Malaysian Journal of Analytical Sciences Vol 25 No 3 (2021): 446 - 465

 

 

 

 

PREPARATION AND CHARACTERIZATION OF COGON GRASS NATURAL FIBER AS A CONCRETE FILLER FOR GAMMA RADIATION SHIELDING

 

(Penyediaan dan Pencirian Serat Semula Jadi Rumput Cogon sebagai Pengisi Konkrit untuk Perisai Sinar Gama)

 

Yusrina Mohd Yusof and Siti Amira Othman*

 

Department of Physics and Chemistry, Faculty of Applied Sciences and Technology

Universiti Tun Hussein Onn Malaysia, 84600 Pagoh, Johor, Malaysia

 

*Corresponding author:  sitiamira@uthm.edu.my

 

 

Received:  3 April 2021; Accepted: 2 June 2021; Published: 27 June 2021

 

 

Abstract

Concrete is a combination of cement, fine aggregate, coarse aggregate, and water. Concrete has a high shielding potential against gamma radiation from radioactive source. Concretes having a higher attenuation coefficient may be produced by varying the additives of various specific densities to increase the shielding performance. This study uses a cogon grass fiber, an invasive and unwanted grass due to their ability to grow, and disrupt desirable vegetation efficiently as a reinforcement material mixed into the concrete composite to observe its performance in radiation shielding. Natural fiber is known to have a tolerance to post splitting, high energy absorption and increased fatigue resistance of cement-based composites. Cogon grass fibers are use with different percentages of 0%, 0.5%, 1.0% and 1.5% fiber content with four different thicknesses. In this study, the chemical and physical properties of cogon grass were characterized by the hydrolysis process (Chesson Method) and Atomic Force Microscopy (AFM), respectively. The effect of different percentage of cogon grass fiber in concrete with different thickness to linear attenuation coefficient, the difference of linear attenuation coefficient value between lead concrete and cogon grass fiber concrete and half value layer (HVL) were also investigated. The possibility of using cogon grass natural fiber as a block of concrete for gamma radiation shielding was also evaluated based on the results obtained in this study. The results show that the hemicellulose, cellulose and lignin content of raw cogon grass fiber were 27.60%, 36.62% and 6.11%, respectively. AFM micrograph of cogon grass showed a blocky and rough surface. The calculated linear attenuation coefficient of cogon grass fiber showed an increase with the increase of fiber content and thickness. However, lead concrete showed a higher attenuation coefficient and lower HVL value compared to cogon grass fiber. Despite that, cogon grass fiber concrete may have the potential to be used as shielding material with some improvement.

 

Keywords:  cogon grass, fiber, concrete, filler, gamma radiation

 

Abstrak

Konkrit adalah campuran dari simen, agregat halus, agregat kasar, dan air. Konkrit mempunyai potensi pelindung yang tinggi terhadap sinaran radioaktif gama daripada sumber radioaktif. Konkrit yang mempunyai pekali pelemahan yang lebih tinggi dapat dihasilkan dengan mengubah bahan tambahan dari pelbagai ketumpatan tertentu untuk meningkatkan kadar pelindung. Kajian ini menggunakan serat semula jadi rumput lalang, sejenis rumput invasif dan tidak diingini kerana kemampuan mereka untuk tumbuh, dan mengganggu tumbuh-tumbuhan yang diinginkan dengan cekap sebagai bahan tambahan yang dicampurkan dalam komposit konkrit untuk menilai kemampuannya dalam pelindung radiasi. Serat semula jadi diketahui mempunyai toleransi terhadap pemisahan pasca, penyerapan tenaga yang tinggi dan peningkatan ketahanan komposit berasaskan simen. Serat rumput lalang yang digunakan dengan peratusan 0%, 0.5 %, 1.0% dan 1.5% kandungan serat dengan empat ketebalan yang berbeza. Dalam kajian ini, sifat fizikal dan kimia rumput lalang dicirikan dengan menjalankan proses hidrolisis (Kaedah Chesson) dan Mikroskop Daya Atom (AFM). Kesan peratusan serat rumput cogon yang berbeza terhadap pekali pelemahan linear konkrit, kesan ketebalan berbeza dari konkrit serat rumput lalang terhadap pekali pelemahan linear dan perbezaan pekali pelemahan linear antara konkrit plumbum dan konkrit serat rumput lalang juga disiasat. Potensi menggunakan serat semula jadi rumput lalang sebagai blok konkrit sebagai pelindung radiasi gamma juga dinilai berdasarkan hasil kajian ini. Kajian menunjukkan kandungan hemiselulosa, selulosa dan lignin dari serat rumput lalang masing-masing adalah 27.60%, 36.62% dan 6.11%. Mikrograf AFM rumput lalang menunjukkan permukaan yang tersekat dan kasar. Pekali pelemahan linear yang dikira dari konkrit serat rumput lalang menunjukkan peningkatan dengan peningkatan kandungan serat dan ketebalan konkrit. Walau bagaimanapun, konkrit plumbum menunjukkan pekali pelemahan yang lebih tinggi dan nilai HVL yang lebih rendah berbanding dengan serat rumput cogon. Walaupun begitu, konkrit serat rumput cogon mungkin berpotensi digunakan sebagai bahan pelindung dengan sedikit peningkatan.

 

Kata kunci:  rumput cogon, serat, konkrit, pengisi, sinaran gama, perisai

 

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