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Phoenix666 writes:

Today the Built Environment department's concrete printer starts printing the world's first 3-D printed reinforced, pre-stressed concrete bridge. The cycle bridge will be part of a new section of ring road around Gemert [Netherlands] in which the BAM Infra construction company is using innovative techniques.

[O]ne of the advantages of printing a bridge is that much less concrete is needed than in the conventional technique in which a mold is filled. By contrast, a printer deposits only the concrete where it is needed. This has benefits since in the production of cement a lot of CO2 is released and much less of this is needed for printed concrete. Another benefit lies in freedom of form: the printer can make any desired shape, and no wooden molding frames are needed.

They have managed to not only 3-D print concrete, they have also developed a technique to lay down a cable within the concrete so that it can be 'pre-stressed' — avoiding tensil stress.

The researchers successfully tested a 1:2 scale model under a 2000kg load.

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