temperatureeffectonthethermalconductivityofexpanded...

Research ArticleTemperature Effect on the Thermal Conductivity of ExpandedPolystyrene Foamed Concrete Experimental Investigation andModel Correction

Jinyan Shi12 Yuanchun Liu 1 Baoju Liu2 and Dan Han3

1School of Water Conservancy and Civil Engineering Northeast Agricultural University Harbin 150030 China2School of Civil Engineering Central South University Changsha 410075 China3School of Civil and Environmental Engineering Harbin Institute of Technology Shenzhen Graduate SchoolShenzhen 518055 China

Correspondence should be addressed to Yuanchun Liu yuanchun_liu126com

Received 22 March 2019 Revised 4 June 2019 Accepted 9 June 2019 Published 17 June 2019

Academic Editor Luigi Nicolais

Copyright copy 2019 Jinyan Shi et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

In this research ultralightweight expanded polystyrene foamed concrete (EFC) was made by the chemical foaming method andits thermal insulation property was measured by the transient method at different environment temperatures (from minus10 to 40degC)en the effect of temperature and EPS volume fraction on the thermal conductivity and dry density of EFC were observedUltimately the ChengndashVachon equation was modified by introducing the temperature parameter e results indicated that EFCthermal conductivity decreases with increasing temperature It was also demonstrated that the suitable volume of EPS particlescan not only decrease the EFC thermal conductivity but also reduce the impact of temperature on the thermal conductivity ethermal conductivity of EFC at different temperatures was accurately predicted in this study using the proposed model

1 Introduction

Foamed concrete (FC) is a type of cement-based lightweightporous material with a density between 400 kgm3 and1900 kgm3 that is widely used in the construction fieldespecially for reducing the dead load of structures and forheat preservation damping sound insulation and porefilling [1] Compared with organic insulating materials FChas higher strength better resistance to fire and durability[1ndash3] However in order to meet the higher requirements ofthermal insulation performance density of FC should befurther decreased to less than around 400 kgm3 In therelevant researches it has been found that the chemicalfoaming method is more suitable for ultralightweight FCthan mechanical foaming [4ndash9]

Expanded polystyrene (EPS) was firstly introduced aslightweight aggregate for concrete by Cook in 1973 [10] Dueto its excellent insulation and close cellular properties EPSparticles have significant effect on the thermal performanceof FC For instance Sayadi et al [11] added regenerated EPS

particles into FC and found that the thermal conductivity ofthe FC sample with an EPS volume fraction of 82 wasreduced by 45 and the density was reduced by 625 It canbe seen that EPS has broad application prospects and greatpotential value in FC [12ndash14]

ermal conductivity is an important parameter inrepresenting the ability of concrete to transfer heat Manyresearches have studied thermal conductivity of compositematerials and revealed the influence of various factors onthermal conductivity [15] Temperature as an externalcondition has an important effect on thermal conductivity ofconcrete [16ndash20] Rahim et al [21] tested the thermalconductivities of three bio-based concrete materials undervarious temperature conditions (10 to 40degC) in steady stateby using the guarded hot plate method ey found that thethermal conductivity of concrete materials becomes largerwith an increase in temperature Tandiroglu [22] studied thethermal conductivity of lightweight raw perlite aggregateconcrete and established relationship functions for thethermal conductivity the water-cement ratio perlite

HindawiAdvances in Materials Science and EngineeringVolume 2019 Article ID 8292379 9 pageshttpsdoiorg10115520198292379

amount by mass and temperature e proposed empiricalcorrelations of thermal conductivity can be applicable withinthe range of temperatures minus70 to 30degC Li et al [23] discussedcommon thermal conductivity models based on the ex-perimental data and proposed a prediction model for thethermal conductivity of FC but they failed to consider theinfluence of external environmental factors on the thermalconductivity of themodel such as temperature In summarythe thermal conductivities of various types of concrete aresignificantly different when the temperature changesPresently theoretical models of FC thermal conductivityignore the temperature effects

In this study ultralightweight expanded polystyrenefoamed concrete (EFC) with different EPS contents isprepared by the chemical foaming method and its thermalconductivity is measured at different environment tem-peratures (from minus10 to 40degC) Based on test results andexisting models of thermal conductivity a thermal con-ductivity model of EFC is derived by temperature correction

2 Experimental Programs

21 Raw Materials and Mixture Ratio e gelled materialused in this study was made from Chinese 425 ordinaryPortland cement and class I fly ash e relevant technicalindicators for these twomaterials are shown in Tables 1 and 2e addition of fly ash can optimize the pore structure ofFC and enhance its thermal insulation performance In ad-dition e EPS has particle sizes between 2 and 4mm withapparent density of 188 kgm3 and thermal conductivity of00313W(mmiddotK) e foaming agent used in this test was ahydrogen peroxide solution with a concentration of 30estabilizer was calcium stearate e early strength agent wassodium nitrite and the thickening agent was an acrylatecopolymer emulsion e water used was tap water ewater-binder ratio foaming agent content and fly ash dosagewere adjusted to determine the benchmark mixture ratiowhich is shown in Table 3 A total of 12 test blocks of chemicalfoaming EPS foamed concrete were prepared by changing thevolume fraction of EPS (0sim60)

22 Testing Instrument

221 ermal Conductivity Tester e ISOMET 2114thermal characterization analyzer produced in Slovakia wasused for the thermal conductivity test (Figure 1) e in-strument can be used to determine the thermal conductivityvolumetric heat flux and thermal diffusivity of cement-based composites [24] It is based on the transient testprinciple and the measuring temperature range is 15sim+50degCwith an accuracy of 1times 10minus4W(mmiddotK) e instrument canbe tested with a probe or a flat plate is test uses a surfaceprobe with a test range of 004sim03W(mmiddotK)

