- Email: [email protected]
Impact of fiber treatment on the fire reaction and thermal degradation of building insulation straw composite
Available online at www.sciencedirect.com
ScienceDirect Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available Energy Procedia 00 (2017) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia
Energy (2017) 000–000 544–549 EnergyProcedia Procedia139 00 (2017) www.elsevier.com/locate/procedia
International Conference On Materials And Energy 2015, ICOME 15, 19-22 May 2015, Tetouan, Morocco, and the International Conference On Materials And Energy 2016, ICOME 16, 17-20 May 2016, La Rochelle, France The 15th International Symposium on District Heating and Cooling
Impact of fiber treatment on the fire reaction and thermal Assessing the feasibility of insulation using the heat degradation of building strawdemand-outdoor composite temperature function for a long-term district heat demand forecast Naima Belayachi*, Dashnor Hoxha, Brahim Ismail a,b,c a b c I. Andrić *, A. INSA-CVL, Pinaa, P. Ferrão , J. 8Fournier ., Vinci, B. Lacarrière , O.2,Le Correc Université d’Orléans, PRISME, EA 4229, Rue Léonard de 45072 Orléans cedex France 1
a
IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France Abstract
In this paper, both treated and untreated straw fibers are used to manufacture the light-weight composite for building insulation. The main objective of this work is to investigate the effect of the treatment on the thermal degradation and flammability of the Abstract material in order to examine his fire behavior. The selected wheat and barley straws are mixed with lime or gypsum plaster in this experimental investigation. In order to improve the mechanical properties of the composite, the straw fibers are treated with District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the linseed oil and boiled water for decreasing their water absorption and increasing their compatibility and adhesion with the binder greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat respectively. The treatment is carried out by total impregnation in the boiled water and linseed oil. The different composites are sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, manufactured using mixture procedure optimized in previous works of the authors. Then the treated and untreated composite prolonging the investment return period. specimens are analyzed and compared through TG-DSC analysis to study their combustion process at microscopic level, and The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand flammability test to study their fire reaction at macroscopic level. The properties of composites based on the fibers treated with forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 linseed oil vary significantly. buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were © 2017 The Authors. Published by Elsevier Ltd. compared with results from a dynamic heat demand model, previously developed and validated by the authors. Peer-review under responsibility of the scientific committee of ICOME 2015 and ICOME 2016. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation Keywords: fire rection, fiber treatment, building insulation, staw composite scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +33-023-849-2502; fax: +33-023-841-7063. E-mail address: [email protected] Keywords: Heat demand; Forecast; Climate change
1876-6102 © 2017 The Authors. Published by Elsevier Ltd.
Peer-review under responsibility of the scientific committee of ICOME 2015 and ICOME 2016. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.
1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of ICOME 2015 and ICOME 2016 10.1016/j.egypro.2017.11.251
2
Naima Belayachi et al. Procedia / Energy Procedia (2017) 544–549 N. Belayachi et al. / Energy 00 (2017)139 000–000
545
1. Introduction Addition of low density biodegradable natural fibers to mineral or polymer matrix present attractive alternatives to synthetic fibers for different applications with various performances, and low environmental impact. Most of these composites have been developed in order to reduce weight and produce environmentally friendly materials in particular in building sector resulting in a decrease of energy consumption of the building and the reduction of the GHG emission. In the recent years, several research have been undertaken on the production of innovative materials with specific properties and mechanical performance [1, 2]. However, many major difficulties limit the large use of natural fibers for structural applications, like their low strength compared to metals and polymers, water absorption and low fire resistance. These factors results inadequate properties for many purposes. Then, the treatment of fibers is an area of research more important for improve the properties of the natural fiber composites [3, 4]. These treatments improve significantly the mechanical properties but it is difficult to find a single effective treatment for all properties. Few analysis are carried out for example to examine the effect of these treatments used generally for mechanical properties on the thermal degradation and fire behavior. This is an important point to establish the use conditions and performance criteria of the natural fiber composites in