Argamassa com a incorporação de rejeito de minério de ferro nanoestruturado

Abstract

Mining is an activity with great economic impact; however, the generation of waste such as IOT has caused concern in the scientific community and governments, which has driven the search for ways to use these materials on a large scale. This work verified the effects of adding iron ore tailing (IOT) impregnated with Carbon Nanotubes (CNT), i.e., nanostructured IOT in the manufacture of mortars (cementitious composite), observing the increase in mechanical resistance and electrical conductivity. With this in mind, the effects of applying multi-walled carbon nanotubes (MWCNT) in mortars with different concentrations of CNTs, synthesized in situ on IOT, using an innovative method of dispersion of the nanomaterial, without the use of functionalization elements, additives and/or surfactants, and specialized labor, were investigated. Mechanical tensile tests in flexion and compression, water absorption tests by immersion, moisture loss tests by heat treatment, and electrical tests and characterizations (morphological, chemical, and microstructural) were performed, proving the efficiency of dispersion by the proposed method. The samples studied were prepared with MWCNT concentrations of 0.12%, 0.20%, and 0.80% of CNTs by the weight of cement in the mix, obtaining, in mechanical tests, an increase of 16%, 27% and 30% in flexural traction, respectively. With the electrical tests, an increase of 2266,35% in the electrical conductivity of the 0.80% CNT sample was observed. In the immersion absorption test, a decrease in water absorption was observed with an increase in the concentration of CNTs in the samples due to the hydrophobic nature of the CNTs. From the evaluation of moisture loss due to heat treatment, a behavior was observed in agreement with the literature regarding the loss of physical water (below 300°C), increasing the evaporation rate with the increase in the concentration of CNT in the samples. Together with X-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (FTIR) tests, the results obtained show the homogeneous dispersion of nanomaterials in the mortar. Thus, this work proposed a new method for incorporating CNTs into mortars in an effective, economically viable, and simple way using IOT in a quarter of the aggregates in the mortar mix.