Assessing the Mechanical and Durability Properties of Recycled Polyethylene Terephthalate (PET) Plastic Soil

Abstract

Non-biodegradable plastic wastes for example, polyethylene terephthalate (PET) bottles, wrapping etc. can be found in the street, farm, inside dustbin in major or main cities in Cameroon (Douala, Yaoundé); this may cause infertility of soil, contamination of groundwater and surface water and pollution of environment with consequences for both ecosystems and human health. It has been found that in Douala, the largest city and economical capital of Cameroon about 20 tons of plastic wastes are produced daily, also, plastic wastes account for about 10% of generated waste in Douala city. In a bid to put an end to plastic pollution in Douala city, Cameroon, there is a dire need to recycle and use them in a wide range of fields such as in Civil Engineering works, for example in the manufacturing of stabilized soil bricks. In this regard, the influences of PET plastic waste bottles on the strength and durability properties of stabilized soil brick were investigated in this study. To achieve this, we collected the soil at the depth of 70 cm from earth surface at EKOUDOUM around corners called “Carrefour de l’amitié”, Yaoundé, Cameroon; the particle size distribution curve showed that the soil is composed of 5% gravel, 50% sand and 45% silts and clay. It optimal dry density is 1.61 g/cm3 obtain when the water content is 21.4%. Atterberg limits tests have shown that the soil had liquid limit of 61.8%, plastic limit of 26.86% and the plasticity index of 34.95%. Liquid PET bottles were used as stabilizer agent /binder. The preparation of the soil-liquid PET bottles composites was as follows: Firstly, a mixture of soil and PET bottles were carefully mixed and then the composite was filled in the compaction mold and statically compacted. To evaluate the performance of the composites, such tests as compressive strength, flexural strength, resilience factor and water absorption were examined. The findings revealed that when we have increased the percentage of PET bottles, the compressive strength, flexural strength, water absorption have decreased while the resilience factor and Young’s modulus have increased; the minimal compressive strength, flexural strength, Young’s modulus and resilience factor were 5.625 MPa, 2.11 MPa, 2.552 GPa and 77.55 J/cm2, respectively while the maximum water absorption was 3.69%.