Pushing boundaries with innovative sustainable materials

Designing for lightweight, sustainable construction

Due to site constraints limiting excavation to 2.5m in depth, the three domes of the pavilion, with spans of 20m and 40m, had to be built without the use of driven piles. This made lightweight construction essential.

To meet these challenges, Arup and the project team used three novel materials for the structural framing of the domes: paper tubes, CFRP and laminated bamboo, enabling the creation of large-span structures with minimal foundation requirements.  

The design also accounted for dismantling, component reuse, and relocation, as the pavilion is scheduled to be relocated to the Maldives after the Expo concludes.

While focusing on reducing dome weight, strategies were devised to prevent structural instability without the use of driven piles. Simplified foundation and joint designs were crucial, considering future relocation plans.

CFRP dome

The CFPR dome consists of three layers, marking the first use of CFRP as an earthquake-resistant structure in Japan.

CFRP, a plastic reinforced with carbon fibres, boasts exceptional lightweight properties, with a specific gravity roughly one-fifth that of steel, while maintaining comparable strength. This enabled the realisation of a 40m-span dome on a shallow foundation, significantly reducing the  weight per unit area.

However, as CFRP is sensitive to temperature changes, thermal simulations were carried out to verify its load-bearing capacity in the high-heat, high-humidity conditions expected after the pavilion’s relocation to the Maldives.

A steel frame was integrated into the outer layer supporting the membrane structure, with CFRP pipes used in the second and third layers. Designed with relocation and reuse in mind, the pavilion not only prioritises safety but also emphasises environmental sustainability, exceeding decarbonisation benchmarks.

Laminated bamboo dome

The 20m diameter dome is constructed with six layers of curved laminated bamboo. Bamboo offers the benefit of rapid growth and efficient CO₂ absorption compared to timber. However, due to variations in thickness, size and surface uniformity, laminated bamboo is used to enhance its strength and stability. 

To ensure structural safety, material tests were conducted over a year in collaboration with laminated bamboo suppliers and universities.

Paper tube dome

The paper tube dome is constructed using 100% recycled paper tubes and cross-laminated timber (CLT) joints. This hybrid structure combines the bending rigidity strength of paper tubes with the compression and tension-resistant properties of steel. The steel joints incorporate CLT nodal-type joints, demonstrating that trusses with wooden joints represent a promising next-generation truss design.

Testing, certification and future impact

Extensive testing and rigorous evaluations confirmed that three new materials, with limited prior use in construction, can be effectively adopted as building materials.

To secure certifications, comprehensive experiments were carried out to ascertain their properties and load-bearing capacities. These experiments included long-term verification of material and joint strength criteria, encompassing compression, bending and buckling tests.

The Blue Ocean Dome Pavilion is more than a temporary structure – it’s a proof of concept for the future of sustainable building design. By combining cutting-edge materials, thoughtful engineering, and a focus on circular design, this project redefines what’s possible in environmentally conscious architecture.

_{Top image: ©Hiroyuki Hirai}