Eco-friendly Xiriton boosts coastal reef recovery

November 25, 2025

A new biobased alternative to traditional concrete is emerging as a promising tool for coastal restoration and marine habitat recovery.

Researchers at the Royal Netherlands Institute for Sea Research (NIOZ) have been evaluating several formulations of Xiriton, an eco-friendly building material created from grass fibers, volcanic pozzolan, slaked lime, shells, sand, and seawater. Early tests indicate that this natural composite could play a significant role in rebuilding tidal ecosystems and supporting shellfish populations.

Strong growth in real-world tidal tests

In field trials on the mudflats of Yerseke, NIOZ scientists placed Xiriton blocks in the intertidal zone and tracked their performance through daily tidal cycles. After one year, the blocks showed extensive biological growth.

“After a year, every block was around 70 per cent covered with life such as oysters, mussels and algae,” explains PhD researcher Victoria Mason. The findings suggest Xiriton can encourage shellfish settlement and may help restore biodiversity in degraded coastal environments.

Mason highlights an additional benefit: Xiriton can be engineered to break down naturally once a reef becomes self-sustaining. “By adjusting the lifetime of the material, it can also break down naturally into harmless substances once a reef can sustain itself, instead of remaining permanently in the ecosystem.”

Material composition influences strength

The team experimented with different grass types—including regionally abundant cordgrass and fast-growing Elephant grass—to refine the mixture. Mason found that drying time and binder ratios directly affected durability. “After five weeks of drying, it was at its hardest,” she notes.

Importantly, the material’s pH range (8–9) is far more neutral than conventional concrete, making it more suitable for marine organisms that rely on stable, non-alkaline conditions to settle.

Testing durability under extreme flow

To test structural resilience, the researchers used the Fast Flow Fume system, exposing Xiriton samples—molded in coffee-cup shapes—to high-velocity currents. This setup subjected the material to harsher conditions than typical tile-based tests.

Despite the intense flow, the biobased mixture performed well. After 63 days, the team reported strength levels comparable to historical Roman-cement alternatives.

According to Mason, restoration materials must be sustainable, adaptable, and cost-effective: “For the purpose of intertidal restoration, we need materials that are not environmentally harmful in the short or long term.” She adds that affordability and practical scalability are essential for widespread adoption.

A next-phase study will examine whether Xiriton can be used in larger wave-dampening structures and how its lifespan can be fine-tuned for semi-permanent reef-building frameworks.

Potential uses beyond marine restoration

Xiriton was originally developed in 2009 by Swiss inventor Frank Bucher, who believes the material can replace traditional bricks in many low-rise construction applications. “All buildings up to three stories high, for example,” he says. Because Xiriton requires no firing or clean water, its production has an exceptionally low environmental footprint. “You can make it with ditch or sea water.”

Bucher also points to the synergy between wood and Xiriton: “Wood reinforces Xiriton, and Xiriton protects the wood,” creating new opportunities for hybrid green building systems.

Senior NIOZ researcher Jim van Belzen sees Xiriton as part of a broader shift toward regenerative construction. He notes that human-made materials now outweigh all global biomass and stresses the need for nature-positive, circular design.

“New biobased concepts – where nature, circularity and regeneration are central – are not a luxury, but a necessity.”

He believes eco-friendly materials like Xiriton could redefine coastal protection: “The future of water safety? It could well be greener than stone and concrete.”

The full study appears in Frontiers in Marine Science.