222 High-Low Temperature Test Box is test used thehigh-low temperature simulation test box developed byNortheast Agricultural University Its main performanceindicators are shown in Table 4

23 Preparation Technology and Experimental Method ofChemical Foaming EPS Foamed Concrete

231 Preparation Technology According to the EPS per-formance and the molding technology of chemical foamingfoamed concrete chemical foaming EPS foamed concretesamples were prepared according to the following process

(a) e EPS particles were wet for one minute with one-third of the total water

(b) e mixing cement fly ash other solid materialsremaining water and the thickening agent weremixed and stirred until the mixture was evenlyblendeden the wetted EPS particles were put intothe mixture and stirred for one minute e tem-perature of the slurry was maintained at 25degC

(c) Sodium nitrite solution was added e mixture wasstirred at a low speed for 30 seconds and then stirredat high speed for 10 seconds

(d) Hydrogen peroxide was poured into the mixtureand it was stirred for 10 seconds

(e) e mixture was quickly poured into the mold andleft to stand for 24 hours at 20degC en the speci-mens were removed from the mold when they hadcertain strength and standard curing was thenimplemented e concrete sample is shown inFigures 2(a) and 2(b)

232 Experimental Methods A dry density test of thespecimens was carried out according to the Chinese stan-dard GBT11969-2008 Measurements were taken after thespecimens were dried to a constant weight A constanttemperature environment was provided by the high-lowtemperature test box e thermal conductivities of thespecimens were tested after standing at a constant tem-perature for two hours When the temperature was constantthe thermal conductivity of the polished samples on bothsides was measured using a thermal characteristic analyzere thermal conductivities of some of the EFC samples at20degC are shown in Table 5 Due to the heterogeneity of FCthree molding face positions were tested and the average ofthe results was calculated

3 Results and Discussion

31 Relationship between the Dry Volume Density andermal Conductivity of EFC Samples at DifferentTemperatures ermal conductivity is a basic physicalparameter used to characterize the heat transfer perfor-mance of materials e heat conduction mechanism isdifferent for different substances According to the heattransfer theory [25 26] free electron mobility and latticevibration are the two main independent heat transfermechanisms of solid It is mainly the elastic wave (or latticewave) that produced from the lattice vibration at the place ofhigher temperature drives the adjacent lattice vibration totransfer heat in inorganic nonmetal solid materials Becauseconcrete is composed of primarily solid components the

2 Advances in Materials Science and Engineering

heat transfer mechanism of the skeleton is similar to that of asolid erefore the thermal conductivity of concrete pri-marily depends on the density of the materials Usually alow density corresponds to low thermal conductivity [27]

e variation law was obtained by fitting the test resultsof the dry volume density and thermal conductivity atdifferent temperatures as shown in Figure 3e dry volumedensity of chemical foaming EPS foamed concrete is posi-tively correlated with the thermal conductivity

e test data were fitted to obtain the relational ex-pression between the dry volume density and thermalconductivity of EFC when the temperature was 0degC erelational expression may be written as

λ 00028ρ05629

R2

08826(1)

e foam content and EPS content determine its dryvolume density in EFC and affect the thermal conductivityof EFC Under the same conditions the pore number inthe porous material determines its thermal conductivityWhen the pore number is the same the thermal con-ductivity increases with the increase of pore size How-ever connected pores will increase the thermalconductivity of concrete Additionally the EPS volumefraction is a key factor that changes the dry volume densityof FC Figure 4 presents the influence curve of the EPSvolume fraction on the dry volume density of FCAccording to Figure 4 the micropores did not change withthe addition of a small amount of EPS particles until 10of EPS particles were added At this point the ratio of largepores in the specimens showed an increasing trendresulting in a decrease in the dry volume density How-ever when the pore percentage with diameters reaching200sim400 μmwas too big the internal pore structure wouldbe unstable and some large pores may be destroyed iswould result in an increase in the dry volume density ofthe specimen and thus affect the thermal conductivity ofthe EFC [28]

32 Effect of Temperature on theermal Conductivity of EPSFoamed Concrete is experiment used five temperaturesnamely minus10degC 0degC 20degC 30degC and 40degC ese temper-atures were used to study the thermal insulation perfor-mance of EFC e thermal conductivities of FC mixedwith different contents of EPS particles were tested toobtain a variation law for the thermal conductivity of FCwith different EPS volume fractions with temperature asshown in Figure 5 As seen from Figure 5 the thermalconductivity of chemical foaming concrete is positivelycorrelated with the external temperature With a change intemperature the largest variation amplitude of the FCwithout EPS particles reached 52 which shows thesignificant effect of temperature on the thermal conduc-tivity of FC [29] is is because the thermal conductivityof FC is related to not only the intensity of particlemovement in the solid liquid and gas phases but also the

Table 1 Physical and mechanical properties of ordinary Portland cement

Cement type Specific surface area (m2kg)Setting time (min) Flexural

strength (MPa)Compressive

strength (MPa)Initial set Final set 3d 28d 3d 28d

PO 425 34500 150 210 50 80 165 462

Table 2 Technical parameters of the fly ash

Chemical composition ()Apparent density (kgm3) Bulk density (kgm3)

SiO2 Al2O3 Fe2O3 Cao MgO NaO2

58 30 43 15 28 32 2100 1086

Table 3 Experimental ratio

Specimens Cement (g) Fly ash (g) wb Foam volume ()A1 193 157 048 63wb water-binder ratio

