In this current era, there are some concerns of using synthetic fibres in regards to their impact on the environment since they are non-recyclable and non degradable. There are many attempts by various groups of engineers and researchers to use natural fibres in engineering applications, in the hopes of replacing synthetic fibres with natural fibres. In this project, the possibility of using natural fibres in building materials is investigated in terms of their compression strength and heat conductivity. Sisal fibres are selected as reinforcement for gypsum walls for the application in industrial and commercial buildings. To gain high interfacial adhesion of the sisal fibres with gypsum, a study on the optimum chemical treatment concentration of NaOH (0-10 %) is considered. To study the heat conductivity of the composites, a newly designed heat conductivity test setup is developed to study the influence of different volume fractions of glass and sisal fibres on the conductivity of gypsum. In addition, compressive test was performed for the selected materials. Failure mechanisms of the samples after compressive testing are examined with the aid of the scanning electron microscopy (SEM).
The results revealed that the alkalization on the sisal fibres have provided different levels of interfacial adhesion in the composites which were pronounced on the
surface topography of the fibres. Based on this observation and supported by other literatures, 6% NaOH was selected as the optimal concentration for composite fabrication. From the compressive test, it was observed that the addition of fibres to the gypsum matrix improves the compressive strength and resulted in reduced brittleness. For sisal fibre-gypsum composite, the optimum fibre content is at 25
vol.% while for glass fibre-gypsum composite, the optimum fibre content is at 30 vol.%. The thermal conductivity resulted showed that pure gypsum was found to have the highest thermal conductivity. The thermal conductivity of the composites decrease with the increment of fibre volume fraction for both synthetic and natural addition of the fibres. Sisal fibre-gypsum composites performs slightly better at insulating heat as compared to glass fibre-gypsum composites possibly due to its porous nature, as heat transfer is impeded by the presence of air voids
