Lightweight Reinforced Concrete Slab (2022-09)¶

Although increased efforts have been made in recent years to reduce the environmental impact in construction, greenhouse gas emissions in this sector are at record levels worldwide. In addition to reducing energy consumption and using environmentally friendly materials, the optimization and further development of conventional construction methods could make a significant contribution to achieving the given climate goals. In this regard, concrete, the most commonly used building material worldwide, plays a major role. Additive fabrication offers promising perspectives to change conventional reinforced concrete construction. 3Dconcrete printing does not require complexformwork construction and it makes targeted and economical fabrication of small quantities of concrete possible. This raises the question of whether the use of 3D printing technologies can reduce the CO2 emissions of the construction industry and whether the digital planning and production used in the manufacturing process represents an economical alternative on the construction site compared to conventional construction methods [1]. Previous work shows that material savings of 30% to even 70% are possible by using this technology [2]. However, these values do not usually correspond to the CO2eq saved. The calculations often do not take into account the high cement value of the printed concrete. In order to be able to exploit the potential of the technology and enable successful, large-scale use, it is essential to use a print material that meets the ecological and economic requirements [3]. This paper investigates the use ofthis new technology to produce a lightweight concrete slab using printed voids and additional in-situ concrete. It provides information on the design, the entire planning, the construction on site and the implementation in the context of a real construction project - a 100 m2 slab with 130 3D-printed voids. The research project provides information on the functionality, economic efficiency, CO2 savings, practicality and applicability of the new fabrication technology from the digital design to the production of the prefabricated parts in the production facility as well as the reinforcement and concreting of the structure on site. The project in Lunz am See proves that additive fabrication can be applied in construction practice in a timely manner and that the technology is suitable as a supplement to and further development of conventional construction methods. The wide-span slab construction is representative for a sustainable attitude towards the use of reinforced concrete, which, relies on economical, digital fabrication methods for saving resources.