Potentials of Steel Fibres for Mesh Mould Elements

Abstract

Mesh Mould is a digital fabrication technique developed at ETH Zurich in which the reinforcement and formwork production are unified in a robotically controlled system. An industrial robot fabricates a dense, three-dimensional, double-sided, welded reinforcement mesh that is infilled with a special concrete mix that achieves sufficient compaction without flowing out the mesh, which acts as porous formwork. Since the project started in 2012, the actual generation of robot end-effector is capable of bending and welding conventional steel reinforcement of 6 and 4.5 mm in diameter. Due to the process, the load-bearing capacity of these Mesh Mould elements is not equal in both directions due to geometrical restrictions in the end-effector. This study aims to increase the loadbearing capacity in the weaker direction by using steel fibre reinforced concrete (SFRC), which orients the fibres during flowing in this direction and in addition prevents the leakage of the concrete by enhancing jamming. A total of 10 specimens with 540×210×80 mm dimensions were tested in a displacement controlled symmetric four-point bending test. By combining SFRC with a mesh, the bending strength increased significantly with respect to the samples without fibres. The capacity is higher than the capacity of the individual parts, which are evaluated in separate material tests. Nonetheless, the bending strength in this study was limited by the weld strength, which was considerably lower than the one achieved by the robot. Higher weld strength would lead to better performance than in this first study, which is a part of an ongoing research effort.

Digital Concrete: A Review

“…Alternatively, in specific digital fabrication processes, it is possible to place the reinforcement first, and subsequently deposit the concrete around it. This approach has been applied rather crudely by contractor HuaShang Tengda, using a forked nozzle to print around pre-placed conventional reinforcement mesh, and in a more sophisticated manner in Smart Dynamic Casting [40,117] in which a dynamic formwork slip-forms the geometry around a pre-placed reinforcement element, or in the Mesh Mould process [34,[118][119][120] where a free form reinforcement mesh is robot-welded and subsequently used as an open formwork for the application of a concrete.…”