Geotechnical and Environmental Assessment of Blast Furnace Slag for Engineering Applications

Determination of the Basic Geotechnical Parameters of Blast-Furnace Slag from the Kremnica Region

A decisive aspect of site evaluation for construction is the presence of anthropogenic materials occurring in the geological environment. The geotechnical properties of blast-furnace slag were investigated as a potential substitute for aggregates in the construction industry. The basic geotechnical parameters of the slag were determined, which are critical for evaluating its stability, environmental impact, and usability in geotechnical construction. The research focused on monitoring the physical and mechanical properties of the two samples, and also included mineralogical analysis. The obtained results demonstrated that the slag belongs to the category of poorly graded gravel, G2/GP, and gravel with an admixture of fine-grained soil, G3/G-F. In addition, other important parameters, such as the water disintegration of the slag aggregate, the minimum and maximum bulk densities, the California bearing ratio (CBR), the oedometric modulus (Eoed), and shear tests (the angle of internal friction φ and cohesion c), were determined. The results from this paper provide important information for the proper management of blast-furnace slag so to minimize its environmental impact and achieve sustainability in the mining industry. At the same time, it enables a better understanding of the use of slag as a substitute for aggregates in geotechnical tasks. Despite its local importance in relation to the investigated case, the presented study has significant educational and scientific value for the construction sector, where it is necessary to evaluate anthropogenic activities and materials.

Mechanical Characterization of Industrial Waste Materials as Mineral Fillers in Asphalt Mixes: Integrated Experimental and Machine Learning Analysis

In this study, the effect of seven industrial waste materials as mineral fillers in asphalt mixtures was investigated. Silica fume (SF), limestone dust (LSD), stone dust (SD), rice husk ash (RHA), fly ash (FA), brick dust (BD), and marble dust (MD) were used to prepare the asphalt mixtures. The obtained experimental results were compared with ordinary Portland cement (OPC), which is used as a conventional mineral filler. The physical, chemical, and morphological assessment of the fillers was performed to evaluate the suitability of industrial waste to replace the OPC. The volumetric, strength, and durability of the modified asphalt mixes were examined to evaluate their performance. The experimental data have been processed through artificial neural networks (ANNs), using k-fold cross-validation as a resampling method and two different activation functions to develop predictive models of the main mechanical and volumetric parameters. In the current research, the two most relevant parameters investigated are the filler type and the filler content, given that they both greatly affect the asphalt concrete mechanical performance. The asphalt mixes have been optimized by means of the Marshall stability analysis, and after that, for each different filler, the optimum asphalt mixtures were investigated by carrying out Indirect tensile strength, moisture susceptibility, and abrasion loss tests. The moisture sensitivity of the modified asphalt mixtures is within the acceptable limit according to the Indian standard. Asphalt mixes modified with the finest mineral fillers exhibited superior stiffness and cracking resistance. Experimental results show higher moisture resistance in calcium-dominant mineral filler-modified asphalt mixtures. Except for mixes prepared with RHA and MD (4% filler content), all the asphalt mixtures considered in this study show MS values higher than 10 kN, as prescribed by Indian regulations. All the values of the void ratio for each asphalt mix have been observed to range between 3–5%, and MQ results were observed between 2 kN/mm–6 kN/mm, which falls within the acceptable range of the Indian specification. Partly due to implementing a data-augmentation strategy based on interpolation, the ANN modeling was very successful, showing a coefficient of correlation averaged over all output variables equal to 0.9967.

Blast Furnace Slag, Post-Industrial Waste or Valuable Building Materials with Remediation Potential?

In recent years, the construction industry has struggled with a variety of issues such as material availability, supply channel management, and the increasing cost of construction materials. These issues have encouraged the search for replacements and substitutes for existing construction materials. Blast Furnace Slag is used in the construction industry as a mineral amendment or aggregate. Their use in Earth Construction, due to their post-industrial origin, may be associated with increased levels of potentially toxic elements (PTE) in the soil. This study aimed to evaluate the effectiveness of the immobilization potential of Blast Furnace Slag and to compare it with the addition of Blast Furnace Slag with Activated Carbon using different concentrations of these amendments. We were able to determine the concentrations of selected PTE (zinc, copper, nickel, cadmium and lead) in the soil, roots and aerial parts of Lolium perenne L., using different concentrations of Blast Furnace Slag (3%, 5% and 10%), and Blast Furnace Slag with Activated Carbon (3% and 5%) as soil amendments. Measurements were carried out with Flame Atomic Absorption Spectrometry (FAAS). Both the addition of Blast Furnace Slag and Activated Carbon with Slag increased plant biomass. The addition of slag effectively reduced the zinc, copper, cadmium and lead content of the soil, while the addition of Activated Carbon slag significantly increased the content of selected PETs in the roots and aerial parts of plants. It was considered reasonable to use Blast Furnace Slag with the addition of Activated Carbon in supporting the processes of the assisted phytostabilization of PTE polluted soils.