Performance evaluation of treated coconut fibre in cementitious system

Abstract

In this study, concentrated cement pore solution (CPS) was prepared and coconut fibre was soaked in it, to mimic worst condition of cementitious medium. Four coconut fibre samples were studied; the first was untreated fibre (NT), the second sample was NaOH treated fibre, while the third and fourth samples were NT and NaOH fibres soaked in CPS for 28 days, respectively. Each fibre was characterized by determining their physical and mechanical properties. Hydrophilic/hydrophobic characters were determined by measuring contact angles in water, while surface morphology of the fibre samples were studied with the aid of scanning electron microscopy. EDS was used to determine the elemental composition of the fibres, while Thermogravimetric analysis was performed to assess thermal stability of the fibre samples. Crystallinity of the fibres as well as the functional group composition present in each fibre samples, was determined using XRD and FTIR respectively. The results showed that fibres treated with NaOH and those exposed to CPS had higher densities (1.94 g/cm3) than untreated fibre (1.64 g/cm3), while the tensile strength was greatly increased by about 120%. SEM images of the fibres indicated that NaOH and CPS caused removal of lignin and hemicellulose, making the lumens to be smaller compared to untreated fibre. Similarly, crystallinity of the fibre was increased due to NaOH and CPS treatment, compared to the untreated fibres. CPS was found to improve thermal stability of the fibres. It was concluded that CPS did not pose any threat to performance of fibre.