Study of the Viability of 3D Printing Reinforced Cementitious Materials

Abstract

Cementitious materials are the most used materials in the planet. However, the traditional manufacturing processes with these materials have limitations in terms of geometries and formwork, which make projects with greater complexity often unworkable. And that can be solved with the implementation of 3D printing technologies. In the construction industry, the use of additive manufacturing presents an enormous potential for the design of more adapted and optimized solutions, promoting concepts of sustainability, as well as shapes freedom. To be able to print these materials, one of the critical aspects is the adjustment of the properties of the material in the fresh state to the requirements of 3D printing extrusion. That is, a fresh consistency is required, allowing the material to be transported and extruded, followed by a rapid evolution of the resistance that allows the deposition of successive layers of material without excessive deformation of the previous layers, but ensuring a good bond between them. Considering these requirements, 3 mortar mixtures were developed; one without fibers, and the other two incorporating 6 and 13 mm metallic fibers, for use in an manual extrusion system adapted for cementitious materials. Initially, the flowability evolution with time was studied in order to find the optimal printing parameters. The mechanical properties of the mortars were determined after 28 days of curing, and results obtained were compared with traditional moulded samples. Capillary water absorption tests were carried out to evaluate the potential loss in durability of the printed samples. Using the formulation with better properties, 2 types of pieces were printed one by the traditional concept of extrusion and the other by a concept used by BetAbram which uses a support material to create voids in the piece, in our case sand will be the support material.