Mechanical and Durability Characteristics of Particulate-Filled Recycled Thermoplastic Composites (RTCs): A Comprehensive Review.

Globally, over 350 million tonnes of thermoplastic waste are generated annually, with more than 60% either landfilled or mismanaged. This attracts innovative pathways to increase their recyclability, among which particulate-filled recycled thermoplastic composites (RTCs) are emerging as a potential waste reuse strategy for diverse civil and industrial applications. This review systematically analyses the current understanding of the physical, mechanical, and durability performance of RTCs, focusing on how various particulate filler types, content, and interfacial compatibility influence key properties. Reported studies show that incorporating particulate organic or inorganic fillers such as waste glass, sand, wood flour, etc., can increase density by 10-45%, tensile and flexural moduli by 30-120%, and thermal stability by up to 40%, though strength and ductility often decrease by 15-50% due to poor filler-matrix adhesion. This review further evaluates durability enhancements under prolonged exposure to water, thermal, and UV radiation, where filler addition reduces water absorption and UV degradation by 20-60%. Despite these advancements, challenges remain in optimising interfacial bonding, long-term performance modelling, and scalability for civil infrastructure. This review also outlines research directions to advance high-performance, sustainable RTCs through a structured review approach using defined keywords on recycled thermoplastics, fillers, and durability.