Abstract

Optimizing the shape of concrete construction elements is significant in reducing their material consumption and totalweight while improving their functional performance. However, the resulting non-standard geometries are difficult andwasteful to fabricate with conventional formwork strategies. This paper presents the novel fabrication method of mineralfoam 3D printing (F3DP) of bespoke lost formwork for non-standard, material-efficient, lightweight concrete elements. Manyinnovative formwork studies have shown that stay-in-place formwork can help to reduce waste and material consumptionwhile adding functionality to building components. Foams are particularly suitable for this application because of their highstrength-to-weight ratio, thermal resistance, and good machinability. F3DP allows the waste-free production of geometricallycomplex formwork elements without long lead times and production-specific tooling. This paper presents the materialsystem and robotic F3DP setup with two experimental case studies: a perforated facade panel and an arched beam slab. Bothcases use concrete as structural material and strategically placed custom-printed foam elements. In this first preliminarystudy, concrete savings of up to 50% and weight reduction of more than 60% could be achieved. This is competitive withstandardized solutions such as hollow-core slabs but, in contrast, allows also for non-standard element geometries. Additionalfunctionality, such as programmed perforation, acoustic absorption, and thermal insulation, could be added through thestay-in-place formwork. Moreover, the challenges and future developments of F3DP for sustainable building processes arediscussed. Further studies are required to verify the findings. However, considering the urgent need for resource-efficient,low embodied-carbon solutions in the construction industry, this work is an important contribution to the next generation ofhigh-performance building components.