Figure 1 ISOMET 2114 thermal characteristics analyzer

Table 4 Performance parameters of the high-low temperaturesimulation test boxEffective volume 5mtimes 4mtimes 25mTemperature range minus45sim+60degCTemperature fluctuation plusmn(005sim01)degCHeating power 1500WRefrigerating capacity 1500W

Advances in Materials Science and Engineering 3

interaction forces between the different phases of theparticles and their spatial distributions Due to the largeporosity of FC a high temperature would intensify

irregular movement and the collision of gas molecules inthe pores is would enhance the interactions betweendifferent phases of the particles thus enhancing thethermal conductivity

(a) (b)

Figure 2 EPS foamed concrete (EFC) specimens (a) After standing for 24 hours at 20degC and (b) after 28 days under standard curing

Table 5 Dry volume density porosity and thermal conductivity of the EFC

Dry volume density(kgm3)

Porosity()

Average thermal conductivity(W(mmiddotK))


Porosity()


304 7347 00838 291 7304 00704366 6806 00926 230 7993 00761357 6885 00890 315 7251 00921362 7007 01000 237 7932 00750336 7199 00810 267 7670 01037

012

010

008

006

004

002

000

er

mal

cond

uctiv

ity (W

(mmiddotK

))

220 240 260 280 300 320 340 360 380Dry volume density (kgm3)

T = 0degCT = ndash10degC

T = 40degCT = 20degC

Figure 3 e thermal conductivities of FC composed of differentdry densities at various temperatures

100

150

200

250

300

350

400

Dry

vol

ume d

ensit

y (k

gm

3 )

60100 5020 30 40Volume fraction of EPS beads ()

Figure 4 e dry volume densities of FC with various EPS volumefractions


Figure 5 shows compared with the thermal conductivitycurve of FC without EPS beads the other curves with EPSbeads are obviously smoother and with smaller slopes in thesame temperature gradient range When the EPS volumecontent was 55 the thermal conductivity was the least af-fected by temperature change is result demonstrates thatthe proper amount of EPS particles can not only reduce thethermal conductivity of EFC but also buffer changes in thethermal conductivity caused by temperature changes iseffect is a primary benefit from EPSrsquos structure and its im-provement of FC pore structure e empirical correlationsbetween the FC thermal conductivity and the temperatureunder different volume fractions of EPS are shown in Table 6

33 Effect of EPS Content on the ermal Conductivity ofFC at Different Temperatures e excessive content ofbubbles introduced into the cementitious matrix will causesome difficulty in concrete formation erefore it is difficultto reduce the density and thermal conductivity of ultralightFC by increasing the amount of the foaming agent In thisstudy a certain volume fraction of EPS particles was added tochemical foaming foamed concrete to modify the self-weightand thermal insulation performance of the concrete

EPS particles have good thermal performance e effectof the EPS volume fraction on the thermal conductivity ofFC at different temperatures is shown in Figure 6 eaddition of EPS particles greatly changed the thermalconductivity of the FC Compared with that of FC withoutEPS the maximum change amplitude of the thermal con-ductivity of the FC decreased by 46 after a certain volumefraction of EPS particles were added According to Figure 6the thermal conductivity of the EFC decreased at first andthen increased with an increase in EPS content is wasprimarily because EPS particles (98 air and 2 poly-styrene) have many closed pores inside them and these havea large thermal resistance With an increase in the EPScontent the thermal resistance of the EFC increased

correspondingly erefore its thermal conductivity de-creased Recent research demonstrates that when addingfoam to EPS concrete the foaming agent creates a microporegap structure among EPS granules [30] However when theEPS volume fraction is too large the distance between EPSparticles will decrease is causes the surrounding foam togather together and connect to form larger pores As a resultthe internal connected porosity increased and the thermalconductivity increased significantly which even affected thenormal foaming molding of the FC

As can be seen from Figures 4 and 6 the results show thata chemical foaming EPS ultralightweight foamed concretewith a dry density of less than 300 kgm3 and a normalthermal conductivity between 00704 and 00767W(mmiddotK)could be prepared when the volume fraction of EPS was25sim35 In addition compared with ordinary FC itdisplayed an effective thermal insulation property withchanges in temperature

4 TemperatureModifiedThermalConductivityModel for EFC

41 Basic ermal Conductivity Model for Foamed Concrete

411 Series and Parallel Models e main form of heattransfer inside concretematerials is thermal conductionHashinand Shtrikman have proposed effective thermal conductivity

004

005

006

007

008

009

010

011

er

mal

cond

uctic

ity (W

(mmiddotK

))

ndash10 3020 400 10Temperature (degC)

CF (VEPS = 0)CF (VEPS = 5)


Figure 5 ermal conductivity of different EPS volume fractionFC with temperature

Table 6 Empirical correlations of thermal conductivity andtemperature (T)

EPS volumefraction () λ a(T2) + bT+ c R2

0 λ0 minus0000008T2 + 00008T+ 0071 R2 09955 λ5 minus000001T2 + 0001T+ 00749 R2 099520 λ20 minus0000001T2 + 00009T+ 00659 R2 099855 λ55 minus0000009T2 + 00007T+ 00625 R2 0987

000

T = 20degCT = 0degCT = ndash10degC

002

004

006

008

010

012

er

mal

cond

uctic

ity (W

(mmiddotK

))

20 30 40 500 10EPS volume fraction ()

