Sargassum-based particleboards for sustainable construction: Performance of pelagic and benthic biomass combined with agro-industrial residues

Every year, massive quantities of brown seaweed wash up on beaches across the Caribbean, Mexico, and Brazil. This seaweed, known as sargassum, is a natural part of the ocean, but climate change and pollution have caused it to arrive in overwhelming amounts. As the piles rot on the sand, they release toxic gases that harm local ecosystems, disrupt tourism, and threaten public health. At the same time, the global furniture and construction industries rely heavily on cutting down trees to make wood panels for cabinets, shelves, and walls. These two problems—too much rotting seaweed and too many trees being cut—seem unrelated, yet they both involve a surplus of organic material that needs a new purpose. Scientists are increasingly looking for ways to turn these waste streams into useful products, a concept known as the circular economy, where materials are reused rather than discarded. The challenge lies in finding a way to bind these wet, fibrous, and often salty materials into something strong enough to be used in buildings or homes.

A team of researchers from Brazil and Canada set out to test whether this rotting seaweed could be transformed into a building material. They focused on creating particleboards, which are flat sheets made by compressing small pieces of wood or plant fibers together with a glue. The team collected two different types of sargassum: one that floats in the open ocean and washes ashore in huge mats, and another that grows on the sea floor near the coast. To help hold these seaweed pieces together, they mixed them with two common agricultural leftovers: sugarcane bagasse, the fibrous pulp left after crushing sugarcane, and coconut husk fibers. They used a special glue made from castor oil, a plant-based adhesive that is less toxic than the petroleum-based glues usually used in factories. The goal was to see if these mixtures could form solid panels that met the safety and strength standards required for furniture and interior walls.

The researchers created four different types of panels to compare how the ingredients worked together. Some panels used sugarcane bagasse for the outer layers and seaweed for the center, while others used coconut fibers on the outside with seaweed inside. They pressed these mixtures into boards about the size of a large cutting board and tested them rigorously. The tests measured how much the boards swelled when soaked in water, how much weight they could hold before breaking, and how well the layers stuck together. The results showed a clear difference between the two agricultural partners. Panels made with sugarcane bagasse performed very well, meeting the strict requirements for non-structural use in dry environments, such as office partitions or furniture. These boards were strong, held their shape, and did not absorb too much water.

In contrast, the panels made with coconut husk fibers did not perform as well. While they met the minimum safety standards for sticking together, they absorbed significantly more water and swelled more than the sugarcane versions. When the researchers looked at the boards under a powerful microscope, they saw why. The sugarcane particles packed together tightly, creating a dense and solid structure. The coconut fibers, however, were longer and thinner, leaving gaps and empty spaces inside the board that allowed water to seep in easily. This difference in how the particles fit together proved more important than the type of seaweed used. Whether the seaweed came from the open ocean or the sea floor made little difference to the final strength of the board, as long as it was mixed with the right agricultural partner.

The study also measured how well these new boards could keep heat from passing through them, a key feature for insulation. The panels made with sugarcane and seaweed conducted heat at a rate similar to standard wood products used in construction, suggesting they could help keep buildings warm or cool. The researchers concluded that while seaweed alone is too weak and water-absorbent to be used as the main building block, it works very well as a filler material when combined with sugarcane bagasse and a plant-based glue. This approach offers a practical way to turn a growing environmental nuisance into a valuable resource. By using seaweed that would otherwise rot on the beach, communities can reduce the toxic gases released during decomposition while simultaneously creating a sustainable alternative to wood products, turning a coastal problem into a solution for the construction industry.