Un geopolímero a base de metacaolin fue fabricado con 5 proporciones de dos nanomateriales diferentes. Por un lado, nanowhiskersde carburo de silicio y, por otro lado, nanopartículas de dióxido de titanio. Ambos fueron colocados en agua y recibieron energía ultrasónica para ser dispersados. Fueron analizadas los efectos sobre las propiedades mecánicas y la cinética de reacción. Comparados con la matriz de referencia, los resultados evidenciaron una tendencia al incremento de la resistencia a la flexión. Probablemente por la geometría de los nanowhiskersde SiC y el refinamiento de poros por las partículas de nano-TiO2. Las curvas de calorimetría mostraron que al incorporar nanopartículas de TiO2se obtuvo una reducción del 92 % en el calor total, mientras que, los nanowhiskers de SiC produjeron una reducción del 25 % en el calor total.
Nanomaterials are potential candidates to improve the mechanical properties and durability of cementitious composites. SiC nanowhiskers (NWs) present exceptional mechanical properties and have already been successfully incorporated into different matrices. In this study, cementitious composites were produced with a superplasticizer (SP) and 0–1.0 wt % SiC NWs. Two different NWs were used: untreated (NT-NW) and thermally treated at 500 °C (500-NW). The rheological properties, cement hydration, mechanical properties, and microstructure were evaluated. The results showed that NWs incorporation statistically increased the yield stress of cement paste (by up to 10%) while it led to marginal effects in viscosity. NWs enhanced the early cement hydration, increasing the main heat flow peak. NWs incorporation increased the compressive strength, tensile strength, and thermal conductivity of composites by up to 56%, 66%, and 80%, respectively, while it did not statistically affect the water absorption. Scanning electron microscopy showed a good bond between NWs and cement matrix in addition to the bridging of cracks. Overall, the thermal treatment increased the specific surface area of NWs enhancing their effects on cement properties, while SP improved the NWs dispersion, increasing their beneficial effects on the hardened properties.
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