Figure 6 ermal conductivity of different temperature FC withvarious EPS volume fractions


models of the two-phase system [31] e series and parallelmodels are based on the upper and lower limits of thermalconductivity of the materials respectively In these modelsfoam and EPS particles are used as the dispersed phase and thecement fly ash and slurry are used as the continuous phase tocalculate the thermal conductivity of concrete e expressionscan generally be written as shown in the following equations

Series models

λ 1

(1minus ])λ1 + ]λ2 (2)

Parallel models

λ (1minus ])λ1 + ] (3)

412 MaxwellminusEucken Model eMaxwellminusEucken modelassumes that the foam consists of homogeneous spheres thatare irregularly dispersed and without interaction forcesMore succinctly the model asserts that heat transfer cannotbe carried out between dispersed phases On this basis theminimum boundaries of the thermal conductivities of iso-tropic and macroscopic homogeneous two-phase materialswere able to be successfully deduced [32]

When foam is mixed into concrete its shape and dis-tribution will be changed due to squeeze from the slurry butthe model only considers an index of porosity Its expressionis as follows [32]

λ 2λ1 + λ2 + 2] λ2 minus λ1( 1113857

2λ1 + λ2 minus ] λ2 minus λ1( 1113857λ1 (4)

413 Modified Volume Model for Foamed Concrete Liconsidered the volume content of foam and proposed amodified model that could be applied to the calculation ofFC thermal conductivity by combining FC test data based onthe ChengminusVachon thermal conductivity model [23] emodel assumes that there are no pores in the concrete slurryand the thermal convection radiation and contact re-sistance are not considered It primarily corrects the volumecontent of the dispersed phase and considers the influence ofcomplex factors such as the heat transfer path and tortuosityduring the heat transfer process is model can accuratelypredict the thermal conductivity of FC

e following are the equations for the thermal con-ductivity volume correction model of FC [23]

e difference in the thermal conductivity between thefoam and the cement-fly ashmortar is represented by using asimple equation

M kc

kd (5)

e modified volume content of the foam can beexpressed as follows

φprime φ1tM1t minusφ1t

M1t minus 1 (6)

From equations (5) and (6) the effective thermal re-sistance of FC is represented as follows

Re

φprime1113969

kc + kd minus kc( 1113857

φprime1113969 +

1minus

φprime1113969

kc (7)

en the thermal conductivity equation for FC is

keprime 1Re

(8)

It should be noted that t is the foam volume contentcorrection coefficient obtained by fitting the test data

42 Model Evaluation and Parameter Determination evolume correction model proposed by Li was used to verifyand study the experimental results of FC in the study Be-cause 98 of the EPS particles were air and the difference inthe thermal conductivity between them was small the po-rosity and EPS were simplified to be the dispersed phase andthe cement-fly ash mortar was the continuous phaseComparisons between the predicted value and the experi-mental value of the series and parallel models theMaxwellndashEucken model and the volume correction modelare shown in Figure 7

According to Figure 7 the thermal conductivity datapredicted by the parallel and series models were in the upperand lower limits respectively and they were significantlydifferent from the experimental results e thermal con-ductivity predicted by the MaxwellndashEucken model wasmuch larger than that of the experimental data is wasbecause the MaxwellndashEucken model assumed that the sto-mata in the test blocks were homogeneous and independentspheres In reality these pore shapes vary greatly and someof them are connected pores leading to a large deviationbetween the predicted value and the experimental value

A least squares fitting of the modified volume modelproposed by Li was performed by using partial test dataWhen t 215 the best fitting effect was obtained and thepredicted result was closest to the test value erefore themodified volume model proposed by Li was used to predictand evaluate the thermal conductivity of EFC in this study

e model evaluated the effect of temperature on thethermal conductivities of different phases based on themodified volume model proposed by Li and corrected thevolume correction coefficient using the temperature function

In the present study we propose a new correlation forthe dispersed phase

kPrimed minus0000002T2

+ 00078T + 24363 (9)

e difference between two phases in the thermalconductivity with correction was given by

Mx kc

kPrimed (10)

e influence of temperature was introduced into thethermal conductivity to correct the volume content cor-rection coefficient of foam


tprime 00003T2 minus 00229T + 24783 (11)

e porosities at different temperatures were thencorrected can be written as shown in the followingequations

n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)

e volume correction coefficient of the foam after twotimes of correction can be written as follows

tx ηtprime (14)

e correction equation of the volume content of thefoam at different temperatures was as follows

φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)

By combining equations (9) and (15) the modifiedthermal resistance of FC was obtained

RPrimee

φx

radic

kc + kPrimed minus kc1113872 1113873φx

radic +1minus φx

radic

kc (16)

en the modified thermal conductivity equation of FCcan be expressed by the simplified form

kPrimee 1RPrimee

(17)

e experimental data of EFC thermal conductivities atdifferent temperatures were input into the corrected EFCthermal conductivity model to obtain Figure 8 In the figurethe predicted values of the temperature-modified model atdifferent temperatures are compared with the experimentalvalues Results show that the predicted values coincided with

the experimental values at different temperatures indicatinga good prediction effect of the model Compared with otherprediction models the model in this study not only rep-resented the influence of temperature parameters but alsocalculated the EFC thermal conductivities at differenttemperatures

5 Conclusions

(1) Temperature had a significant effect on the thermalconductivity of EFC e thermal conductivity ofEFC increased with an increase in temperature Witha change in temperature the amplitude changes inthe thermal conductivity of the same EFC reached28minus52

(2) With an increase in the EPS content the influence oftemperature on the thermal conductivity of FC wasreduced which indicated that an appropriateamount of EPS particles could not only reduce itsthermal conductivity but also buffer the change ofthermal conductivity caused by temperaturechanges

