Date of Award
Spring 5-3-2024
Level of Access Assigned by Author
Open-Access Thesis
Degree Name
Master of Science (MS)
Department
Civil Engineering
Advisor
Roberto Lopez-Anido
Second Committee Member
Sunil Bhandari
Third Committee Member
Reed Miller
Abstract
Large-scale extrusion-based additive manufacturing (AM), or 3D printing, has shown promise for a multitude of applications within civil infrastructure; specifically within transportation infrastructure applications. The complexity and scale to which this manufacturing method can fabricate parts has been previously demonstrated. This demonstration has led to increased interest and use of this technology; subsequently leading to an increased generation of waste. This waste is due, in part, to the linear process implemented by large-format 3D printing; where parts are manufactured, used, and disposed of after reaching the end of their service life. Efforts to reduce this generated waste have become increasingly of interest within industrial and research settings. However, the effects of the recycling process are still not fully understood.
This thesis focuses on the experimental characterization of two short fiber reinforced thermoplastic polymer composites, following a thermomechanical recycling process. This work employed the use of two different thermoplastic composite materials, one commonly used synthetic material and one novel bio-based material. Characterization of key material property retention across different levels of processing was essential to this work. Mechanical, physical, and thermal material properties were experimentally evaluated and monitored, for both materials. Where it was found that the mechanical performance was dependent upon the changes monitored in the physical properties of the composite constituent materials. The monitored physical properties of the reinforcing fibers showed that attrition of fiber length was present within each additional material processing level; where this attrition had negative effects on the synthetic fiber’s aspect ratio and positive effect’s on the bio-based fiber’s aspect ratio. The physical properties of the thermoplastic polymer matrices, for both synthetic and bio-based polymers, was seen to experience degradation with each additional processing level, with a concentration of degradation within the processing levels that incorporated the use of heat. Changes in thermal properties were minimal across both materials and all processing levels. However, changes in rheologic properties were variable in significance across all levels of processing.
In addition to this experimental material characterization, this thesis conducted an evaluation of the overall process using a life cycle perspective. A life cycle assessment was conducted to evaluate the environmental and climate impacts of the entire process employed during this study. The impact contributions of the virgin materials, manufacturing, post-processing, recycling, and eventual disposal processes were evaluated. These results were then used in comparison with the impacts associated with single use formworks. The results yielded from this assessment clearly showed that selecting material recycling as an end-of-life treatment instead of material disposal or landfilling significantly reduced the environmental and climate impacts.
Recommended Citation
Schweizer, Katie M., "Material and Environmental Impacts of Large-Format 3D Printed Formworks with Thermomechanical Recycling" (2024). Electronic Theses and Dissertations. 3956.
https://digitalcommons.library.umaine.edu/etd/3956