SACNAS poster presentation: Exploring seawater and coconut fiber for sustainable construction
In Pacific Island communities, where fresh water is precious and imported building materials are expensive, the ocean and the coconut tree may offer an unlikely solution.
University of Guam (UOG) School of Engineering student Azer L. Bilimon brought that idea to the 2026 SACNAS Annual Conference, where he presented a poster on seawater-based cement mortar reinforced with natural coconut fiber and synthetic fiberglass.
Bilimon credits the guidance of his mentor, Ernesto J. Guades, Ph.D., associate professor and chair of civil engineering at UOG SENG, as well as the support of Guam NSF EPSCoR E-CORE for the research.
The construction industry consumes a lot of fresh water. Bilimon asks whether seawater can stand in for this resource when mixing mortar. It also asks whether locally available fibers can help the resulting material perform well. The work also looks at alternatives to traditional steel reinforcement, which is prone to corrosion.
Bilimon described his focus: “I am studying how these different fibers affect the strength and ductility of mortar while also exploring ways to reduce the use of freshwater in construction, especially in Pacific Island communities.”
As someone who grew up in the Marshall Islands, Bilimon found his motivation in the realities of island life,
“I was inspired by the challenges Pacific Island communities face with limited freshwater resources and the high cost of imported construction materials.”
From there, the question became practical: “I wanted to explore whether locally available materials, such as coconut fiber, could be used together with seawater to support more sustainable construction.”
The team prepared mortar specimens using a 1:2 cement-to-sand ratio and a water-cement ratio of 0.5, with seawater as the mixing medium. The team compared coconut fiber, which they harvested from locally sourced coconut husks, against fiberglass. They cut the fibers to short lengths (0.5 inch in the main mixes) and added them at varying percentages by volume.
The team cast the mortar in 2 in x 4 in cylindrical molds and cured it for 28 days. They then tested the specimens in a Universal Testing Machine (UTM) for compressive strength, and the testing also included split tensile strength.
The study compares freshwater mortar, seawater mortar, and seawater mortar reinforced with coconut or glass fiber, allowing it to separate the effects of seawater mixing from those of fiber reinforcement.
The results show a clear trade-off between strength and ductility. Mortar reinforced with coconut fiber reached its peak strength at 1% fiber content. At 2%, ductility improved, but compressive strength dropped. Overall, coconut fiber showed a trend of decreasing strength and increasing ductility as fiber percentage increased.
Meanwhile, fiberglass-reinforced mortar was stronger than coconut fiber at every percentage tested, and its strength rose with fiber content. The highest strength came from a mix with 3% fiber at 0.75-inch length. Fiberglass, however, was less ductile overall, with the 1% mix more ductile than the 2% mix.
Bilimon hoped visitors to his poster would leave with this idea, ”One key takeaway I hope people learn is that there is a trade-off between strength and ductility: fiberglass generally provides higher compressive strength, while coconut fiber shows potential for improving ductility and offers the added benefit of being locally available and renewable.”
According to the poster presentation, ductility is easy to overlook, but structural engineers often consider it more important than peak strength. A ductile material absorbs energy and deforms before it fails, which improves safety and resilience.
Cost also matters, as the presentation notes. Coconut fiber is a renewable agricultural byproduct that is generally less expensive than glass fiber. While glass fibers typically deliver higher and more consistent mechanical properties, coconut fibers offer an economical alternative that puts natural waste to use. Together, seawater and coconut fiber could reduce freshwater consumption and material costs, a combination that may be especially valuable for tropical and island communities such as Guam and the Marshall Islands, where seawater is abundant.
For Bilimon, the conference was as much about conversation and networking as presentation, “I am also excited to connect with people from different STEM backgrounds and learn more about opportunities that can benefit island communities in the future.” Bilimon received the Native American/Indigenous Student Research Abstract Award from SACNAS in 2025.
AT A GLANCE
- The big idea: Can seawater and locally sourced coconut fiber replace fresh water and imported materials in mortar, helping Pacific Island communities build more sustainably?
- What they did: Made mortar (1:2 cement-to-sand, 0.5 water-cement ratio) mixed with seawater and reinforced with coconut fiber from Guam or fiberglass. Cast it in 2″ x 4″ cylinders, cured it for 28 days, and tested it in a Universal Testing Machine.
What they found:
- Coconut fiber gave peak strength at 1% content; at 2% it improved ductility but lowered compressive strength.
- Fiberglass was stronger than coconut fiber at all percentages tested, with the highest strength at 3% content and 0.75″ length, but it was less ductile.
- The core finding is a trade-off between strength and ductility.
What it means: Seawater and local fibers show real promise for sustainable, resilient, lower-cost construction in island environments such as Guam and the Marshall Islands. Fiberglass favors strength, while coconut fiber favors ductility and local availability.
Acknowledgments: This material is based on work supported by the National Science Foundation under Grant Number OIA-2438132.