An environmentally friendly thermal insulation material from sunflower stalk, textile waste and stubble fibres PDF

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Construction and Building Materials 51 (2014) 24–33 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat An environmentally friendly thermal insulation material from sunflower stalk, textile waste and stubble fibres Hanifi B...

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Construction and Building Materials 51 (2014) 24–33

Contents lists available at ScienceDirect

Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat

An environmentally friendly thermal insulation material from sunflower stalk, textile waste and stubble fibres Hanifi Binici a,⇑, Mustafa Eken a, Mustafa Dolaz b, Orhan Aksogan c, Mehmet Kara a a

Department of Civil Engineering, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100, Turkey Department of Environment Engineering, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100, Turkey c Department of Civil Engineering, Toros University, Mersin 33140, Turkey b

h i g h l i g h t s

g r a p h i c a l a b s t r a c t

 Heating costs in winter and cooling

costs in summer is very high.  To reduce heating and cooling costs

are building insulation.  Sunflower production in Turkey

carried out a significant amount.  This type of use is causing serious

problems in the environment.  The use of waste materials to produce

a new insulation material.

a r t i c l e

i n f o

Article history: Received 24 June 2013 Received in revised form 7 October 2013 Accepted 19 October 2013 Available online 15 November 2013 Keywords: Sunflower stalk Stubble Textile waste Insulation material

a b s t r a c t Heating costs in the winter and cooling costs in the summer are very high. Building insulation reduces heating costs in the winter and cooling costs in the summer. Although sunflower production in Turkey is significant, after the production the sunflower stem is a serious problem for farmers. Sunflower stems are cleaned, burned or used for temporary heating purposes. This type of use is causing serious problems to the environment. Sunflower stalks and cotton textile waste, such as stubble, cause serious environmental problems. To circumvent this problem, the present study puts forth an advantageous use of those waste materials for insulation of buildings. In Turkey there are a lot of both of the aforementioned materials. As the binder for those two materials epoxy was used. As samples, 30  40  2.5 cm rectangular blocks were prepared under different pressures. The samples were tested for their mechanical properties and the coefficients of thermal conductivity, as well. The results obtained satisfied the Turkish Standard TS 805 EN 601. Thus, the method proposed in this study solves two industrial problems at the same time. A useful construction material is produced while some waste materials causing environmental problems are warded off. Ó 2013 Elsevier Ltd. All rights reserved.

1. Introduction

⇑ Corresponding author. Tel.: +90 (344) 2801660; fax: +90 (344) 2801602. E-mail addresses: [email protected] (H. Binici), [email protected] (M. Eken), [email protected] (M. Dolaz), [email protected] (O. Aksogan), mehmetkara@ ksu.edu.tr (M. Kara). 0950-0618/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.conbuildmat.2013.10.038

Insulation materials in buildings have become widely used since the beginning of the 20th century. The new building and construction systems provide many benefits and some drawbacks in terms of building physics and the conditions of comfort that emerge as time passes. The exterior walls must be thin to prevent

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H. Binici et al. / Construction and Building Materials 51 (2014) 24–33 O

O H2 N

NH2

H

H

O

O

O H2N

+

NH CH2 OH

+

NH HOH 2C

NH CH2 OH

+

NH HOH 2 C

N

CH2 OH

CH2 OH

Fig. 3. Formation of mono-, di-, and trimethylolurea by the addition of formaldehyde to urea.

Fig. 1. Cotton waste.

Table 1 Potential of agricultural waste in Turkey [14]. Agricultural residues

Annual production (million tonnes)

Sunflower stalks Wheat stalks Barley grips Corn stalks Cotton stalk and cocoons Sugar beet grips Hazelnut shells Oats grips Rye grips

2.7 26.4 13.5 4.2 2.9 2.3 0.8 0.5 0.4

the load carrier system [1]. In recent years, energy resources have rapidly decreased. Approximately 40% of the energy is spent on buildings in Turkey [2]. Although the total energy consumption per capita in the last 25 years has increased by 5%, this ratio has increased by over 100% in Turkey [3] due to the energy consumption to heat uninsulated houses with an average of 200 kW h/m2 per year. Heating houses requires financial resources of 3.5 billion dollars. Today, the cost of the energy required for the heating of houses is estimated to be more than 4 billion dollars. The calculations made by the isolation of the entire building stock according to the existing standards shows energy savings of over 2 billion dollars per year. Therefore, the use of insulation materials has become a necessity. The production of appropriate materials for insulation materials is of great importance. Insulation materials are usually produced from inorganic materials. In recent years, these materials have been prohibited due to the suspicion of health risks Thus, it is important to investigate organic-based insulation materials. Mengeloglu and Alma [4] studied intensive technological developments and solved production problems with wheat stalks, which led to the successful production of composite panels. Wheat straw particle board and fibre boards have been found to be more advantageous than others. In Turkey, there is a significant amount of sunflower production. There are 2,500,000 tons of waste per year in the form of sunflower stalks, which is a serious problem for farmers growing sunflower stalks. Monika et al. [5] determined the coefficients of thermal conductivity of composites obtained by using natural fibres. The results for these composites are lower than the heat transfer coefficients of artificial fibres, and they are more economical, do not harm the environment, and have better

