Available online at ScienceDirect. Energy Procedia 96 (2016 )

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1 Aville online t ScienceDirect Energy Procedi 96 (216 ) SBE16 Tllinn nd Helsinki Conference; Build Green nd Renovte Deep, 5-7 Octoer 216, Tllinn nd Helsinki Performnce of Constructions with Cly Plster nd Timer t Elevted Tempertures Johnn Lilik, *, Alr Just Tllinn University of Technology, Ehitjte tee 5, Tllinn 1986 Astrct The comustiility of timer is one of the min resons tht too mny uilding regultions nd stndrds restrict its use. Lck of understnding of the fire technicl properties of cly plster is wht most likely prevents this trditionl mteril in comintion with timer from eing widely used. The purpose of the following reserch is to designte the fire technicl properties for cly plster for the fire design of timer structures. For this study the fire testing of cly plster ws crried out in smll nd model scle to determine the min chrcteristics. In this pper the recommendtions for the improvement of the design method for timer structures with cly plster ccording to the sfety philosophy of Eurocode 5 Prt 1-2 re pulished. 216 The Authors. Pulished y Elsevier Ltd. This is n open ccess rticle under the CC BY-NC-ND license 216 The Authors. Pulished y Elsevier Ltd. ( Peer-review under responsiility of the orgnizing committee of the SBE16 Tllinn nd Helsinki Conference. Peer-review under responsiility of the orgnizing committee of the SBE16 Tllinn nd Helsinki Conference. Keywords: timer constructions ; fire design ; cly plster ; EN ; cross-lminted timer 1. Introduction There is n incresing chllenge to reduce the energy nd environmentl impcts from the construction sectors. It hs een recognized tht trditionl nd ecologicl uilding mterils could e perfect for utilizing sustinle design principles. Timer s one of the most verstile renewle resources nd lrge-scle construction mterils is cknowledged to hve gret potentil to improve the development of energy efficient uildings. Innovtive new * Corresponding uthor. Tel.: E-mil ddress: johnn.lilik@gmil.com The Authors. Pulished y Elsevier Ltd. This is n open ccess rticle under the CC BY-NC-ND license ( Peer-review under responsiility of the orgnizing committee of the SBE16 Tllinn nd Helsinki Conference. doi:1.116/j.egypro

2 718 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) uilding technologies nd development in product design enle wide rnge of different solutions in timer constructions tht minimize the future environmentl impct. In ddition, the demnd for more sustinle nd helthier indoor environment is incresing. Therefore, there hs een growing interest in nontoxic, reusle nd recyclle mterils together with low emodied energy. At the sme time in order to reduce the opertionl energy use in uilt environment, the pssive role of uilding mterils hs ecome n importnt fctor to investigte. It hs een scientificlly explined tht exposed surfces of cly plster ct s pssive regultor of internl humidity level due to its excellent hygroscopic nd vpour permele properties [1]. Historiclly, cly plster hs een used in vrious construction techniques with timer. Cly hs een neglected y modern mterils in the lst decdes ut it hs een once gin recognized nd there is growing interest towrds wider use of cly products. However, nowdys the restrictions of the fire design of timer structures re one of the min resons for limiting the use of trditionl mterils. Fire sfety hs een one of the erliest issues ddressed y uilding regultions nd is currently n essentil prmeter to e investigted in uilding design. In generl, one of the min ostcles for the wider use of timer is the comustiility of timer. The stndrd for structurl fire design of timer structures, EN [2], provides some informtion for protection mterils ut it hs no informtion concerning plsters. This is most proly ecuse of the miniml mount of knowledge out the fire technicl properties of cly plster in conjunction with timer structures. The fire resistnce of timer is generlly determined y full-scle furnce testing. However, full-scle testing is highly complex nd expensive tool for the verifiction of the fire resistnce of different timer comintions. In this presented study, smll scle testing ppered to e the most resonle testing