building applications [5, 6]. The fire risk is defined as the potential factor for structure and materials design [5]. The majority of the existing studies in the literature is on the polymer composites or natural fibers reinforcing polymer matrix [7-12]. The more used test for understanding the fire behavior in these investigations is the flammability test according UL94 (ASTM D3801), and TG-DSC-FTIR thermal analysis. In this context, the present paper aims to study the fire behavior of the straw lime and straw-plaster composite proposed in the framework of a previous research program PROMETHE on the materials with low environmental impact based on the cereal straw fibers for thermal insulation rehabilitation. Samples were manufactured for the different experiments in laboratory without compaction with barley or wheat straw and lime and gypsum plaster binders [13, 14]. For thermal degradation and fire behavior, the study combines microscopic and macroscopic methods respectively, thermal analysis (thermogravimetric and differential scanning calorimetry) and reaction to fire tests ignitability in accordance with test methods and Euro-class system defined by European standardization [15]. The flammability test described in this European standards is equivalent to the UL 94 test widely used for polymer materials [15, 16]. In most investigations on composite materials used in building applications, the fire behavior is studied by flammability test, TG-DSC analysis [16, 17] and fire resistance test [18] or only PCFC calorimeter [19]. The effect of fiber treatment, the fiber variety and binder natures are examined. The fibers are treated by total immersion in boiled water and linseed oil for different times. 2. Experimental Investigation In this laboratory experiments, the fire behavior is studied by flammability test for small flame. It is the first step to analyze the fire behavior but it is not sufficient to give the final fire classification of the composite. In this section, the brief description of the experimental work is given. 2.1. Materials The bio-composite studied in this investigation is a new innovative material based on wheat and barley straw. The straw-concrete is made with two types of binders lime and gypsum plaster. The selection of the used natural fibers and the binder was carried out in previous studies [13, 14] in the framework of research program PROMETHE. In this work, an attention is focused on the treatment of straw fibers and the change of the thermal degradation of the bio-composite. Then, the fibers are treated before there mixture with the lime or gypsum-plaster binders. There are a significant number of studies on different treatments in order to improve the compatibility between the natural fibers and the binders and increase the tensile or compressive strength, like alkali treatment [3] or boiled water treatment [4]. In this work, two treatments are selected, boiled-water to improve the straw-surface and linseed treatment to decrease the water absorption.
546
Naima Belayachi et al. / Energy Procedia 139 (2017) 544–549 N. Belayachi et al. / Energy Procedia 00 (2017) 000–000
3
Straw treatment: For linseed treatment the crushed wheat/barley fibers have been firstly immersed in the linseed oil for different times (10s, 5, 10, 15 minutes, 1h). Then, fibers have been dried at 60 °C during 48 hours before there use in the mixture. For the second treatment, the straw fibers were impregnated (Figure 1) for the same times in the boiled water at 100°C beforehand. Fibers have been dried at 60 °C in the oven in the same way.
Fig. 1. Straw fibers treatment: (a) crushed straw; (b) linseed oil immersion; (c) boiled water immersion.
Composite manufacture: In order to limit the number of tested samples, only optimal time of impregnation is used (10 minutes), determined before the composite manufacture based on a comparison of Young modulus and the water absorption coefficients not presented here. The mixture procedure, the introduction in the molds and the curing conditions are the same of previous works [13] in order to compare the behavior and to keep the same thermal and mechanical compromise. The samples used for flammability are cut according the standard NF EN 11925-2 [15]. They measures 250 mm of height, 90 mm of length and 60 mm of width. According to the type of straw (wheat and barley), of binder (lime and plaster) and the treatment, eight composites with treated fibers are studied and compared with four composites prepared with non-treated fibers (Table 1). 2.2. Flammability test and thermal analysis In this work only flammability test for small flame is performed, in order to examine the reaction to fire of the straw composite and his fire classification according to the European standards. The flammability test has been conducted as described by EN 11925-2 [15]. For each straw-composite, the test is carried out for three specimens. The test consists to expose the material to a single flame for 15 s in class E and 30 s in class D. The burner was angled at 45° with the flame length of 20 mm. The distance between the burner and the tested surface is 5 mm. A plate is disposed below the tested surface to collect the burning droplets. Figure 2 present the flammability test performed in this work.
