Stone wool and steel slag make up a significant proportion of construction/demolition and industrial waste in the construction and steel processing industries. Unprocessed steel slag was not considered a potential resource in the past, but after processing it is now considered a by-product and is used in road construction (steel aggregate), as a steel inlay in steel processing (steel granulate) and for simpler technical applications (mineral product). The mineral product, which is also used in this work, has been processed but not yet used successfully. In comparison, stone wool generated from civil engineering and/or demolition work usually ends up in landfill, whereas stone wool generated as a by-product of production processes is recycled. One of the ways to successfully reuse these materials is to use them in the production of new building materials with alkali activation. In this master’s thesis, we investigated the potential of stone wool and steel slag as precursors for new alkali-activated materials by evaluating the mechanical, physical and chemical properties of the final products made from precursor fractions of different particle sizes. All used precursors were analysed separately; the particle size distribution in each fraction was determined, as well as their chemical composition by X-ray fluorescence spectroscopy and an estimate of the proportion of the amorphous phase by X-ray diffraction analysis. We also compared the morphological composition of precursor fractions using a scanning electron microscope. After curing the newly produced alkali-activated materials at three different temperatures and different curing times, the compressive and bending strength of the final products were evaluated and compared. Alkali activation reaction was evaluated by comparing the infrared spectra of the precursor and the final product. The starting materials used in this work were reused from previous industrial processes. Therefore, the leaching behaviour of some of the most common potentially toxic metals (Cr, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sb, Ba, Hg, Pb) had to be investigated. This was done by mass spectrometric analysis with inductively coupled plasma of the filtered eluates of prepared alkali-activated materials. The element concentrations were compared with the limits set by the official legislation of Slovenia. In this way, the potential toxicity of the use of alkali-activated materials and the suitability of their disposal in a landfill was determined.
|
