-
QianFaculty
h
Factors affecting thermally mechanical properties of concrete
were reviewed.
a r t i c l e i n f o
Article history:
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
2.4.5. Aggregates. . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . 3742.5. Spalling . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . 374
3. Factors influencing the performance of concrete subjected to
high temperature . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . 3753.1. w/b and
moisture content . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3753.2.
Type of aggregate . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . 3753.3. SCMs . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . 377
Corresponding author. Tel.: +86 13095358933.E-mail address:
[email protected] (Q. Ma).
Construction and Building Materials 93 (2015) 371383
Contents lists available at ScienceDirect2.4.4. Microstructure .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . 3732.4.1. Water
evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . .2.4.2. Hydration products. . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.2.4.3. Pore structure . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
.http://dx.doi.org/10.1016/j.conbuildmat.2015.05.1310950-0618/ 2015
Elsevier Ltd. All rights reserved.. . 373
. . 373
. . 373Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . 3722. Mechanical properties of concrete
at high temperature . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . 372
2.1. Compressive strength . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . 3722.2. Flexural strength, splitting tensile strength and
modulus of elasticity . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3722.3.
Stressstrain relationship . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3722.4. Physical and chemical changes. . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . 373Received 9 October 2014Received in revised form 11 May
2015Accepted 14 May 2015
Keywords:ConcreteHigh temperatureMechanical propertiesa b s t r
a c t
High temperature is well known for seriously damaging concrete
micro- and meso-structure, whichbrings in a generalised mechanical
decay of the concrete and even detrimental effects at the
structurallevel, due to concrete spalling and bar exposure to the
ames, in case of re. Because of the relevanceof concrete behaviour
at high temperature and in re, many studies have been carried out,
even veryrecently, on cementitious composites at high temperature,
and the most relevant parameters have beenidentied and
investigated. Within this framework, the authors provide a
comprehensive and updatedreport on the temperature dependency of
such parameters as the compressive strength, modulus of
elas-ticity, strength in indirect tension (bending and splitting
tests), stressstrain curves and spalling, but theroles played by
the waterbinder ratio (w/b), aggregate type, supplementary
cementitious materials(SCMs) and bres are investigated as well.
Among the objectives of the paper, the approaches currentlyadopted
to improve concrete mechanical properties at high temperature are
treated as well. Meanwhile,the inuence of test modalities on the
mechanical properties of concrete at high temperature is also
dis-cussed in the paper.
2015 Elsevier Ltd. All rights reserved.Mechanical properties of
concrete at high temperature were reviewed. Physical and chemical
changes of concrete at high temperature were reviewed.i g h l i g h
t smin Ma , Rongxin Guo, Zhiman Zhao, Zhiwei Lin, Kecheng Heof
Civil Engineering and Mechanics, Kunming University of Science and
Technology, 727, Jingming South Road, 650500 Kunming,
ChinaReview
Mechanical properties of concrete at high temperatureA
reviewjournal homepage: www.elsevier .com/locate /conbui
ldmatConstruction and Building Materials
-
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 378e at
high temperature . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . 379. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . 379. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . 379. . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
380. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 380. . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 380. . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . 381
stenate tin Fig.specimcs
(1)
Residual exural strength, residual splitting tensile strengthand
residual modulus of elasticity of concrete after exposure to
ele-vated temperatures are shown in Figs. 24, respectively. Same
datacollection regime with compressive strength is used. Similar to
thecompressive strength reviewed in the previous section,
exuralstrength, splitting tensile strength andmodulus of elasticity
of con-crete decreases with the increase of temperature, but at a
nearlylinear rate.
2.3. Stressstrain relationship
Stressstrain relationship of concrete at elevated
temperatureshas been investigated by many researchers
[2,12,30,37,48,6473].It has been found that with the increase of
temperature, stress
1.4
1.6
1
1.2
f,20
ilding Materials 93 (2015) 371383: 0 200 400 600 800 1000
1200Temperature (oncrete after heating to high temperature
experiences three maintages
0he possible effect caused by these factors, the data
collection1 is carried out only on the residual results of
unstressed cubeens. It can be seen that the residual compressive
strength of
0.2
0.4tates, also inuence the mechanical properties of concrete at
highmperature (details are in Section 4). Therefore, in order to
elimi-
0.6
f f,T
/ fas specimen size, stressed/unstressed conditions and
hot/residualstrength of concrete when it is exposed to high
temperature (seeFig. 1). In spite of concretemixtureproportions,
testmodalities, such 0.83.4. Fibres . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.
Influence of test modalities on the mechanical properties of
concret
4.1. Hot and residual tests . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . .4.2. Stressed and unstressed tests . . .
. . . . . . . . . . . . . . . . . . . . . . .4.3. Uni-axial and
multi-axial tests . . . . . . . . . . . . . . . . . . . . . . . .
.4.4. Specimen size . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . .
5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .References . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . .
1. Introduction
Under the pressure of population boom and land limitation,
inorder to effectively resolve housing and transportation issues,
theneed for high-rise buildings and underground construction is
rapidincreasing. Such civil engineering is facing tremendous
challengeof re damage during its constructing and service. Fire on
theseengineering is frequently reported worldwide in recent years,
seri-ously threatening personal and property safety. High
temperatureis well known for seriously damaging concrete micro-
andmeso-structure, which brings in a generalised mechanical decayof
the concrete and even detrimental effects at the structural
level,due to concrete spalling and bar exposure to the ames, in
case ofre. Because of the relevance of concrete behaviour at high
tem-perature and in re, many studies have been carried out, even
veryrecently, on cementitious composites at high temperature, and
themost relevant parameters have been identied and
investigated.Within this framework, the authors provide a
comprehensive andupdated report on the temperature dependency of
such parame-ters as the compressive strength, modulus of
elasticity, strengthin indirect tension (bending and splitting
tests), stressstraincurves and spalling, but the roles played by
the w/b, aggregatetype, SCMs and bres are investigated as well.
Among the objec-tives of the paper, the approaches currently
adopted to improveconcrete mechanical properties at high
temperature are treatedas well. Meanwhile, the inuence of test
modalities on themechanical properties of concrete at high
temperature is also dis-cussed in the paper. Electrical furnace
heating and gas/oil heating(re), these two different heating
models, are used in the studiesto investigate the thermal behaviour
of concrete at high tempera-ture. Furnace heating is usually used
for the studies on the thermalchanges of concrete characteristics,
while re is usually consideredwhen the studies are at a
structurally elemental level. This papermainly focuses on the
discussion on the thermal changes of con-crete characteristics at
high temperature, the effect of re on thebehaviour of concrete is
exclusive in this paper.
2. Mechanical properties of concrete at high temperature
2.1. Compressive strength
It is unavoidable that there is a reduction for compressive
372 Q. Ma et al. / Construction and BuRoom temperature300 C,
compressive strength of con-crete keeps constant or even increases
slightly.(2) 300800 C, compressive strength of concrete
decreasesdramatically.
(3) 800 C afterwards, almost all the compressive strength
ofconcrete has been lost.
2.2. Flexural strength, splitting tensile strength and modulus
ofelasticity
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600 800 1000 1200f cu
/f cu,
20Temperature ( C)
Fig. 1. Residual compressive strength of concrete at elevated
temperatures (dataadapted from [146]).Fig. 2. Residual exural
strength of concrete at elevated temperatures (dataadapted from
[26,42,4755]).
-
1.2
ildin0.6
0.8
1
f t,T
/ ft,2
01.4
Q. Ma et al. / Construction and Bustrain curves become atter,
and the peak stress shifts downwardsand rightwards, as shown in
Fig. 5. These indicate that the peakstress and the modulus of
elasticity of concrete decrease with theincrease of temperature,
but the strain at peak stress increaseswith temperature.
2.4. Physical and chemical changes
With the elevation of temperature, concrete would experiencethe
following physical and chemical changes and these changes
0
0.2
0.4
0 200 400 600 800 1000 1200Temperature (
Fig. 3. Residual splitting tensile strength of concrete at
elevated temperatures (dataadapted from [9,52,54,5663]).
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600 800 1000
E T/ E
20
Temperature (
Fig. 4. Residual modulus of elasticity of concrete at elevated
temperatures (dataadapted from
[1,6,10,13,17,18,37,38,48,58,59,63]).
Fig. 5. Residual stressstrain relationship of concrete at
elevated temperatures[68].are considered to be responsible for the
changes of the mechanicalproperties:
2.4.1. Water evaporationHydration products lose their free water
and physically
absorbed water completely, and start to lose their
chemicallybonded water at 105 C [74]. Capillary water is lost
completely at400 C [75].
Up to 300 C, hydration of unhydrated cement grains isimproved
due to an internal autoclaving condition as a result ofthe high
temperature and the evaporation of water [76]. This isparticularly
true for high strength concrete as its low permeabilityresists
moisture ow. This can be used to explain the constantcompressive
strength when the temperature is below 300 C asdiscussed in Section
2.1.
2.4.2. Hydration productsAFt/AFm dehydrates at 110150 C [77].
Above 350 C, calcium
hydroxide either decomposes into lime and water or further
con-verts into CSH due to the accelerated pozzolanic reaction at
ahigh temperature [7880]. The decomposition of Ca(OH)2 has
nocritical inuence on the reduction of strength for
concrete.However, if concrete is water cooled after exposure to
high tem-perature, the rehydration of lime will cause a great
reduction ofstrength for concrete due to a considerable expansion
will becaused due to such a reaction [81]. CSH starts to decompose
ataround 560 C [79] and it decomposes into b-C2S at around 600700 C
[77,79]. CSH (I) decomposes at 800 C, which, however,only results
in a slight reduction of strength for concrete [81].During 580900
C, decarbonation of carbonates occurs[64,78,8183].