Fig. 2. Experimental flammability test under small flame of straw concrete. After removing the flame, the flame spread and the droplet occurrence are examined. For the class E and D, the flame spread should be less than 150 mm after 15 s and 30 s of flame exposure respectively. Infrared camera is
4
Naima Belayachi et al. / Energy Procedia 139 (2017) 544–549 N. Belayachi et al. / Energy Procedia 00 (2017) 000–000
547
installed for the temperature examination during and after the flame exposure. Thermogravimetric analyzer coupled to a differential scanning calorimetry was used to follow both the mass loss and the heat flow exchange during the thermal degradation of the different composites. These analysis are performed by LINSEIS STA PT-1000 apparatus under inert atmosphere. Powder samples of about 20 mg were placed in an alumina crucible and heated from ambient temperature to 1000 °C with a heating rate of 20 °C/min. 3. Results and discussion Table 1 summarizes the flame propagation height and the observation of the occurrence of the flaming droplets for the different straw composites. The Flame spread has been measured after 20 s after removing the burner. We can observed that for the different composites, the flame does not exceed 15 cm. The results shows also that the composites based on treated fibers with linseed oil record the smallest flame propagation. For a time of flame exposure more important (30 s), we can observed that the flame spread heights are larger but still less than 15 cm. Table 1. Flame spread for 15 s and 30 s of burner exposure. Composites and designation
Flame Height (cm) after 20 s removal burner for 15 s of exposure
Droplets Yes/No
Flame Height (cm) after 60 s removal burner for 30 s of exposure
Droplets Yes/No
Wheat-Plaster-Non treated (W-P-NT)
8.5
No
13.4
Yes
Wheat-Plaster-Boiled water (W-P-BW)
9.1
No
10.5
No
Wheat-Plaster-Linseed oil (W-P-LO)
6.1
No
10.2
No
Wheat - lime - Non Treated (W-L-NT)
7.9
No
8.6
No
Wheat-Lime-Boiled Water (W-L-BW)
6.7
No
8.1
No
Wheat-Lime-Linseed Oil (W-P-LO)
5.7
No
7.2
No
Barley-Plaster-Non Treated (B-P-NT)
13.1
Yes
14.2
Yes
Barley-Plaster-Boiled Water (B-P-BW)
7.5
No
9.3
No
Barley-Plaster-Linseed Oil (B-P-LO)
4.5
No
6.7
No
Barley-Lime Non Treated (B-L-NT)
8.2
No
8.5
No
Barley-Lime-Boiled Water (B-L-BW)
6.3
No
9.3
No
Barley-Lime-Linseed Oil (B-L-LO)
3.4
No
4.1
No
The linseed oil treatment behaves as a flame retardant. It was observed a few flaming droplets on the horizontal plate only for the composite based on non- treated barley straw. The boiled water treatment showed an effect on the flame spread in the case of the barley composite. It is observed also that the composite based on the lime binder have the smallest flame spread in the two times exposure for the two types of straw fibers. Figure 3 shows an example of the exposed surface to burner flame and the temperature during burning and after 5 minutes of exposure for barley lime composite. This figure demonstrate the fire performance of the straw composite, there is no spread flame after removing the burner with this time exposure. The exposure surface is not degraded material without dripping during this time ignition. The temperature decreases greatly after removal of the burner.
548
Naima Belayachi et al. / Energy Procedia 139 (2017) 544–549 N. Belayachi et al. / Energy Procedia 00 (2017) 000–000
5
Fig. 3. State of exposed surface and temperature field at 15 s and 5 min after flame for barley lime composite : (a) B-L-NT; (b) B-L-BW; (c) B-LLO.
The results represented on Figure 4, shows the effect of the treatment on mass loss and heat flow of the composites. It is clear on the TG curves that the two treatment showed an important effect on the composite degradation which reached 50 % for the linseed oil treatment. The highest mass loss about (30 %, 35% and 50%) respectively for non-treated, boiled water treated fibers and linseed oil treated fibers occurs in temperature interval of 260-500°C. The mass loss for the two stages occurs first for the composite based on linseed oil treated fibers with differences of about 40°C. The last stage at 700°C, shows a very low mass loss about 2%.
Fig. 4. TG curve and heat flow exchange of wheat-plaster composites with treated and non-treated fibers.
The important mass loss is accompanied by endothermic peak for the three composites with a difference for the linseed oil treated fibers. The exothermic peak presented on the DSC curve is occurs for the plaster binder due to a reaction which the molecular structure of the anhydrite rearranges to an insoluble anhydrite. The results of this part shows also, a significant effect of linseed oil treatment at the microscopic level with important mass loss. However, this effect is different for macroscopic level where his role was rather to spread flame retardant. So, the question remains open for the representative volume of TG-DSC tests for this type of highly heterogeneous material with high fibers content with multidirectional orientation. In addition, it is clearly observed that the binder nature and fiber variety have an important effect on the thermal degradation.