(3) EPS particles had good thermal performance Withan increase in the EPS volume fraction the thermalconductivity of EFC decreased However when theEPS volume fraction was too large the thermalconductivity increased obviouslye results showedthat the chemical foaming EPS ultralight foamedconcrete with a dry density of less than 300 kgm3

and a normal thermal conductivity between 00704and 00767W(mmiddotK) could be prepared when the

066 072 074 080076 078 082068 070Porosity ()

00

Equation (2)Experimental

Equation (3)

Equation (4)Equation (8) with t = 215

01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))

Figure 7 Comparison between the theoretical and experimentalresults

Predicted values(T = ndash10degC)Predicted values(T = 0degC)Predicted values(T = 20degC)Predicted values(T = 40degC)

Experimental(T = ndash10degC)Experimental(T = 0degC)Experimental(T = 20degC)Experimental(T = 40degC)

066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))

Figure 8 Comparison between the theoretical and experimentalresults at different temperatures


volume fraction of EPS was 25sim35 with thechange of temperature In addition compared withordinary FC it had good temperature stability

(4) An EFC thermal conductivity prediction model thatconsidered the influence of temperature was estab-lished based on a modified thermal conductivitymodel of the dispersed phase volume Also thepredicted results were verified using experimentaldata to prove its accuracy It is important to note thatthe model is only applicable for the prediction ofEFC thermal conductivity under the condition of anoutdoor ambient temperature and the de-termination of the temperature correction coefficientwas not unique

List of Symbols

kc ermal conductivity of cement-fly ash slurry(W(mmiddotK))

kd Air thermal conductivity (W(mmiddotK))kPrimed Modified thermal conductivity of dispersed phase

(W(mmiddotK))keprime ermal conductivity of foamed concrete (W(mmiddotK))kPrimee Modified thermal conductivity of foamed concrete

(W(mmiddotK))M Magnification coefficient between two phasesRx Temperature correction magnification coefficient

between two phasesn Proportional coefficientRe Modified thermal resistance ((mmiddotK)W)RPrimee Temperature correction thermal resistance ((mmiddotK)W)T Test temperature (degC)tprime Volume correction coefficient predictiontx Temperature correction coefficient of foam volume

contentv Porosity ()η Temperature correction constantλ Effective thermal conductivity (W(mmiddotK))ρ Dry volume density (kgm3)λ1 ermal conductivity of continuous phase (W(mmiddotK))λ2 ermal conductivity of dispersed phase (W(mmiddotK))φ Volume fraction of dispersed phase ()φprime Modified volume fraction of dispersed phase ()φx Temperature correction volume content of dispersed

phase ()

Data Availability

e data used to support the findings of this study are in-cluded within the article

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

e authors gratefully acknowledge the financial supportfrom the National Natural Science Fund of China

(51541901) e Science and Technology Key Project ofHeilongjiang Province (GZ16B010) and the HeilongjiangPostdoctoral Financial Assistance (LBH-Z13045)

References

[1] Y H M Amran N Farzadnia and A A Abang AlildquoProperties and applications of foamed concrete a reviewrdquoConstruction and Building Materials vol 101 no 1pp 990ndash1005 2015

[2] K Ramamurthy E K Kunhanandan Nambiar and G InduSiva Ranjani ldquoA classification of studies on properties of foamconcreterdquo Cement and Concrete Composites vol 31 no 6pp 388ndash396 2009

[3] M R Jones and A McCarthy ldquoPreliminary views on thepotential of foamed concrete as a structural materialrdquoMagazine of Concrete Research vol 57 no 1 pp 21ndash31 2005

[4] E Kilincarslan and Z R Kaya ldquoUsage of chromite wastes asaggregate in foam concrete productionrdquo Arabian Journal ofGeosciences vol 11 no 18 p 555 2018

[5] S Kilincarslan M Davraz andM Akccedila ldquoe effect of pumiceas aggregate on the mechanical and thermal properties offoam concreterdquoArabian Journal of Geosciences vol 11 no 11p 289 2018

[6] E Papa V Medri D Kpogbemabou et al ldquoPorosity andinsulating properties of silica-fume based foamsrdquo Energy andBuildings vol 131 pp 223ndash232 2016

[7] J Feng R Zhang L Gong Y Li W Cao and X ChengldquoDevelopment of porous fly ash-based geopolymer with lowthermal conductivityrdquo Materials amp Design (1980ndash2015)vol 65 pp 529ndash533 2015

[8] E K K Nambiar and K Ramamurthy ldquoAir-void charac-terisation of foam concreterdquo Cement and Concrete Researchvol 37 no 2 pp 221ndash230 2007

[9] A Hajimohammadi T Ngo and P Mendis ldquoEnhancing thestrength of pre-made foams for foam concrete applicationsrdquoCement and Concrete Composites vol 87 pp 164ndash171 2018

[10] D J Cook ldquoExpanded polystyrene beads as lightweight ag-gregate for concreterdquo Precast Concrete vol 4 no 4pp 691ndash693 1973

[11] A A Sayadi J V Tapia T R Neitzert and G C CliftonldquoEffects of expanded polystyrene (EPS) particles on fire re-sistance thermal conductivity and compressive strength offoamed concreterdquo Construction and Building Materialsvol 112 no 1 pp 716ndash724 2016

[12] DM KW Dissanayake C Jayasinghe andM T R JayasingheldquoA comparative embodied energy analysis of a house withrecycled expanded polystyrene (EPS) based foam concrete wallpanelsrdquo Energy and Buildings vol 135 pp 85ndash94 2017

