Evaluation of Concrete Incorporated with Waste Plastic and Tyre Rubber as Partial Replacements for Fine Aggregate

Abstract

The improper disposal of waste plastic and tyre rubber significantly contributes to environmental pollution; however, these materials can be repurposed for use in construction. This study investigates the impact of partially replacing fine aggregates with recycled plastic and tyre rubber waste on the strength properties of concrete. Concrete samples were prepared with 0, 5, 10, and 15% replacement of fine aggregates using plastic waste, tyre rubber waste, and a combination
of both, while maintaining a constant water-cement ratio of 0.5. The samples, cast using 100 mm x 100 mm x 100 mm size cubic moulds were tested for compressive strength at 7, 14, and 28 days. Results revealed that increasing the percentage of waste replacement improved workability and compacting factor but reduced compressive strength. At 28 days, compressive strength ranged from 10.83 N/mm² to 8.28 N/mm² for plastic waste, 12.83 N/mm² to 5.67 N/mm² for rubber waste, and 12.02 N/mm² to 9.10 N/mm² for the combined waste, compared to 15.80 N/mm² for the control mix. The findings indicate that 5 to 15% of all waste-based mixtures exhibited lower strength than the control, rubber waste contributed to higher strength than plastic, while the combined waste mixtures displayed intermediate strength.
At 5% of plastic and rubber (12.02 N/mm2) is higher than 10% and 15% (11.74 N/mm2 and 9.10 N/mm2) respectively. It also clearly showed that as the percentage of the plastic and rubber fibres increased from 10% upward the compressive strength of the concrete decreased. This study highlights the potential of using recycled waste materials in concrete, particularly for low-bearing structural applications, promoting sustainable construction practices and environmental conservation.