6
Naima Belayachi et al. Procedia / Energy Procedia (2017) 544–549 N. Belayachi et al. / Energy 00 (2017)139 000–000
549
4. Conclusion This paper investigates the effect of fiber treatment on the fire behavior and thermal degradation of the new biocomposite based on straw proposed for building insulation. The performed tests of the flammability and TG-DSC analysis in this work is a first attempt to understand the fire behavior of the straw based composite materials. The major conclusion of this investigation is the significant effect of the linseed oil treatment at macroscopic level by flammability test and microscopic level by TG-DSC analysis. The linseed oil treatment retards the flame spread and prevents the composite degradation. The flame spread is stopped after removing the flame burner for all composites. Barley based composite show a delicate fire behavior than the wheat-composite. In order to clarify the difference between macroscopic and microscopic level, further investigation is proposed by using the cone calorimeter test with representative samples to provide a better understanding of the fire performance of the proposed straw composite. Acknowledgements The authors express their special thanks Alain Bret for his help in performing the flammability tests. References [1] Wei, J, Meyer, C. Degradation rate of natural fiber in cement composites exposed to various accelerated aging environment conditions. Corrosion science, 2014, 88, p. 118-132. [2] Ali, M, Chouw, N. Experimental investigations on coconut-fibre rope tensils strength and pullout from coconut fibre reinforced concrete. Construction building materials, 2013, 41, p. 681-690. [3] Gomes, A, Matsuo, T, Goda, K, Ohgi, J, Development and effect of alkali treatment on tensile properties of curaua fiber green composites Composites : Part A, 2007, 38, p. 1811–1820. [4] Sellami, A, Merzoud, M, Amziane, S, 2013, Improvement of mechanical properties of green concrete by treatment of the vegetals fibers, Construction and Building Materials, 2007, 47, p. 1117–1124. [5] Hidalgo, J. P, Welch, S, Torero, J. L. Performance criteria for the fire safe use of thermal insulation in buildings, Const. and Build. Mat, 2015, 100, p. 285-297. [6] Naughton, A, Fan, M, Bregulla, J. Fire resistance characterization of hemp fibre reinforced polyster composites for use the construction industry, Comp. part B, 2014, 60, p. 546-554. [7] Bocz, K, Szolnoki, B, Marosi, A, Tabi, T, Wladyka-Przybylak, M, Marosi, G,. Flax fibre reinforced PLA/TPS biocomposites flame retarded with multifunctional additive system, Poly. Degrad. And Stab, 2013, 106, p. 63-73. [8] Chattopadhyay, D. K, Webster Dean C,. Thermal stability and flame retardancy of polyurethanes, Prog. Poly. Scien, 2009, 34, p. 1068 1133. [9] Fox, D. M, Novy, M, Brown, K, Zammarano, M, Harris, R. H, Murariu, M, McCarthy, E, Seppala, J. E, Gilman, J. W,. Flame retarded poly(lactic acid) using POSS-modified cellulose:2. Effect of intumescing flame retardant formulations on polumer degradation and composite physical properties, Poly. Degrad. And Stab, 2009, 106, p. 54-62. [10] Laoutid, F, Bonnaud, L, Alexandre, M, Lopez-Cuesta, J. M, Dubois, Ph. New prospects in flame retardant polymer materials: from fundamentals to nanocomposites, Mat. Sci. and Eng R, 2009, 63, p. 100-125. [11] Monti, M, Tsampas S. A, Fernberg, S. P, Blomqvist, P, Cuttica, F, Fina, A, Camino, G. Fire reaction of nanoclay-doped PA6 composites reinforced with continuous glass fibers and produced by commingling technique, Poly. Degrad. & Stab. 2015, 121, p. 1-10. [12] Ju, Y, Liao, F, Dai, X, Cao, Y, Li, J, Wang, X. Flame-retarded biocomposites of poly(lactic acid): distiller’s dried grains with solubles and resorcinol di (phenyl phosphate), Composites A, 2016, 81, p. 52-60. [13] Belayachi, N, Bouasker, M, Hoxha, D, Al-mukhtar, M. Thermo-mechanical behaviour of an innovative straw lime composite for thermal insulation applications, Applied. Mechan. and Mat, 2013, 390, p. 542-546. [14] Bouasker, M, Belayachi, N, Hoxha, D, Al-Mukhtar, M. Physical characterization of natural straw fibers as aggregates for construction materials applications, Materials, 2014, 7, p. 3034-3048. [15] EN ISO 11925-2, Reaction to fire tests, Ignitability of building products subjected to direct impingement of flame-Part 2: single flame source test. [16] Younis, A. A. Evaluation the flammability and thermal properties of a new flame retardant coating applied on polyster fabric, Egypt. J. Petrol. http://dx.doi.org/10.1016/j.ejpe.2015.04.001 [17] Garcia, M, Hidalgo, J, Garmendia, I, Garcia-Jaca, J. Wood-plastics composites with better fire retardancy and durability performance, Comp. part B, 2009, 40, p. 1772-1776. [18] Haurie, L, Mazo, J, Delgado, M, Zalba, B. Fire behavior of a mortar with different mass fractions of phase change material for use in radiant floor systems, Energy. Build., 2014, 84, p. 86-93. [19] Palumbo, M, Formosa, J, Lacasta, A, M. Thermal degradation and fire behavior of thermal insulation materials based on food crop byproducts, Const. and Build. Mat., 2015, 79, p. 34-39.
