Development of fiber-reinforced cementitious composites for 3D printing
Fecha
2024-09-16Primeiro coorientador
Daudt, Natália de Freitas
Primeiro membro da banca
Salazar, Rafael Andres Robayo
Segundo membro da banca
Matos, Paulo Ricardo de
Terceiro membro da banca
Webber, Jaíne
Metadatos
Mostrar el registro completo del ítemResumen
Additive manufacturing has significantly impacted various industries, driving the digitization of industrial
procedures and aligning with concepts like Lean production and Industry 4.0. Advanced materials are crucial
for achieving high performance. However, a major challenge in adopting cementitious materials in additive
manufacturing is developing concrete pastes with suitable rheological properties for 3D printing to achieve
high strength. A comprehensive understanding of the rheological and mechanical behavior of concrete can
improve its performance, particularly in 3D printing applications. One persistent challenge in this field is the
cracking that often results from high cement consumption. The incorporation of short fibers has emerged as
a promising solution, significantly improving the material's structural integrity and reducing the risk of
cracking. The use of microfibers requires adapt not only to the required performance of the hardened material
but also to the development of the printing process, which is highly dependent on workability. The use of
microfibers in 3D printing is also closely related to limitations concerning flow and the size of the printer
nozzle. This research investigated fundamental aspects of the rheological and mechanical behavior of fiberreinforced cementitious composites for 3D printing. Firstly, the impact of adding microfibers on the yield
stress and structural integrity of printed concretes was evaluated, revealing that the incorporation of rock
wool, in particular, resulted in a significant increase in yield stress. This behavior contributed to better layer
support capacity in the printed structures. Additionally, the processability and correlation between the
rheological properties of composites reinforced with different fibers (steel/ST, rock/RK, and cellulose/CL)
were assessed in terms of extrudability and buildability. Tests showed that cellulose microfibers provide
greater stiffness to the material during the printing process, which impacts print quality and the ability to
support successive layers without structural failure. The rheological results for ST and RK demonstrated
superior adaptability to the 3D printing process in terms of workability and buildability, thus leading to their
selection for the subsequent stages of the study. The mechanical properties and anisotropy of 3D-printed
cementitious composites reinforced with steel and rock microfibers were investigated. The results indicated
that the addition of fibers significantly reduced material shrinkage and improved shear strength, particularly
in the printed samples, with anisotropy playing a key role in these enhancements. Although some defects
introduced during the printing process reduced mechanical properties such as tensile and compressive
strength, shear strength remained stable, highlighting the potential of fibers to improve the structural
performance of 3D-printed cementitious composites. This study contributes to the understanding of fiberreinforced concrete behavior applied to 3D printing, demonstrating that the use of microfibers offers
advantages in controlling rheology when evaluated together with mechanical properties, allowing for the
optimization of quality and increased performance of concrete. It also confirms the important role attributed
to anisotropy, due to construction from filaments. The findings also highlight the necessity of adjusting the
printing process and optimizing fiber distribution to achieve improved results in future applications.
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