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- Potential for reuse of tungsten mining waste-rock in technical-artistic value added productsPublication . Gomes, João Castro; Silva, Abílio P.; Peralbo Cano, Rafael; Durán Suárez, Jorge Alberto; Albuquerque, AntónioMining and quarrying activities in Europe generate approximately 55% of total industrial wastes, according to a recent Eurostat report. Most of these wastes are directly dumped on land or deposited in landfill sites. The first solution may lead to negative environmental impacts on land (removal of vegetation, deforestation, land slope changes and increased risk of erosion), water (pollutant transport through surface runoff, soil infiltration and contamination of water resources), may lead to the contamination of agricultural goods and may impose risks on human health. In Portugal, about 20% of industrial waste produced originates from mines and quarries, particularly from Panasqueira mining, one of the largest tungsten mines in the world. Currently, Panasqueira mining generates almost 100 tonnes of waste-rock, per day. Such waste-rock have accumulated over a number of years into very large heaps and it is desirable to seek new economic solutions that can contribute towards their reuse. In this context, this work discusses the potential for reuse of waste-rock piles of Panasqueira tungsten mine, which may be a case statement to be followed. The proposed solution described in this paper consists in developing innovative polymer-based composite materials, obtained from non-contaminated waste-rock tailings. Such materials must have suitable properties for technical-artistic value added applications, such as conservation, restoration and/or rehabilitation of historic monuments, sculptures, decorative and architectural intervention, or simply as materials for building revetments.
- Improving the Behaviour of Green Concrete Geopolymers Using Different HEMP Preservation Conditions (Fresh and Wet)Publication . Saez-Perez, Maria Paz; Jorge Alberto, Duran-Suarez; Castro-Gomes, JoãoThis paper evaluates a type of geopolymer concrete that uses hemp fibres as a natural aggregate due to the various advantages offered by these woody materials. These advantages include ease of cultivation and processing and their use in the essential structure of concretes used for green construction purposes. The sampling study was prepared using an environmentally friendly inorganic binder, based on geopolymerization reactions (Si-Na). The improvement in the hemp aggregate using two different preservation methods (fresh and wet) was assessed. The type of conservation enables anaerobic reactions to take place in the structure of the hemp, in such a way as to modify the proportions of the organic compounds contained in the hemp and the morphology of the fibres. It also encourages the proliferation of cellulose nanofibrils (CNC), which enhance the mechanical results, improving plasticity and thixotropy. The hempcrete studied in this paper could be a good alternative material for sustainable, environmentally friendly construction, as much less CO2 is emitted during the production process in comparison with conventional concrete. Using wet-preserved hemp means that less water must be added to the mix during preparation of the concrete. This also helps reduce production costs, and by extension, the cost of the final product.