Research of Physical Properties of Straw for Building Panels

Transcription

1 Intenational Jounal of Engineeing Science Invention ISSN (Online): , ISSN (Pint): Volume 6 Issue 5 May 017 PP Reseach of Physical Popeties of Staw fo Building Panels Atūas Lebed, Neijus Augaitis Scientific Institute of Themal Insulation, Vilnius Gediminas Technical Univesity, Linkmenųst. 8, LT-0817 Vilnius, Lithuania Abstact: The development of new themal insulation mateials needs to evaluate popeties and stuctue of aw mateials, technological factos that make influence on the themal conductivity of mateial. One of the most pomising aw mateials fo poduction of insulation mateial is staw. The use of natual fibes as insulation is closely linked to the ecological building secto, whee selection of mateials is based on factos including ecyclable, enewable aw mateials and low esouce poduction techniques. In cuent wok esults of eseach on stuctue, themal conductivity, wate vapou pemeability and shot tem wate immesion of titicale staw fo poduction of themal insulating staw panels ae pesented. Staw panels withdiffeent densitywee pepaed fo themal conductivity measuement. It was detemined that lowest themal conductivity of staw is eached when staw density anges fom 80kg/m 3 to 10 kg/m 3. It was found that the macostuctue that changes with density incease has the geat effect on themal conductivity of mateials. At the density ange of kg/m 3 incease of themal conductivity values ae obseved. Wate vapou pemeabilitywas analysed at the density anges fom 80 kg/m 3 to 156 kg/m 3. Vapou pemeability values gew with density incease fom to.5. Shot tem wate absoption was evaluated by two paametes - as wate absoption coefficient due to capillay action and shot tem wate absoption by patial immesion. Wate absoption coefficient shows sudden mass incease within the fist 10 minutes and subsequent slow mass incease. Shot tem wate absoption values show significant weight incease duing 48 hous, which eaches pecent by mass. Keywods:titicale staw, themal conductivity, wate vapoupemeability, shot tem wate absoption wate absoption coefficient, macostuctue. I. INTRODUCTION In cuent time in global maket wide choose of themal insulation mateials ae supplied. Newest themal insulation such as vacuum insulation panels, gas-filled panels, aeogels, and phase change mateials [1] o ecological themal insulation such as fibeboads, loose fill insulation o panels fom diffeent plants o thei tails [-4] takes a pat of this maket. In the last 0 yeas cellulose based plant fibes have gained impotance as aw mateial fo themal insulations. The use of natual fibes in insulation is closely linked to the ecological building secto, whee selection of mateials is based on factos including ecyclable, enewable aw mateials and low esouce poduction techniques [5, 6]. Moeove, themal insulation fom cellulose based plant fibes ae used fo sound absoption pupose [7-10]. One of main equiements fo building envelopes is to ensue acoustic comfot, especially in multi-dwelling buildings [11, 1]. Plant fibes fo sound absoption ae used inside buildings fo floos, enclosues, patitions and ceiling insulation. Outdoo following poducts ae used as sound-absobing walls (fences) to potect against of ca noise [13]. Staw is an agicultual by-poduct, the dy stalks of ceeal plants, afte the gain and chaff have been emoved. Staw makes up about half of the yield of ceeal cops such as baley, oats, ice, ye, flax and wheat [14-16]. It has many uses, including fuel, livestock bedding and fodde, thatching and basket-making. Staw ae used as aw mateial in the poduction of themal insulating fibeboads, einfoced themoplastic composites and staw bales [17-]. Euopean houses built of staw o eeds ae now ove two hunded yeas old. In the United States, too, people tuned to staw houses, paticulaly afte the hay/staw bale enteed common usage in the 1890s. Homesteades in the nothwesten Nebaska "Sandhills" aea, fo example, tuned to baled-hay constuction, in esponse to a shotage of tees fo lumbe. Bale constuction was used fo homes, fam buildings, chuches, schools, offices, and gocey stoes [3, 4]. The aim of the pesent study was to detemine ational density of titicale staw fo poduction of staw panels. As main paamete themal conductivity was used. Moistue egime was evaluated by wate vapou pemeability and wate absoption paametes. 9 Page