mechanical properties. However, the wheat stubble remaining in the fields after harvesting is significant, and the environmental pollution is caused by the incineration of waste [6]. Most of the farmers burn the stubble after harvest due to the lack of economic value of wheat stalks. The burning stubble represents a loss of national wealth and destroys soil micro-flora in addition to polluting the atmosphere. Approximately 40% of cereal stubble fields in Turkey are burned every year and 10 million tons of exposed stalks and straw disappears. As a result, the release of smoke and carbon dioxide into the atmosphere causes global warming. However, the use of lignocelluloses has a long history. In ancient Egypt, adobe mud mixed with straw was used. In the experimental studies, it was found to have a much lower coefficient of heat conduction than mud bricks [7]. Cristel et al. [8] changed the ratio of vegetable fibre in cement composites. The vegetable fibres produced a slight decrease in the thermal conductivity, and the mechanical strength of the composites increased. In addition, the use of more fibre composites can reduce weight and reduce the coefficient of thermal conductivity. Zhou et al. [9] manufactured an environmentally friendly heat insulation material using a resin and cotton stalks. The cotton stalk fibres created an insulation material that can compete with others. The thermal insulation properties of fabrics formed from natural and synthetic fibres are compared. Artificial fabrics composed of cotton based fabrics that have a lower value than the corresponding thermal conductivity, thermal absorption, and thermal diffusion resistance were found in the study. In addition, the thermal insulation characteristics of the type of weaving are effective [10]. Briga-Sá et al. [11] investigated the feasibility of fabric waste as a heat insulation material. It appears to be an adequate solution as a possible heat insulation material to recycle these wastes, and environmental sustainability and economic benefits may result from these applications. Binici et al. [12] studied a new insulating material produced by light cotton waste and textile ash and investigated the properties of the materials produced. In another study, cotton waste, fly ash, and light building materials manufactured with epoxy resin could be used as thermal and acoustic insulation materials [13]. As shown in previous studies, waste is of great importance in our world now. The use of alternative waste due to the rapid

Fig. 2. Sunflower stalks.

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H. Binici et al. / Construction and Building Materials 51 (2014) 24–33

Table 2 Chemical, physical and mechanical properties of the gypsum used. Chemical properties

Physical and mechanical properties Specific gravity (g/cm3)

CaSO41/2H2O

0.95

Sieve analysis (%) Residue on 0.2 mm

Residue on 1.25 mm

18

0.2

Table 3 The weights of mixing parts. Components (g) Gypsum

Sunflower stalks

Textile waste

Water

1500

180

90

1450

Setting time (min)

Compressive strength (MPa)

4

8.4

burning causes an enormous amount of soil, plant, and environmental damage. Therefore, it reduces the soil fertility, and nutritional floras are destroyed. Soil erosion is caused by wind and flood. The natural balance is disturbed and will lead to forest fires, where neighboring fields and gardens are sometimes burned. Among the other dangers of burning stubble is the burning of telephone poles and, even worse, the reduction of the visibility of cars passing by, which causes fatal accidents. The stubble used for this study was obtained from Elbistan.

2.1.2. Textile wastes Turkey is ranked seventh in the world in terms of area sown for cotton, fourth for cotton yield per unit area in terms of fibre obtained, sixth in terms of the amount of production, fifth in consumption, and fourth in imports [12]. Turkey’s domestic fibre consumption in the year 2004 was a total of 2.75 million tons. Textile wastes were obtained in the factories in Kahramanmarasß.

Fig. 4. Insulation boards.

depletion of natural resources is inevitable. The aim of the present study was to produce a new insulation material with a low heat transfer coefficient using lighter waste materials.