ScienceDirect Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available Energy Procedia 00 (2017) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia
Energy (2017) 000–000 544–549 EnergyProcedia Procedia139 00 (2017) www.elsevier.com/locate/procedia
International Conference On Materials And Energy 2015, ICOME 15, 19-22 May 2015, Tetouan, Morocco, and the International Conference On Materials And Energy 2016, ICOME 16, 17-20 May 2016, La Rochelle, France The 15th International Symposium on District Heating and Cooling
Impact of fiber treatment on the fire reaction and thermal Assessing the feasibility of insulation using the heat degradation of building strawdemand-outdoor composite temperature function for a long-term district heat demand forecast Naima Belayachi*, Dashnor Hoxha, Brahim Ismail a,b,c a b c I. Andrić *, A. INSA-CVL, Pinaa, P. Ferrão , J. 8Fournier ., Vinci, B. Lacarrière , O.2,Le Correc Université d’Orléans, PRISME, EA 4229, Rue Léonard de 45072 Orléans cedex France 1
a
IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France Abstract
In this paper, both treated and untreated straw fibers are used to manufacture the light-weight composite for building insulation. The main objective of this work is to investigate the effect of the treatment on the thermal degradation and flammability of the Abstract material in order to examine his fire behavior. The selected wheat and barley straws are mixed with lime or gypsum plaster in this experimental investigation. In order to improve the mechanical properties of the composite, the straw fibers are treated with District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the linseed oil and boiled water for decreasing their water absorption and increasing their compatibility and adhesion with the binder greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat respectively. The treatment is carried out by total impregnation in the boiled water and linseed oil. The different composites are sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, manufactured using mixture procedure optimized in previous works of the authors. Then the treated and untreated composite prolonging the investment return period. specimens are analyzed and compared through TG-DSC analysis to study their combustion process at microscopic level, and The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand flammability test to study their fire reaction at macroscopic level. The properties of composites based on the fibers treated with forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 linseed oil vary significantly. buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were © 2017 The Authors. Published by Elsevier Ltd. compared with results from a dynamic heat demand model, previously developed and validated by the authors. Peer-review under responsibility of the scientific committee of ICOME 2015 and ICOME 2016. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation Keywords: fire rection, fiber treatment, building insulation, staw composite scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +33-023-849-2502; fax: +33-023-841-7063. E-mail address: [email protected] Keywords: Heat demand; Forecast; Climate change
1876-6102 © 2017 The Authors. Published by Elsevier Ltd.
Peer-review under responsibility of the scientific committee of ICOME 2015 and ICOME 2016. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.
1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of ICOME 2015 and ICOME 2016 10.1016/j.egypro.2017.11.251
2
Naima Belayachi et al. Procedia / Energy Procedia (2017) 544–549 N. Belayachi et al. / Energy 00 (2017)139 000–000
545
1. Introduction Addition of low density biodegradable natural fibers to mineral or polymer matrix present attractive alternatives to synthetic fibers for different applications with various performances, and low environmental impact. Most of these composites have been developed in order to reduce weight and produce environmentally friendly materials in particular in building sector resulting in a decrease of energy consumption of the building and the reduction of the GHG emission. In the recent years, several research have been undertaken on the production of innovative materials with specific properties and mechanical performance [1, 2]. However, many major difficulties limit the large use of natural fibers for structural applications, like their low strength compared to metals and polymers, water absorption and low fire resistance. These factors results inadequate properties for many purposes. Then, the treatment of fibers is an area of research more important for improve the properties of the natural fiber composites [3, 4]. These treatments improve significantly the mechanical properties but it is difficult to find a single effective treatment for all properties. Few analysis are carried out for example to examine the effect of these treatments used generally for mechanical properties on the thermal degradation and fire behavior. This is an important point to establish the use conditions and performance criteria of the natural fiber composites in building applications [5, 6]. The fire risk is defined as the potential factor for structure