method to exmine the sic properties of cly plster s fire protection mteril since there re lrge numer of possile comintions of timer nd different mixtures of cly plster ville. In this pper short introduction out the min conception of the fire design of timer structures nd cly plster s protection mteril is presented. For this study the fire testing of cly plster ws crried out in smll nd model scle to determine the min chrcteristics of cly plster which influence the fire technicl properties of cly plster the most. A short overview of the initil study on protective effect of cly plster in smll scle investigted y Lilik in her mster thesis [3] is introduced. The results of this pper provide future development in wider use of nturl uilding mterils. Nomenclture time (min) strt time of chrring (min) chrring depth for one-dimensionl chrring (mm) thickness of timer memer (mm) plster thickness (mm) one-dimensionl chrring rte (mm/min) reduced one-dimensionl chrring rte (mm/min) protection phse fctor temperture ( C) 2. Design of timer structures 2.1. Design principles The fire design of timer structures is specified in EN [2]. It descries the principles, requirements nd rules for the structurl design of timer structures exposed to fire. One of the min ojectives of structurl fire sfety is to gurntee the lod-ering cpcity of the structure for required period of time. The required time is specified y the uilding regultions. The resistnce to fire concerns structurl elements which must withstnd fully developed fire while fulfilling certin requirements. The fully developed fire is descried y the stndrd temperture-time curve given in ISO 834 [4]. Chrring is generlly the

3 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) dominting effect influencing the mechnicl resistnce of timer structures since cross-section of timer memer is reduced y fire. According to EN [2] chrring of wood shll e tken into ccount for ll surfces of timer directly exposed to fire nd for surfces initilly protected from fire exposure, ut where chrring of timer occurs during relevnt time of fire exposure. Importnt design prmeters for different protection mterils stted in EN [2] re the strt time of chrring, chrring rte t the protected chrring phse nd post-protection chrring phse s well s the filure time of protection. The verifiction of fire resistnce of timer elements cn either e sed on the lrge-scle fire tests, or on clcultions ccording to EN [2], performed in conjunction with the respective ntionl ppliction documents Behviour of timer in fire When sufficient het is pplied to wood, chemicl degrdtion tkes plce with the resultnt formtion of chrcol nd comustile gses, ccompnied y loss in mss. EN [2] specifies tht the temperture vlue of 3 C is greed to e tken s the strt time of chrring. For timer surfces unprotected throughout the time of fire exposure, the residul cross-section cn e clculted y constnt sic chrring rte, see Fig.1 (). The chrring rtes re specified in EN [2]. The chrring depth is the distnce etween the outer surfce of the originl memer nd the position of the chr-line, see Fig.1 (). It should e clculted from the time of fire exposure nd the relevnt chrring rte. According to EN [2] the chrring rte for one-dimensionl chrring of timer should e tken s constnt with time, see the eqution elow (1) While timer surfce is initilly protected from fire exposure the strt time of chrring is delyed nd the chrring is slowed down in comprison to unprotected timer surfces, see Fig.1 (). When the chrring of timer hs strted ut the protection lyer is still in plce, there re expressions given in EN [2] to clculte the reduced chrring rte. The reduced chrring rte is clculted y protection phse fctor which is multiplied to the chrring rtes of the unprotected timer memers (2). It is importnt to note tht the reduced chrring rte is only pplicle when the protection mteril is ttched on timer. (2) According to EN [2] chrring rte is tken s sic vlue oserved for one-dimensionl het trnsfer under ISO-fire exposure in semi-infinite sl. Since lrge timer surfces re usully exposed to fire on one side, the one-dimensionl chrring is tken s the sis of this study [5]. Fig. 1. () Chrring of protected nd unprotected timer; () Chrring depth for one-dimensionl chrring.