[13] N H R Sulong S A S Mustapa and M K A RashidldquoApplication of expanded polystyrene (EPS) in buildings andconstructions a reviewrdquo Journal of Applied Polymer Sciencevol 136 no 20 article 47529 2019

[14] I M Nikbin and M Golshekan ldquoe effect of expandedpolystyrene synthetic particles on the fracture parametersbrittleness andmechanical properties of concreterdquoeoreticaland Applied Fracture Mechanics vol 94 pp 160ndash172 2018

[15] Y Xu L H Jing J P Liu Y Zhang J X Xu and G Q HeldquoExperimental study and modeling on effective thermalconductivity of EPS lightweight concreterdquo Journal of ermalScience and Technology vol 11 no 2 article JTST0023 2016

[16] G Weidenfeld G Aharon and I Hochbaum ldquoe effect ofhigh temperatures on the effective thermal conductivity ofconcreterdquo Power vol 1 no 2 pp 3-4 2002


[17] W N Dos Santos ldquoEffect of moisture and porosity on thethermal properties of a conventional refractory concreterdquoJournal of the European Ceramic Society vol 23 no 5pp 745ndash755 2003

[18] K Y Shin S B Kim J H Kim M Chung and P S Jungldquoermo-physical properties and transient heat transfer ofconcrete at elevated temperaturesrdquo Nuclear Engineering andDesign vol 212 no 1ndash3 pp 233ndash241 2002

[19] W Khaliq and V Kodur ldquoermal andmechanical propertiesof fiber reinforced high performance self-consolidatingconcrete at elevated temperaturesrdquo Cement and ConcreteResearch vol 41 no 11 pp 1112ndash1122 2011

[20] W Wang C Lu Y Li and Q Li ldquoAn investigation onthermal conductivity of fly ash concrete after elevated tem-perature exposurerdquo Construction and Building Materialsvol 148 pp 148ndash154 2017

[21] M Rahim O Douzane A D Tran Le and T Langlet ldquoEffectof moisture and temperature on thermal properties of threebio-based materialsrdquo Construction and Building Materialsvol 111 pp 119ndash127 2016

[22] A Tandiroglu ldquoTemperature-dependent thermal conductivityof high strength lightweight raw perlite aggregate concreterdquoInternational Journal of ermophysics vol 31 no 6pp 1195ndash1211 2010

[23] X Y Li X L Zhao X Y Guo Z M Shao andM X Ai ldquoNewtheoretical equation for effective thermal conductivity of two-phase composite materialsrdquoMaterials Science and Technologyvol 28 no 5 pp 620ndash626 2012

[24] P Posi C Ridtirud C Ekvong D ChammaneeK Janthowong and P Chindaprasirt ldquoProperties of light-weight high calcium fly ash geopolymer concretes containingrecycled packaging foamrdquo Construction and Building Mate-rials vol 94 pp 408ndash413 2015

[25] D C Jia and G M Song Properties of Inorganic NonmetallicMaterials (in Chinese) Science Publishing House BeijingChina 2008

[26] Y S Touloukian R W Powell C Y Ho and P G Klemensldquoermophysical properties of mattermdashthe TPRC data series(V1)rdquo inermal Conductivity Metallic Elements and AlloysIFIPlenum New York USA 1970

[27] U J Alengaram B A Al Muhit M Z bin Ju-maat andM L Y Jing ldquoA comparison of the thermal conductivity of oilpalm shell foamed concrete with conventional materialsrdquoMaterials amp Design vol 51 pp 522ndash529 2013

[28] X Zhang M Hu and D P Chen ldquoEffect of water content andtemperature on thermal conductivity of steel slag foamedconcreterdquo Journal of Anhui University of Technology (NaturalScience) vol 35 no 2 pp 104ndash109 2018 in Chinese

[29] I Asadi P Shafigh Z F B Abu Hassan andN B Mahyuddin ldquoermal conductivity of concretemdasha re-viewrdquo Journal of Building Engineering vol 20 pp 81ndash93 2018

[30] B Chen and N Liu ldquoA novel lightweight concrete-fabricationand its thermal and mechanical propertiesrdquo Construction andBuilding Materials vol 44 pp 691ndash698 2013

[31] Z Hashin and S Shtrikman ldquoA variational approach to thetheory of the effective magnetic permeability of multiphasematerialsrdquo Journal of Applied Physics vol 33 no 10pp 3125ndash3131 1962

[32] J Wang J K Carson M F North and D J Cleland ldquoA newapproach to modelling the effective thermal conductivity ofheterogeneous materialsrdquo International Journal of Heat andMass Transfer vol 49 no 17-18 pp 3075ndash3083 2006


CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018


Journal of

Chemistry

Analytical ChemistryInternational Journal of


ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of



Advances in Condensed Matter Physics


International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of


High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in



ChemistryAdvances in


Advances inPhysical Chemistry


BioMed Research InternationalMaterials

Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

amount by mass and temperature e proposed empiricalcorrelations of thermal conductivity can be applicable withinthe range of temperatures minus70 to 30degC Li et al [23] discussedcommon thermal conductivity models based on the ex-perimental data and proposed a prediction model for thethermal conductivity of FC but they failed to consider theinfluence of external environmental factors on the thermalconductivity of themodel such as temperature In summarythe thermal conductivities of various types of concrete aresignificantly different when the temperature changesPresently theoretical models of FC thermal conductivityignore the temperature effects

In this study ultralightweight expanded polystyrenefoamed concrete (EFC) with different EPS contents isprepared by the chemical foaming method and its thermalconductivity is measured at different environment tem-peratures (from minus10 to 40degC) Based on test results andexisting models of thermal conductivity a thermal con-ductivity model of EFC is derived by temperature correction

