Thesis Bachelor of Science in Civil Engineering University of Rizal System-Morong 2023

The current condition of the Philippines’ plastic waste problem and soil erosion susceptibility led to the creation of this research study where the main objective is to create PET bottle geocells that functions as soil reinforcement on hillslopes. The wastage of PET plastic bottles is prevented by upcycling it into soil reinforcement which lessens soil erosion at the same time. Design development and experimentations were conducted within the span of 7 months of the academic year 2022-2023 to conclude the properties and effectiveness of the PET Geocells. This research paper answers to the question of whether or not the sizes of perforation of the PET geocell designs cause a significant difference to its tensile strength and what differences it causes in terms of the mass per unit area and functional longevity. It also determined if the PET Geocell soil reinforcement is effective in functioning as soil erosion control in the chosen site of Sitio Manggahan, Brgy. San Carlos, Binangonan, Rizal, while integrating the appropriate perforation design in line with the site’s slope ratio. By utilizing the developmental and experimental research design, the PET Geocells are placed under design development before being tested and evaluated for effectiveness. The experimental conduct of evaluating the effectiveness of the PET geocells as soil reinforcement relied on the results of the design development phase that dictated the perforation sizes to use and the site investigation process that determined the appropriate aperture dimensions to follow during installation. After installation, the monitoring process was conducted with the use of a record sheet to keep track of the soil runoff collection and the weather conditions of the site. The results tell us that the three preliminary perforation designs which are 4mm, 8mm and 12 mm diameter perforations, vary in tensile strengths, where the smallest perforation diameter yield the highest strength. The functional longevity, mass per unit area and effectiveness is conducted for the 4mm and 8mm diameter perforation designs which had the higher tensile strength. The mass per unit area has been determined to be inversely proportional to the perforation size as the mass per unit area is higher for the smaller perforation design, and vice versa. The functional longevity, however, is not fully defined in this research study due to lack of tensile degradation during the time span of this research. The effectiveness of the samples as soil reinforcement is determined to be higher on the design with the perforation size of 4mm. After the conduct of the tests and evaluating the results through data analysis, it was determined that the perforation sizes of the PET geocell design has an impact on its properties. Upon the preliminary tensile strength tests, it was ruled through analysis of variance that there is a significant difference between the strengths of the three perforation designs. The top two perforation designs in terms of tensile strength that moved on to the succeeding tests showed little difference between the two perforation sizes. On the other hand, in terms of site installation, the runoff collector of the slope with PET Geocell soil reinforcement accumulated less soil runoff than that of the unreinforced slope. And the performance of the perforation design with diameter of 4mm, in terms of soil runoff yield a significant difference from the soil that eroded from the unreinforced slope. Based on the findings and given the state of weather during the conduct of this research, it is recommended by the researchers that further studies of this topic should integrate the rainy season to fully determine the performance of the samples under precipitation. Also, given that the functional longevity of the PET geocell was not defined through the method of natural tensile strength degradation, the researchers recommend that further studies on this topic utilize the environmental stress cracking test if it is available.