Evaluation of self-healing capacity of 3D printable bio-based fiber-reinforced cement-lime mortars

Abstract

3D printing (3DP) of concrete is an innovative technology towards digitalisation and sustainability of construction industry. The design of printable materials is in the spotlight of research and some issues related to durability of 3DP members, such as cold joints between successive layers and cracking due to shrinkage, need to be overcome for widespread applications. Self-healing, also referred to as self-repairing capacity, combined with short-fiber reinforcement to control crack width, are some possible solutions to increase 3DP members durability. This study addresses this gap evaluating the self-healing capacity of cement-lime 3DP mortars reinforced with vegetal fibers and self-healing capacity. Printability was assessed through a rheological characterization using a Dynamic Shear Rheometer (DSR) and field-oriented tests, such as penetration and flow table tests. Extrudability and buildability were also studied by extrusion and uniaxial unconfined compression tests (UUCT). The evolution of mortar properties was monitored at Early age (EA) to better understand the hydration and shrinkage underlying mechanisms. Finally, small-scale prototypes were constructed by a robotic 3D printing arm and the self-healing capacity was evaluated. This work could have an impact on the design of new materials with self-healing capacity applied on digital fabrication techniques for more durable construction.