4 72 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Cly plster Components of dry nturl cly plster re fixed proportion of snd nd silt, cly nd some form of fires. Snd nd silt provide the structure, ulk nd strength to the plster. Cly cts s inding gent for developing the inding nd dhesive forces etween snd nd fires. Nturl fiers re dded in order to resist the tensile stresses within the surfce of plster. There re vrious fiers which cn e used s strw, cttil, flx, swdust etc. [6]. Cly plster hs excellent vpour permeility nd hygroscopic qulities. Of prticulr note, cly plster could sor lrge mount of moisture from the ir nd releses it while the humidity level is low in the room. This is lso due to the exposed therml mss nd hygroscopic properties tht help uffer the temperture nd reltive humidity of the internl environment [1] Wter ctivtes the inding forces of cly nd is dded to the dry mixture in the ppliction process. Cly distinguishes themselves from other plsters s they hrden y drying while the excess wter dded during mixing is lost. Therey it cn e re-worked when some wter is dded on the surfce of cly plster [6]. Since cly plster does not chemiclly rect with the sustrte, the surfce hs to e sufficiently rough in order to develop good physicl ond. Therefore, plster supports s reed mt re widely used in order to ensure good mechnicl ond etween the surfce nd the plster. Cly plster cn e pplied on wlls nd ceiling in uildings y using tools nd techniques common to conventionl plsters. A plster thickness mximum 1-15 mm is pplied t once. Susequent lyers cn e pplied s the previous lyer is firm. There is no product stndrd for cly plsters on Europen level. However, Germn stndrd DIN [7] for cly plster ws pulished in Initil study 4.1. Generl The im of the initil study ws to investigte the protective effect of cly plster for the fire design of timer structures. In this study the min prmeters for the fire design were determined - the strt time of chrring nd the chrring rte of timer memers protected with plster. This work hs een crefully exmined in mster thesis of Lilik t TUT [3]. In this work, smll scle instrument ws used to conduct the testing. Tests were performed t SP Technicl Reserch Institute of Sweden in Stockholm. Previous studies hve proven tht Cone Clorimeter (ISO 566) [8] is dependle instrument to determine the properties of chrring of timer memers s simultion of full scle furnce tests [9-11]. The study concentrted only on the secot of cly plster with reed mt on timer memer. In order to receive more comprehensive overview of the properties of cly plster, different cly/snd rtios of components of cly plster with constnt strw fire consistent were tested. The rnge of plster thicknesses ws chosen y the prcticl use of plster in uildings. For reference, gypsum plsterord s widely used fire protection mteril ws tested nd the results re presented in grphs elow Test specimens The dimensions of tested timer memers were 1x1x1 mm which were set y the mesurements of the retiner frme of Cone Clorimeter see Fig.2 (). Timer memers were instrumented with thermocouples to mesure the tempertures under plster throughout the testing. A reed mt ws fixed on top of the timer specimen nd covered with lyers of plster. Plstering ws conducted mechniclly y trowel. Only secot of cly plster ws tested with grin size of 4 mm. Three different rtios of components of cly plster were tested with plster thicknesses of 1, 2, 3 nd 4 mm. Testing comprised doule-testing for ech unique specimen.

5 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Het Flux [kw/m²] Het flux t this study 3 4 ISO 834 het flux 2 2 ISO 834 temperture Time [min] Temperture [ºC] Fig. 2. () Schemtic of prepred test specimen; () ISO 834 temperture-time curve nd het flux curve t this study. All mterils used in this study were mnufctured in Southern Estoni. The components of cly plster were crefully processed y professionl crftsmn. Preprtions of the specimens nd plstering were conducted y professionls in Estoni. Prepred specimens were trnsported to Stockholm nd conditioned in controlled climte chmer efore testing Test method Cone Clorimeter (ISO 566) [8]s smll-scle instrument ws used to determine the chrring of timer specimens. Temperture mesurements were received y the mounted thermocouples. The chrring rte ws nlyzed y the residul cross-sections of timer specimens. The stndrd temperture-time fire exposure (ISO 834) [4] ws followed y het flux during the most relevnt time period to determine the strt time of chrring, see Fig.2 (). It illustrtes the het flux curve which corresponds to the stndrd ISO 834 [4] temperture-time curve nd is roughly followed y the het flux t this study. The durtion of ech test ws 6 minutes Results A totl of 24 specimens were tested with n dditionl test concerning gypsum plsterord with thickness of 15 mm. The temperture mesurements indicted tht the use of cly plster s protection lyer increses the strt Strt time of chrring t ch [min] t ch = 2.8h p Cly Plster 2 (Initil study 15 t ch = 1.21h p - 1 Lilik 215) 1 Gypsum Plsterord, 5 EN Plster thickness h p [mm] Fig. 3. () Comprison of the strt time of chrring etween cly plster nd gypsum plsterord; () Comprison of the protection phse fctor etween cly plster nd gypsum plsterord. Protection phse fctor k 2 1,,9,8,7,6 k 2 = h p,5 k 2 = h p,4 Cly Plster,3 (Initil study Lilik 215),2 Gypsum,1 Plsterord, EN , Chrring time t [min]

6 722 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) time of chrring of timer. The otined vlues indicte tht the min fctor influencing significntly the protective effect of timer is the thickness of plster, see Fig.3 (). Different cly/snd rtios of components of cly plster hve minimum effect on the chrring ehviour of timer. The proposed expressions for the clcultion of the strt time of chrring of timer nd the decresed chrring rte re presented on the Figure 3. In ddition, the Figures illustrte the comprison of properties of cly plster with gypsum plsterord. Fig.3 () shows the chrring ehviour of timer under protective lyer. Lower vlue of the protection phse fctor corresponds to slower chrring rte for timer. It cn e concluded tht the strt time of chrring is significntly incresed when gypsum plsterord is used, however the chrring rte of timer protected y gypsum plsterord is higher compred to cly plster. 5. Smll scle verifiction tests 5.1. Introduction One of the min ojectives of the initil study y Lilik [3] ws focusing on the sic investigtion of protective effect of cly plster with different cly/snd composition rtios. No redy-mix products from the mrket were used. However, there is lrge vriility of cly plsters on the mrket from different mnufcturers worldwide. Plsters re flexile in the use of different cly/snd rtios of components nd types of cly, fiers nd other dditives. As result, it is essentil to compre the test results gined from the initil study with cly plsters on the mrket. The verifiction tests in smll scle re focusing on two types of redy-mix cly plsters y Estonin min mnufcturers. Cly plster only s se cot with grin size 4 mm is tested in order to compre the results to the initil study. This present testing with the Cone Clorimeter follows strictly the test methodology used in the initil study. The otined results out the strt time of chrring nd the chrring rte of timer re presented nd nlyzed Test specimens The preprtion process followed strictly the steps of the initil study. Dimensions of ech timer specimen were 1x1x1 mm. A reed mt s plster support ws ttched on the timer memer nd covered with cly plster. All components of cly plsters were mnufctured in Southern Estoni. A totl of 16 test specimens were prepred in Estoni y professionl crftsmen. Two redy-mix plsters were tested with thicknesses rnging from 1 4 mm, see Tle 1. One type of plster with strw fiers hs een tested to the Germn erth plster stndrd DIN [7] nd meets the stndrd of highest strength clss SII. The second type of plster from nother mnufcturer consists of cttil fier insted of strw. In order to gin reliility of results doule-testing for ech unique specimen ws conducted. Generl rules of the ppliction process were followed Testing procedure Tests were performed t SP Technicl Reserch Institute of Sweden in Stockholm. Specimens were conditioned in controlled climte chmer t 2 C nd 65% RH out two weeks efore testing. Testing ws crried out with Cone Clorimeter nd the sme steps were followed s in the initil study. Necessry equipment for testing of the specimens is shown in Fig.4 (). Test specimens were seled with n luminum tpe on the edges to prevent the ir flow. Tests were crried out t horizontl orienttion exposed directly to the het flux using retiner frme, see Fig.4 (). Durtion of ech test ws 6 minutes. Test specimens were exposed to the het flux corresponding pproximtely to the stndrd temperture-time curve fire exposure (ISO 834) [4]. The strt time of chrring of timer ws mesured y thermocouples. Thermocouples were locted in the center nd on top of the timer surfce directly under plster. Full contct ws ensured y fixing the wires with stples. The chrring rte ws nlyzed fter the testing nd cooling down the specimens y residul cross-section. A totl of 16 specimens were tested.

