Additive Manufacturing in Construction

Large scale additive manufacturing moves the printing process out of a controlled machine enclosure and onto a site where temperature, humidity and vibration are no longer constant. That single change affects almost every parameter of the process.

Process families

Three families dominate current practice: extrusion of cement based mixes, binder jetting of granular material, and the placement of reinforcement in a separate pass. Each imposes a different limit on geometry, and none of them yet matches the tolerance of precast production.

Tolerances

Measured layer deviation on the systems we have surveyed ranges from two to eight millimetres over a one metre height, and the dominant error source is not the print head but the substrate it starts from. Levelling the first layer properly removes a surprising share of the total deviation.

Open questions

Long term durability remains the least documented aspect. Published test series rarely exceed two years, which is far too short to describe the behaviour of a structural element expected to last decades.