Banca de DEFESA: RUAN CARLOS DE ARAUJO MOURA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : RUAN CARLOS DE ARAUJO MOURA
DATA : 02/12/2021
HORA: 14:00
LOCAL: Escola Politécnica - Online
TÍTULO:

DURABILITY ANALYSIS OF POLYMERIC REBARS WITH FIBERGLASS SUBMITTED TO ALKALINE ENVIRONMENT AND HIGH TEMPERATURES

PALAVRAS-CHAVES:

GFRP rebars. Durability. Microstructure. Accelerated aging. Performance.

PÁGINAS: 144
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
SUBÁREA: Construção Civil
ESPECIALIDADE: Materiais e Componentes de Construção
RESUMO:

Glass fiber reinforced polymer rebar (GFRP) has been considered as a solution to prevent the degradation of reinforced concrete structures, thus reducing the economic impact resulting from the maintenance and rehabilitation activities of these structures. However, the durability of these rebars, in alkaline environment or high temperatures, is still a concern, due to the physical, chemical, and mechanical changes that can occur, causing the reduction of their useful life. In this context, seeking a better understanding of degradation mechanisms in high aggressive environments, this study evaluated the durability of GFRP rebars, manufactured with polymeric isophthalic polyester, vinyl ester and epoxy, with nominal diameters of 6.0 and 13.0 mm. Thus, accelerated aging tests of GFRP rebars were performed in alkaline solution (pH 8.5, 12.6, and 13.5) and in concretes without mineral addition and with the addition of silica fume and carbonated concrete, at temperatures of 23 ˚C,40 ˚C and 60 ˚C and with different exposure periods (500 h, 1000 h and 3000 h). In addition, an exposure test was performed at high temperatures at 23 ˚C, 150 ˚C, 300 ˚C and 350 ˚C in two situations: the first with direct exposure in the GFRP rebars and the second, the rebar were embedded in concrete with cover thickness of 20 mm. The degradation in glass fibers, polymer matrix, fiber-matrix interface and rebar/concrete interface were evaluated before and after exposures using thermogravimetric analysis (TGA), differential exploratory calorimetry (DSC), differential thermal analysis (DTA), scanning electron microscopy (SEM), spectroscopy (FTIR), in addition, mechanical analysis was performed by tensile tests, shear, interlaminar shear strength and adhesion. The results showed the degradation of GFRP rebars aged in concrete was lower when compared to aged rebars in alkaline solution. The degradable effects were attenuated using silica fume in concrete, with loss in interlaminar shear strength of 11.3%. In addition, the carbonation of concrete resulted in an environment less harmful to GFRP rebars, with a 10.7% reduction in interlaminar shear strength after 3000 h of exposure. When exposed to high temperatures, the traction behavior of GFRP rebars has a significant influence of the polymer matrix, and the epoxy matrix showed the best performance after exposure, followed by rebar with vinyl and polyester matrix. The use of active silica improved the performance of concrete covering and, consequently, improved the protection to GFRP rebars, making it difficult to diffuse oxygen and heat. The rebar/concrete adhesion was compromised by the thermal degradation of the ribs of the GFRP rebar.

MEMBROS DA BANCA:
Presidente - 1779028 - DANIEL VERAS RIBEIRO
Interno - 2137887 - CLEBER MARCOS RIBEIRO DIAS
Interno - 549.925.915-15 - PAULO ROBERTO LOPES LIMA - UFRJ
Externa à Instituição - GLÁUCIA MARIA DALFRÉ - UFSCAR
Externo à Instituição - SANDRO CAMPOS AMICO - UFRGS
Externo à Instituição - BERNARDO FONSECA TUTIKIAN - Unisinos