Non-destructive tests for performance evaluation of self-healing concrete by addition of methyl methacrylate-containing microcapsules

• Published in: Revista IBRACON de estruturas e materiais 2024, Vol.17 (2)
• Main Authors: Valerio, Daniel, Fernandes, Juliana Ferreira, Futai, Marcos Massao, Figueiredo, Antonio Domingues de, Aoki, Idalina Vieira
• Format: Article
• Language: English
• Subjects: corrosion; durability; ENGINEERING, CIVIL; fissures; non-destructive tests; self-healing concrete
• ISSN: 1983-4195; 1983-4195
• DOI: 10.1590/s1983-41952024000200006

Abstract The objective of this work was to develop a chemical admixture to make concrete capable to heal its fissures autonomously and, consequently, mitigate the concrete’s reinforcement corrosion due to the ingress of aggressive agents. For that, polymeric microcapsules built by a shell of urea-formaldehyde-melamine (UFM) and a core of methylmethacrylate were developed and added to the concrete to further evaluation. The concrete specimens containing 0%, 3% and 6% of the proposed microcapsules (mass of microcapsules / mass of cement) were subjected to destructive and non-destructive tests. The water absorption and the mechanical tests i.e., compressive strength and indirect tensile strength (Brazilian test) were carried out to characterize concrete, while the electrochemical impedance spectroscopy (EIS) and the non-destructive ultrasonic pulse velocity (UPV) tests were conducted to evaluate the concrete self-healing ability. These tests showed that the proposed admixture was able to heal the concrete’s fissures partially. In addition, it was concluded that the samples with 3% of microcapsules presented higher self-repairing rates. Despite the microcapsules developed in this work have presented a satisfactory self-healing efficiency, their effectiveness looks to be affected by the mixing procedure once part of them is broken during the process. Resumo O objetivo deste trabalho foi desenvolver um aditivo químico capaz de tornar o concreto auto reparável e, consequentemente, mitigar a corrosão da armadura em seu interior devido à entrada de agentes agressivos. Para isso, microcápsulas poliméricas compostas por uma casca de uréia-formaldeído-melamina (UFM) e um núcleo de metilmetacrilato foram desenvolvidas e adicionadas ao concreto para posterior avaliação. Os corpos de prova de concreto contendo 0%, 3% e 6% das microcápsulas propostas (massa de microcápsulas / massa de cimento) foram submetidos a ensaios destrutivos e não destrutivos. O ensaio de absorção de água e os mecânicos, ou seja, resistência à compressão e resistência à tração indireta (teste brasileiro) foram realizados para caracterizar o concreto, enquanto a espectroscopia de impedância eletroquímica (EIS) e os ensaios não destrutivos de velocidade de pulso ultrassônico (UPV) foram conduzidos para investigar a ocorrência de autorreparação. Esses testes mostraram que o aditivo proposto foi capaz de cicatrizar as fissuras do concreto parcialmente. Além disso, analisando os dados coletados com o pr