Banca de DEFESA: HENRIQUE ALMEIDA SANTANA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : HENRIQUE ALMEIDA SANTANA
DATA : 13/02/2020
HORA: 14:00
LOCAL: Programa de pós-graduação em engenharia civil
TÍTULO:

REINFORCED GEOPOLYMER WITH 3D PRINTED MESH

PALAVRAS-CHAVES:

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PÁGINAS: 135
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
RESUMO:

The high mechanical performance of geopolymers, combined with the low CO₂ emissions associated with them, as well as the potential to be used as a binder in self-compacting mixtures, has aroused great interest in civil construction. However, the fragile behavior of geopolymers, inherent to ceramic materials, demands the use of reinforcement materials capable of making them suitable for applications involving dynamic or tensile loads.  In this context, seeking to unite concepts of textile concrete technology and additive manufacturing, this work proposes, embryonically, the concept and development of composites of geopolymeric matrices reinforced with 3D printed meshes. For the dosage of the geopolymeric matrix, a statistical design of mixtures associated with multiple optimization was used. Thirteen basic formulations, which served for the elaboration of models that relate the flow properties (mini-slump spread and V-funnel flow time), physical (apparent porosity) and mechanical (axial compressive strength and flexural tensile strength), with the mass fractions of the ingredients of the mixtures, were established using the statistical project called “extreme vertices screening design”. The mixtures were prepared with metakaolin, a NaOH activating solution, alternative sodium silicate (SiO₂/Na₂O = 3.81), quartz sand and superplasticizer additive based on polycarboxylate. In this stage, the optimal self-compacting formulation was determined, the one with the maximum performance-to-cost ratio. This mixture was prepared with a NaOH activating solution with a molarity equal to 9.02 M, molar ratio Na₂O/Al₂O₃ equal to 1.42 and a volumetric concentration of solids equal to 0.52. The next stage, which involved the reinforcement phase, consisted of assessing the resistance to the alkaline environment of filaments used in 3D, PLA and PETG printing. In the prolonged test of exposure to the alkaline solution for 7 days, it was verified after the exposure that, the PLA presented a mass loss of 35.83% and 45.62% of tensile strength. PETG, did not undergo significant physical and mechanical changes. These results led to the choice of PETG as the material for the production of 3D reinforcement meshes. Two mesh geometries for use as reinforcement for composites were developed: a homogeneous one, which allows to obtain composites with a uniform distribution of reinforcement and another with functional gradation, designed to concentrate the reinforcement in the stressed region of the composite when subjected to bending. The composites were prepared and evaluated under flexion following the method established in EN 14651 (2007). The homogeneous and graduated meshes increased the fracture toughness and energy and preserved the maximum supported load and the critical fracture factor of the composites. In addition, the gradation of the meshes made it possible to reduce material consumption without compromising the mechanical performance of the composites. Composites developed with a self-compacting geopolymeric matrix and with printed reinforcement meshes, provided new technological concepts, with the prospect of wide application in civil construction.    

MEMBROS DA BANCA:
Presidente - 2137887 - CLEBER MARCOS RIBEIRO DIAS
Externo à Instituição - DACHAMIR HOTZA - UFSC
Interno - 1779028 - DANIEL VERAS RIBEIRO
Interno - 2315713 - MARCELO STROZI CILLA