7 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Fig. 4. () Prepred test specimen nd equipment for the testing; () Testing in Cone Clorimeter. Tle 1.Prepred specimens for the smll scle tests Thickness of cly plster [mm] Type of cly plster Plster 1 cly/snd/fire Plster 2 cly/snd/fire Nturl fire Chopped strw Cttil Numered test specimens Doule-testing A B A B 5.4. Results nd nlysis The temperture mesurements indicte temperture rise on timer surfces under plster. Different thicknesses of plster re well distinguished y different slopes of curves, see Fig.5 (). Higher temperture curves relte to thinner thickness of plster. Fig.5 () clerly illustrtes tht the protective effect of cly plster is significntly influenced y the thickness of plster. The evportion of the moisture content in wood, plteu t 1 C is clerly recognized on thicker lyers of plster s the insultion cpcity increses. Temperture T [ºC] mm 2 mm 4 mm Plster 1 Plster Time t [min] Strt of chrring t ch [min] t ch = 1.1h p -5 R² =.96 t ch = 1.1h p -8 R² =.98 Plster 1 Plster Plster thickness h p [mm] Fig. 5. () Comprison of temperture rise curves on the interfce of timer nd plster; () Comprison of strt time of chrring.

8 724 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Protection phse fctor k 2 1,,9,8,7,6,5,4,3,2,1 k 2 = h p R² =.91 k 2 = h p R² =.99 Plster 1 Plster 2, Plster thickness h p [mm] Fig. 6. () Documenttion of residul cross-section of tested specimen; () Protection phse fctor for the clcultion of reduced chrring rtes. There is good repetility of temperture curves of doule-testing. Men mesured tempertures re presented for ech thickness of plster. Since two different mixtures of plster were tested they re pointed out in different line colours, see Fig. 5 (). This Figure illustrtes tht there is no significnt difference in temperture mesurements etween two tested plsters. Slight differences in temperture mesurements could e result of different mixtures nd thicknesses of plster nd the fier content, ut lso the ppliction technique y different crftsmen. There is slight inccurcy of lyer thicknesses, see the exct mesured lyer thicknesses on Fig.5 (). This proly explins the slight differences in temperture mesurements on Fig.5 (). Some ouncing lines cn e detected from the grph. Tht is most proly cused y the comustion of timer. The temperture vlue of 3 C is greed to e tken s the strt time of chrring ccording to EN [2]. For ech test the strt times of chrring were pinpointed from the dt received from the thermocouples, respectively. The reltionship etween the strt time of chrring nd the thickness of plster is shown on the Fig.5 (). Importnt note is tht oth mixtures of plster show good liner regression, respectively. Although, the temperture mesurements showed good correltion etween Plster 1 nd 2, the trend lines of the strt time of chrring show slight difference. Plster 2 refers to the plster with cttil fiers nd indictes incresed strt time of chrring compred to the Plster 1 with strw fiers, see Fig.5 (). The possile fctors concerning the different results were discussed ove. In this study the chrring rte for timer memers ws clculted y the residul cross-section of timer nd the time rnge from the strt time of chrring until the 6 minutes of test period. No crcking or dmge of the plster cot ws detected during nd fter the test. Test specimens retined their shpe fter cooling down. Plster ws removed from the timer memer. Therefter, timer specimens were swn into two species long the centre line in order to mesure the residul cross-section, see Fig.6 (). The cut species showed smooth plteu of chrcol in the middle of the timer memer which corresponds to the one-dimensionl chrring. The chrring depth is mesured from the centre line where the thermocouples were plced. The chrring rte is clculted from the reltionship etween the chrring depth nd the time of chrring of timer. A men protection phse fctor ws clculted from these results, see Fig.6 (). 6. Model scle verifiction tests 6.1. Introduction In this study two model scle tests were conducted with cross-lminted timer (CLT) protected with cly plster with thicknesses of 1 nd 3 mm under ISO 834 fire exposure. A redy-mix cly plster s secot with cttil fire ws used. CLT ws used to mke the specimen comprle to the previous tests in smll scle.

