Environmental Conditions Affecting the Shrinkage Behavior of Low Clinker 3D Printable Mortar (2024-09)¶

3D concrete printing is rapidly growing in the construction industry, and the sector is adapting to new technology. Significant progress has been made in recent years, which is of great interest to the 3D concrete printing (3DCP) industry. The 3DCP equipment available on the market is continuously being adapted to meet new requirements. One of the main challenges for successful 3D printing with printable materials is high shrinkage crack resistance. It is well-known that if restrained, cementitious materials develop internal stress due to increasing deformation, and cracking may occur if the stress value exceeds the material’s tensile strength. This phenomenon is even more critical in 3DCP applications. The 3D printed object has a high surface-to-volume ratio and is fully exposed to the environment since no formworks cover the fresh mortar, limiting water evaporation. Shrinkage depends on several factors, including mix-design composition, water-to-cement ratio, curing treatment, and environmental conditions (e.g., temperature, humidity, and wind speed). Although many investigations have been carried out in the literature to study the effect of on-site conditions on shrinkage deformation, no standard method is currently available. This study proposes a new testing setup to quantify the effect of high temperature and wind speed on shrinkage deformations. The outcomes demonstrate the reliability of the experimental method employed, allowing for the estimation of material performance in a real construction site. This information can guide mix-design development and optimization. The research activities are currently focused on defining a technique to assess the crack risk of printed elements exposed to different environmental conditions.