A Study on Absorption Coefficient of Sustainable

INTERNATIONAL CONFERENCE ON GLOBAL SUSTAINABILITY AND CHEMICAL ENGINEERING (ICGSE) 2014

A Study on Absorption Coefficient of Sustainable Acoustic Panels from Rice husks and Sugarcane Baggase Farrah Zuhaira Ismaila* Mohamad Nidzam Rahmatb Norishahaini M Ishakc acb

Centre of Construction Management, Faculty of Architecture, Planning and Surveying, Universiti Teknologi MARA 40450 Shah Alam, Selangor, Malaysia *

Corresponding author. Tel.: +06 012 6599724; Fax: +06 03 5543 6591 E-mail address: [email protected] / [email protected]

Abstract. Noise has detrimental effects on human lives and it is a nuisance to the environment. As many of the available sound reduction materials in the current market are hazardous, there are demands for alternative sustainable materials to reduce the noise problem. Therefore, the aim of this research is to study the potential of using an agricultural waste as sound absorption panel. For the purpose of this study, the combination of two materials was under studied; rice husks and sugarcane baggase. There were two main objective of the research; first is to develop absorption panels from the combination of rice husks and sugarcane baggase at different percentage of mixture. Second objective is to identify the absorption rate of the panels. The study encompasses the fabrication of the sustainable sound panels using the rice husk and sugarcane fibre and bond using Phenol formaldehyde (PF). Five panels of sized 12 inch x 12 inch and 12 mm thick were fabricated. The absorption coefficient of the samples was done at the acoustic lab, Faculty of Engineering & Build Environment, Universiti Kebangsaan Malaysia (UKM), Bangi. The panels were tested using an impedance tube. The procedure of the test was carried out in accordance with ISO 10534-2:1998 standards. Based on the results, sample 1 gave the highest absorption coefficient compared to sample 2, 3, 4 and 5. It can be concluded that the acoustic panel made from a mixture of 100% rice husks had higher absorption co-efficient compared to the performance of the other samples given the fact that the characteristic of the rice husks which has air gap in every single piece of rice husk. The spongy properties of the sample 1 panel has created many void spaces which encouraged more sound absorption capability due to the porous surface of the panel. Sound absorption is very much affected by the availability of porosity level of the panel. Thus, further studies on other potential materials from waste should be conducted. Keywords. Noise, Agriculture waste, sound, absorption panels, absorption co-efficient Introduction The issue of noise has becoming unavoidable these days. People are exposed more and more to the danger of noise. Noise can cause general types of negative effects. They are; hearing loss, no auditory health effect, individual behavior, effect on sleep, communication interference and effect on domestic animals and wildlife (Z. Rozli et al, 2010). This nuisance has resulted in many means of mitigations pertaining to it. This includes the production of sound panels which could reduce the noise by absorbing the sound. All materials absorb sound to some extent. Acoustical materials are those materials whose primary function is to absorb sound which they usually absorb a large fraction of the acoustical energy which strikes them. Salter (2002) stated that all materials have some sound-absorbing properties. The more fibrous a material is the better its absorption capability; and denser materials on the other hand are less absorptive. Sound absorption coefficient is the efficiency of the material or the surface to absorb the sound. The range of sound absorption coefficients for building materials normally varies from 0.01 to 0.99. Materials with medium to high sound absorption coefficients (usually > 0.50) are referred to as sound – absorbing; those with low coefficients (usually 0.20) are sound reflecting (Egan, 2007). Comprehensive information is provided not only of the sound absorption 1|Page