9 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Fig. 7. () Pln nd cross-section of the test specimen; () Test specimen fter the test Experimentl study Tested timer specimens were 3-lyered CLT pnels with totl thickness of 12 mm. The dimensions of ech ord were 4 mm in thickness nd 15 mm in width. A ord thickness of 4 mm ws chosen in order to ensure the solid timer effect in testing. The verge density of timer ws 451 kg/m³. The test specimens were prepred in Estoni y professionl crftsmn. Tests were crried out t SP Wood Technology in Sweden, Stockholm. Verticlly positioned specimen hd n exposed cly plster re of 1, x 1, m. A redy-mix cly plster with cttil fires without ny finishes nd pints ws tested (Plster 2 in smll scle tests). Only secot with grin size of 4 mm ws used. The test specimen with 1 mm plster ws prepred without reed mt since it is lightweight nd plster fstens esily to the timer surfce. A reed mt ws pplied for the 3 mm thickness of plster. The 3 mm plster ws pplied in 3 lyers, 1 mm t time. Once the previous lyer hd dried new lyer ws pplied. Both specimens were instrumented with five thermocouples on timer surfce under plster for temperture mesurements. The positioning of thermocouples nd the construction of tested specimen is shown on Fig.7. Durtion of the Test 1 for the specimen with 1 mm plster ws 9 minutes. After 3 minutes verticl crck ws formed in the middle of the surfce nd y the time of 6 minutes the verticl crck hd expnded to the side. Mximum width of the crck ws out 1 cm. After 6 minutes the flmes in the furnce developed fst nd fter 8 minutes the flmes were extended ll over the surfce. No flling off of plster ws detected. Test 2 with 3 mm plster ws crried out 12 minutes. After out 17 minutes one horizontl crck formed in the middle of the surfce. After out 38 minutes this crck hd developed only horizontlly. After 47 minutes the line hd extended to the oth sides of the specimen. No other crcks were detected. The crck ws slowly developing wider ut not significntly. Mximum crck width ws detected round 1 cm. After 62 minutes smll verticl crck formed in the ottom of the specimen. No other crcks were detected. The plster did not fll off during the test of 12 minutes. It remined solid except the formed dominnt crck in the middle of the surfce Results nd nlysis For oth tests, the temperture mesurements were received y thermocouples from 5 positions mrked s TC1 TC5 on timer surfce under plster. The temperture mesurements re shown on Fig.8 (). The mesurements of The strt time of chrring showed good greement for oth tests. For Test 1 the times for the temperture vlues to rech 3 C on timer memer were in etween 7.8 nd 1.4 minutes. For Test 2 the strt times of chrring were 28.3 nd 3.5 minutes. The chrring of timer ws mesured from the residul cross-sections. Fig.8 ().