and materials design [5]. The majority of the existing studies in the literature is on the polymer composites or natural fibers reinforcing polymer matrix [7-12]. The more used test for understanding the fire behavior in these investigations is the flammability test according UL94 (ASTM D3801), and TG-DSC-FTIR thermal analysis. In this context, the present paper aims to study the fire behavior of the straw lime and straw-plaster composite proposed in the framework of a previous research program PROMETHE on the materials with low environmental impact based on the cereal straw fibers for thermal insulation rehabilitation. Samples were manufactured for the different experiments in laboratory without compaction with barley or wheat straw and lime and gypsum plaster binders [13, 14]. For thermal degradation and fire behavior, the study combines microscopic and macroscopic methods respectively, thermal analysis (thermogravimetric and differential scanning calorimetry) and reaction to fire tests ignitability in accordance with test methods and Euro-class system defined by European standardization [15]. The flammability test described in this European standards is equivalent to the UL 94 test widely used for polymer materials [15, 16]. In most investigations on composite materials used in building applications, the fire behavior is studied by flammability test, TG-DSC analysis [16, 17] and fire resistance test [18] or only PCFC calorimeter [19]. The effect of fiber treatment, the fiber variety and binder natures are examined. The fibers are treated by total immersion in boiled water and linseed oil for different times. 2. Experimental Investigation In this laboratory experiments, the fire behavior is studied by flammability test for small flame. It is the first step to analyze the fire behavior but it is not sufficient to give the final fire classification of the composite. In this section, the brief description of the experimental work is given. 2.1. Materials The bio-composite studied in this investigation is a new innovative material based on wheat and barley straw. The straw-concrete is made with two types of binders lime and gypsum plaster. The selection of the used natural fibers and the binder was carried out in previous studies [13, 14] in the framework of research program PROMETHE. In this work, an attention is focused on the treatment of straw fibers and the change of the thermal degradation of the bio-composite. Then, the fibers are treated before there mixture with the lime or gypsum-plaster binders. There are a significant number of studies on different treatments in order to improve the compatibility between the natural fibers and the binders and increase the tensile or compressive strength, like alkali treatment [3] or boiled water treatment [4]. In this work, two treatments are selected, boiled-water to improve the straw-surface and linseed treatment to decrease the water absorption.
546
Naima Belayachi et al. / Energy Procedia 139 (2017) 544–549 N. Belayachi et al. / Energy Procedia 00 (2017) 000–000
3
Straw treatment: For linseed treatment the crushed wheat/barley fibers have been firstly immersed in the linseed oil for different times (10s, 5, 10, 15 minutes, 1h). Then, fibers have been dried at 60 °C during 48 hours before there use in the mixture. For the second treatment, the straw fibers were impregnated (Figure 1) for the same times in the boiled water at 100°C beforehand. Fibers have been dried at 60 °C in the oven in the same way.
Fig. 1. Straw fibers treatment: (a) crushed straw; (b) linseed oil immersion; (c) boiled water immersion.
Composite manufacture: In order to limit the number of tested samples, only optimal time of impregnation is used (10 minutes), determined before the composite manufacture based on a comparison of Young modulus and the water absorption coefficients not presented here. The mixture procedure, the introduction in the molds and the curing conditions are the same of previous works [13] in order to compare the behavior and to keep the same thermal and mechanical compromise. The samples used for flammability are cut according the standard NF EN 11925-2 [15]. They measures 250 mm of height, 90 mm of length and 60 mm of width. According to the type of straw (wheat and barley), of binder (lime and plaster) and the treatment, eight composites with treated fibers are studied and compared with four composites prepared with non-treated fibers (Table 1). 2.2. Flammability test and thermal analysis In this work only flammability test for small flame is performed, in order to examine the reaction to fire of the straw composite and his fire classification according to the European standards. The flammability test has been conducted as described by EN 11925-2 [15]. For each straw-composite, the test is carried out for three specimens. The test consists to expose the material to a single flame for 15 s in class E and 30 s in class D. The burner was angled at 45° with the flame length of 20 mm. The distance between the burner and the tested surface is 5 mm. A plate is disposed below the tested surface to collect the burning droplets. Figure 2 present the flammability test performed in this work.
