Banca de DEFESA: SILAS DE ANDRADE PINTO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : SILAS DE ANDRADE PINTO
DATE: 29/04/2022
TIME: 14:00
LOCAL: DCTM - Remota
TITLE:
INFLUENCE OF THE ADDITION OF CARBON NANOTUBES (NTC) ON THE PROPERTIES AND DURABILITY OF CEMENT MATRIXES
KEY WORDS:
Carbon nanotube. Durability. Nanotechnology. Chlorides. Carbonation. Concrete.
PAGES: 175
BIG AREA: Engenharias
AREA: Engenharia Civil
SUBÁREA: Construção Civil
SPECIALTY: Materiais e Componentes de Construção
SUMMARY:
In recent decades, the use of nanotechnology has grown in several sectors, including the production of clinkers and incorporation into cement-based matrices. However, there is a need to understand the action of these nanomaterials on the properties of cementitious matrices. Among the different nanomaterials, carbon nanotubes (CNT) have been used in several kinds of research. Due to the difficulties in dispersing CNTs in water, there is a need to use alternative techniques to obtain homogeneous results matrices. Recent studies show the beneficial effect of CNTs when added to the cementitious matrix. However, few address the durability of these matrices. The present work uses techniques to evaluate the durability of matrices with CNT through chloride migration tests, corrosion potential, electrochemical impedance spectroscopy (EIS), and electrical resistivity. Therefore, it is expected to analyze the influence of CNT on the properties of cementitious matrices, determining the optimal levels of use and, mainly, their effects on durability in terms of corrosion in reinforced concrete structures. Studies on mortars indicate that the CNT used tends to be dispersed more efficiently when using 0.10% of a polycarboxylate-based admixture by weight of cement. The cementitious matrices showed an increase of up to 41% in the tensile strength in bending, in mortars with the incorporation of 0.075% of NTC (considered ideal), by weight of cement, with less expressive improvements when evaluating the performance of concretes with NTC. When evaluating the durability parameters of concrete and the corrosivity of the steel embedded in this matrix, it was observed that the presence of CNT promotes a significant reduction in electrical resistivity due to the high conductivity of this material. However, the migration test indicates that the non-stationary diffusion of chloride ions is reduced, promoting a lifetime increase of up to 52%. Furthermore, the corrosion potential and EIS tests indicate that the densification caused in the matrix, due to the use of CNT, has a main effect on the protection capacity of the steel, with a behavior that is minimally similar to the reference concretes.
BANKING MEMBERS:
Externo à Instituição - FERNANDO DO COUTO ROSA ALMEIDA
Interno - 2137887 - CLEBER MARCOS RIBEIRO DIAS
Presidente - 1779028 - DANIEL VERAS RIBEIRO
Interno - 2315713 - MARCELO STROZI CILLA
Interno - 549.925.915-15 - PAULO ROBERTO LOPES LIMA - UEFS
Externo à Instituição - ROMILDO DIAS TOLEDO FILHO - UFRJ