10 726 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Strt time of chrring t ch [min] Cly 3 TC1 5 Cly 3 TC2 Cly 3 TC3 4 Cly 3 TC4 3 Cly 3 TC5 Cly 1 TC1 2 Cly 1 TC2 Cly 1 TC3 1 Cly 1 TC4 Cly 1 TC Plster thickness h p [mm] Fig. 8. () Temperture mesurements on timer memer elow 1 nd 3 mm plster; () Documenttion of the residul cross-section fter fire test. The chrring depth mesured in the position of thermocouples vries in mximum rnge of 7 or 8 mm. This difference could e influenced y minor fctors s prticulrities of timer, positioning of the wood fire, density of plster, positioning of plster support or the slight differences in the temperture vlues in the furnce. In ddition, in Test 1 the chrring depth ws oserved more thn thickness of one lmell - 4 mm. Bsed on the possile influences, the differences of chrring rtes re considered not significnt. As result, men vlues for the strt time of chrring, chrring depth, chrring rte nd protection fctor re presented, see Tle 2. During the tests, the plster did not show significnt chnge in colour or structure. Despite one dominnt crck in the plster surfce on oth test, the surfce of plster remined solid nd firm. The filure time of cly plster ws not detected due to the expnsion of plster to the furnce wlls. However, positive outcome is the ility of plster to mintin its strength nd structure throughout the testing. No plster ws flling off during the test. No therml dmge in the form of discolortion or urning ws found. After the test, the wll ws esily removed from the furnce. Tle 2.Tested specimens nd mesured strt time of chrring, chrring depth, chrring rtes nd protection phse fctors Test Thickness of plster [mm] Plster support Durtion of fire test [min] Men strt time of chrring [min] Men chrring depth [mm] Men chrring rte [mm/min] Protection phse fctor Test 1 1 non Test 2 3 reed mt Discussion 7.1. Comprison of test results The min fire design prmeters for initilly protected timer structures re the strt time of chrring nd the chrring rte of initilly protected timer nd the filure times. The filure times of plster were not detected in the conducted tests. Therefore prmeters of strt time of chrring nd reduced chrring rte re discussed in the following nlysis. The results of the descried smll scle nd model scle studies re compred in Fig. 9. For reference, the design prmeters for gypsum plsterord re presented. Fig.9 () provides the comprison of the strt times of chrring. The results from the initil study pper most conservtive. The results from the model scle show tht the strt time of chrring of timer protected with 1 mm of plster is significntly incresed compred to the smll scle tests.

11 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Strt time of chrring t ch [min] t ch = 2.8h p - 14 Gypsum Plsterord, EN t ch = h p Cly plster (Initil study Lilik 215) Plster 1 (strw) Plster 2 (cttil) 5 Cly plster (Model scle Lilik 215) Plster thickness h p [mm] Protection phse fctor k 2 1,,9,8,7,6,5,4,3,2,1 k 2 =.9 -.1h p Cly plster (Initil study Lilik 215) Gypsum Plsterord, EN Cly plster (Model scle Lilik 215) Plster 1 (strw) Plster 2 (cttil), Plster thickness h p [mm] Fig. 9. () Comprison of strt time of chrring etween smll nd model scle tests; () Comprison of the protection phse fctor etween smll nd model scle tests. Since model scle furnce follows strictly the stndrd temperture-time fire curve ISO 834 [4] from the very eginning of the test, these temperture mesurements re more ccurte. The slower chrring of wood t cone clorimeter test is cused y lower tempertures ffecting the plster surfce fter 3 minutes of fire exposure compred to the model scle tests. However, in generl the results re in good greement nd no significnt disgreement is noted. The comprison of the strt time of chrring in smll nd model scle clerly shows tht the study in smll scle roughly follows the temperture mesurements in the model scle furnce. The difference of the chrring ehviour of protected timer is recognized etween the initil study nd the verifiction tests, see Fig.9 (). The men vlues re presented for ech test. The verifiction tests in smll nd model scle show quite good greement. However, the results of the initil study slightly differ. The difference in protection fctor could e ffected y the density of timer, the orienttion of wood grin, the type of plster nd the preprtion of the specimens s well s the heting conditions descried ove. The verifiction tests in smll scle of two different plsters from the mrket show good greement to the results from the initil study y Lilik [3] Suggestions for further reserch Further investigtion is necessry in order to improve the reliility of given expressions of cly plster sed on performed studies nd nlysis. Similr studies should e conducted with cly plsters from other mnufcturers in Europe. Additionl dt is needed to widen the knowledge of the ehviour of cly plster s protection mteril. Filure times of plster should e determined with different sustrtes nd plster support systems. Further, the mechnicl properties of the plster, support mterils nd fixing re importnt to reserch in detil since the reduction of the chrring rte pplies only when the plster is ttched to the timer surfce. Lrge scle fire tests re necessry to determine filure times. The properties of cly plster should e stndrdized in order to comply with the Europen system. Different mnufcturers produce highly vrying plsters in their chrcteristics. Cly plster is complex mteril nd the possile comintions of plster mke it hrd to gin comprehensive overview of the fire technicl properties in generl. Fire technicl properties of cly plster should led to therml modelling. Lime plster should lso e investigted in the sme wy in the future. 8. Recommendtions for the fire design The following recommendtions re sed on the studies presented in this pper nd no generl conclusions must e mde. The proposed formuls re limited y the tested cly plsters with grin size of 4 mm.