Fig. 2. Experimental flammability test under small flame of straw concrete. After removing the flame, the flame spread and the droplet occurrence are examined. For the class E and D, the flame spread should be less than 150 mm after 15 s and 30 s of flame exposure respectively. Infrared camera is
4
Naima Belayachi et al. / Energy Procedia 139 (2017) 544–549 N. Belayachi et al. / Energy Procedia 00 (2017) 000–000
547
installed for the temperature examination during and after the flame exposure. Thermogravimetric analyzer coupled to a differential scanning calorimetry was used to follow both the mass loss and the heat flow exchange during the thermal degradation of the different composites. These analysis are performed by LINSEIS STA PT-1000 apparatus under inert atmosphere. Powder samples of about 20 mg were placed in an alumina crucible and heated from ambient temperature to 1000 °C with a heating rate of 20 °C/min. 3. Results and discussion Table 1 summarizes the flame propagation height and the observation of the occurrence of the flaming droplets for the different straw composites. The Flame spread has been measured after 20 s after removing the burner. We can observed that for the different composites, the flame does not exceed 15 cm. The results shows also that the composites based on treated fibers with linseed oil record the smallest flame propagation. For a time of flame exposure more important (30 s), we can observed that the flame spread heights are larger but still less than 15 cm. Table 1. Flame spread for 15 s and 30 s of burner exposure. Composites and designation
Flame Height (cm) after 20 s removal burner for 15 s of exposure
Droplets Yes/No
Flame Height (cm) after 60 s removal burner for 30 s of exposure
Droplets Yes/No
Wheat-Plaster-Non treated (W-P-NT)
8.5
No
13.4
Yes
Wheat-Plaster-Boiled water (W-P-BW)
9.1
No
10.5
No
Wheat-Plaster-Linseed oil (W-P-LO)
6.1
No
10.2
No
Wheat - lime - Non Treated (W-L-NT)
7.9
No
8.6
No
Wheat-Lime-Boiled Water (W-L-BW)
6.7
No
8.1
No
Wheat-Lime-Linseed Oil (W-P-LO)
5.7
No
7.2
No
Barley-Plaster-Non Treated (B-P-NT)
13.1
Yes
14.2
Yes
Barley-Plaster-Boiled Water (B-P-BW)
7.5
No
9.3
No
Barley-Plaster-Linseed Oil (B-P-LO)
4.5
No
6.7
No
Barley-Lime Non Treated (B-L-NT)
8.2
No
8.5
No
Barley-Lime-Boiled Water (B-L-BW)
6.3
No
9.3
No
Barley-Lime-Linseed Oil (B-L-LO)
3.4
No
4.1
No
The linseed oil treatment behaves as a flame retardant. It was observed a few flaming droplets on the horizontal plate only for the composite based on non- treated barley straw. The boiled water treatment showed an effect on the flame spread in the case of the barley composite. It is observed also that the composite based on the lime binder have the smallest flame spread in the two times exposure for the two types of straw fibers. Figure 3 shows an example of the exposed surface to burner flame and the temperature during burning and after 5 minutes of exposure for barley lime composite. This figure demonstrate the fire performance of the straw composite, there is no spread flame after removing the burner with this time exposure. The exposure surface is not degraded material without dripping during this time ignition. The temperature decreases greatly after removal of the burner.
548
Naima Belayachi et al. / Energy Procedia 139 (2017) 544–549 N. Belayachi et al. / Energy Procedia 00 (2017) 000–000
5
Fig. 3. State of exposed surface and temperature field at 15 s and 5 min after flame for barley lime composite : (a) B-L-NT; (b) B-L-BW; (c) B-LLO.
The results represented on Figure 4, shows the effect of the treatment on mass loss and heat flow of the composites. It is clear on the TG curves that the two treatment showed an important effect on the composite degradation which reached 50 % for the linseed oil treatment. The highest mass loss about (30 %, 35% and 50%) respectively for non-treated, boiled water treated fibers and linseed oil treated fibers occurs in temperature interval of 260-500°C. The mass loss for the two stages occurs first for the composite based on linseed oil treated fibers with differences of about 40°C. The last stage at 700°C, shows a very low mass loss about 2%.
Fig. 4. TG curve and heat flow exchange of wheat-plaster composites with treated and non-treated fibers.
The important mass loss is accompanied by endothermic peak for the three composites with a difference for the linseed oil treated fibers. The exothermic peak presented on the DSC curve is occurs for the plaster binder due to a reaction which the molecular structure of the anhydrite rearranges to an insoluble anhydrite. The results of this part shows also, a significant effect of linseed oil treatment at the microscopic level with important mass loss. However, this effect is different for macroscopic level where his role was rather to spread flame retardant. So, the question remains open for the representative volume of TG-DSC tests for this type of highly heterogeneous material with high fibers content with multidirectional orientation. In addition, it is clearly observed that the binder nature and fiber variety have an important effect on the thermal degradation.
