Development and mechanical characterization of cenosphere-reinforced CFRP and natural rubber core sandwich composite

Driven by the growing concern for environmental sustainability, there is an increasing need to explore innovative approaches for repurposing industrial waste materials. This study focuses on investigating the potential uses and challenges associated with cenosphere, a waste product derived from coal combustion in thermal power plants. Typically regarded as waste, cenosphere offers an opportunity to contribute to sustainability efforts. The objective of this research is to evaluate the influence of cenosphere, a ceramic-rich industrial waste, on the mechanical properties of woven CFRP-Rubber-CFRP (Carbon fibre-reinforced polymers) sandwich composites. The composite specimens were fabricated using the conventional hand lay-up technique, incorporating different weight percentages (5, 10, 15, and 20 wt.%) of cenosphere as a particulate filler. Tensile, flexural, and impact testing were conducted according to ASTM standards to assess the impact of the filler content on the mechanical properties. The results demonstrate that the inclusion of approximately 15% by weight of discarded cenosphere significantly enhances the tensile strength, flexural strength, interlaminar shear strength (ILSS), and impact strength of the sandwich composites, yielding improvements of approximately 1.6, 1.56, 2.06, and 1.85 times, respectively, compared to unfilled composites. Microscopic analysis of the composites reveals a well-dispersed cenosphere distribution within the matrix, contributing to the notable enhancement in overall strength characteristics.