Abstract

Geopolymers are sustainable alternatives to Ordinary Portland Cement (OPC) and have been in existence for some decades. The usage of coir fiber as reinforcement for metakaolin-based geopolymer binders is examined in this work. Here, process optimization study was carried out to develop a consistent method producing the geopolymer binder. NaOH and Na2SiO3 were used as alkaline activators for the binders while fibre volume fractions of 0.03, 0.05, 0.07, 0.1 and 0.12 were used for the mix design. Elemental and mineralogical characterisation was carried out on the kaolin and coir fibres with the aid of an x-ray fluorescence analyser and x-ray diffractometer. Compressive tests on all samples at 28 days showed an optimum of 14.91MPa for the 0.1 fibre volume fraction while an optimum flexural strength of 3.53 was achieved for the 0.07 fibre volume fraction. A good interfacial adhesion between the fibers and the matrix was also revealed by Scanning Electron Microscope (SEM) analysis. The present study investigated the potential for developing a sustainable geopolymer technology by utilizing locally available coir fibre. Utilizing coir fiber has benefits including affordability and sustainability. The geopolymer binders produced showed comparable strengths to OPC and would be suitable as construction materials for less critical applications. The optimization of fiber composition and long-term durability can be studied further.