Comparative Study of Recycling between Waste of Granules and Raw Thermoplastics (LDPE, HDPE and PET) Mixed with Sand for the Manufacture of Paving Stones in the City of Kinshasa in DRC

Abstract

Objectives: The utilization of waste LDPE, HDPE, and PET, either in their raw or granulated forms, for manufacturing paving stones raises several challenges, including the production of weaker and less durable paving stones, increased atmospheric pollution, and material loss. This research aims to identify the most advantageous process for employing thermoplastic waste in paving stone production.
 Research Design: The study is structured into five sections: introduction, methodology, results, discussion, and conclusion.
 Location and Duration: The study was conducted in the city of Kinshasa, and the experiments were carried out in July 2021.
 Methodology: Raw and granulated thermoplastic waste (LDPE, HDPEE and PET) were respectively mixed with fine grained sand (] 0.063 – 0.2 mm [).The mixture was heated to obtain homogeneous paste. The later was poured into molds in order to manufacture the paving stones which were tested for resistance.
 Results: On average, the ratio of thermoplastic granules to raw material yielded a recycling time of 17/22 minutes, producing 13/7 pavers. The weight loss of materials was 5.29±0.98/9.95±1.89 kg, and the strength was measured at 12.3±2.19/6.4±1.61 N/mm². The optimal material composition demonstrating the highest strength at 22.45 N/mm² comprised 30% LDPE and HDPE, 10% PET, and 60% sand.
 Conclusion: Comparing raw thermoplastic waste with granulated thermoplastic waste, the latter proves more beneficial. Granulated thermoplastic waste yields more consolidated pavers, reduces weight loss of materials, shortens recycling time, minimizes smoke emission, and provides a superior average strength of pavers.