Groundnut shell and coir reinforced hybrid bio composites as alternative to gypsum ceiling tiles

Ground nut shells (GNS) and coir are agricultural byproducts available in large quantities at low cost and are sustainable and renewable resources. Gypsum based false ceiling tiles were developed by using the shells and coir as reinforcement individually and also as blends to improve the performance properties. Various ratios of the shells and coir were added into gypsum and made into tiles. Flexural properties at different temperatures and humidities, thermal and sound absorption, morphology of the samples and flammability were tested. Groundnut shells did not improve strength or modulus compared to pure gypsum whereas a 35% higher strength was noticed with the addition of 10% coir. Hence, hybrid gypsum composites containing both shells and coir were developed leading to better properties than pure gypsum and commercially available gypsum boards. The hybrid composites showed unique sound absorption peaks and a higher thermal resistance between 0.092 and 0.150 m2k/W. Presence of the reinforcement provided considerably high resistance to humidity suggesting that the bio based ceiling tiles will be suitable for applications in most conditions. Hybrid GNS and coir reinforced gypsum boards match or exceed the properties of similar gypsum-based tiles in commercial use. The shells, coir and other residues provide a sustainable and green alternative to replace gypsum for false ceiling, partition boards and other applications. •Ground nut shells and coir are agricultural residues available in large quantities at low cost.•Gypsum based tiles are relatively weak, non-biodegradable and susceptible to degradation.•Ground nut shells have high thermal resistance and coir imparts strength and durability.•Groundnut shells and coir enhances the strength, thermal and acoustic resistance.•Hybrid composites satisfy thermal and insulation properties specifications for buildings.