2 Experimental Programs

21 Raw Materials and Mixture Ratio e gelled materialused in this study was made from Chinese 425 ordinaryPortland cement and class I fly ash e relevant technicalindicators for these twomaterials are shown in Tables 1 and 2e addition of fly ash can optimize the pore structure ofFC and enhance its thermal insulation performance In ad-dition e EPS has particle sizes between 2 and 4mm withapparent density of 188 kgm3 and thermal conductivity of00313W(mmiddotK) e foaming agent used in this test was ahydrogen peroxide solution with a concentration of 30estabilizer was calcium stearate e early strength agent wassodium nitrite and the thickening agent was an acrylatecopolymer emulsion e water used was tap water ewater-binder ratio foaming agent content and fly ash dosagewere adjusted to determine the benchmark mixture ratiowhich is shown in Table 3 A total of 12 test blocks of chemicalfoaming EPS foamed concrete were prepared by changing thevolume fraction of EPS (0sim60)

22 Testing Instrument

221 ermal Conductivity Tester e ISOMET 2114thermal characterization analyzer produced in Slovakia wasused for the thermal conductivity test (Figure 1) e in-strument can be used to determine the thermal conductivityvolumetric heat flux and thermal diffusivity of cement-based composites [24] It is based on the transient testprinciple and the measuring temperature range is 15sim+50degCwith an accuracy of 1times 10minus4W(mmiddotK) e instrument canbe tested with a probe or a flat plate is test uses a surfaceprobe with a test range of 004sim03W(mmiddotK)

222 High-Low Temperature Test Box is test used thehigh-low temperature simulation test box developed byNortheast Agricultural University Its main performanceindicators are shown in Table 4

23 Preparation Technology and Experimental Method ofChemical Foaming EPS Foamed Concrete

231 Preparation Technology According to the EPS per-formance and the molding technology of chemical foamingfoamed concrete chemical foaming EPS foamed concretesamples were prepared according to the following process

(a) e EPS particles were wet for one minute with one-third of the total water

(b) e mixing cement fly ash other solid materialsremaining water and the thickening agent weremixed and stirred until the mixture was evenlyblendeden the wetted EPS particles were put intothe mixture and stirred for one minute e tem-perature of the slurry was maintained at 25degC

(c) Sodium nitrite solution was added e mixture wasstirred at a low speed for 30 seconds and then stirredat high speed for 10 seconds

(d) Hydrogen peroxide was poured into the mixtureand it was stirred for 10 seconds

(e) e mixture was quickly poured into the mold andleft to stand for 24 hours at 20degC en the speci-mens were removed from the mold when they hadcertain strength and standard curing was thenimplemented e concrete sample is shown inFigures 2(a) and 2(b)

232 Experimental Methods A dry density test of thespecimens was carried out according to the Chinese stan-dard GBT11969-2008 Measurements were taken after thespecimens were dried to a constant weight A constanttemperature environment was provided by the high-lowtemperature test box e thermal conductivities of thespecimens were tested after standing at a constant tem-perature for two hours When the temperature was constantthe thermal conductivity of the polished samples on bothsides was measured using a thermal characteristic analyzere thermal conductivities of some of the EFC samples at20degC are shown in Table 5 Due to the heterogeneity of FCthree molding face positions were tested and the average ofthe results was calculated

3 Results and Discussion

31 Relationship between the Dry Volume Density andermal Conductivity of EFC Samples at DifferentTemperatures ermal conductivity is a basic physicalparameter used to characterize the heat transfer perfor-mance of materials e heat conduction mechanism isdifferent for different substances According to the heattransfer theory [25 26] free electron mobility and latticevibration are the two main independent heat transfermechanisms of solid It is mainly the elastic wave (or latticewave) that produced from the lattice vibration at the place ofhigher temperature drives the adjacent lattice vibration totransfer heat in inorganic nonmetal solid materials Becauseconcrete is composed of primarily solid components the





λ 00028ρ05629

R2

08826(1)







PO 425 34500 150 210 50 80 165 462




58 30 43 15 28 32 2100 1086








(a) (b)




Porosity()



Porosity()


304 7347 00838 291 7304 00704366 6806 00926 230 7993 00761357 6885 00890 315 7251 00921362 7007 01000 237 7932 00750336 7199 00810 267 7670 01037

012

010

008

006

004

002

000

er

mal

cond

uctiv

ity (W

(mmiddotK

))





100

150

200

250

300

350

400

Dry

vol

ume d

ensit

y (k

gm

3 )












004

005

006

007

008

009

010

011

er

mal

cond

uctic

ity (W

(mmiddotK

))








000


002

004

006

008

010

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





Series models

λ 1

(1minus ])λ1 + ]λ2 (2)

Parallel models

λ (1minus ])λ1 + ] (3)



λ 2λ1 + λ2 + 2] λ2 minus λ1( 1113857





M kc

kd (5)



M1t minus 1 (6)


Re

φprime1113969


φprime1113969 +

1minus

φprime1113969

kc (7)


keprime 1Re

(8)








+ 00078T + 24363 (9)


Mx kc

kPrimed (10)



tprime 00003T2 minus 00229T + 24783 (11)


n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)


tx ηtprime (14)


φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)


RPrimee

φx

radic


radic +1minus φx

radic

kc (16)


kPrimee 1RPrimee

(17)



5 Conclusions





066 072 074 080076 078 082068 070Porosity ()

00


Equation (3)


01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))




066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls







λ 00028ρ05629

R2

08826(1)