2.4.3. Pore structureAs a result of the water evaporation and
the chemical changes
of hydration products, elevation of temperature increases
porosityand pore size of cement and concrete
[11,21,23,64,75,76,78,8391]. The coarsening of the pore structure
is mainly responsible forthe reduction of the mechanical properties
as discussed in the pre-vious sections.
2.4.4. MicrostructureUp to 200 C, no micro-cracks are observed
in either hardened
cement matrix or interfacial transition zone (ITZ) [81,92].
Whenthe temperature rises to 400 C, micro-cracks in cement
matrixand ITZ start to propagate and their intensity increases with
tem-perature [3,21,23,26,28,9399].
It is considered that the different thermal strains for
hardenedcement matrix and aggregates have resulted in the
developmentof the micro-cracks at high temperature. From Fig. 6 it
can be seenthat with the increase of temperature, the hardened
cement matrixexpands rst and then shrinks as a result of the loss
of water, whileaggregates keep expansion during the whole heating.
Similarresults have also been found by Fu et al. [100]. Such
differentstrains will produce a stress between cement matrix and
aggre-gates, causing micro-cracks in the ITZ. This is also
responsible forthe reduction of the mechanical properties of
concrete at hightemperatures.
When temperature is very high, such as above 1000 C, porosityand
microstructure of concrete are smaller and better than those ata
lower temperature due to concrete has been sintered at such ahigh
temperature [83,85]. However, it does not indicate that
themechanical properties of concrete at the very high
temperaturewas better than those at a lower temperature as the
relationship
g Materials 93 (2015) 371383 373between mechanical properties
and pore structure is not trueany further due to the syntherization
has changed the characteris-tic of concrete material [85].
-
Distance from heat
Temperature
Pore pressure
Distance from heat
Temperature
Pore pressure
Temperature
Pore pressureTemperature
Pore pressure
ildinFig. 6. Thermal strains of cement matrix and aggregates
[102].374 Q. Ma et al. / Construction and Bu2.4.5. AggregatesAt
around 573 C, siliceous aggregates transform from a-phase
to b-phase causing expansion of concrete [81,83].
Disintegrationof calcareous aggregates, such as limestone, occurs
at a tempera-ture above 600 C [101].
2.5. Spalling
Spalling may occur for concrete at high temperature, which
willgreatly reduce mechanical properties of concrete structure
andeven cause collapse of the structure [103]. The mechanisms of
spal-ling of concrete at high temperature could be mainly
explainedfrom vapour pressure in pores and thermal stresses these
twoaspects [103].
Hardened concrete is saturated with water in its pores at
differ-ent extents. The moisture content in concrete is dependent
on w/b,age of concrete and environment. When concrete surface is
sub-jected to sufciently high temperature, a portion of water will
bevaporised and move out from concrete into atmosphere. There
isalso certain amount of water will be vaporised and move
oppositeto the inner part of concrete. Due to thermal gradient, the
innerpart of concrete is cooler and the vapour there will be
condensed.With the accumulation of the condensed water, a saturated
layer isgradually formed. This layer will resist the further
movement ofvapour into the inner of concrete, but move towards the
dry regionof the concrete surface with an attempt to escape out of
concreteinto atmosphere. If the pore structure of the concrete is
sufcientlydense and/or the heating rate is sufciently high, the
escape of thevapour layer would be not fast enough, resulting in a
large increaseof pore pressure in the concrete. If the tensile
stress of concretecould not resist the pore pressure, spalling of
concrete would occur[104]. Fig. 7 illustrates the whole process of
the thermal spalling ofconcrete as a result of the pore vapour
pressure.g Materials 93 (2015) 371383Fig. 8 shows the maximum pore
pressures of concrete at hightemperature. From Fig. 8 it can be
seen that the maximum porepressure is generally observed in the
inner part of concrete.Compared to the inner part, vapour in the
outer part is easier toescape out from concrete. This would reduce
the pore pressure inconcrete at the near surface zone. Furthermore,
the maximum porepressure in high strength concrete is generally
larger than that inthe normal strength concrete [105108]. The high
strength of con-crete is usually achieved by densifying its pore
structure to lowerits permeability. Due to the low permeability,
when the high
Distance from heat Distance from heat
Fig. 7. Spalling of concrete induced by pore vapour pressure
[104].
0
1
2
3
4
5
6
0 10 20 30 40 50 60
Max
imum
por
e pr
essu
re (M
Pa)
Distance from the heated surface (mm)
Ref. [106]Ref. [107]Ref. [108]
Fig. 8. Pore pressure in concrete at high temperature (radiant
heating to 600 C).
-
ildinstrength concrete is exposed to high temperature, the
vapour gen-erated is not easy to escape out from the concrete,
therefore result-ing in the larger maximum pore pressure. Fig. 7
also simulates the
Temperature
Tensile stress
Compressive stress
Compressive stress
Fig. 9. Spalling of concrete induced by thermal stresses.Tensile
stress
Q. Ma et al. / Construction and Budevelopment of pore pressure
in the concrete at high temperature,and which is corresponded to
the steps of the pore vapour pressureinduced spalling of
concrete.
Simultaneously, thermal gradient will also be formed betweenthe
heated surface and the inner part of concrete when the con-crete is
subjected to high temperature. This is particularly truewhen
temperature increases very fast, which is always named asthermal
shock. With temperature increases faster at the surfaceof concrete,
compressive stress is generated parallel to the heatedconcrete
surface, while tensile stress is generated in the inner con-crete
in a perpendicular direction. When the compressive stressexceeds
the tensile stress, spalling of concrete occurs [109], asshown in
Fig. 9.
Both the above two causes would result in cracking of concreteat
high temperature. Besides, the cracking of concrete at high
tem-perature would also be caused by the decomposition of
hydrationproduct, shrinkage of cement matrix and expansion of
aggregates.The different thermal response between cement matrix and
aggre-gates is also considered to distribute cracks in the ITZ
between thetwo phases, damaging concrete meso-structure. Finally,
all thecauses mentioned above make the spalling of concrete at high
tem-perature to occur in the models of aggregate spalling, surface
spal-ling, corner spalling and explosive spalling [103].
3. Factors inuencing the performance of concrete subjected
tohigh temperature
3.1. w/b and moisture content
The study carried out by Chan et al. [7] has illustrated that up
tothe temperature of 1000 C, the compressive strength loss of
thehigh w/b concrete (w/b = 0.6) was higher than that of the loww/b
concrete (w/b = 0.28, 0.35). Phan et al. [10] found that com-pared
to the concrete with w/b of 0.22, the losses of both compres-sive
strength and modulus of elasticity were higher for theconcrete with
w/b of 0.57. Similar results have been found for con-crete
containing slag [86,110], y ash [86,111] and metakaolin[111] when
w/b ranged from 0.3 to 0.5 [86,111] and from 0.23 to0.71 [110].
Lightweight concrete also gave similar results when dif-ferent w/b
of 0.43 and 0.46 was studied [27].
However, a lower w/b is prone to cause spalling of concrete
athigh temperature. As reported by Phan et al. [10], spalling
occurredfor the concrete with w/b of 0.22 when temperature was
elevatedto 450 C, while the concrete with w/b of 0.33 was still
intact at thesame temperature. As discussed in the previous
section, spallingoccurs when pore vapour pressure in concrete
accumulates to acertain extent. It is considered that such an
accumulation wouldbecome faster when the pore structure is denser,
which could becaused by using a lower w/b. That is why spalling of
concrete iseasy to occur at high temperature when a lower w/b is
used.Despite of w/b at the beginning of concrete mixing, spalling
is alsomuch dependent on the moisture content of concrete at the
time ofits exposure to high temperature. Fig. 10 gives an example
of spal-ling of concrete at different moisture contents. It is
clear to see thatthe possibility and the extent of spalling
increase with moisturecontent of concrete as a result of the
increased pore vapourpressure.
3.2. Type of aggregate
Effects of type of aggregate on compressive strength,
exuralstrength, splitting tensile strength andmodulus of elasticity
of con-crete at high temperatures are presented in Figs. 1114,
respec-tively. The scatter from data to regression line may be
caused bydifferent mixes and different test modalities. Generally
speaking,the concretes made of siliceous aggregates, such as
granite, expressunfavourable mechanical properties at high
temperature com-pared to the concretes manufactured by using
dolomite and lime-stone these calcareous aggregates. Furthermore,
Cheng et al. [16]also found that the increase in strains for the
concrete made of cal-careous aggregates was larger than that for
the siliceous aggregatesconcrete. It is also found that spalling
occurs at a higher tempera-ture and a later time for limestone
concrete [112]. As stated inSection 2.4, calcareous aggregates
decompose at a higher temper-ature than siliceous aggregates. This
could be used to explain thebetter performance of the concrete with
calcareous aggregates athigh temperature.
Lightweight aggregates, such as expanded clay, pumice and
cer-amsite, are formed by volcano eruption or incineration. As a
result,they have low heat conductivity and exhibit a high
resistance toheat. Therefore, the concrete manufactured by using
such aggre-gates should deliver improved mechanical properties at
high tem-perature in comparison to normal aggregates concrete. Sun
et al.[113] used high alumina cement to manufacture normal
refractoryconcrete (normal aggregates), ceramsite refractory
concrete I (cer-amsite as coarse aggregates), ceramsite refractory
concrete II (cer-amsite as coarse and ne aggregates) and refractory
brick concrete(broken refractory brick as coarse aggregates). The
concrete speci-mens were heated to 1000 C. After the heating,
ceramiste refrac-tory concretes I and II still had 3350%
compressive strengthremained, which was much higher than that of
normal refractoryconcrete of 17%. In the studies carried out by
both Sancak et al.[27] and Tanyildizi and Coskun [29], pumice was
used as coarseaggregates to manufacture lightweight concretes. The
lightweightconcrete specimens had 2838% compressive strength
remained
g Materials 93 (2015) 371383 375after exposure to 800 C, which
was higher than the value of 1316% for normal reference concrete.
