Browsing by Author "Gaitero, J. J."
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Item Characterisation of cement pastes with innovative self-healing system based in epoxy-amine adhesive(2015-07-01) Perez, G.; Gaitero, J. J.; Erkizia, E.; Jimenez, I.; Guerrero, A.; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNTwo innovative additions are considered for the development of self-healing concrete: epoxy-containing silica microcapsules and amine-functionalized nanosilica. The effect of two concentrations of the additions on the microstructure of a cement paste with silica fume is studied. The results indicate a proper dispersion of the additions within the matrix, a pozzolanic reaction induced by nanosilica and the stability of the microcapsules that reliably isolate the epoxy from the paste. As the concentration of additions increases, a preferential orientation of the portlandite phase is observed, together with a decrease of the compressive strength due to the presence of a minor content of macropores and to the low strength of the capsules. The self-healing efficiency is confirmed in concrete specimens for 150 μm wide cracks and a particular concentration of the additions. These results will be essential for the subsequent development of a reliable self-healing concrete based in the epoxy-amine adhesive.Item Development of ultra-high performance concretes with self-healing micro/nano-additions(2017-05-01) García Calvo, J. L.; Pérez, G.; Carballosa, P.; Erkizia, E.; Gaitero, J. J.; Guerrero, A.; Gerrero, A.; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓN; Tecnalia Research & InnovationUHPC are developed in present paper incorporating an innovative self-healing system based on two micro/nano-additions: silica microcapsules containing epoxy sealing compound (CAP) and amine functionalised silica nanoparticles. Although CAP are well integrated within the cementitious matrix, their inclusion promotes a reduction in the mechanical performance so CAP could act as weak points. However, the inclusion of these additions refines pore distribution thus increasing the expected durability in aggressive media. An effective autonomous self-healing capacity is assessed/confirmed which is unexpectedly higher in the concretes with the lower healing additions content studied. This capacity depends on the crack width and the healing period considered.Item Synthesis and characterization of epoxy encapsulating silica microcapsules and amine functionalized silica nanoparticles for development of an innovative self-healing concrete(2015-09-01) Perez, G.; Erkizia, E.; Gaitero, J. J.; Kaltzakorta, I.; Jiménez, I.; Guerrero, A.; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓN; Tecnalia Research & Innovation; CIRMETALSilica microcapsules encapsulating an epoxy compound (CAP) and silica nanoparticles functionalized by an amine group (NS) are synthesized to be used as self-healing system for smart cementitious composites. The innovative character of this system comes from the use of silica shell microcapsules to improve the durability and compatibility with the cement and from the use of functionalized nanosilica to obtain an amine functionalized cementitious matrix. Characterization of the particles indicates that they are amorphous and possess a proper morphology and size to be considered as additions to cement. The stability of the epoxy compound inside the microcapsules and the presence of amine groups bonded to silica nanoparticles are also confirmed. Moreover, NS shows a pozzolanic activity superior to that of the silica fume used as reference, while CAP is to a high degree stable upon reaction with lime. The results confirm that the synthesized particles are a suitable starting point to address the development of a smart self-healing concrete.