Utilization of Rubber and Plastic Waste as  A Partial Replacement of Aggregate for  Improved Sound Insulation

Abstract: Globally, billions of tons of rubber and plastic waste are produced annually, and because these wastes degrade so slowly (about 450 years for plastic bottles and 80 years for tire rubbers), they are extremely difficult to dispose of. As a result, utilizing these wastes directly in building materials can significantly reduce the environmental load while also increasing the sustainability of the building material. This study compares the roles and effects of using recycled plastic and rubber as aggregates on the properties as well as the performance of concrete. This research focuses on sound insulation properties in particular. Each artificial polymer material of rubber and plastic has a special structure but consists of the same essential components. Plastic and rubber wastes, replacing fine/coarse aggregates are determined by their sort, size, replacement content, and shape. Plastic-based aggregates generally reduce the concrete's workability, but the impact of rubber-based aggregates is mostly influenced by their size and replacement amount. The main objective of this study is to review the evaluation of the sound insulating properties of concrete containing particles of plastic and rubber wastes based on their size, replacement amount, shape, and other factors. For the recycled PET, the results showed that the best percentage of recycled PET fibers mixed with ordinary concrete was in the range of 0.5 – 1.5% compared with other percentages. Low values in the range of 0.5 - 2%, especially 0.5%, of recycled PET mixed with concrete demonstrated the best value in terms of compressive strength compared with ordinary concrete. For the recycled rubber aggregate, the improved sound loss transmission for coarse crumb rubber was higher than the sound loss when using the same percentage of fine crumb. This could belong to that the coarse aggregate caused the voids to appear and increased the porosity in the system compared with the fine aggregate. When these aggregates were included the sound absorption can be improved drastically. The compressive strength of the samples containing fine crumbs of rubber was decreased compared to the control concrete sample without added rubber.   Many previous studies found a clear drop in compressive strength when using a fine rubber aggregate compared with coarse rubber aggregate. Generally, when adding a higher percentage of rubber, the sound absorption coefficient increased, while the compressive strength decreased.  Many researchers found that the thermal insulation increased when adding higher percentages of plastic and rubber waste to concrete. The degree of thermal insulation improvement for mixing concrete with plastic and rubber is also determined by the shape of the pieces. The density of concrete decreased as the percentage of plastic and rubber particles in the mixture increased.