MECHANICAL RESPONSE OF DISTINCT GEOPOLYMER MIXTURES REINFORCED WITH PVA FIBERS

Reference Presenter Authors
(Institution)
Abstract
04-021 Ana Carolina Constâncio Trindade Trindade, A.C.(Pontifícia Universidade Católica do Rio de Janeiro); Batista, R.P.(Centro Federal de Educação Tecnológica de Minas Gerais); Borges, P.R.(Centro Federal de Educação Tecnológica de Minas Gerais); Silva, F.d.(Pontifícia Universidade Católica do Rio de Janeiro); Geopolymers appear as an innovative class of materials capable to suppress the growing demand for environmental friendly components. The production of its raw constituents, when compared to OPC, results in lower amounts of CO2 emissions. They are obtained through alkali activation of aluminosilicates, and its mechanical behavior may vary according to its molar ratios, curing regime and processing conditions. Even though presenting superior mechanical behavior, geopolymers can still be considered brittle materials. Fiber reinforcement appear as an interesting solution to overcome this vulnerability, and generates an expectation related to its life service quality. Strain-hardening ceramic composites (SHCC) reinforced with PVA fibers exhibit moderate stresses and ultra-ductility. This study presents an experimental evaluation of distinct geopolymer mixtures reinforced with 2% of PVA fibers. The aluminosilicates were composed by metakaolin and silica fume, activated by combinations of Na-hydroxide and Na-silicate, in different molar ratios. The use of diverse aggregate granulations was also investigated. Compression, tensile and flexural tests were performed. In addition, pull-out responses were also investigated, allowing a study of the composites regarding the classical theories of energy. X-ray diffraction and scanning electron microscopy (SEM) were used to comprehend its microstructural properties. All composites exhibited strain-hardening behavior with multiple cracking formation. However, the composite based on metakaolin without aggregate incorporation presented the larger margin between complementary energy calculated from the bridging stress and composite crack tip toughness. This response is directly related to an intense multiple cracking formation, evidencing its superior ductility.
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