In addition, the lightweightconcrete specimens still had 18%
splitting tensile strength
-
ildin376 Q. Ma et al. / Construction and Buremained [29]. Cao et
al. [114] compared the residual compressivestrength among
lightweight concrete I (ceramiste as coarse aggre-gates),
lightweight concrete II (ceramiste as both coarse and neaggregates)
and normal concrete at high temperature. The resultsshowed that the
normal concrete specimens had lost all the
Fig. 10. Relationship between moisture conte
00.20.40.60.8
11.21.41.61.8
0 200 400 600 800 1000 1200 1400
f cu,T
/f cu,
20
Temperature (C)dolomite limestone granitegravel basalt
regression for dolomiteregression for limestone regression for
granite regression for gravelregression for basalt
Fig. 11. Inuence of type of aggregate on residual compressive
strength of concretesubjected to elevated temperatures (data for
dolomite was adapted from[41,66,96]; data for limestone was adapted
from [2,17,20,23,24,32,42,57,60,98];data for granite was adapted
from [7,11,18,21,25,30,31,35,46,48,54,86]; data forgravel was
adapted from [5,8,9,13,19,22,33,34,44,45,73,98]; data for basalt
wasadapted from [15,49,97]).g Materials 93 (2015) 371383compressive
strength at temperature of 1000 C, whilst 20.5%and 21% of the
compressive strength was left for lightweight con-crete I and II,
respectively. Turkmen and Findik [115] usedexpanded clay to replace
natural sand at a replacement of 25% toproduce lightweight mortar.
Such mortar still had 38% of compres-sive strength and 23% of
exural strength remained after exposure
nt and possibility and extent of spalling.
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600 800 1000 1200
f f,T/f f
,20
dolomite limestonegranite gravelbasalt regression for
dolomiteregression for limestone regression for graniteregression
for gravel regression for basalt
Temperature (C)
Fig. 12. Inuence of type of aggregate on residual exural
strength of concretesubjected to elevated temperatures (data for
dolomite was adapted from [53]; datafor limestone was adapted from
[24,42,50]; data for granite was adapted from[21,54]; data for
gravel was adapted from [19]; data for basalt was adapted
from[47,49]).
-
ildin0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 200 400 600 800 1000 1200 1400
f t,T/
f t,20
limestone granitegravel basaltregression for limestone
regression for graniteregression for gravel regression for
basalt
Temperature (C)
Fig. 13. Inuence of type of aggregate on residual splitting
tensile strength ofconcrete subjected to elevated temperatures
(data for limestone was adapted from[45,56,57,60,61]; data for
granite was adapted from [7,30,54]; data for gravel wasadapted from
[8,58]; data for basalt was adapted from [15,49]).
1.2
Q. Ma et al. / Construction and Buto 800 C. In the study carried
out by Jiang et al. [116], compared tonormal concrete which had 10%
of the compressive strengthremained at the temperature of 1000 C,
the value was 20% forlightweight concrete manufactured by using
ceramiste. BothJiang et al. [117] and Wang et al. [118] used
industrial sewagesludge ceramsite to manufacture lightweight
concrete. After theexposure to 800 C, 46.9% of compressive strength
and 40% of split-ting tensile strength remained for the lightweight
concrete [117].In addition, 20.2% of initial modulus of elasticity
and 18.4% of peakdeformation modulus remained for the lightweight
concrete,which was higher than the normal reference concrete
[118].
The study carried out by Jiang et al. [116] points out that
hightemperature induced spalling did not occur when moisture
contentin normal concrete was below 75%. However, for lightweight
con-crete, when its moisture content was above 25%, spalling
occurredat high temperature. This indicates that spalling of
lightweightconcrete at high temperature is much more sensitive than
normalconcrete to moisture content. It is known that the porosity
of light-weight aggregate is much higher than that of normal
aggregate,and so is the water absorption consequently. Therefore,
in practice,in order to minimise the water absorption of
lightweight aggre-gates and its effect on fresh concrete
workability and subsequentsetting and hardening, lightweight
aggregate is usuallypre-saturated before being used to mix
concrete. However, suchtreatment will bring extra water into
lightweight concrete to
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000 1200
MT/
M20
dolomite limestonegranite gravelregression for dolomite
regression for limestoneregression for granite regression ofr
gravel
Temperature (C)
Fig. 14. Inuence of type of aggregate on residual modulus of
elasticity of concretesubjected to elevated temperatures (data for
dolomite was adapted from [41]; datafor limestone was adapted from
[16,17]; data for granite was adapted from[16,18,21,48]; data for
gravel was adapted from [8,9,73]).increase its moisture content,
and then increasing the possibilityof spalling for lightweight
concrete at high temperature. This willextremely limit the super
resistance of lightweight aggregate toheat. In literatures
[27,29,115], the authors did not follow the prac-tical process to
pre-saturate the lightweight aggregates. In litera-tures
[113,114,117,118], the authors dried the lightweightconcrete
specimens at 100 C before exposing them to high tem-perature, which
minimised the possible spalling at a large extent.Therefore, from
above it can be seen that further studies areneeded to investigate
the effect of high temperature on lightweightconcretes in a
condition similar to the practice. In such case, anovel
pre-treatment should be applied to lightweight aggregatesto reduce
the possibility of spalling of lightweight concrete, andthen to
allow the super resistance of lightweight aggregates to heatto
serve well.
3.3. SCMs
Table 1 summarises the literatures on the effect of SCMs on
theresidual mechanical properties of concrete at high
temperatures,including compressive strength, splitting tensile
strength, exuralstrength and modulus of elasticity.
The incorporation of pulverised y ash (PFA) and slag in PC
cangenerally remain the mechanical properties of concrete at a
higherlevel after heating to high temperature up to 900 C and 1050
C,respectively. Compared to PC, the residual compressive
strength,splitting tensile strength, exural strength and modulus of
elastic-ity of PC blended with PFA increase by 1.2270%, 1.180%,
4.5200% and 338%, respectively. The values for PC blended with
slagare 1.5510%, 1.243%, 1180% and 1.3117%, respectively. Thevalues
vary mainly with different temperatures, replacementsand types of
aggregates. In the research carried out by Wang[110], PC paste had
lost its compressive strength and modulus ofelasticity completely
at the temperature of 1050 C. However,18% of the compressive
strength and 81% of the modulus of elastic-ity were still remained
for PC blended slag paste with the replace-ment of 80% at the same
temperature. Furthermore, PCs blendedwith PFA and slag also exhibit
a high resistance to spalling at hightemperatures
[86,91,124,122].
Aydin and Baradan [97] and Aydin [123] detected the formationof
gehlenite in the PC samples incorporated PFA and slag at
thetemperature of 900 C by using XRD analysis. Such phase may llin
the pores caused by the high temperature. Therefore, the
cementmatrix could be rened and the ITZ between cement matrix
andaggregate could be enhanced so that the values of the
mechanicalproperties for PCs blended with PFA and slag retain at a
higherlevel. Furthermore, Karakurt and Topcu [120] found that
thermalcracking did not occur in PFA and slag blending samples and
thatthe degradation of CSH decreased compared to PC sample byusing
SEM analysis. Moreover, the incorporation of slag signi-cantly
reduces the amount of portlandite in PC so that decreasingthe
degradation of portlandite at high temperatures [124,125]. Asa
result of the above three aspects, the total porosity and the
aver-age pore diameter of PCs blended PFA and slag are smaller
thanthose of PC at high temperatures [86]. This could explain the
higherresistance of PCs blended PFA and slag to high
temperature.
On the other hand, the incorporation of silica fume (SF)
appar-ently reduces the resistance of PC to high temperatures.
Comparedto PC, the residual compressive strength, splitting tensile
strength,exural strength and modulus of elasticity of PC blended SF
at hightemperatures decrease by 1100%, 212%, 225% and
27%,respectively. The values also vary mainly with different
tempera-tures, replacements and types of aggregates. Furthermore,
severe
g Materials 93 (2015) 371383 377spalling was detected for PC
blended SF in several studies[10,86]. Behnood and Ziari [128]
explained that due to the llereffect and pozzolanic reactions
provided by SF, cement matrix
-
cal
; ff,
ildinTable 1Summary of the researches carried out on the effect
of SCMs on the residual mechani
Refs. Type of specimen Replacement (%)
PFA [11] Concrete with granite 0, 25, 55[17] Concrete with
limestone 0, 10, 30[18] Concrete 0, 30[80] Mortar 0, 25, 35, 45[86]
Concrete with granite 0, 20, 30, 40[97] Pumice mortar 0, 20, 40,
60[119] Lightweight concrete 0, 10, 20, 30[120] Concrete with
limestone 0, 30[121] Mortar 0, 5, 10, 15, 20[122] Concrete with
granite 0, 25, 55
Slag [38] Concrete 0, 10, 30, 50[63] Concrete 0, 20, 40, 60[86]
Concrete with granite 0, 30, 40[110] Paste 0, 5, 10, 20, 50,
80[120] Concrete with limestone 0, 30[123] Pumice mortar 0, 20, 40,
60, 80[124] Paste 0, 35, 50, 65[125] Mortar 0, 20, 50, 80[63]
Concrete 0, 20, 40, 60[126] Concrete with limestone 0, 30, 40,
50[127] Concrete 0, 30, 40, 50
SF [10] Concrete with limestone 0, 10[27] Lightweight concrete
0, 5, 10[32] Concrete with limestone 0, 10[61] Concrete with
limestone 0, 10[80] Mortar 0, 2.5, 5, 7.5[86] Concrete with granite
0, 5, 10[91] Paste 0, 5, 10, 15, 20[121] Mortar 0, 5, 10, 15,
20[128] Concrete with limestone 0, 6, 10
Note: fcu, compressive strength; E, modulus of elasticity; ft,
splitting tensile strength
378 Q. Ma et al. / Construction and Buand ITZ of PC blended with
SF would be much denser than those ofPC. This, however, could
restrain the expansion of aggregates whensubjecting to high
temperatures and then reduce the mechanicalproperties noticeably.
