imperial
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[11] Yuzer, Nabi , Fevziye Akoz, Leyla Dokuzer O zturk, “Compressive
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[12] IS: 383-1970 "Specifications for coarse and fine aggregates from natural
sources for concrete", Bureau of Indian Standards, New Delhi.
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 20 40 60
Strength Ratio
Recuring days
200
300
400
500
600
700
800
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 7 14 21 28 35 42 49 56
StrengthRatio
Recuring (days)
200
300
400
500
600
World Academy of Science, Engineering and Technology
International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering Vol:9, No:3, 2015
272International Scholarly and Scientific Research & Innovation 9(3) 2015
InternationalScienceIndexVol:9,No:3,2015waset.org/Publication/10000795