2 II. MATERIALS AND METHODS In tests titicale staw wee used. In ode to analyse maco stuctue of staw, specimens with density ange fom 60 kg/m 3 to 180 kg/m 3, wee pepaed. The samples wee inspected by Digital camea Nikon COOLPIX P90 with 4 enlagement and esolution 1.1Mpix.Staw paametes wee detemined usingcomputeized image pocessing and analysis pogam ImageTool. Themal conductivity tests wee caied out by guaded hot plate appaatus λ-mete EP 500 with additional potective heating ings and cooling ing accoding to (ISO 830). Themal conductivity measuements wee caied out at mean tempeatue of 10 ºC and tempeatue diffeence though specimen of 10 C. All specimens wee conditioned at constant climate conditions (3±) C and (50±5)%. The wate vapou pemeability studies wee conducted in accodance with EN 1086 standad. Duing the test in a chambe and in the test dishes espectively 50% and 95% RH and 3 C tempeatue conditions wee maintained. Capillay absoption coefficient of C w,s, g/(m s) was detemined in accodance with EN Insulation composite samples wee soaked fo 90 min., ecoding the change in mass evey 10 minutes. Shot-tem wate absoption was detemined accoding to standad EN 1609: 013, method A. Wate absoption of the samples was detemined afte 48 hous. Intemediate weighing afte 10 minutes, 1.5, 3, 6 and 4 hous wee pefomed. III. RESULTS 3.1. Macostuctue View of specimens fo macostuctue analysis is pesented in Fig. 1. All specimens ae chaacteised by diffeent voids between the stalks and compession of staw stem. In Fig. 1a all staw stems ae laid out feely without compession signs. With incease of loading (Fig. 1b) macostuctue of staw infill gets a fom vetically and hoizontally oiented staw, thei fom and size became moe visible and fom of spaces betweenstaw stems may be evaluated. Changes of staw fom ae not visible. When density eaches140 kg/m 3 a) b) 15 mm 15 mm c) d) 15 mm 15 mm Fig. 1. Macostuctue of titicale staw, when density of specimens, kg/m 3 : a 60; b ; c 140; d 180 (Fig.1c), no significant changes in macostuctue of staw stems ae obseved. Voids between staw steams become smalle and sepaate staw stems stat to defom. Significant changes ae obseved when density of staw infill eaches 180 kg/m 3. At such density macostuctue of staw infill looks as homogeneous poduct without voids between staw stems, all staw ae defomed and good contact between staw stem walls ceated. Attention should be paid to the fact that with inceasing density of the specimens, mechanical teatment options ae impoved. As it is seen in Fig. 1, at low density (Fig. 1a) the suface of staw specimen is ough and at high density smooth (Fig. 1d).As it is known, fo plasteing moe suitable suface is ough. 10 Page

3 3.. Themal conductivity The esults of themal conductivity of measuement of titicale staw ae pesented in Fig.. Themal conductivity of staw with densities ange fom 80 kg/m 3 to 190 kg/m 3 was analysed. Fo expeiments panels with staw infill mm wee pepaed. Pocessing of expeimental data show that themal conductivity values may be descibed by equation (1): , (1) C whee is density of staw infill in kg/m 3. Mean squae deviation is S W/(m K) ( n 17, squae coelation coefficient R ). Gaphical intepetation accoding to equation (1) is pesented in Fig. In addition the possible value of eo t S (Fig. 1,dotted line)with pobability (1 α)=0.9 is pesented fo egessionequation () which enables to pass on to inteval pediction accoding to the following fomula: ped. 10 C 10 C () wheet α;f is Student's citeion ( n 17 and t );S is standad deviation. Fig..Dependenceof themal conductivity on the density of staw stems: solid line - egession line accoding to equation (1); the dotted line - pedictive lineaccoding to equation () The lowest themal conductivity of staw is obseved at densities ange fom 80 kg/m 3 to 10 kg/m 3.Fom the density 10 kg/m 3 stats intensive incease of themal conductivity values. It is elated with a stengthening of the contact zones between staw stems and heat tansfe by solid cacass. It should be noted that at the low-density staw is unstable bad fixation in a wooden fame is obseved. This phenomenon is obseved till staw infill density eaches ~ kg/m 3, i.e. while staw stems stat to defom Wate vapou pemeability Wate vapou pemeability of staw infill was expessed by wate vapou diffusion esistance factoµ. Gaphical intepetation of test esults is pesented in Fig. 3. Fig. 3.Dependence of wate vapoudiffusion esistance facto on the density of staw infill, kg/m 3 11 Page

4 Dependence of wate vapou diffusion esistance facto on the density, kg/m 3, can be appoximated by egession equation (Fig. 3): , (3) whee standad deviation S ( n 11 ) andsquae coelation coefficient R. As it is seen in Fig. 3, due to oppotune macostuctue and micostuctue as well [5]staw infill is chaacteised by good wate vapou pemeability. With incease of density wate vapou pemeability decease, but values of wate vapou diffusion esistance facto ae much bette than of othe themal insulating mateials of simila density. Low wate vapou diffusion esistance factopovides good hydothemal egime inbuilding envelopes Wate absoption due to capillay action Shot-tem wate impact on staw was evaluated by capillay absoption coefficient. The dependence of capillay absoption coefficient of staw on the time and density is pesented gaphically in Fig. 4. Test esults wee fixed evey ten minutes. Test esults show, that lagest capillay absoption coefficient is obseved duing fist 10 minutes and vey slow absoption duing the emaining 80 minutes. It can be assumed that poes of staw stalks ae filled by wate in the fist stage and duing othe stages of slow wate suction to futhe staw stalk poes is obseved. As it is stated in [6] cellulose based mateials ae chaacteised by high hygoscopic natue. The hygoscopicity is caused by the cellulose molecule itself, wheeas the ate of wate absoption is influenced by many paametes. Fothedesciptionofcapillayabsoptioncoefficientonthe bases oftestesultsmultiple egession equation (4) was obtained: C T w, s exp ln T e, (4) whee mean squae deviation is S g/(m s) ( n 108 ) and squae coelation coefficient L , whichshowsthatcapillayabsoptioncoefficientby97.6% dependsonthetimeanddensityand just by.4% - ontheothefactos, whichhavenotbeendetemined. 3.5.Shot tem wate absoption Results of shot tem wate absoption by patial immesion ae pesented in Fig. 5. As it is in Fig.5, wate absoption pocess may be divided into two stages. Fist stage (duation about 10 hous) fast wate absoption at which end wate absoption values eaches 60-80% by mass. Second stage slow and unifom incease of wate absoption values. C w,s, g/(m s) , kg/m T, min Fig. 4.Gaphical intepetation of egession equation (4) of the dependence of capillay absoption coefficient of staw on the time T, min, and density, kg/m 3 Dependence of wate absoptionvalues W, %, on staw infill density, kg/m 3, and time T, hous, was appoximated by egession equation: T W T e, (5) whee mean squae deviation is S % ( n 96 ) and squae coelation coefficient , which shows, that 98.8% wate absoption values depend on the time and mateials density. 0 > 1 < 1 < 9 < 6 < 3 L 1 Page