coefficients of the materials but also other characteristics that are important in the selection of acoustical materials, such as their physical characteristics and weight per unit area (C. M. Harris, 1994). Agricultural waste products such as coir (Cocosnucifera) fiber, rice (Oryza sativa) husk and oil palm (Elaeisguinnesis) frond fibre can be found in a lot in Malaysia. For that reason, many researches had been carried out to study the potential of turning the agricultural waste into sound absorption panel. Not only this can solve the waste problem, it could also help reducing the noise issue. Dam et al (2003) agreed that at some level the coconut coir can be made an acoustic panel for its sound absorption character such as spongy and fibrous. Khedari et al. (2004) has developed particle composite boards from agricultural waste products using combinations of durian peel and coir fibre straw particles replacing wood as an insulation board in wooden construction industry. In some research conducted by Zulkifli et al (2009), they concluded that organic natural fibres have various usages in many structural and non-structural applications such as automotive lining component and acoustic absorption barrier. Yang et al. (2003) had initiated a study on the acoustic properties of rice straw-wood particle composite boards and found that the sound absorption coefficient is higher than other wood-based materials which are due to the low specific gravity of the composite boards. Other potential agricultural wastes are sugarcane baggase and rice husks. Sugarcane baggasse is the ﬁbrous residual material of the sugarcane stems which usually are abandon after the crushing process and extraction process from sugar mills, which normally accounts for 20–24% of the cane. The outer rind made of hard fibrous substances which are surrounds of the central core of the pith which has the softer and spongy characteristics (Wirawan et al., 2010). Rice husk on the other hand is quite fibrous by nature and particle board which made from rice husks can be extremely durable. (Johnson, A. C., & Nordin, Y. 2009). Various types of boards can be produced from rice husk. By-products include particleboard, insulation board and ceiling board. This paper aims to study the potential of producing sound absorption panels from the combination of two agricultural waste; rice husks and sugarcane baggasse. This study revolved around the sound absorption performance of both materials. Materials and Experimental Design a) Target Materials For the purpose of the research, two types of agricultural waste were used; rice husks were supplied by Tiram Jaya Factory and sugarcane baggase was collected from street hawkers within Shah Alam. The properties of rice husk and sugarcane baggase are shown in Table 1. Table 1: The properties of risk husk and sugarcane baggase Composition (Wt %) Rice Husk 1 Sugarcane Baggase 2 SiO2 18.80 – 22.30 Lignin 9.00 – 20.00 Cellulose 28.00 – 38.00 Hemicelluloses Protein 1.90 – 3.00 Fat 0.30 – 0.80 Other nutrients 9.30 – 9.50 1 2 Johnson and Yunus (2009), (Wirawan et al., 2010).

19.95 46.00 24.50 3.50 -

2|Page


b) Specimen Preparation Five samples were produced for this study. The mix proportions of rice husk fibers and sugarcane baggase are as follows: • • • • •

Panel 1 contains 100% of rice husk fibres, Panel 2 contains 70% of rice husk fibre, 30% of sugarcane baggase, Panel 3 contains 50 % of rice husk, 50% sugarcane baggase, Panel 4 contains 30% of rice husk, 70% of sugarcane baggase Panel 5 contains 100% sugarcane baggase (acts as a control).

The study encompasses the fabrication of the sustainable sound panels using the rice husk and sugarcane fibre. PF resin was used to bond the fibres together. Five panels of sized 12 inch x 12 inch and 12 mm thick were fabricated. Process of fabrication from the raw material to the sound panels involved several steps. First, the raw materials were dried to get rid of any moisture. Only the sugarcane baggase were then crushed using the crushing machine to turn them into smaller size. The crushing machine was installed with 5mm filter which only allowed less than 5mm residue to pass through. More than 5mm residue were left behind and crushed again to ensure it turns into the size desired. The crushed sugarcane baggase were again dried in the oven. When the raw materials were ready, the mixing of the materials was done according to the fixed proportions. The mixtures were then casted into the mould which was coated with oil and later compressed using cold press machine. Finally, the compressed mixtures were compressed using the hot press method. At this stage, the panels were nicely formed and left to cool off before proceeding with the sound absorption test procedure using the impedance tube test. The procedure of the test can be seen in Figure 1.

1) Samples were prepared for testing. Samples were cut to 99.8mmø and 27.8mmø. 99.8mmø for low frequency and 27.8mmø for high frequency.

6) Data recorded using DBFA Suite software.

2) Details of the samples were recorded : a. Weight of the specimen b. Thickness of the specimen(10mm to 70mm)

3) The specimen was inserted into the tube.

5) The generator and amplifier were switched on and the sound test started.

4) The tube was closed firmly.