Poon et al. [86] also found that the totalporosity and the average
pore diameter of PC with 10% SF weremuch larger than those of PC at
the temperature of 800 C. Thiscould be the result of the restraint
effect mentioned above and con-sequently inuence the retaining of
the mechanical properties ofPC blended with SF at high
temperature.
3.4. Fibres
A number of studies have been carried out on the effect of breon
the mechanical properties of concrete after exposure to
hightemperatures, and a summary is presented in Table
2.Polypropylene and steel bres are usually used in these
studies.
Polypropylene bre generally has no signicant inuence onthe
improvements of residual compressive strength and residualmodulus
of elasticity for concrete after heating to high tempera-ture.
However, such improvement is clearer to a certain extentwhen
residual exural strength and residual splitting tensilestrength are
considered. This is particularly at the temperaturebelow 400 C.
Polypropylene bre can increase the resistance ofconcrete to
cracking, improving its behaviour under tension.However, the
melting and ignition points of polypropylene breare around 150 C
and 400500 C, respectively. That is why theimprovement of residual
exural and residual splitting tensilestrengths of polypropylene bre
reinforced concrete reduces whenthe temperature is above 400 C due
to the bre has been meltedup at such high temperature and the pores
left are disadvantagefor the performance of concrete under tension
[49,51,58,129].However, also due to the melting and ignition of
polypropylenewhich is randomly distributed in concrete, at a
relatively lowproperties of concrete.
Test temperatures (C) Mechanical properties tested
20, 250, 450, 650, 800 fcu20, 100, 300, 600, 750 fcu, E20, 100,
200, 400, 600 fcu, E20, 400, 700 fcu, ff20, 200, 400, 600, 800
fcu20, 300, 600, 900 fcu, ff20, 200, 400, 800 fcu, ft20, 100, 300,
450, 600 fcu20, 150, 300, 450, 600, 750 fcu20, 200, 400, 600, 800
ft
20, 150, 300, 400, 500, 600, 700 fcu, E20, 100, 200, 350 fcu,
ft, E20, 200, 400, 600, 800 fcu20, 105, 200, 440, 580, 800, 1050
fcu, E20, 100, 300, 450, 600 fcu20, 300, 600, 900 fcu, ff20, 100,
200, 300, 400, 500, 600, 700, 800 fcu20, 150, 300, 600, 900 fcu,
ft20, 100, 200, 350 fcu20, 400 ft20, 400 ff
20, 100, 200, 300, 450 fcu, E20, 100, 400, 800, 1000 fcu20, 100,
200, 300, 600 fcu20, 100, 200, 300, 600 ft20, 400, 700 fcu, ff20,
200, 400, 600, 800 fcu20, 250, 450, 600 fcu20, 150, 300, 450, 600,
750 fcu20, 100, 200, 300, 600 fcu
exural strength.
g Materials 93 (2015) 371383temperature, the left pores radiate
out to form microcracks, con-necting the existing capillary pores
to provide channels for theescaping of water vapour. Consequently,
it is found that thepolypropylene bre reinforced concrete has much
better resistanceto thermal spalling compared to the concrete
without bre[47,52,60,130133]. This is particularly true for high
performanceconcrete as water vapour is more difcult to escape in a
densermatrix. An optimum dosage of polypropylene bre around 0.10.5%
by volume of mix is recommended for concrete to obtain aproper high
temperature resistance [134136], and it is found thatthe resistance
of polypropylene bre reinforced concrete to hightemperature
increases with the increase of the length of the bre[131].
The addition of steel bre can generally improve the
residualmechanical properties of concrete at high temperature when
com-pressive strength, exural strength and splitting tensile
strengthare considered. The improvement in the residual modulus of
elas-ticity is not clearly observed. The reason for such
improvementscould be attributed to the fact that the testing
temperatures arenot high enough to allow steel bre to be melted so
that its ductil-ity could effectively contribute to concrete
resisting the failureunder tension during the whole test period.
Furthermore, steelbre has higher thermal conductivity than cement
matrix andaggregates. Consequently, heat can transmit more
uniformly inthe concrete reinforced with steel bre to reduce the
cracks causedby thermal gradient in concrete, improving the
performance ofconcrete under both compression and tension
[55,57,136]. Alsodue to the reduced thermal gradient, the steel bre
reinforced con-crete shows resistance to thermal spalling [49,137].
However, theresistance to spalling provided by steel bre is weaker
than thatprovided by polypropylene bre, which may indicate that
watervapour is the primary reason to cause spalling of concrete at
hightemperature [57].
-
ical
e)
; ff,
ildinTable 2Summary of the researches carried out on the effect
of bres on the residual mechan
Refs. Dimension of bre Replacement (% by volum
PP bre [43] L: 19 mm; D: 45 lm 0, 0.05, 0.1, 0.15[45] L: 12 mm;
D: 18 lm 0, 0.3[47] N/A 0, 0.15, 0.2[48] L: 19 mm 0, 0.1[51] L: 19
mm; D: 35 lm 0, 0.1[53] L: 15 mm; D: 100 lm 0, 0.6[55] L: 6 mm, 30
mm; D: 60 lm 0, 0.25, 0.5[57] L: 12 mm 0, 0.1, 0.2, 0.3[63] L: 19
mm; D: 53 lm 0, 0.22[67] L: 30 mm 0, 0.6[126] L: 12 mm; D: 18 lm 0,
0.5, 1.0, 1.5, 2.0[127] L: 13 mm; D: 20 lm 0, 0.05, 0.1, 0.15,
0.2[128] L: 3, 6, 12, 19, 30 mm; D: 40 lm 0, 0.05, 0.1, 0.15[129]
L: 15 mm; D: 100 lm 0, 0.5, 1[130] L: 20 mm; D: 20 lm 0, 0.1,
0.3[131] L: 12 mm; D: 50 lm 0, 0.1, 0.2, 0.3, 0.4[132] L: 6 mm; D:
18 lm 0, 0.1[133] L: 15 mm; D: 45 lm 0, 0.2[134] L: 19 mm; D: 45 lm
0, 0.1, 0.2, 0.3
Steel bre [44] L: 35, 60 mm; D: 440, 750 lm 0, 0.5, 1[45] L: 30
mm; D: 600 lm 0, 0.6[51] L: 30 mm; D: 550 lm 0, 0.4[53] L: 25 mm;
D: 500 lm 0, 0.6[55] L: 30 mm; D: 600 lm 0, 0.25, 0.5[56] L: 2 mm;
D: 2000 lm 0, 1[58] L: 25 mm; D: 400 lm 0, 0.5, 1, 1.5, 2[63] L: 25
mm; D: 42 lm 0, 1[67] N/A 0, 0.5[132] L: 12 mm; D: 50 lm 0, 1[135]
L: 32.6 mm; D: 950 lm 0, 1[136] L: 30 mm; D: 500 lm 0, 2
Note: fcu, compressive strength; E, modulus of elasticity; ft,
splitting tensile strength
Q. Ma et al. / Construction and Bu4. Inuence of test modalities
on the mechanical properties ofconcrete at high temperature
4.1. Hot and residual tests
Bamonte and Gambarova manufactured a self-compacting con-crete
[37] and a very high strength durable concrete [138], andtested the
compressive strengths of both the concrete specimensat hot state
and after heating. According to the results, when tem-perature was
below 300 C, the compressive strength of both theconcretes at hot
condition was lower than the residual ones.However, when
temperature increased up to 600 C, a contrarytrend was observed.
Qin and Zhao [139] and Hager [75] also foundsimilar results where
hybrid bre reinforced slag concretes andhigh performance concrete
were heated to 800 C and 600, respec-tively. Normal and
self-compacting concretes were investigated inthe study carried out
by Seshu and Pratusha [46]. The authors didnot test the compressive
strength of the concretes below the tem-perature of 400 C, but
afterwards till 800 C, the compressivestrength results also showed
a similar trend with the previousstudies. Similar trend was also
observed for the modulus of elastic-ity of high strength concrete
when temperature was up to 450 C[14]. It is believed that when the
temperature is below 400 C,the primary mechanism for the declines
of compressive strengthand modulus of elasticity is the vapour
pressure caused by theevaporation of the free water in capillary
pores. The pores arepressed during the compressive test at hot
state, increasing thevapour pressure and then intensifying the
damage of the concrete.Consequently, the compressive strength and
modulus of elasticityof concrete at hot state decrease at a larger
rate than the residualones [138,139]. 400 C afterwards, cracks in
the ITZ caused bythe different thermal responses between aggregates
(expansion)and cement matrix (shrinkage) dominate the declines of
compres-sive strength and modulus of elasticity. During cooling,
expandedproperties of concrete.