12 728 Johnn Lilik nd Alr Just / Energy Procedi 96 ( 216 ) Since the model scle test follows strictly the stndrd fire curve [2], the recommended formul for the strt time of chrring is sed on the model scle test results. Although, for the clcultion of the reduced chrring rte more conservtive formul is presented. This is due to the vrious influencing fctors explined ove. A recommended eqution for the clcultion of the strt time of chrring ehind the cly plster for design model EN [2] is presented (3). (3) A recommendtion eqution for the clcultion of the protection coefficient for chrring ehind cly plster for the design model of EN [2] is presented (4). 9. Conclusion Test results show tht trditionl uilding mteril cly plster is suitle protection mteril for timer constructions in fire. The use of cly plster s protection for timer structures delys the strt time of chrring nd decreses chrring rte of timer memer s long s cly plster is ttched on timer memer. Thickness of cly plster is the most significnt prmeter to e considered to predict the chrring ehvior of timer. Since there is limited informtion out the fire technicl properties of cly plster, the proposed recommendtions for the fire design of timer structures re sed only on the studies explined in this pper. Further investigtion is necessry in order to wider the dtse of tested cly plsters nd ppliction systems. Development in stndrdiztion of cly plster could led to more ccurte results in the fire tests. Investigtions in the comintion of timer nd cly hve gret potentil to meet the demnds nd requirements for the entire uilding envelope in the future. Acknowledgements Authors of this pper will show deep grtitude to B. Östmn, M. Tiso, J. Noren, M. Sterley, D. Brndon nd T. Muring for their dvices nd SP for the testing fcilities; Estonin cly plster mnufcturers for providing nd prepring the tested mterils. Authors would like to cknowledge COST FP144 WG2 for the support. References [1] Thomson, A, Mskell, D., Wlker, P., Lemke M., She A., Lwrence M. Imrpoving the hygrotherml properties of cly plster. ReserchGte, BRE Centre for Innovtive Construction Mterils, University of Bth, Bth, UK, 215. [2] EN (Eurocode 5): Design of timer structures, Prt 1-2: Generl Strcuturl fire design, CEN, Brussels, 24. [3] Lilik, J. Protective effect of cly plster for the fire design of timer constructions. Mster thesis. Tllinn University of Technology, Tllinn. Estoni, 215. [4] ISO Fire resistnce tests Elements of uilding construction Prt 1: Generl requirements. Interntionl Orgniztion of Stndrdiztion, Genève, Switzerlnd, [5] Frngi, A., Fontn, M., Knoloch M nd Bochicchio G. Fire ehviour of cross-lminted solid timer pnels, Fire Sfety Science Proceedings of the 9 th Interntionl Symposium, pp , 28. [6] Allen, P., My, N. Cly Plsters. Building Conservtion. Online t: ccessed t [7] DIN 18947: 213: Erth plsters Terms nd definitions, requirements, test methods (in Germn). NABu: Berlin, 213. [8] ISO 566:215. Rection-to-fire tests -- Het relese, smoke production nd mss loss rte -- Prt 1: Het relese rte (cone clorimeter method) nd smoke production rte (dynmic mesurement). Interntionl Orgniztion for Stndrdiztion, Geneve, Switzerlnd. [9] Tiso, M. Chrring ehviour of cross lminted timer with respect to the fire protection. Comprison of different methods in smll, model nd lrge scle with simultions. SP Report 214:27. SP Technicl Reserch Institute of Sweden, 214. [1] Tsntridis, L. D., Östmn, B. A. L. Chrring of protected wood studs. Fire nd mterils, 22(2), 55-6; [11] Tsntridis L.D., Östmn B. A. L, König, J. Short Communiction: Fire Protection of Wood y Different Gypsum Plsterords. Fire nd mterils, 23, 45-48, 1999.