6
Naima Belayachi et al. Procedia / Energy Procedia (2017) 544–549 N. Belayachi et al. / Energy 00 (2017)139 000–000
549
4. Conclusion This paper investigates the effect of fiber treatment on the fire behavior and thermal degradation of the new biocomposite based on straw proposed for building insulation. The performed tests of the flammability and TG-DSC analysis in this work is a first attempt to understand the fire behavior of the straw based composite materials. The major conclusion of this investigation is the significant effect of the linseed oil treatment at macroscopic level by flammability test and microscopic level by TG-DSC analysis. The linseed oil treatment retards the flame spread and prevents the composite degradation. The flame spread is stopped after removing the flame burner for all composites. Barley based composite show a delicate fire behavior than the wheat-composite. In order to clarify the difference between macroscopic and microscopic level, further investigation is proposed by using the cone calorimeter test with representative samples to provide a better understanding of the fire performance of the proposed straw composite. Acknowledgements The authors express their special thanks Alain Bret for his help in performing the flammability tests. References [1] Wei, J, Meyer, C. Degradation rate of natural fiber in cement composites exposed to various accelerated aging environment conditions. Corrosion science, 2014, 88, p. 118-132. [2] Ali, M, Chouw, N. Experimental investigations on coconut-fibre rope tensils strength and pullout from coconut fibre reinforced concrete. Construction building materials, 2013, 41, p. 681-690. [3] Gomes, A, Matsuo, T, Goda, K, Ohgi, J, Development and effect of alkali treatment on tensile properties of curaua fiber green composites Composites : Part A, 2007, 38, p. 1811–1820. [4] Sellami, A, Merzoud, M, Amziane, S, 2013, Improvement of mechanical properties of green concrete by treatment of the vegetals fibers, Construction and Building Materials, 2007, 47, p. 1117–1124. [5] Hidalgo, J. P, Welch, S, Torero, J. L. Performance criteria for the fire safe use of thermal insulation in buildings, Const. and Build. Mat, 2015, 100, p. 285-297. [6] Naughton, A, Fan, M, Bregulla, J. Fire resistance characterization of hemp fibre reinforced polyster composites for use the construction industry, Comp. part B, 2014, 60, p. 546-554. [7] Bocz, K, Szolnoki, B, Marosi, A, Tabi, T, Wladyka-Przybylak, M, Marosi, G,. Flax fibre reinforced PLA/TPS biocomposites flame retarded with multifunctional additive system, Poly. Degrad. And Stab, 2013, 106, p. 63-73. [8] Chattopadhyay, D. K, Webster Dean C,. Thermal stability and flame retardancy of polyurethanes, Prog. Poly. Scien, 2009, 34, p. 1068 1133. [9] Fox, D. M, Novy, M, Brown, K, Zammarano, M, Harris, R. H, Murariu, M, McCarthy, E, Seppala, J. E, Gilman, J. W,. Flame retarded poly(lactic acid) using POSS-modified cellulose:2. Effect of intumescing flame retardant formulations on polumer degradation and composite physical properties, Poly. Degrad. And Stab, 2009, 106, p. 54-62. [10] Laoutid, F, Bonnaud, L, Alexandre, M, Lopez-Cuesta, J. M, Dubois, Ph. New prospects in flame retardant polymer materials: from fundamentals to nanocomposites, Mat. Sci. and Eng R, 2009, 63, p. 100-125. [11] Monti, M, Tsampas S. A, Fernberg, S. P, Blomqvist, P, Cuttica, F, Fina, A, Camino, G. Fire reaction of nanoclay-doped PA6 composites reinforced with continuous glass fibers and produced by commingling technique, Poly. Degrad. & Stab. 2015, 121, p. 1-10. [12] Ju, Y, Liao, F, Dai, X, Cao, Y, Li, J, Wang, X. Flame-retarded biocomposites of poly(lactic acid): distiller’s dried grains with solubles and resorcinol di (phenyl phosphate), Composites A, 2016, 81, p. 52-60. [13] Belayachi, N, Bouasker, M, Hoxha, D, Al-mukhtar, M. Thermo-mechanical behaviour of an innovative straw lime composite for thermal insulation applications, Applied. Mechan. and Mat, 2013, 390, p. 542-546. [14] Bouasker, M, Belayachi, N, Hoxha, D, Al-Mukhtar, M. Physical characterization of natural straw fibers as aggregates for construction materials applications, Materials, 2014, 7, p. 3034-3048. [15] EN ISO 11925-2, Reaction to fire tests, Ignitability of building products subjected to direct impingement of flame-Part 2: single flame source test. [16] Younis, A. A. Evaluation the flammability and thermal properties of a new flame retardant coating applied on polyster fabric, Egypt. J. Petrol. http://dx.doi.org/10.1016/j.ejpe.2015.04.001 [17] Garcia, M, Hidalgo, J, Garmendia, I, Garcia-Jaca, J. Wood-plastics composites with better fire retardancy and durability performance, Comp. part B, 2009, 40, p. 1772-1776. [18] Haurie, L, Mazo, J, Delgado, M, Zalba, B. Fire behavior of a mortar with different mass fractions of phase change material for use in radiant floor systems, Energy. Build., 2014, 84, p. 86-93. [19] Palumbo, M, Formosa, J, Lacasta, A, M. Thermal degradation and fire behavior of thermal insulation materials based on food crop byproducts, Const. and Build. Mat., 2015, 79, p. 34-39.