Test temperatures (C) Mechanical properties tested
20, 200, 400, 600, 800 fcu, ff20, 200, 400, 600, 800 fcu, ft,
ff20, 200, 300, 400, 800 fcu, ft20, 200, 300, 400, 600, 800 fcu,
ft, ff20, 200, 400, 600, 800 fcu, ff20, 200, 400, 600, 800 fcu,
ft20, 200, 400 fcu, ft, E20, 100, 200, 300, 600 fcu, ft20, 600, 800
fcu, E20, 100, 300, 500, 700 fcu20, 100, 450, 650 fcu, ffISO 834
fcu, EISO 834 fcu20, 200, 400, 600 fcu20, 200, 400, 600, 800 fcu,
ft20, 600, 900 fcu, ff, E20, 200, 400, 600 fcu20, 100, 200, 300,
400, 500, 600, 700, 800, 900 fcu, ff20, 200, 300, 400, 500, 600,
700, 800, 900 fcu, ft, ff
20, 150, 500 fcu, E20, 200, 400, 600, 800 fcu, ft, ff20, 200,
400, 600, 800 fcu, ff20, 200, 400, 600, 800 fcu, ft20, 200, 400
fcu, ft, E20, 400, 600, 800 fcu, ft20, 300, 500, 800 fcu, ft20,
600, 800 fcu20, 100, 300, 500, 700 fcu20, 600, 900 fcu, ff, E20,
200, 400, 600, 800 ft20, 350, 500, 600, 700 fcu, ft
exural strength.
g Materials 93 (2015) 371383 379aggregates appear to shrink,
further spreading the cracks in theITZ. As a result, the residual
compressive strength and modulusof elasticity are much lower than
the ones tested in hot state[138,139].
Bamonte and Gambarova [37] also studied the
compressivestressstrain relationship of self-compacting concretes
at the twotesting conditions. It was found that when the
temperature wasbelow 400 C, the peak stress of the specimens after
cooling washigher than the hot tested ones. However, when the
temperaturewas above 400 C up to 600 C, the trend was contrary.
Duringthe whole period of heating, the peak stress of the hot
tested spec-imens was always observed at a later stage.
In the study carried out by Watanabe et al. [132], it was
foundthat the bending strength of concrete specimens at hot state
waslower than that after cooling during the whole heating period
upto temperature of 600 C. The authors attributed the reason for
thisto the fact that tensile stresses increased during the heating,
butdid not exist any further in the residual state.
4.2. Stressed and unstressed tests
In the study carried out by Castillo and Durrani [1], during
thewhole heating process up to temperature of 800 C, a stress of40%
of the ultimate compressive strength at room temperaturewas loaded
onto the high strength concrete cylinder specimens.The results
showed that the compressive strength of the stressedspecimens was
comparable to the unstressed ones during thewhole heating process.
However, according to the results reportedby Phan and Carino [14]
and Fu et al. [18], during the whole heat-ing process up to
temperatures of 450 C and 600 C, respectively,the compressive
strength of the specimens at stressed state washigher than the
unstressed ones when a stress of 40% of the ulti-mate compressive
strength at room temperature was applied ontothe stressed
specimens. In the study carried out by Tao et al. [140],
-
cylinder specimens. The authors attributed this to the
friction
ildin20% of the ultimate compressive strength at room
temperature wasloaded onto the self-compacting concrete cylinder
specimens dur-ing the whole heating process up to temperature of
800 C. Thestressed results were compared to the unstressed ones,
and itwas also found that the compressive strength of the
specimenswas higher for the stressed test. In the study carried out
by Fuet al. [18], modulus of elasticity of high strength concrete
atstressed (40% of the ultimate compressive strength at room
tem-perature) and unstressed states was tested during heating
processup to temperature of 600 C. It was found that the stressed
modu-lus of elasticity was higher than the unstressed ones during
thewhole heating process. The reason for the higher
compressivestrength and modulus of elasticity at the stressed state
could beattributed to the fact that the pre-loading induced
friction betweenthe ends of specimens and the heads of testing
machine limits thethermal stress in expansion and then restrains
the thermal crack-ing [18]. In addition, the coarsened pores caused
by high tempera-ture could be compressed under the pre-loading,
densifying thepore structure of concrete. This could also be
benecial for theimprovement of the compressive strength and modulus
of elastic-ity of the concrete under stressed state [18].
The stressstrain relationship of concrete at stressed (40% of
theultimate compressive strength at room temperature) andunstressed
states during heating process was also studied in theresearch
carried out by Fu et al. [18]. It was found that during theheating
process up to temperature of 600 C, the peak stress of thestressed
specimens was higher than the unstressed ones and wasobserved at an
earlier stage. In the study carried out by Kim et al.[130], two
levels of pre-loading of 20% and 40% of the ultimate com-pressive
strength at room temperaturewere applied onto bre rein-forced
concrete cylinder specimens during the whole heatingprocess (the
heating regime was in accordance with ISO834).Stressstrain
relationship of the specimens was studied and theresults were
compared to the unstressed ones. The ndings weresimilar to the ones
reported previously [18] when 20% pre-loadingis considered.
However, the data for 40% pre-loading was invalidas spalling
occurred for most specimens under such pre-loadinglevel, which
could be used to indicate that spalling of concrete athigh
temperature is more prone to occur under stressed condition.
4.3. Uni-axial and multi-axial tests
In the study carried out Ehm and Schneider [141], strength
ofconcrete under bi-axial condition was tested during a heating
pro-cess, and the results were compared to the ones tested
underuni-axial condition. The stresses applied were in a tensile
directionfor both axes. It was found that the concrete specimens
were dam-aged more seriously under bi-axial condition during the
wholeheating process up to temperature of 600 C. In addition, it
wasfound that no matter the fraction between the horizontal
stressapplied and the perpendicular one, compared to the
uni-axialstrength at room temperature, the strength loss in the
perpendic-ular direction was smaller than that in the horizontal
direction.At temperature of 600 C, when the ratio between the
horizontalstress and the perpendicular stress was 1:5, only 5% of
the ultimateuni-axial strength at room temperature was remained in
the hori-zontal direction, while the value was 25% for the
perpendicularone. Similar results were also reported by Theinel and
Rostasy[142].
In the study carried out by He and Song [143], bi- and
tri-axialtensile-compressive tests were performed on high
performanceconcrete specimens at different stress ratios after
heating to hightemperature up to 600 C. The results showed that the
strength
380 Q. Ma et al. / Construction and Buloss of concrete specimens
under tri-axial state was greater thanthat under bi-axial state
during the whole heating process. In addi-tion, it was found that
the tensile strength increased with theeffect between the press
platens and the specimen.Arioz [145] also tested the residual
splitting tensile strength of
concrete cubes with sizes of 100 100 100 mm,150 150 150 mm and
200 200 200 mm after their expo-sures to temperatures from 20 C to
1200 C. It was found thatbelow 400 C, the residual splitting
strength of the larger speci-mens was higher than that of the
smaller specimens. Afterwards,the difference was not pronounced.
The author attributed the rea-son for this to the fact that the
temperature in the centre of thespecimens was lower than the
temperature at the surface duringheating process due to concrete is
poorly heat conducted, and sucheffect was more signicant for the
larger specimens, especiallyduring the earlier stage of the
heating.
5. Conclusion
Deterioration of mechanical properties of concrete occurs athigh
temperature.
During the high temperature exposure, concrete experiences
aseries of physical and chemical changes, such as water
evapora-tion, disintegrations of hydration products and
aggregates,coarsening of microstructure and increase of porosity.
Thesechanges are considered to be responsible for the
deteriorationof mechanical properties of concrete at high
temperature.
Spalling may occur for concrete at high temperature. Watervapour
pressure and thermal stress at high temperature mayinduce the
spalling.
The residual compressive strength and modulus of elasticity
ofthe concrete with lower w/b are higher than the concrete
withhigher w/b. A lower w/b at the beginning of mixing and/or
ahigher moisture content at the time when concrete is exposedto
high temperature is prone to induce spalling of concrete athigh
temperature as a result of high vapour pressure.
Calcareous aggregates provide greater high temperature
resis-tance to concrete compared to siliceous
aggregates.Lightweight concretes have a high resistance to heat due
tothe natural characteristics of lightweight aggregates.
However,the pre-saturation regime of lightweight aggregates which
isdecrease of stress ratio for any given temperature, while
thechange of compressive strength was contrary.
4.4. Specimen size
In the study carried out by Barnagan et al. [144], residual
mod-ulus of elasticity of concrete cylinder specimens of 150 300
mmand prism specimens of 75 105 430 mm after heating to
tem-perature of 500 C was tested. The results showed that the loss
ofmodulus of elasticity caused by the heating was comparablebetween
the two types of concrete specimens. Arioz [145] alsofound that the
difference of the residual compressive strengthbetween the concrete
cubes of 100 100 100 mm and the cubesof 150 150 150 mm was not
signicant after the exposures totemperatures from 20 C to 1200 C.
Similar results were alsoreported in the study carried out by Erdem
[146] when cylinderspecimens with sizes of 50 100 mm, 100 200 mm
and150 300 mm were studied during heating process up to
tem-perature of 800 C.
Bamonte and Gambarova [138] tested the residual
compressivestrengths of concrete cubes (40 40 40 mm) and concrete
cylin-ders (36 110 mm) after their exposures to elevated
tempera-ture up to 750 C. It was found that the cube specimens
alwaysexhibited higher residual compressive strength compared to
the
g Materials 93 (2015) 371383usually used in practice would
induce spalling of lightweightconcretes at high temperature.
-
ildin The addition of PFA and slag in concrete could increase
its resis-tance to high temperature, while the addition of SF
wouldreduce such resistance.
