DURABILITY ASSESSMENT OF 3D PRINTED CEMENTITIOUS ELEMENTS WITH INTERLAYER REINFORCEMENT

Abstract

Due to the lack of formwork and the weak morphology at the interface between layers in layer-on-layer extrusion techniques, tensile reinforcement incorporated at the interface between successive layers may be at an increased risk of exposure to environmental conditions like chloride ingress, which affect the durability of such elements, which can be seen in day-to-day conditions. The study addresses two questions: What is the effect of deterioration mechanisms, such as chloride ingress, on the mechanical performance and flexural strength capacities of cementitious binders with successive layers with steel, glass, and carbon fiber reinforced polymer reinforcement incorporated at the interface between successive layers? What are the solutions to mitigate these effects? The methodology of this study involves the development of a thixotropic mix design with rheological and set time parameters suitable for extrusion-based techniques using concrete 3D printing. Subsequently, mechanical and material characterization is conducted on the element after exposure to the deterioration mechanism, i.e., chloride ingress under short-term and long-term exposures. Microstructural analysis at failure interfaces is focused on understanding reinforcement behavior, the bond between binder and reinforcement, and failure modes with exposed vs non-exposed interlayers. In addition, this study reports the suitability of polymer surface finishings and the mismatch of the outer protection system to create an impenetrable barrier system against aggressive ions.