Cardboard tubes are so commonplace that we may no longer even notice them. Yet they are everywhere: in a roll of toilet paper, in the packaging of the college diploma, in fireworks, and in the tissue and paper industries. And now, more and more, they can be found in unusual places, such as on the walls of houses and buildings. The material is part of modern life and is being produced for a multitude of industrial applications and consumer products. The vast majority are used as structural cores in winding operations. Immediately after manufacturing, paper, film or textiles are rolled directly onto cardboard tubes resulting in a stable roll that is easily stored and transported.
Although considered unremarkable commodities, they are actually stellar works of engineering. The tubes for industrial markets are optimized and designed for a specific use and take into account multiple characteristics, such as adequate strength and stiffness, textured surfaces, adhesives, and so on. Some tubes, for example, should be designed not only to withstand heavy loads, but also to limit vibration when unwound using high-speed presses.
In the construction industry, cardboard tubes have been widely used since the 1950s as molds for concrete columns. More recently, however, they have been used as architectural structures. In the last 20 years, cardboard tubes have been attractive to architects not only because they are a low-cost, 100% recyclable and environmentally sustainable option, but also because they have the mechanical properties required to withstand structural loads.
According to research carried out by the architect Gabriela Barros from the Municipal University of São Caetano do Sul, the convenience of the material does not stop there. Because it is lightweight, it does not require very sturdy foundations, reducing construction time and cost. As the installation process is done using fittings and ties, it is easy to disassemble and reassemble. It's simple and quick installation means that it is not necessary that the workmanship is specialized. In addition, the tubular shape offers the possibility of embedding hydraulic and electrical systems and optimizes thermal and acoustic resistance (as a function of the air wall inside the tubes).
The pioneer in using the material in architecture is the Japanese architect who won the Pritzker Prize in 2014, Shigeru Ban. In 1986 he began testing temporary and semi-permanent structures made out of cardboard tubes. At first, he used the material in indoor partitions. By 1989, the architect built a paper arbor and used cardboard tubes structurally for the first time. For this, Ban performed laboratory tests and identified that the cardboard tubes withstand 10 MPa when subjected to compression and 15 MPa under flexion. As the structural complexity of the designs changed, new tests were designed to ensure the integrity of the specific constructions. After six months, the arbor was dismantled for testing. Although it was totally exposed to bad weather, the resistance of the cardboard tubes had actually increased due to the hardening of the glue used in its manufacturing process.
In 1994, Ban proposed a shelter made of cardboard tubes to the United Nations High Commissioner for Refugees, which hired him as a consultant. After the great Hansobe-Awaji earthquake in 1995 left 310,000 people homeless, he created the first "Paper Log House" using cardboard tubes for walls and beer cartons weighed by sandbags as foundations. That would become the prototype for cheap, comfortable, and beautiful disaster relief buildings. In the following years, Ban used the material to build countless temporary housing projects designed to help nations hit by disasters in places like Haiti, Rwanda, and Japan.
The architect also designed a temporary school after an earthquake hit the town of Ya'na, Sichuan, China, in 2013. The dimensions of the base are 6 x 21 meters with a structure composed of cardboard tubes, wooden ties, metal angles and steel cables. The tubular shape of the cardboard made it possible to create a free span inside the building, without pillars. The construction was carried out with the help of volunteers, the local population and students of Kyoto's art and design course, led by the architect Shigeru Ban.
Ban also used cardboard tubes to construct spaces for temporary exhibitions. In 2000, in Hannover, Germany, he was invited to design a recyclable paper pavilion for an exhibition themed around environmental issues. The project was developed in partnership with the architect Frei Otto and was one of the most complex structures ever built with cardboard tubes. For the envelope, a membrane was developed without PVC in order not to release dioxides when burned.
Concerned about the living conditions of refugees from Japan’s 2011 tsunami, Ban developed privacy guards for those who were housed in classrooms and gyms. The architect used paper tubes, canvas and pins to erect instant walls in only a few hours. In the same year, Ban designed the Cardboard Church in Christchurch, New Zealand after an earthquake struck the city. With an expected shelf life of 50 years, the temporary cathedral serves as a replacement for the iconic Anglican cathedral built in 1864—one of Christchurch's most valued buildings—until a permanent structure is built.
The cardboard tube structures developed by Shigeru Ban are rigorously engineered to ensure proper stability, safety and maintenance and includes special treatments to make them fireproof and inhibit moisture penetration. The paper school in China has been in use for over 10 years and has survived several earthquakes ever since, and the Takatori Catholic Church, built in 1995 in Japan, was donated to a city in Taiwan where it remains to this day.
Though Shigeru Ban’s projects have already proven the potential of cardboard, it is important to point out that their use is still experimental and demands more technical studies and codes for its more broader application in the construction industry. Regardless, Ban's main merit in transforming such banal material into true works of art proves the transformative power of architecture.