Polypropylene bre generally has no signicant inuence on
theimprovements of residual compressive strength and modulus
ofelasticity for concrete after heating to high temperature.
Itsimprovement on residual splitting tensile strength and
exuralstrength would be greatly lost after around 400 C.
However,polypropylene reinforced concrete has great resistance to
spal-ling due to the release of vapour pressure.
Steel bre could generally improve the residual
mechanicalproperties of concrete after heating to high temperature.
Itcould also increase the resistance of concrete to spalling,
butthe extent of such increase is less than that provided
bypolypropylene bre.
When temperature is below 400 C, the compressive strength
ofconcretes tested at hot state is lower than the one tested
afterthe heating. 400 C afterwards, the residual
compressivestrength is lower than the one tested at hot condition.
Theresidual bending strength of concretes is higher than the
onetested at hot state.
The compressive strength of concretes at high temperaturetested
under stressed state is higher than the one tested underunstressed
state.
Compared to uni-axial test, bi-axial and tri-axial tests
bringmore serious damage for concretes at high temperature.
When the difference of specimen size is signicant enough,
thespecimens with smaller size exhibits higher residual
compres-sive strength than the larger specimens at high
temperature.
References
[1] Castillo C, Durrani AJ. Effect of transient high temperature
on high-strengthconcrete. ACI Mater J 1990;87(1):4753.
[2] Li G, Feng L, Zheng S. Investigation on the properties of
concrete and itscomposites after exposure to high temperature.
Sichuan Build Sci 1991;2:15[in Chinese].
[3] Papayianni J, Valiasis T. Residual mechanical properties of
heated concreteincorporating different pozzolanic materials. Mater
Struct 1991;24:11521.
[4] Li W, Guo Z. Experimental investigation of strength and
deformation ofconcrete at elevated temperature. J Build Struct
1993;14(1):816 [inChinese].
[5] Noumowe AN, Clastres P, Debicki G, Costaz J-L. Transient
heating effect onhigh strength concrete. Nucl Eng Des
1996;166:99108.
[6] Phan LT, Carino NJ. Review of mechanical properties of HSC
at elevatedtemperature. ASCE-J Mater Civil Eng 1998;10(1):5864.
[7] Chan YN, Peng GF, Anson M. Residual strength and pore
structure of high-strength concrete and normal strength concrete
after exposure to hightemperatures. Cem Concr Compos
1999;21:237.
[8] Zhang B, Bicanic N, Pearce CJ, Balabanic G. Residual
fracture properties ofnormal- and high-strength concrete subject to
elevated temperatures. MagConcr Res 2000;52(2):12336.
[9] Xu Y, Xu Z, Zhu M. Experiment investigation of strength and
reformation ofconcrete after high temperature. J Changsha Railway
Univ 2000;18:137 [inChinese].
[10] Phan LT, Lawson JR, Davis FL. Effects of elevated
temperature exposure onheating characteristics, spalling, and
residual properties of high performanceconcrete. Mater Struct
2001;34:8391.
[11] Xu Y, Wong YL, Poon CS, Anson M. Impact of high temperature
on PFAconcrete. Cem Concr Res 2001;31:106573.
[12] Hu H, Dong Y. Experimental research on strength and
deformation of high-strength concrete at elevated temperature.
China Civil Eng J 2002;35:447 [inChinese].
[13] Janotka I, Bagel L. Pore structures, permeabilities, and
compressive strengthsof concrete at temperatures up to 800 C. ACI
Mater J 2002;99(2):196200.
[14] Phan LT, Carino NJ. Effects of test conditions and mixture
proportions onbehavior of high-strength concrete exposed to high
temperatures. ACI Mater J2002;99(1):5466.
[15] Li M, Qian C, Sun W. Mechanical properties of high-strength
concrete afterre. Cem Concr Res 2004;34:10015.
[16] Cheng F-P, Kodur VKR, Wang T-C. Stress-strain curves for
high strengthconcrete at elevated temperatures. J Mater Civ Eng
2004;16(1):8494.
Q. Ma et al. / Construction and Bu[17] Savva A, Manita P,
Sideris KK. Inuence of elevated temperatures on themechanical
properties of blended cement concretes prepared with limestoneand
siliceous aggregates. Cem Concr Compos 2005;27:23948.[18] Fu YF,
Wong YL, Poon CS, Tang CA. Stress-strain behaviour of
high-strengthconcrete at elevated temperatures. Mag Concr Res
2005;57(9):53544.
[19] Sakr K, El-Hakim E. Effect of high temperature or re on
heavy weightconcrete properties. Cem Concr Res 2005;35:5906.
[20] Wang K, Xu Q, Liu T. Experimental research on mechanics
performance ofconcrete after high temperature and cooled down from
high temperature.Constr Technol 2005;34:13 [in Chinese].
[21] Lau A, Anson M. Effect of high temperatures on high
performance steel brereinforced concrete. Cem Concr Res
2006;36:1698707.
[22] Chen L, Meng H, Lin Y. Experimental research on properties
of concrete afterhigh temperature. New Build Mater 2006;9:124 [in
Chinese].
[23] Hossain KMA. High strength blended cement concrete
incorporating volcanicash: performance at high temperatures. Cem
Concr Compos 2006;28:53545.
[24] Husem M. The effects of high temperature on compressive and
exuralstrengths of ordinary and high-performance concrete. Fire Saf
J2006;41:15563.
[25] Sideris KK. Mechanical characteristics of
self-consolidating concretes exposedto elevated temperatures. J
Mater Civ Eng 2007;19:64854.
[26] Li L, Xie W, Liu F, Chen Y, Lu H, Wang R. Performance of
100 MPa highstrength concrete (HSC) after high temperature
treatment. J Build Mater2008;11:1004 [in Chinese].
[27] Sancak E, Sari YD, Simsek O. Effects of elevated
temperature on compressivestrength and weight loss of the
light-weight concrete with silica fume andsuperplasticizer. Cem
Concr Compos 2008;30:71521.
[28] Biolzi L, Cattaneo S, Rosati G. Evaluating residual
properties of thermallydamaged concrete. Cem Concr Compos
2008;30:90716.
[29] Tanyildizi H, Coskun A. Performance of lightweight concrete
with silica fumeafter high temperature. Constr Build Mater
2008;22:21249.
[30] Anagnostopoulos N, Sideris KK, Georgiadis A. Mechanical
characteristics ofself-compacting concretes with different ller
materials, exposed to elevatedtemperatures. Mater Struct
2009;42:1393405.
[31] Tang WC, Lo TY. Mechanical and fracture properties of
normal- and high-strength concretes with y ash after exposure to
high temperatures. MagConcr Res 2009;61(5):32330.
[32] Ghandehari M, Behnood A, Khanzadi M. Residual mechanical
properties ofhigh-strength concretes after exposure to elevated
temperatures. J Mater CivEng 2010;22:5964.
[33] Demirel B, Kelestemur O. Effect of elevated temperature on
the mechanicalproperties of concrete produced with nely ground
pumice and silica fume.Fire Saf J 2010;45:38591.
[34] Nayef A-M, Fahad A-R, Ahmed B. Effect of microsilica
addition oncompressive strength of rubberized concrete at elevated
temperatures. JMater Cycles Waste Manage 2010;12:419.
[35] Ismail M, Ismail ME, Muhammad B. Inuence of elevated
temperatures onphysical and compressive strength properties of
concrete containing palm oilfuel ash. Constr Build Mater
2011;25:235864.
[36] Sideris KK, Manita P, Tsanaktsidis E. Mechanical
characteristic of berreinforced self-compacting concretes exposed
to elevated temperatures. In:2nd international RILEM workshop on
concrete spalling due to re exposure,Delft, The Netherlands; 2011.
p. 165172.
[37] Bamonte P, Gambarova PG. A study on the mechanical
properties of self-compacting concrete at high temperature and
after cooling. Mater Struct2012;45(9):137587.
[38] Li Q, Li Z, Yuan G. Effects of elevated temperatures on
properties of concretecontaining ground granulated blast furnace
slag as cementitious material.Constr Build Mater 2012;35:68792.
[39] Yu J, Yu K, Lu Z. Residual fracture properties of concrete
subjected to elevatedtemperatures. Mater Struct 2012;45:115565.
[40] Uysal M. Self-compacting concrete incorporating ller
additives:performance at high temperatures. Constr Build Mater
2012;26:7016.
[41] Netinger I, Varevac D, Bjegovic D, Moric D. Effect of high
temperature onproperties of steel slag aggregate concrete. Fire Saf
J 2013;59:17.
[42] Ergun A, Kurklu G, Baspinar MS, Mansour MY. The effect of
cement dosage onmechanical properties of concrete exposed to high
temperatures. Fire Saf J2013;55:1607.
[43] Felicetti R, Gambarova PG, Bamonte P. Thermal and
mechanical properties oflight-weight concrete exposed to high
temperature. Fire Mater2013;37:20016.
[44] Luo Y, Chen C, Tang S, Zhang X. Research on the compressive
strength ofconcrete under high temperature. Nat Sci J Xiangtan Univ
2013;35(2):3040[in Chinese].
[45] Marques AM, Correia JR, de Brito J. Post-re residual
mechanical properties ofconcrete made with recycled rubber
aggregate. Fire Saf J 2013;58:4957.
[46] Seshu DR, Pratusha A. Study on compressive strength
behaviour of normalconcrete and self-compacting concrete subjected
to elevated temperatures.Mag Concr Res 2013;65(7):41521.
[47] You Y, Qian C, Miao C. Study on the properties of high
strength concrete withshort polypropylene ber after high
temperature. Saf Environ Eng2004;11(1):636 [in Chinese].
