Heat transfer in a 3D-printed multilayer wall system: An experimental and numerical analysis

Abstract

As the construction industry explores new technologies, particularly automated methods, the thermal performance of 3D-printed concrete walls remains under-researched. This paper presents a study combining experimental tests and numerical simulations to evaluate the thermal behaviour of a multilayer wall system designed for 3D printing (3DP). The wall consists of two outer cement-based layers, commonly used in 3DP constructions, with an inner layer of thermal mortar for insulation. To assess its effective performance, a large-scale prototype wall was 3D-printed, and thermal tests were conducted in a hot box under both steady-state and dynamic conditions. Additional tests were performed after humidifying the thermal mortar to better understand the moisture impact. Numerical simulations were carried out using WUFI 2D to model transient heat transfer, and these results were validated against experimental measurements of temperature and heat flux. After the model was validated, the study extended to a sensitivity analysis of the insulation's thermal properties and the comparative simulation of seven additional wall configurations to evaluate the impact of insulation thickness, insulation positioning, and the inclusion of an air space on the thermal response. The wall's U-value in standard conditioning conditions was 0.746 W/(m2 & sdot;degrees C). The numerical model showed good agreement with experimental data. Introducing an air gap had a more significant effect on thermal performance than the insulation's position, with thinner insulation correlating with greater temperature fluctuations.