5 W, % , kg/m T, h Fig. 5.Gaphical intepetation of egession equation (5) of the dependence of shot tem wate absoption of staw on the time T, min, and density, kg/m 3 IV. CONCLUSIONS Macostuctue analysis show that staw macostuctue contol depends on compession level i.e. staw infill density. On the constuction point of view the most suitable stuctue of staw is when the staw ae compessed but sepaate ai spaces between staw stalks ae obseved. To obtain such macostuctue, staw with a density of -10 kg/m 3 should be used. Themal conductivity of staw mostly depends on the density of mateial. The lowest themal conductivity value of staw infill is at the densities ange fom 80kg/m 3 to 10 kg/m 3. At highe densities sudden incease of themal conductivity values ae obseved. Wate vapou pemeability is high at all density anges and vaies fom.0 to.5. Dependence of wate vapou pemeability on staw density was obtained, but such chaacteistics as mico- and macostuctue, hygoscopic natue must be analysed evey time too. Capillay absoption coefficient shows vey high wate absoption at initial stage and slow wate absoption at futhe stage. It can be assumed that poes of staw stalks ae filled by wate in the fist stage and duing othe stages of slow wate suction to futhe staw stalk poes is obseved. Analysis of esults of shot tem wate absoption show that 60-80% by weight staw absobs duing the fist 10 hous. At a late stage, a slow incease of wate absoption values of staw may be elated to the eliminationof emaining ai fom the stuctue of staw infill. REFERENCES [1] JelleB.P. Taditional, state-of-the-at and futue themal building insulation mateials and solutions Popeties, equiements and possibilities, Enegy and Buildings 43 (011) [] KymalainenH.R., SjobegA.M. Flax and hemp fibes as aw mateials fo themal insulations, Building and Envionment 43 (008) [3] Zach J., KojenicA., PetanicV., HoudovaJ., Bedna T. Pefomance evaluation and eseach of altenative themal insulations based on sheep wool, Enegy and Buildings 49 (01) [4] Pinto J., PaivaA., VaumH., Costa A., Cuz D., Peeia S. Con s cob as apotential ecological themal insulation mateial, Enegy and Buildings 43 (011) [5] Kymalainen, H. R., Sjobeg, A. M. Flax and hemp fibes as aw mateials fo themal insulations, Building and envionment : pp [6] Muphy, D. P. L., Behing, H., Wieland, H. The use of flax and hemp mateials fo insulating, Pocessing of flax and othe bast plants symposium, Poznan, Poland, 30 Septembe-1 Octobe P [7] Pan, M., Zhou, D., Zhou, X., Lian, Z. Impovement of staw suface chaacteistics via themomechanical and chemical teatments Bioesouce Technology : pp [8] Zou, Y., Huda, S., Yang, Y. Lightweight composites fom long wheat staw and polypopylene web Bioesouce Technology : pp [9] Yang, H., S., Kim, D., J., Kim, H., J. Rice staw-wood paticle composite fo sound absobing wooden constuction mateials Bioesouce Technology : pp [10] Oldham, D., J., Egan, C., A., Widman, R. The Development of a Boad Band Sound Absobe using Mateials fom the Biomass Poceedings Euonoise009, Edinbugh 009: 9p. [11] Dikavičius, V., Miškinis, K. Change of Dynamic Stiffness of Open and Closed Cell Resilient Mateials afte Compessibility Test, Mateials Science (Medžiagotya) Vol. 15, No : pp [1] Dikavičius, V., Miškinis, K., Stankevičius, V. Influence of Mechanical Defomation on Compessive Stength of Open and Closed Cell Resilient Mateials, Mateials Science (Medžiagotya) Vol. 16, No : pp [13] [14] Panthapulakkal, S. Biopocess pepaation of wheat staw fibes and thei chaacteization, Industial Cops and Poducts 3 006: pp > < < 80 < 60 < 40 < 0 13 Page

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