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upstart writes:

3D-printed concrete bridge doesn't need supports:

3D-printed concrete bridge doesn't need supports

Concrete is the most consumed material in the world, second only to water. The material is pervasive because it has many practical uses — from building homes to forging dams that protect from storm surges. Reinforced concrete, concrete with steel embedded in it, is a foundation for the infrastructure of many essential industries: education, healthcare, transportation, government, and more. It would be next to impossible to live without reinforced concrete.

But the 2.8 billion tonnes of CO2 concrete emits falls just behind the total emissions of China or the United States — the two countries with the most CO2 emissions, reports Yale Environment 360.

Emissions aside, concrete thwarts natural habitats, covers and chokes ecosystems, and heats cities. We produce more concrete every two years than the plastic made in the past 60 years. Planet Earth is becoming a concrete world. And the steel used for reinforcement and the cement that binds the concrete together are at the heart of the problem.

[...] A team from Zaha Hadid Architects, ETH Zurich, and the Block Research Group decided to remove the reinforcement to build their approximately 39×52 foot arched pedestrian bridge.

While their construction methods harken back to the classic masonry arch construction, their materials are novel, with angled blocks arranged in an arch. They 3D printed concrete and applied it at right angles instead of pouring it horizontally. In doing so, they built a strong bridge without the added steel.

Due to the design, the loadbearing concrete structure uses significantly less material overall — including no steel or mortar. And, due to the bridge's geometry, the angular blocks transfer the load to the footings, keeping the entire structure stable. And because it doesn’t need mortar, the bridge can be taken apart and reassembled elsewhere.

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