The creation of concrete shells from customized prefabricated modules is a novel approach that facilitates the construction of free-form surfaces considerably. In the framework of the Adaptive Concrete Diamond Construction (ACDC) project at TU Dresden, a material for 3D printing of the outer contours of such modules has been developed based on the principles of Strain Hardening Cementitious Composite (SHCC). In addition to its high ductility, the required material must also be suitable for 3D printing while enabling the achievement of high geometric accuracy in the manufacture of the modules. To gain the required performance, cellulose ether and starch ether were used specifically to extend the open time, for a longer period of maintaining initial workability, as well as for enhancing shape stability and surface quality. An extensive experimental program was carried out to evaluate the outcomes of the material modifications, including flow table tests, water retention tests, and several specific tests to determine the adhesiveness of the fresh SHCC. For hardened SHCC, surface roughness was assessed using a laser 3D scanner in addition to testing its mechanical properties.
Keywords: 3D concrete printing; ECC; SHCC; additive manufacturing; digital concrete; digital fabrication.