Analysing the Behaviour of Soil Reinforced with Polyethylene Terephthalate (PET) Plastic Waste

Luwalaga, John Groover. (2016-03)

Thesis (MEng)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Environmental issue effects like natural resource depletion, climatic change and global warming have significantly influenced the innovations in material science and technology with the aim of attaining sustainable materials to avert calamities. Conservation and sustainability of quality natural materials in the civil engineering field is a challenge currently due to their scarcity brought about by increased population, rapid development of cities and continued depletion of such materials. On the other hand, currently there is a boom in the plastic industry as most of the sectors like agriculture, automotive, education, government, health, marketing and advertising, transportation, to mention but a few use plastic products. Due to the wear and tear of the plastic products there is a challenge in handling the non-biodegradable plastic waste by the solid waste management field. This research has been conducted to mitigate the challenges faced by the civil engineering field and the solid waste management field by analysing sand-PET (Polyethylene Terephthalate) plastic waste composite. The research was conducted at Stellenbosch University (SUN), using materials like PET plastic waste flakes from the Kaytech factory and sand of medium dense, clean quartz uniformly graded with round shaped particles which is predominant in Western Cape region, South Africa. Furthermore, the aim of this research was achieved through the experimental work which included particle size distribution testing, compaction testing, California Bearing Ratio (CBR) testing, and direct shear box testing. Sand was reinforced with randomly mixed PET plastic waste flakes of different varying percentages of 12.5%, 22.5% and 32.5%, and tests were performed on unreinforced sand and sand-PET plastic waste composite specimens. It was established that sand reinforced with 22.5% of PET plastic waste flakes gave an optimum value of PET plastic waste giving a maximum percentage increase in friction angle of 15.32%, hence the highest shear strength with an angle of friction equal to 44.4o.Furthermore, the optimum maximum dry density of 1547kg/m3 resulted into a maximumfriction angle of 44.4o. It was concluded that the appropriate percentage of PET plastic wasteto use while reinforcing sandy soil used in this study is 22.5%. Therefore, it was established that reinforcing soil with 22.5% PET plastic waste can improve its bearing capacity and CBR. The soil-22.5% PET plastic waste composite can be applicable in civil engineering applications like as material for foundation bearing strata, light road sub-base or subgrade, and as backfill materials for foundations and retaining walls. Additionally, the study has established that reinforcing soil with 22.5% PET plastic waste is sustainable, hence mitigating the social, economic and environmental impacts by reducing need for natural resources, no land filling of PET plastic waste, and increased utilisation of poor quality construction soils like sand. Furthermore, calculations where done and found out that reinforcing sand with 22.5% reduced the width of the foundation by 3% which made it more economical compared to unreinforced sand.

AFRIKAANSE OPSOMMING: Omgewings verwante probleme soos die vermindering van natuurlike hulpbronne, klimaatsverandering en globale verwarming het die materiaal wetenskap en tegnologie beïnvloed wat verwant hou met die gebruik van volhoubare materiale om natuurrampe te voorkom. Beskerming en die volhoubaarheid van kwaliteit natuurlike van materiale in siviele ingenieurswese is tans ʼn uitdaging weens die skaarsheid asevolvan toenemende bevolking, vinnige ontwikkeling van stede en toenemende gebruik materiale verwant aan die bedryf. Daar is ook ʼn geweldige groei in die plastiek industrie. Meeste van die sektore soos die landbou, motorindustrie, onderwys, regeringsinstansies, gesondheid, bemarking en advertensies, vervoer en vele andere gebruik plastiek. As gevolg van die gebruik van plastiekprodukte is daar ʼn uitdaging in die hantering van nie-afbreekbare plastiek afval deur die vasteafvalindustrie. Die navorsing was gedoen om van die uitdagings te verlig in die siviele ingenieurs en vaste afval industrie. Die uitwerking van versterkde sand met Polyethylene Terephthalate (PET) plastiek afval was geanaliseer. Die navorsing was gedoen by Universiteit Stellenbosch (US), deur gebruik te maak van materiale soos PET plastiekafvalvlokkies vanaf die Kaytech fabriek en medium digte sand, was skoon uniforme gegradueerde kwarts met ronde gevormde partikels is wat volop is in die Wes Kaap provinsie, Suid Afrika. Die resultate van die navorsing was verkry deur eksperimentele werk wat insluit toetse soos; partikel grootte verspreiding -, kompaksie -, Kaliforniese Dravermoë-Verhouding (KDV) -, en direkte skuifkas toetse. Sand was versterk met willekeurige gemengde PET plastiekvlokkies van verskillende persentasies van onder andere 12.5%, 22.5% en 32.5%, en toetse was gedoen op onversterkte sand en sand-PET plastiek-afval kombinasie. Dit was vasgestel dat sand versterk met 22.5% PET plastiekvlokkies die optimale waarde gegee het met ʼn verhoging in die wrywingshoek van 15.32% wat gevolglik lei tot die hoogste sterkte met ʼn wrywingshoek van 44.4o. Optimale maksimum droë digtheid van 1547 kg/m3 het geleitot ʼn maksimum wrywingshoek van 44.4o. ʼn Gevolgtrekking was gemaak dat die gepastepersentasie van PET plastiekafval om te gebruik tesame met die versterking van sanderige grond in die studie 22.5% is. Deur grond te versterk met 22.5% PET plastiek afval kan dit die grond se dravermoë en KDV verbeter. Die grond-22.5% PET plastiek kombinasie kan toegepas word in siviele ingenieurs toepassings soos materiaal vir funderingslaag, ligte pad sub-basis of en as opvul materiaal vir fondasies en keermure. Die studie het ook getoon dat deur grond met 22.5% PET plastiek afval te versterk volhoubaar is. Dit is volhoubaar in so opsig dat die druk verminder op sosiale, ekonomiese en omgewings impakte deur die vraag na natuurlike hulpbronne te verminder, die nodigheid van PET plastiek afval op vullisstostingsterreine uitskakel, en die verhoogde gebruik van swak gehalte konstruksie materiaal soos sand.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98557
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