PO 425 34500 150 210 50 80 165 462




58 30 43 15 28 32 2100 1086








(a) (b)




Porosity()



Porosity()


304 7347 00838 291 7304 00704366 6806 00926 230 7993 00761357 6885 00890 315 7251 00921362 7007 01000 237 7932 00750336 7199 00810 267 7670 01037

012

010

008

006

004

002

000

er

mal

cond

uctiv

ity (W

(mmiddotK

))





100

150

200

250

300

350

400

Dry

vol

ume d

ensit

y (k

gm

3 )












004

005

006

007

008

009

010

011

er

mal

cond

uctic

ity (W

(mmiddotK

))








000


002

004

006

008

010

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





Series models

λ 1

(1minus ])λ1 + ]λ2 (2)

Parallel models

λ (1minus ])λ1 + ] (3)



λ 2λ1 + λ2 + 2] λ2 minus λ1( 1113857





M kc

kd (5)



M1t minus 1 (6)


Re

φprime1113969


φprime1113969 +

1minus

φprime1113969

kc (7)


keprime 1Re

(8)








+ 00078T + 24363 (9)


Mx kc

kPrimed (10)



tprime 00003T2 minus 00229T + 24783 (11)


n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)


tx ηtprime (14)


φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)


RPrimee

φx

radic


radic +1minus φx

radic

kc (16)


kPrimee 1RPrimee

(17)



5 Conclusions





066 072 074 080076 078 082068 070Porosity ()

00


Equation (3)


01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))




066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






(a) (b)




Porosity()



Porosity()


304 7347 00838 291 7304 00704366 6806 00926 230 7993 00761357 6885 00890 315 7251 00921362 7007 01000 237 7932 00750336 7199 00810 267 7670 01037

012

010

008

006

004

002

000

er

mal

cond

uctiv

ity (W

(mmiddotK

))





100

150

200

250

300

350

400

Dry

vol

ume d

ensit

y (k

gm

3 )












004

005

006

007

008

009

010

011

er

mal

cond

uctic

ity (W

(mmiddotK

))








000


002

004

006

008

010

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





Series models

λ 1

(1minus ])λ1 + ]λ2 (2)

Parallel models

λ (1minus ])λ1 + ] (3)



λ 2λ1 + λ2 + 2] λ2 minus λ1( 1113857





M kc

kd (5)



M1t minus 1 (6)


Re

φprime1113969


φprime1113969 +

1minus

φprime1113969

kc (7)


keprime 1Re

(8)








+ 00078T + 24363 (9)


Mx kc

kPrimed (10)



tprime 00003T2 minus 00229T + 24783 (11)


n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)


tx ηtprime (14)


φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)


RPrimee

φx

radic


radic +1minus φx

radic

kc (16)


kPrimee 1RPrimee

(17)



5 Conclusions





066 072 074 080076 078 082068 070Porosity ()

00


Equation (3)


01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))




066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls












004

005

006

007

008

009

010

011

er

mal

cond

uctic

ity (W

(mmiddotK

))








000


002

004

006

008

010

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





Series models

λ 1

(1minus ])λ1 + ]λ2 (2)

Parallel models

λ (1minus ])λ1 + ] (3)



λ 2λ1 + λ2 + 2] λ2 minus λ1( 1113857





M kc

kd (5)



M1t minus 1 (6)


Re

φprime1113969


φprime1113969 +

1minus

φprime1113969

kc (7)


keprime 1Re

(8)








+ 00078T + 24363 (9)


Mx kc

kPrimed (10)



tprime 00003T2 minus 00229T + 24783 (11)


n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)


tx ηtprime (14)


φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)


RPrimee

φx

radic


radic +1minus φx

radic

kc (16)


kPrimee 1RPrimee

(17)



5 Conclusions





066 072 074 080076 078 082068 070Porosity ()

00


Equation (3)


01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))




066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





Series models

λ 1

(1minus ])λ1 + ]λ2 (2)

Parallel models

λ (1minus ])λ1 + ] (3)



λ 2λ1 + λ2 + 2] λ2 minus λ1( 1113857





M kc

kd (5)



M1t minus 1 (6)


Re

φprime1113969


φprime1113969 +

1minus

φprime1113969

kc (7)


keprime 1Re

(8)








+ 00078T + 24363 (9)


Mx kc

kPrimed (10)



tprime 00003T2 minus 00229T + 24783 (11)


n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)


tx ηtprime (14)


φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)


RPrimee

φx

radic


radic +1minus φx

radic

kc (16)


kPrimee 1RPrimee

(17)



5 Conclusions





066 072 074 080076 078 082068 070Porosity ()

00


Equation (3)


01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))




066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




tprime 00003T2 minus 00229T + 24783 (11)


n φ

07347 (12)

η minus1024n2

+ 19519nminus 82249 (13)


tx ηtprime (14)


φx φ1txM1tx

x minusφ1tx

M1txx minus 1

(15)


RPrimee

φx

radic


radic +1minus φx

radic

kc (16)


kPrimee 1RPrimee

(17)



5 Conclusions





066 072 074 080076 078 082068 070Porosity ()

00


Equation (3)


01

02

03

04

Ther

mal

cond

uctic

ity (W

(mmiddotK

))




066 072 074 078076 080068 070Porosity ()

003

004

005

006

007

008

009

010

011

012

er

mal

cond

uctic

ity (W

(mmiddotK

))





List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






List of Symbols







phase ()

Data Availability




Acknowledgments



References





































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls























Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




temperatureeffectonthethermalconductivityofexpanded...

Documents