[48] Giaccio GM, Zerbino RL. Mechanical behaviour of thermally
damaged high-strength steel bre reinforced concrete. Mater Struct
2005;38:33542.
[49] Zhang D, Ju L. Effects of hybrid ber on HPC properties
under hightemperature. Ind Constr 2005;35(1):814 [in Chinese].
g Materials 93 (2015) 371383 381[50] Xiao J, Ren H, Wang P.
Study on residual exural strength of high-performance concrete at
elevated temperature. J Tongji Univ (Nat Sci)2006;34(5):5805 [in
Chinese].
-
382 Q. Ma et al. / Construction and Building Materials 93 (2015)
371383[51] Liu M, Lin Z, Ding Q, Hu S. Study on the properties of
high performanceconcrete with different content polypropylene ber
after high temperature. JHUST (Urban Sci Ed) 2007;24(2):147 [in
Chinese].
[52] Zhao J, Gao D. The experimental study on mechanical
property ofpolypropylene ber reinforced high-strength concrete
after hightemperature. Sichuan Build Sci 2008;34:1335 [in
Chinese].
[53] Netinger I, Kesegic I, Guljas I. The effect of high
temperatures on themechanical properties of concrete made with
different types of aggregates.Fire Saf J 2011;46:42530.
[54] Yan L, Xing Y, Li J. High-temperature mechanical properties
and microscopicanalysis of hybrid-bre-reinforced high-performance
concrete. Mag ConcrRes 2013;65(3):13947.
[55] Gao C, Yang D, Yu J, Wang L, Li P. Mechanical properties of
ber reinforcedconcrete after high temperature. Concrete 2013;1:336
[in Chinese].
[56] Xie D, Qian Z. Research on bond and tension of concrete
after hightemperature. J Zhejiang Univ (Nat Sci) 1998;32(5):597602
[in Chinese].
[57] Chen B, Liu J. Residual strength of hybrid-ber-reinforced
high-strengthconcrete after exposure to high temperatures. Cem
Concr Res2004;34:10659.
[58] Noumowe A. Mechanical properties and microstructure of high
strengthconcrete containing polypropylene bres exposed to
temperatures up to200 C. Cem Concr Res 2005;35:21928.
[59] Suhaendi SL, Horiguchi T. Effect of short bers on residual
permeability andmechanical properties of hybrid bre reinforced high
strength concrete afterheat exposition. Cem Concr Res
2006;36:16728.
[60] Peng G-F, Yang W-W, Zhao J, Liu Y-F, Bian S-H, Zhao L-H.
Explosive spallingand residual mechanical properties of
ber-toughened high-performanceconcrete subjected to high
temperatures. Cem Concr Res 2006;36:7237.
[61] Behnood A, Ghandehari M. Comparison of compressive and
splitting tensilestrength of high-strength concrete with and
without polypropylene bersheated to high temperatures. Fire Saf J
2009;44:101522.
[62] Chen H, Liu F, Sun B, Wang M, Cheng P. Impact of steel bre
dosage onmechanical properties of concrete under high temperature.
J ChongqingJiaotong Univ (Nat Sci) 2010;26(4):5524 [in
Chinese].
[63] Siddique R, Kaur D. Properties of concrete containing
ground granulated blastfurnace slag (GGBFS) at elevated
temperatures. J Adv Res 2012;3:4551.
[64] Janotka I, Nurnbergerova T, Nad L. Behaviour of
high-strength concrete withdolomitic aggregate at high
temperatures. Mag Concr Res2000;52(6):399409.
[65] Wu B, Yuan J, Wang G. Experimental research on the
mechanical properties ofHSC after high temperature. China Civil Eng
J 2000;33(2):812 [in Chinese].
[66] Lv T, Zhao G, Lin Z. Experimental study on mechanical
properties of longstanding concrete after exposure to high
temperature. J Build Struct2004;25(4):6370 [in Chinese].
[67] Poon CS, Shui ZH, Lam L. Compressive behavior of ber
reinforced high-performance concrete subjected to elevated
temperatures. Cem Concr Res2004;34:221522.
[68] Chang YF, Chen YH, Sheu MS, Yao GC. Residual stress-strain
relationship forconcrete after exposure to high temperatures. Cem
Concr Res2006;36:19992005.
[69] Ahmad AH, Abdulkareem OM. Effect of high temperature on
mechanicalproperties of concrete containing admixtures. Al-Radain
Eng2010;18(4):4354.
[70] Tai Y-S, Pan H-H, Kung Y-N. Mechanical properties of steel
ber reinforcedreactive powder concrete following exposure to high
temperature reaching800 C. Nucl Eng Des 2011;241:241624.
[71] Wang K. Study on property of ber reinforced concrete under
hightemperature damage. J Xuzhou Inst Architect Technol
2011;11(4):214 [inChinese].
[72] Nadeem A, Memon SA, Lo TY. Evaluation of y ash and
metakaolin concrete atelevated temperatures through stiffness
damage test. Constr Build Mater2013;38:105865.
[73] Huo JS, He YM, Xiao LP, Chen BS. Experimental study on
dynamic behavioursof concrete after exposure to high temperatures
up to 700 C. Mater Struct2013;46:25565.
[74] Feldman RF, Ramachandran VS. Differentiation of interlayer
and adsorbedwater in hydrated Portland cement on thermal analysis.
Cem Concr Res1971;607620.
[75] Hager I. Behaviour of cement concrete at high temperature.
Bull Pol Acad Sci2013;61(1):14554.
[76] Saad M, Abo-El-Enein SA, Hanna GB, Kotkata MF. Effect of
temperature onphysical and mechanical properties of concrete
containing silica fume. CemConcr Res 1996;26(5):66975.
[77] Taylor HFW. Cement chemistry. 2nd ed. Thomas Telford;
1997.[78] Piasta J, Sawicz Z, Rudzinski L. Changes in the structure
of hardened cement
paste due to high temperature. Mater Constr 1984;17:2916.[79]
Peng G-F, Huang Z-S. Change in microstructure of hardened cement
paste
subjected to elevated temperatures. Constr Build Mater
2008;22:5939.[80] Ibrahim RK, Hamid R, Taha MR. Fire resistance of
high-volume y ash mortars
with nanosilica addition. Constr Build Mater 2012;36:77986.[81]
Lin W-M, Lin TD, Powers-Couche LJ. Microstructures of
re-damaged
concrete. ACI Mater J 1996;93(3):199205.[82] Vydra V, Vodak F,
Kapickova O, Hoskova S. Effect of temperature on porosityof
concrete for nuclear-safety structures. Cem Concr Res
2001;31:10236.[83] Masse S, Vetter G, Boch P, Haehnel C. Elastic
modulus changes incementitious materials submitted to thermal
treatments up to 1000 C. AdvCem Res 2002;14(4):16977.
[84] Rostasy RS, Weiss R, Wiedemann G. Changes of pore structure
of cementmortar due to temperatures. Cem Concr Res
1980;10:15764.
[85] Chan SYN, Luo X, Sun W. Effect of high temperature and
cooling regimes onthe compressive strength and pore properties of
high performance concrete.Constr Build Mater 2000;14:2616.
[86] Poon C-S, Azhar S, Anson M, Wong Y-L. Comparison of the
strength anddurability performance of normal- and high-strength
pozzolanic concretes atelevated temperatures. Cem Concr Res
2001;31:1291300.
[87] Galle C, Sercombe J. Permeability and pore structure
evolution of silico-calcareous and hematite high-strength concretes
submitted to hightemperatures. Mater Struct 2001;34:61928.
[88] Vodak F, Trtik K, Kapickova O, Hoskova S, Demo P. The
effect of temperatureon strength-porosity relationship for
concrete. Constr Build Mater2004;18:52934.
[89] Liu X, Yuan Y, Ye G, Schutter GD. Study on pore structure
evolution of highperformance concrete with elevated temperatures. J
Tongji Univ (Nat Sci)2008;36(11):14738 [in Chinese].
[90] Mendes A, Sanjayan JG, Gates WP, Collins F. The inuence of
water absorptionand porosity on the deterioration of cement paste
and concrete exposed toelevated temperatures, as in a re event. Cem
Concr Compos2012;34:106774.
[91] Heikal M, El-Didamony H, Sokkary TM, Ahmed IA. Behavior of
compositecement pastes containing microsilica and y ash at elevated
temperature.Constr Build Mater 2013;38:118090.
[92] Li XJ, Li ZJ, Onofrei M, Ballivy G, Khayat KH.
Microstructural characteristics ofHPC under different
thermo-mechanical and thermo-hydraulic conditions.Mater Struct
1999;32:72733.
[93] Handoo SK, Agarwal S, Agarwal SK. Physicochemical,
mineralogical, andmorphological characteristics of concrete exposed
to elevated temperatures.Cem Concr Res 2002;32:100918.
[94] Wang X-S, Wu B-S, Wang Q-Y. Online SEM investigation of
microcrackcharacteristics of concretes at various temperatures. Cem
Concr Res2005;35:138590.
[95] Peng G, Chan SYN, Yan J, Liu Y, Yi Q. Characteristic of
crack growth in highperformance concrete subjected to re. J Mater
Sci Technol2005;21(1):11822.
[96] Matesova D, Bonen D, Shah SP. Factors affecting the
resistance ofcementitious materials at high temperatures and medium
heating rates.Mater Struct 2006;39:91935.
[97] Aydin S, Baradan B. Effect of pumice and y ash
incorporation on hightemperature resistance of cement based
mortars. Cem Concr Res2007;37:98895.
[98] Arioz O. Effects of elevated temperatures on properties of
concrete. Fire Saf J2007;42:51622.
