Response of coir fibre reinforced cement composites to water repellent chemical additive and microwave accelerated curing

The present investigation deals with performance of coir fibre reinforced cement boards subjected to matrix modification by silane-based water repellent chemical additive and microwave accelerated curing (MC). The fibre-cement boards were tested for water absorption, modulus of rupture (MOR) and modulus of elasticity (MOE). Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the composite samples. 84% reduction in water penetration was achieved through the use of the water repellent additive while MC samples had higher MOR and MOE values than the water cured samples. SEM characterization showed that MC provided good interfacial adhesion between the matrix and the reinforcement while the chemical additive reduced the occurrence of voids and pores on the surface. FTIR indicated prominent bands at 3423, 1425.44 and 875.41 cm−1 which are indicative of O–H stretching of the portlandite, C-H denoting the lignin deformation with aromatic ring stretching and C-O representing bend of carbonates. Therefore, MC and use of water repellent additive are recommended to improve the performance of cellulose fibre cement based applications.