| Resumo : |
Alkali-activated binders (AAB) present a concern for the environment due to the potential to use waste or renewable raw materials in their production and the potential for lower carbon emissions when compared to Portland cement composites. These types of binders are produced from a mixture of a solid precursor and an alkaline activator, which generates hydrated products with properties similar to those of conventional cement hydration. Any compound, in theory, composed of silica/alumina and silica/alumina/calcium oxides with an amorphous structure can be used as a solid precursor. In this work, the wood residue ash (WRA) that was used as a solid precursor in AAB with NaOH as alkaline solution. WRA was characterized by means of X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), particle size diameter. The effect of milling times (15-600 minutes), Na+ concentration (2.0, 3.5, 5.0, 6.5 and 8.0 mol.kg-1) and curing temperature (25, 60, 75 and 90 ºC). WRA characterization Results showed that WRA presented mainly SiO2 (68.6 wt.%); crystalline (quartz and calcite) and amorphous phases; calculated D[4,3] of the optimum milling time was 9.97 µm; and the particle morphology was irregular. The optimum Na+ concentration and curing temperature was 5.0 mol.kg-1 and 75 ºC, respectively. Microstructural studies showed presence of a porous and irregular hydrated products, and EDS results suggest a formation of a hydrated product composition of low-calcium (C,N)-S-H. Therefore, WRA can show the potential to be used as a solid precursor. Therefore, the project proposes to use wood residue ash (WRA) as a solid precursor in alkali-activated binders. |