In the present work, geopolymer matrices were developed by alkali activation of metakaolin, using NaOH and sodium silicate as activators. The samples of metakaolin and matrices were studied by thermal analysis (TGA/DTA) at temperatures between 22°C and 1000°C in a nitrogen atmosphere with a heating rate of 10°C/min. The analyses showed gradual mass losses for MK1 and MK2, occurring in the temperature range of 350-700°C, associated with the dehydroxylation of the kaolinite present in the metakaolin samples, when transforming into reactive metakaolin. Thermal analysis allowed to identify mass losses associated with the different events that occurred during the formation of the geopolymer structure. The formation of amorphous geopolymer networks was confirmed by the XRD and FTIR techniques. The quantitative analysis of XRD results by using the Rietveld method allowed determine the amorphous and crystalline content of the precursors and geopolymers. The results obtained, after analyzing the matrices, showed that the geopolymers obtained presented a mechanical performance comparable to systems found in the literature, with uniaxial compressive strengths ranging from 38-50 MPa and stiffness around 7 GPa. Hence, these systems are suitable for their future use as alternative binder materials for the production of mortars and concretes.
Geopolymers are a new class of high performance materials able to replace traditional Portland cement due to its excellent mechanical properties, high initial resistance and durability. The raw material used for the production of geopolymers generally consists of industrial wastes such as fly ash and met kaolin, both rich in silica and alumina. Thus, geopolymers are an economically viable alternative for minimizing environmental impact by carbon sequestration. Although extremely resistant, their mechanical properties can be improved by the insertion of reinforcing agents. Among them, the fibers improve several properties such as tensile strength and toughness; besides allow controlling the cracking mechanism and the ductility of the geopolymer composites. Among the fibers used as geopolymer reinforcement the metallic, inorganic, organic and natural fibers should be highlighted. Each of these reinforcement materials influences positively the mechanical properties of the geopolymer composite, thus favoring a wide range of applications, especially in civil construction. Therefore, the objective of this work was to study the influence of the addition of different fibers on the mechanical properties of geopolymer matrix composites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.