[99] Morsy MS, Al-Salloum YA, Abbas H, Alsayed SH. Behavior of
blended cementmortars containing nano-metakaolin at elevated
temperatures. Constr BuildMater 2012;35:9005.
[100] Fu Y-F, Wong Y-L, Poon C-S, Tang C-A, Lin P. Experimental
study ofmicro/macro crack development and stress-strain relations
of cement-based composite materials at elevated temperatures. Cem
Concr Res2004;34:78997.
[101] Schneider U, Diederischs U, Ehm C. Effect of temperature
on steel andconcrete for PCRVs. Nucl Eng Des 1981;67:24558.
[102] Schneider U. Concrete at high temperaturesa general
review. Fire Saf J1988;13:5568.
[103] Fu Y, Huang Y, Pan Z, Tang C. Literature review of study
on mechanism ofexplosive spalling in concrete at elevated
temperatures. J Build Mater2006;9(3):3239 [in Chinese].
[104] Consolazio GR, McVay MC, Rish III JW. Measurement and
prediction of porepressures in saturated cement mortar subjected to
radiant heating. ACI MaterJ 1998;95(5):52536.
[105] Kalifa P, Menneteau F-D, Quenard D. Spalling and pore
pressure in HPC athigh temperatures. Cem Concr Res
2000;30:191527.
[106] Bangi MR, Horiguchi T. Effect of bre type and geometry on
maximum porepressures in bre-reinforced high strength concrete at
elevatedtemperatures. Cem Concr Res 2012;42:45966.
[107] Mindeguia JC, Pimienta P, Hager I, Carre, H. Inuence of
water content on gaspore pressure in concretes at high temperature.
In: 2nd international RILEMworkshop on concrete spalling due to re
exposure, Delft, The Netherlands;2011. p. 113121.
[108] Ko Jeongwon, Noguchi T, Ryu D. The spalling mechanism of
high-strengthconcrete under re. Mag Concr Res 2011;63(5):35770.
[109] Ozawa M, Uchida S, Kamada T, Morimoto H. Study of
mechanisms ofexplosive spalling in high-strength concrete at high
temperatures usingacoustic emission. Constr Build Mater
2012;37:6218.
[110] Wang HY. The effects of elevated temperature on cement
paste containingGGBFS. Cem Concr Compos 2008;30:9929.
[111] Poon C-S, Azhar S, Anson M, Wong Y-L. Performance of
metakaolin concreteat elevated temperatures. Cem Concr Compos
2003;25:839.
[112] Li Y, Li L, Su J. Effect if coarse aggregate varity on
heat burst properties of high
strength concrete. Concrete 2011;4:735.
-
[113] Sun H, Wang L, Cao M. The test research on strength and
durability ofrefractory concrete with high aluminum cement after a
re. Ind Constr2003;33:602 [in Chinese].
[114] Cao W, Sun Q, Zhou M, Yang Y. Study on effect rule of
cementing material andaggregate varieties upon concrete resistance
to high temperature. New BuildMater 2009;3:1720 [in Chinese].
[115] Turkmen I, Findik SB. Several properties of mineral
admixtured lightweightmortars at elevated temperatures. Fire Mater
2013;37:33749.
[116] Jiang Y, Huo D, Teng H, Qiao Y. Study on performance of
shale ceramsiteconcrete after exposure to high temperature. J Build
Mater 2013;16:88892[in Chinese].
[117] Jiang W, Wang J, Cheng B. Experiment and analysis of
ceramsite lightweightaggregate concrete after elevated temperature.
Ind Constr 2014;44(2):1037[in Chinese].
[118] Wang J, Yuan L, Wang N, Jiang W, He Z. Experimental study
on mechanicalperformance of lightweight aggregate concrete after
high temperatureheating. J Nat Disasters 2014;23(1):25863 [in
Chinese].
[119] Tanyildizi H, Coskun A. The effect of high temperature on
compressivestrength and splitting tensile strength of structural
lightweight concretecontaining y ash. Constr Build Mater
2008;22:226975.
[120] Karakurt C, Topcu IB. Effect of blended cements with
natural zeolite andindustrial by-products on rebar corrosion and
high temperature resistance ofconcrete. Constr Build Mater
2012;35:90611.
[121] Yazici S, Sezer GI, Sengul H. The effect of high
temperature on thecompressive strength of mortars. Constr Build
Mater 2012;35:97100.
[122] Xu Y, Wong YL, Poon CS, Anson M. Inuence of PFA on
cracking of concreteand cement paste after exposure to high
temperatures. Cem Concr Res2003;33:200916.
[123] Aydin S. Development of a high-temperature-resistant
mortar by using slagand pumice. Fire Saf J 2008;43:6107.
[124] Mendes A, Sanjayan J, Collins F. Phase transformations and
mechanicalstrength of OPC/slag pastes submitted to high
temperatures. Mater Struct2008;41:34550.
[125] Delhomme F, Ambroise J, Limam A. Effects of high
temperatures on mortar
[130] Kim Y, Lee T, Kim G. An experimental study on the residual
mechanicalproperties of ber reinforced concrete with high
temperature and load. MaterStruct 2013;46:60720.
[131] Heo Y-S, Sanjayan J-G, Han C-G, Han M-C. Critical
parameters of nylon andother bres for spalling protection of high
strength concrete in re. MaterStruct 2011;44:599610.
[132] Zheng W, Li H, Wang Y. Mechanical properties of reactive
powder concretewith different dosage of polypropylene ber after
high temperature. J BuildStruct 2012;33:11926 [in Chinese].
[133] Han C-G, Hwang Y-S, Yang S-H, Gowripalan N. Performance of
spallingresistance of high performance concrete with polypropylene
ber contentsand lateral connement. Cem Concr Res
2005;35:174753.
[134] Shihada S. Effect of polypropylene bers on concrete re
resistance. J CivilEng Manage 2011;17:25964.
[135] Aydin S, Yazici H, Baradan B. High temperature resistance
of normal strengthand autoclaved high strength mortars incorporated
polypropylene and steelbers. Constr Build Mater 2008;22:50412.
[136] Gao D, Yan D, Li X. Splitting strength of GGBFS concrete
incorporating withsteel ber and polypropylene ber after exposure to
elevated temperatures.Fire Saf J 2012;54:6773.
[137] Zheng W, Li H, Wang Y. Compressive stress-strain
relationship of steel ber-reinforced reactive powder concrete after
exposure to elevated temperatures.Constr Build Mater
2012;35:93140.
[138] Bamonte P, Gambarova PG. Thermal and mechanical properties
at hightemperature of a very high-strength durable concrete. J
Mater Civ Eng2010;22:54555.
[139] Qin D, Zhao L. Compressive strength of bre reinforced slag
concrete at andafter high temperature. Henan Build Mater 2011;6:601
[in Chinese].
[140] Tao J, Yuan Y, Taerwe L. Compressive strength of
self-compacting concreteduring high-temperature exposure. J Mater
Civ Eng 2010;22:100511.
[141] Ehm C, Schneider U. The high temperature behaviour of
concrete underbiaxial conditions. Cem Concr Res 1985;15:2734.
[142] Thienel KCH, Rostasy FS. Strength of concrete subjected to
high temperatureand biaxial stress: experiments and modelling.
Mater Struct1995;28:57581.
[143] He Z, Song Y. Multiaxial tensile-compressive strengths and
failure criterion of
Q. Ma et al. / Construction and Building Materials 93 (2015)
371383 383specimens containing Portland cement and GGBFS. Mater
Struct2012;41:34550.
[126] Gao D, Zhao L, Yang S. Splitting tensile properties of ber
reinforced groundgranulated blast furnace slag concrete at high
temperatures. J Chin Cerem Soc2012;40(5):67784 [in Chinese].
[127] Gao D, Li X, Yang S. Flexural properties of ber reinforced
slag concrete afterhigh temperature treatment. China Concr Cem Prod
2012;5:427 [inChinese].
[128] Behnood A, Ziari H. Effects of silica fume addition and
water to cement ratioon the properties of high-strength concrete
after exposure to hightemperatures. Cem Concr Compos
2008;30:10612.
[129] Cavdar A. The effects of high temperature on mechanical
properties ofcementitious composites reinforced with polymeric
bers. Compos Part B2013;45:7888.plain high-performance concrete
before and after high temperatures. ConstrBuild Mater
2010;24:498504.
[144] Barragan BE, Giaccio GM, Zerbino RL. Fracture and failure
of thermallydamaged concrete under tensile loading. Mater Struct
2001;34:3129.
[145] Arioz O. Retained properties of concrete exposed to high
temperatures: sizeeffect. Fire Mater 2009;33:21122.
[146] Erdem TK. Specimen size effect on the residual properties
of engineeredcementitious composites subjected to high
temperatures. Cem Concr Compos2014;45:18.
Mechanical properties of concrete at high temperatureA review1
Introduction2 Mechanical properties of concrete at high
temperature2.1 Compressive strength2.2 Flexural strength, splitting
tensile strength and modulus of elasticity2.3 Stressstrain
relationship2.4 Physical and chemical changes2.4.1 Water
evaporation2.4.2 Hydration products2.4.3 Pore structure2.4.4
Microstructure2.4.5 Aggregates
2.5 Spalling
3 Factors influencing the performance of concrete subjected to
high temperature3.1 w/b and moisture content3.2 Type of
aggregate3.3 SCMs3.4 Fibres
4 Influence of test modalities on the mechanical properties of
concrete at high temperature4.1 Hot and residual tests4.2 Stressed
and unstressed tests4.3 Uni-axial and multi-axial tests4.4 Specimen
size
5 ConclusionReferences