Durability of Additively Manufactured SPI Components (2026-03)¶

In the Pareus Resort Caorle project, the particle-bed-based Selective Paste Injection (SPI) process was used on a large scale for the first time in the production of prefabricated components. Against the backdrop of practice-relevant exposure classes (XC4, XS1, XF2), this paper investigates the mechanical and durability-related behavior of additively manufactured SPI components, with particular attention to layer-dependent microstructural characteristics. The results show that volumetric frost resistance is largely determined by classical concrete technology parameters, particularly the water-cement ratio. No pronounced directional dependence of the relative dynamic modulus of elasticity can be detected. In contrast, transport-driven mechanisms exhibit increased sensitivity to layer-by-layer microstructure formation. In particular, during carbonation, locally greatly increased depths occur along interlaminar transition zones, which are not fully captured by mean-value analyses. Supplementary CDF tests highlight the importance of transport processes near the edge zones. Based on mechanical, durability-relevant, and microscopic findings, a two-stage microstructure model is proposed. The durability of additively manufactured SPI components thus results from the interaction of material-technology-controlled cement paste porosity and process-induced changes in pore connectivity along the layer boundaries.