Effects of Eucalyptus pulp refining on the performance and durability of fibre-cement composites

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.FAPESP (05/59072-4, 07/05299-3)FAPEMIGCAPESCNP