The aim of the present study was to obtain a substitute of Portland cement that implies environmental benefits. According to the above, a cementitious geopolymer was synthesized, at laboratory scale, from the alkaline activation of gold mining tailings from the dep artment of Santander, Colombia. This material was exposed to a series of pre-treatments which included the removal of impurities and moisture; after sieving the material corresponding to the 100-mesh Tyler standard sieve was selected, which was characterized by means of X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. In addition to the mining tailings, high purity kaolin and alumina were used as precursor mat erials. These were exposed to a pre-heat treatment at 600°C for one hour. The activating solution consisted of a mixture of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) in a weight ratio of 7:3. After mixing the precursor material with the activat or solution, by mechanical stirring, the initial curing was performed at 90°C for 24 hours. The performance of the obtained product was determined by the evaluation of its compressive strength under standard conditions and at high temperatures according to the curing time. In addition, a scanning electron microscope (SEM) coupled with a dispersive energy spectrometer (EDS) was used to identify microstructural characteristics of the geopolymer. This presented properties like Portland cement I, so the use of this type of products in engineering applications could be a good option for the treatment of mining tailings and, in turn, the reduction of the pollution produced by the manufacture of the Portland cement.
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