2. Materials and methods 2.1. Materials 2.1.1. Stubble Stubble a result of agricultural production and is cut from the remaining root crops, soil, and deviation. In Turkey, approximately 40 million tons of wheat, barley, and rye are produced. Thus, one million hectares are being cultivated in the area. Here, approximately 10 million tons of stubble can be obtained and up to approximately 128 million m3 of insulation material can be produced. The production of insulating material can prevent contamination of the environment and recycle stubbles. In this way, the atmosphere would receive approximately 2000 kg less CO2. Given the hundreds of thousands of square metres of total area, the amount of CO2 created by the burning of stubble should not be underestimated. Stubble

2.1.3. Cotton wastes The cotton waste obtained from the textile factories in Kahramanmaras was used in this study (Fig. 1). Today, waste recycling is very important due to the maximum level of energy consumption. The potential of agricultural waste in Turkey is shown in Table 1.

2.1.4. Sunflower stalks The sunflower production in Turkey in 2012 was 1.37 million tons. During the production of a ton, approximately 1.4 tons of sunflower seeds and sunflower stalks are grown, which means that approximately 8.8 million m3 of insulation material can be produced from the sunflower stem. The amount of insulating material needed by the country is 5 million m3, and the remaining amount can be offered to foreign markets. Sunflower stalk that emerges after production is a serious problem for farmers (Fig. 2). The stems from the field are usually burnt, which is damaging to the environment and causes economic loss to the country as well.

2.1.5. Urea–formaldehyde adhesive resins Urea–formaldehyde resins are formed by the reaction of urea and formaldehyde. The overall reaction of urea with formaldehyde is quite complex and, although initially studied early in this century, is not completely understood at the present time [15]. The synthesis of a urea–formaldehyde resin occurs in two stages. In the first stage, urea is hydroxymethylolated by the addition of formaldehyde to the amino groups (Fig. 3). This reaction is in reality a series of reactions that leads to the formation of mono-, di-, and trimethylolureas [16].

Fig. 5. Application of insulation material panels on the brick wall.

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H. Binici et al. / Construction and Building Materials 51 (2014) 24–33 Table 4 Mixing ratio by volume. Samples

A B C D E F G H J K L M N O P R S T U V Y Z N1 B1 U1 S1 Z1 N2 Z2 S2 U2 N3 U3 Z3 S3 N4 U4 Z4 S4 U5 N5 N6

Sample content (%) Sponge portion of the sunflower stem

Sunflower stalk fibres

33.85 43.08 40.00 15.79 38.46 31.58 20.00 24.15

35.38 33.85 36.92 31.58 38.46 42.11 30.00 24.15 23.53

Cotton waste

Textile waste

33.33 40.00 33.33 33.33 35.21 39.47 35.29 36.36 37.04 10.53 33.78 33.33 39.22 51.02 46.15 30 31.75 32.14 7.69 9.23 9.23 9.23 7.69 9.23 9.23 7.69 9.23 9.23

21.05

20.00 15.46 23.53 71.88

25.00 70.00 16.67

16.67 20.00 16.67 33.33 8.45 7.89

16.67 28.17 26.32 35.29

7.41 71.93 5.41 16.67

36.36 24.69 33.78 16.67 31.37

8.16 30.77 8 12.70 10.71 3.08

12 23.81 21.43 4.62 6.15

2.46 1.85 3.08

4.62 6.15 4.62 6.15

2.46 3.08 1.54 1.54

4.62 4.62 6.15 7.69

Pressure (bar)

23.08 23.08 23.08 31.58 23.08 26.32 30.00 36.23 52.94 28.13 43.84 22.58 50.00 30.00 33.33 40.00 33.33 33.33 28.17 26.32 29.41 27.27 30.86 17.54 27.03 33.33 29.41 40.82 23.08 20 31.75 35.71 6.15 6.15 6.15 6.15 6.15 6.15 6.15 6.15 6.15 6.15

10 10 10 10 10 10 9 9 9 9 9 8 8 8 8 8 8 8 6 6 6 4 6 6 6 7 6 6 7 7 7 5 7 7 7 7 7 7 8 8 8 7

Stubble

7.69

56.16 77.42 25.00

Epoxy %

Note: 1 bar = 0.0197 kg/cm2.

The addition of formaldehyde to urea occurs over the entire pH range. The reaction rate is dependent on the pH. The rate for the addition of formaldehyde to successively form one, two, and three methylol groups has been estimated to be at the ratio of 9:3:1 [15]. The exact ratio, of course, is dependent on the reaction conditions employed in the addition reaction. The second stage of urea–formaldehyde resin synthesis consists of the condensation of the methylolureas to low molecular weight polymers. The rate at which these condensation reactions occur is very dependent on the pH and, for all practical purposes, occurs only at acidic pHs.

