Thermal Optimization of Additively Manufactured Lightweight Concrete Wall Elements with Internal Cellular Structure through Simulations and Measurements

Abstract

Combining the additive manufacturing (AM) process of extrusion with lightweight concrete, mono-material but multi-functional elements with an internal cellular structure can be created to achieve good thermal performance of a wall at low resource consumption. The aim of this paper is to analyze and optimize the actual thermal performance of such a component. A sensitivity analysis and a parametric optimization were conducted based on a mathematical description of heat transfer in cellular structures. To investigate the thermal performance, 2D and 3D heat transfer simulations were used and validated by heat flux measurements on an existing prototype. A geometric optimization led to a further reduction of the U-value by up to 24%, reaching 0.58 W/m2 K. The ratio of solid material to air inside the cells (relative density) was identified as the main driver, in addition to cell diameter, cell height, and cell wall thickness. The comparison of analytical and numerical results showed high correspondence with deviations of 3–10%, and for the experimental results 25%. These remaining deviations can be traced back to simplifications of the theoretical models and discrepancies between as designed and as built. The presented approach provides a good basis for optimizing the thermal design of complex AM components by investigating practical thermal problems with the help of 2D and 3D simulations, and thus offers a great potential for further applications.

Fabricate 2024

“…This allows for the injection of blow-in insulation material (e.g., perlite or cellulose) after assembly, significantly improving the overall insulation properties, compared with a solid element and air-filled cells (Briels et al, 2023b). The final design's thermal performance was assessed using a heat transfer coefficient of 0.98W/m 2 K, which was averaged across 20 layers (Briels et al, 2023a).…”

Appraising the Feasibility of 3D Printing Construction in New Zealand Housing

“…However, this performance is significantly influenced by factors such as the infill structure, concrete composition, and void fraction [67]. In a study by Briels et al [68], the use of internal cellular structure with encapsulated air-filled voids was investigated, revealing that lightweight concrete elements can achieve commendable thermal performance with lower resource consumption. Furthermore, the utilisation of high-strength concrete in 3D printing technology has the potential to produce lighter structures, which could further enhance thermal performance [69].…”

Monolithic AM façade: multi-objective parametric design optimization of additively manufactured insulating wall elements

“…Lim et al (2020) for instance demonstrated the manufacturing of saddle and dome-shaped concrete surfaces. Furthermore, AM offers the promising potential of fabricating monolithic elements characterized by intricate internal and external geometries, enabling the integration, individualization, hybridization, and optimization of performative features of building components (Dielemans et al, 2021;Briels et al, 2022;Piccioni et al, 2023). This innovative design approach offers high potential, especially for façade elements, one of the most complex building elements (Leschok et al, 2023).…”