Effects of eucalyptus pulp refining on the performance and durability of fibre: cement composites

Abstract

Although Eucalyptus pulp has been widely used in the paper industry, there is limited information concerning its use as reinforcement in fibre—cement composites. The objective of this study was to evaluate effects of mechanical treatment (refining) of the Eucalyptus pulp on fibre properties as well as performance and microstructure of fibre—cement composites. The composites were evaluated before and after accelerated ageing cycles. The refining increased the capacity of Eucalyptus fibres to capture mineral particles, improving the adherence of the fibres with the matrix. This improved fibre—matrix interface led to better mechanical properties at 28 days of cure but higher mineralisation of fibres and consequently increased brittleness of composites after accelerated ageing (soak and dry) cycles. Unrefined fibres maintained the toughness of composites after ageing cycles. This indicates that refining may weaken the fibres thus affecting the mechanical performance (mainly decreasing modulus of rupture and toughness) of composites after ageing cycles. These results are useful for understanding effects of refined fibre conditions (morphology, mechanical strength and surface properties) on mechanisms of fibre—matrix adherence, fibre mineralisation and degradation of fibre—cement composites. Walaupun pulpa Eucalyptus digunakan dengan meluas dalam industri kertas, maklumat tentang penggunaannya sebagai penguat dalam komposit gentian—simen masih terhad. Tujuan kajian ini adalah untuk menilai kesan rawatan pulpa Eucalyptus secara mekanik iaitu penghalusan terhadap ciri gentian serta prestasi dan mikrostruktur komposit gentian—simen. Komposit diuji sebelum dan selepas kitaran penuaan dipercepat. Penghalusan meningkatkan kemampuan gentian Eucalyptus memerangkap zarah mineral dan seterusnya menambah baik lekatan gentian kepada matriks. Perhubungan gentian—matriks yang bertambah baik menghasilkan ciri mekanik yang lebih baik 28 hari selepas rawatan. Namun kadar pemineralan gentian menjadi lebih tinggi dan mengakibatkan peningkatan kerapuhan komposit selepas kitaran penuaan dipercepat (basah dan kering). Gentian yang tidak melalui penghalusan mengekalkan keliatan komposit selepas kitaran penuaan. Ini menunjukkan yang penghalusan mungkin melemahkan gentian dan seterusnya mempengaruhi prestasi mekanik (khususnya menurunkan nilai modulus kepecahan dan keliatan) komposit selepas kitaran penuaan. Keputusan ini berguna untuk memahami kesan keadaan gentian yang melalui penghalusan (morfologi, kekuatan mekanik dan ciri permukaan) terhadap mekanisme lekatan gentian—matriks, pemineralan gentian dan pendegradan komposit gentian—simen.