Circular Economy in Waste Management of Plastic and Sawdust Wastes for Making Eco-Friendly Ceiling Tiles
Ndelema Gloria 1  
,   Okello Thomas 1  
,   Ainomugisha Safiki 1  
,   Bazairwe Annette 1  
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Kyambogo University, P.O Box 01, Kambogo, Uganda
Ainomugisha Safiki   

Uganda generates nearly 600 tons of plastic waste on a daily basis and due to the absence of a suitable management system, 90% of it ends up in landfills. The same is evidenced in the wood production industry which has seen consequent sawdust waste increase. However, with a circular economy where by resources are kept in use, these wastes have a potential to be converted to useful materials again. Therefore, the study aimed at assessing whether treating sawdust with coconut oil and combining it with waste plastics can be harnessed to produce sustainable eco-friendly ceiling tiles to facilitate a circular economy. The sawdust was treated using coconut oil at 9% of the sawdust amount as a coupling agent. Composite mixtures were prepared by melting the low-density polyethylene (LDPE) and polyethylene terephthalate (PET) plastics and mixing them with treated sawdust in percentages of sawdust to plastics of 70:30, 65:35, 60:40, 55:45, and, 50:50 by weight. A total of 45 ceiling tile samples were made after conducting standard tests on the physical properties of the materials. In order to ascertain suitability of the composite tiles prepared, the tests on the density of tiles, water absorption, and flexural strength were conducted. The results of the properties analysed show that the density of tiles produced ranged between 880-1490 Kg/m3, flexural strength increased from 3.05 - 4.06 N/mm2 with increasing plastic loading proportions from 30 – 50 %. Water absorption decreased with treated sawdust loading by 26.4% to an optimum at 5.3% for ceiling composite 60SD-PL40 and later increased by 126% to 12% for 70SD-PL30 composite. This is due to a decrease in the surface activity of the coupling agent and adhesion improvement with increasing sawdust content. The cost of composite tiles made show a very high economic saving of the optimum 60SD-PL40 composite at 766%/M2 in comparison with the current market prices of gypsum boards. Therefore, the tiles produced using coconut oil treated sawdust and waste plastics may be used in manufacturing ceiling tiles for sustainable development and achieving a circular economy.