Compatibility and adhesion between fiberreinforced alkali-activated repair mortar and concrete substrate

• Ano de defesa: 2018
• Autor(a) principal: Nunes, Vitor Alencar
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Centro Federal de Educação Tecnológica de Minas Gerais; Programa de Pós-Graduação em Engenharia Civil; Brasil; CEFET-MG
• Palavras-chave em Português: Reações agregadas alcalinas; Argamassas - Manutenção e reparos; Aderências; Compostos fibrosos
• Link de acesso: https://repositorio.cefetmg.br/handle/123456789/249

Concrete repairing is a complex task that requires a special knowledge of technical building regulations and standards, deterioration mechanism and diagnosis, repair principles and methods, repair materials, execution of repair works, inspections, monitoring and maintenance. So far, most used patch repair mortars fall into two categories, (i) the mortars based on inorganic binders (Portland cement, PC) and (ii) those based on organic binders (polymers). Recent investigations reveal a third category of mortars with high potential to be used in the field of concrete repair, i.e. the alkali-activated based mortars. Alkali-activated materials (AAM) have been widely promoted as a greener binder for sustainable constructions. These binders can be generated from a wide range of aluminosilicate materials under alkaline conditions to produce a hardened component. This study, therefore, aims to evaluate the compatibility and the adhesion between a fiber-reinforced alkali-activated mortar and a concrete substrate. Different formulations of AAM were initially studied, based on the alkaline activation of metakaolin (MK) and blast furnace slag (BFS); their mechanical properties and modulus of elasticity were assessed. Five formulations were selected after this preliminary evaluation in order to produce the repair mortar and to apply onto concrete substrates. A volume fraction of 0.25% of PP fiber was used to mitigate the early-age shrinkage and to increase the adhesion bond of the repair mortar with the concrete substrate. The bond strength was evaluated by pulloff testing. The crack and delamination behaviour were assessed by four-point bending tests. Physical properties were also investigated: water absorption, apparent porosity and apparent density. Results showed a good compatibility and adhesion between alkali-activated repair mortars and the PC substrate. Satisfactory bond strengths were found meeting the required by the structure repair standard BS EN 1504. The delamination issue was observed only in 100 % MK-based mortars and the crack propagation behaviour was typical from brittle materials. The formulation 80MK-20BFS designed with SiO2/Al2O3 molar ratio 3.0 and fiber-reinforced was selected as the most promising one to structural repair proposes.