Figure 1: The procedure of the impedance tube test. 3|Page


Results and Discussion The aim of the research was to study the potential of creating a sustainable sound absorption panel using the combination of rice husks and sugarcane baggase. From the results it can be considered that the sound panels from the combination of these two waste materials could insignificantly absorb sound. Less sound was absorbed especially at the lower frequency. The absorption coefficient of the panels can be seen ranging from 0.00 to 0.58 at frequency of 63Hz to 4000Hz. Table 2 and Figure 1 shows the simulation values of sound absorption coefficient of the panels. Noise reduction coefficient or Alpha value was taken as an average of the absorption coefficient at seven octave band frequencies of 63, 125, 250, 500, 1000, 2000, 4000Hz by using standard method of ISO 10534-2: 1998.

Sample

Panel 1 Panel 2 Panel 3 Panel 4 Panel 5

Table 2: Sound absorption coefficient data of the samples. Absorption Coefficient Content (%) Rice Sugarcane Husk Baggase 63 Hz 125 Hz 250 Hz 500 Hz 1000 Hz 100 0 0.02 0.05 0.10 0.20 0.39 70 30 0.07 0.09 0.10 0.12 0.32 50 50 0.05 0.07 0.08 0.10 0.13 30 70 0.01 0.03 0.05 0.07 0.09 0 100 0.00 0.01 0.03 0.05 0.06

2000 Hz 0.50 0.38 0.20 0.12 0.10

4000 Hz 0.58 0.40 0.31 0.20 0.19

Figure 2 shows that, the sound absorption coefficient are 0.02, 0.05, 0.10, 0.20, 0.39, 0.50 and 0.58 at respective frequency of 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz for panel 1. It can be seen that after the maximum absorption of 58% at 4000Hz, the absorption performance started to decline. However, panel 1 demonstrates the highest absorption coefficient given that the characteristic of the rice husks which has air gap in between piece of rice husk. The spongy properties of the panel 1 has created many void spaces which encouraged more sound absorption capability. Theoretically, the porous material absorbs more sound than the non porous material. For panel 2, the sound absorption coefficient are 0.07, 0.09, 0.10, 0.12, 0.32, 0.38 and 0.40 at the frequency of 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz respectively. After the maximum absorption of 40% at 4000Hz, the absorption coefficient drops significantly at the higher frequency range. This panel consists of major amount of rice husk which is 70%. The rice husk had played a major role in absorbing sound. However, the sugarcane bagasse particles which were in micro size, had made the panels more compacted compared to panel 1 and thus reducing the availability of void space to absorb more sound.

4|Page


Absorption coefficient 0.7

Noise absorption coefficient

0.6

0.5

0.4

Panel 1 Panel 2 Panel 3

0.3

Panel 4 Panel 5

0.2

0.1

0 0

500

1000

1500

2000

2500

3000

3500

4000

4500

Frequencies (Hz)

Figure 2: The absorption coefficient graph for the samples

The sound absorption coefficient for panel 3 are 0.05, 0.07, 0.08, 0.10, 0.13, 0.20 and 0.31 at the frequency of 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz respectively. At the lower frequency range, the absorption rate is less than 10% and after achieving the maximum absorption of 31% at 4000Hz, the absorption starts to decline. The rapid drop of sound absorption coefficient in the high frequency region can be seen in the graph. With equal percentage of 50% of both materials, the capability of the rice husk to absorb sound is limited by the increase amount of compaction affect from the sugarcane baggase. This has made the sample to have more of a reflection character rather than absorption. The same situation can be observed for panel 4. With the majority of 70% content of sugarcane baggase, the sample seemed to have lesser void space to absorb sound effectively. Although the sample is sturdier, the absorption coefficient however, decreases. For sample 4, the sound coefficient are 0.01, 0.03, 0.05, 0.07, 0.09, 0.12 and 0.20 at the frequency of 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz respectively. For panel 5 which contains 100% of sugarcane baggase, the sound absorption coefficients are 0.00, 0.01, 0.03, 0.05, 0.06, 0.10 and 0.19 at the frequency of 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz respectively. The sound coefficient is at the lowest for this sample. The increase amount of sugarcane baggase used seemed to have affected the sound absorption performance. When more sugarcane baggase was used, the panels seemed to be more compacted and the tendency for the panels to reflect the sound is higher.

