Curtailing the Environmental Impact of Waste Plastics through Re-use for Sustainable Paving Stone Manufacture in Kinshasa City

Abstract

In Kinshasa, attacks on the environment and human well-being continue to increase with the accumulation of thermoplastic waste (LDPE, HDPE and PET) mainly produced. Collected in unsanitary landfills, this waste pollutes the environment with all the consequences on health. This study makes it possible to reduce the socio-environmental impacts of thermoplastic waste by reusing them for the manufacture of paving stones for the sanitation of Kinshasa. Specifically, it initiates the collection of thermoplastic waste, recycling techniques for the production of paving stones and raising awareness among Citizens and Decision-Makers of the importance of their management. Thus, a survey questionnaire was administered to a sample of 1276 households. The proportions of materials used to obtain the resistant paving stones are: 60% fine sand, 35% LDPE and HDPE and 5% PET. Melted at 200°C, the thermoplastics are mixed with sand until a homogeneous paste is obtained to be poured into moulds prearranged on a metal table. The consolidated pavers are removed from the mould after 45 minutes using a hammer. The results obtained show that 4% of households manage their waste better and that 96% contribute to plastic pollution. 87.1% of households denounce the harmful effects of thermoplastics on the environment and point out the clogging of gutters (28.4%), the pollution of space (25%) and the pollution of rivers (16.5%). Twenty-two pavers with an average weight of 1953.33 ± 6.22 gr are manufactured. The weight loss of the materials is 14.2% (7.1 kg). The compressive strength of the pavers is 32.74 ± 0.94 N/mm². In short, reducing the socio-environmental impacts of thermoplastic waste in Kinshasa is complex and requires a multidimensional approach with the efforts of all stakeholders.