By Louella Losinio
Can Guam turn its waste stream into a local materials stream for construction—and, in doing so, reduce its dependence on imported materials while building the island's engineering and manufacturing capacity?
Research partnerships led by Ernesto Guades of the University of Guam School of Engineering, in collaboration with the Guam Green Growth Circular Economy Makerspace and Innovation Hub, are exploring whether discarded materials and sustainable resources available on the island can serve as raw materials for new products and construction.
The work reflects a broader approach known as sustainable materials management, or SMM. The U.S. Environmental Protection Agency defines SMM as a systematic approach to using and reusing materials more productively throughout their entire life cycles. Rather than focusing only on what happens after a product becomes waste, SMM considers how materials are extracted, manufactured, used, reused and ultimately managed at the end of their useful life.
One of Guades’ research projects explores which recyclable plastics can be prototyped into construction materials, focusing on producing plastic lumber at the G3 Makerspace. The project received funding through the Pacific Regional Integrated Sciences and Assessments program for the 'Economic Valuation of the Guam Green Growth Initiative,' which is administered through the UOG Center for Island Sustainability and Sea Grant.
Initially, Guades worked with polypropylene, or Type 5 plastic, commonly found in food containers. The research has since expanded to include Type 2 plastic, or high-density polyethylene, and to examine whether different plastics can be combined.
“Previously, we only studied one type of plastic—Type 5, which is polypropylene. So, what we are doing now in the next stage is we try to also cover the other types of plastic,” he said. “We are now going to Type 2, which is called high-density polyethylene.”
While plastic lumber is already commercially available, Guades said existing products can be costly and have limited applications. “The strength of what we found is comparable to what is commercially available,” he said. “We would like to make it affordable so the result is quite comparable.”
Potential applications could extend beyond simple plastic lumber, which Guades said could eventually replace timber.
“But we would like to do more than that. The applications will be for bridges or maybe for structural components of houses. So that’s the target,” he added. “It’s promising. We are getting a comparable result and even better than what is available commercially.”
Guades is also looking at hybridized plastics. These materials combine traditional synthetic plastic polymers with organic or inorganic materials. “We try to combine them and find out what the effect is. Whether we can include them as one or we can separate them,” he said.
The research fits within Guades' broader work at UOG. He is both chair and associate professor of civil engineering, with research interests that include innovative and sustainable construction materials, fiber-reinforced composites, engineered cementitious composites and geopolymer concrete.
His work also includes student research and mentoring. Azer Bilimon, a UOG School of Engineering student from the Marshall Islands, worked with Guades on research examining coconut fibers as a construction material.
Bilimon's project, “Evaluating the Mechanical and Sustainable Benefits of Fibrous Reinforcement in Seawater and Freshwater Mortar Mixtures,” explored how coconut fibers could affect mortar strength and sustainability.
Bilimon tested different fiber types, lengths and amounts using a standard cement-sand-water mix to measure compressive strength. His research also incorporated discarded coconut shells and compared the use of seawater with freshwater, addressing both waste and water scarcity. The research promotes eco-friendly building materials that reflect Indigenous knowledge and environmental sustainability principles in Pacific Island communities.
Bilimon later received the Native American/Indigenous Student Research Abstract Award at the 2025 SACNAS National Diversity in STEM Conference.
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Bilimon reflected on the importance of the research to island communities: “Science has always piqued my curiosity, thanks to my love for sci-fi movies. I was part of the STEM students at my previous institution.”
Bilimon said this type of research aligns with his interest in helping his home community. “Since the Marshall Islands has been struggling with climate change, I want to learn more to find solutions that can improve my community.”
At the G3 Makerspace, these research projects are part of a broader effort to demonstrate what a circular economy could look like on Guam—one where materials are collected, transformed and kept in use rather than discarded. By providing the space, equipment, and partnerships needed to turn waste streams into prototypes and potentially marketable products, the Makerspace is helping connect research with practical applications.
Louella Losinio is a communications professional and the publication and media supervisor for Guam Green Growth and the University of Guam Center for Island Sustainability and Sea Grant.
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