Soil Stabilization using plastic wastes(Case Study on Addis Ababa)

Abstract

There is a rapid increase in generation of waste plastics all around the country Ethiopia due to economic growth, changing consumption and production patterns. The capital city of Ethiopia annual consumption of plastic materials has increased from year to year and the disposal becomes serious problem and generating around two hundred thousand (200,000) tones in a year according to Addis Ababa city solid waste management report of February, 2010. Due to extremely long period required for natural decomposition, waste plastic is often the most visible components in waste dumps and open landfills. On the other hand due to the industrialization, many infrastructure projects such as highways, railways, high rise, industrial buildings, airports and seaports construction has gained lot of importance in every part of the world. All these infrastructure projects can be built on and within the sub surface and it needs firm sub grade. This research has been conducted to mitigate the challenges faced by the civil engineering field and the solid waste management field by analyzing clay soil -PET (Polyethylene Terephthalate) plastic waste composite. The research was conducted by taking soil sample from Addis Ababa around kality sub city and plastic bottle wastes from the surrounding. The laboratory work involved in this research particle size distribution of both soil sample and plastic chips, compaction test, California bearing ratio (CBR) test .CBR-Swell and unconfined compressive strength (UCS) for both soil sample after mixing with plastic chips in different proportion (1.2%, 2.4%, 3.6% and 4.8%) and optimum amount of plastic chips reinforced with black cotton soil is 3.6 % of the soil mass. The test result showed that slight improvement of the engineering behaviors of plastic stabilized soil by decreasing CBR- Swell, increase CBR value of composite soil and slight increasing of UCS value but the MDD value of composite soil decrease and no change on optimum moisture content of the composite soil when the PET chips content increased up to optimum plastic content. Therefore from this study it was found out that PET plastic stabilized soil meet only the minimum requirement of ERA pavement manual specification for use as a sub-grade material in road construction.