5|Page


Conclusion This study had successfully produced the sustainable acoustic panels using the mix proportion of rice husks and sugarcane baggase. Based on the results, sample 1 with 100% content of rice husks gave the highest absorption coefficient. The spongy properties created by the characteristic of the rice husks in the sample 1 panel has created many void spaces which encouraged more sound absorption capability. As for the sound absorption performance of sample 2, 3, 4 and 5, it can be said that the results is marginally achieved. Although the sugarcane baggase contains many fibers, it however gives more of a reflection characteristic rather than absorption when compacted into a panel. The sugarcane baggase may insignificantly perform as a good absorption but it could definitely provide sturdiness to the panel. Acknowledgment The authors would also like to thank Faculty of Architecture, Planning and Surveying, Faculty of Civil Engineering for their technical support and Universiti Teknologi MARA (UiTM) Research Acculturation Grant Scheme (RAGS) 600-RMI/RAGS 5/3 (32/2012) for sponsoring this research. References 1. R. Zulkifli, M.J. Mohd Nor, M.F. Mat Tahir, A.R. Ismail and M.Z. Nuawi, 2010. Noise Control Using Coconut Coir Fiber Sound Absorber with Porous Layer Backing and Perforated Panel, American Journal of Applied Sciences 7 (2): 260-264 2. Salter (2002), Acoustic for Libraries, Institute of Museum and Library Design. 3. M. David Egan (2007), Architecture Acoustics, J. Ross Publishing Classics. 4. Cyril M. Harris, 1994. Noise Control in Buildings, a practical guide for architects and engineers, McGraw Hill Inc. USA. 5. Jan E.G. and Van Dam (2003), Production process for high density high performance binderless boards from whole coconut husk, Elsevier B.V. Industrial Crops and Products 20 (2004) 97–101. 6. Joseph Khedari, Noppanun Nankongnab, Jongjit Hirunlabh, Sombat Teekasap. New lowcost insulation particleboards from mixture of durian peel and coconut coir. Building and Environment, 2004, 39, 59–65. 7. R. Zulkifli, M.J. Mohd Nor, M.F. Mat Tahir, A.R. Ismail and M.Z. Nuawi, 2009. Comparison of Acoustic Properties between Coir Fibre and Oil Palm Fibre, European Journal of Scientific Research, ISSN 1450-216X Vol.33 No.1 (2009), pp.144-152 8. Yang, H.S., D.J. Kim and H.J. Kim, 2003. Rice straw-wood particle composite for sound absorbing wooden construction materials. Bioresour. Technol., 86: 117-121 9. R. Wirawan, S.M. Sapuan, RobiahY, A. Khalina, 2010. Flexural properties of sugarcane bagasse pith and rind reinforced poly(vinyl chloride). Materials Science and Engineering, 11 (2010), pp. 1–4 10. Johnson A.C and Yunus N. (2009, June). Particleboards from Rice Husk:A Brief Introduction to Renewable Materials of Construction. JURUTERA. Retrieved from https://www.myiem.org.my/assets/download/Feature-Particleboard0609.pdf. 11. S. Mahzan, A.M. Ahmad Zaidi, M.I.Ghazali, M.N. Yahya, and M. Ismail, 2009. Investigation on Sound Absorption of Rice-Husk Reinforced Composite, Proceedings of MUCEET 2009 Malaysian Technical Universities Conference on Engineering and Technology. 12. Fiorelli J, Sertori DL, Cravo JCM, Savastano H Jr, Rossignolo JA, Nascimento MF et al. Sugarcane bagasse and castor oil polyurethane adhesive-based particulate composite. Material Research. 2013; 16:439-446. 13. Lee HH and Kang CW. Development of rice hull insulation board using urea formaldehyde resin. Journal of Korean Wood Science and Technology. 1998; 26(4):50-55. 14. Ndazi B, Tesha JV, Karlsson S and Bisanda ETN. Production of rice husks composites with Acacia mimosa tannin-based resin. Journal of Material Science. 2006; 41(21):6978-6983 15. Ashori A, Nourbakhsh A and Karegarfard A. Properties of médium density fiberboard based on bagasse fibers. Journal of Composite Materials. 2009; 43:1927-1934

6|Page