2.1.6. Plaster The chemical, physical and mechanical properties of the plaster used in the study are given in Table 2.

2.2. Method 2.2.1. Insulation boards manufactured with plaster as a binder The grinding machine was used for the agriculture and textile wastes, which were ground in a mixture of sunflower stalks. These materials were used with plaster as a binder. The mixing ratio of the insulation material is given in Table 3. Insulation boards that were 30  40  2.5 cm in size were attached to the wall panels in Figs. 4 and 5. These tests were applied to walls only. The sound and thermal insulation values of the rooms were measured. These rooms were located next to isolated and untreated identical rooms, and other rooms were created with the same points. Acoustic measurements of sound insulation in industrial buildings made with fibre reinforced mud bricks, concrete bricks and red bricks were performed according to the EN TS 415 [16]. The foregoing standard specifies field methods for measuring the airborne sound insulation properties of interier walls

between two rooms [17]. Sound absorption coefficients of the samples were measured under the same humidity conditions. The relative humidity was 40% and the frequency of the sound was 800 Hz1/3 octave filters were used [13]. 2.2.2. Insulation materials made with epoxy binder The fibre insulation material was produced with sunflower stalks, cotton waste, and textile waste fibre and epoxy as binder materials. Using these raw materials, various samples were produced at different rates and under different pressures. Moisture content of samples was 0.15% and the size of the samples was 20  20 cm. The samples produced are described by the volume mixing ratios and by the weight of the samples in Table 4 in Table 5, respectively. The reason for the trial was to determine the heat transfer coefficient, which required a large amount of material in the mixture and a wide range of pressures. Initially, A, B, C, . . . Z attempts were made. Then, the heat transfer coefficient experiments focused on examples smaller than 0.1. The insulation material used in the production of the raw materials, the sunflower stalk fibre, the sunflower stalks, the stubble, the cotton waste, and the textile fibre waste, are given in Figs. 6 and 7. The heat insulating blocks were 14  16  2 cm in size. The production scheme of the insulation material is given in Fig. 8. Each layer of insulating material was made separately and remained under pressure for optimum compaction (Fig. 9). The difference between the pH profiles of the two stages of urea–formaldehyde resin synthesis is used to advantage in the production of urea–formaldehyde adhesive resins. In general, the commercial production of urea–formaldehyde adhesive resins is performed in two major steps. The first step consists of the formation of methylolureas by the reaction of urea and formaldehyde under basic conditions with a pH of 8–9. This step is performed under basic conditions to allow the methylolation reactions to proceed in the absence of reactions involving the condensation of the methylolureas. In the second step, the reaction mixture is brought to

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H. Binici et al. / Construction and Building Materials 51 (2014) 24–33

Table 5 Mixing ratio by weight. Samples

A B C D E F G H J K L M N O P R S T U V Y Z N1 B1 U1 S1 Z1 N2 Z2 S2 U2 N3 U3 Z3 S3 N4 U4 Z4 S4 U5 N5 N6

Sample content (%) Sunflower stem

Sunflower stalk fibres

Cotton waste

110 140 130 37.5 125 150 50 50

115 110 120 75 125 200 75 50 20

25

Textile waste

30 30 30 30 25 30 30 20 30 12 25 20 20 25 30 30 20 18 25 30 30 30 25 30 30 25 30 30

50

50 32 20 115

15 70 15

15 15 15 30 6 6

15 20 20 30

6 82 4 10

20 20 25 10 16

4 20 8 8 6 10

12 15 12 15 20

8 6 10

15 20 15 20

8 10 5 5

15 15 20 25

Pressure (bar)

75 75 75 75 75 75 75 75 45 45 32 35 30 30 30 30 30 30 20 20 25 15 25 20 20 20 15 20 15 20 20 20 20 20 20 20 20 20 20 20 20 20

10 10 10 10 10 10 9 9 9 9 9 8 8 8 8 8 8 8 6 6 6 4 6 6 6 7 6 6 7 7 7 5 7 7 7 7 7 7 8 8 8 7

Stubble (%)

41 120 15

Epoxy %

Fig. 6. Sunflower stalk and stubble.

the acid side, with a pH of approximately 5, and the condensation reactions are performed until a desired viscosity is reached. Then, the reaction mixture is cooled and neutralised. Water is removed by vacuum distillation to give a resin with the desired solids content (typically approximately 60–65%). Urea is ...