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- Development of alkali-activated foamed materials combining both mining waste mud and expanded granulated corkPublication . Beghoura, Imed; Gomes, João Paulo de CastroIn Portugal, the significant amount of mine waste mud from tungsten mining operations has led to growing concerns about their ecological and environmental impacts such as the occupation of large areas of land, generation of powder and the contamination of surface and underground water. Furthermore, natural by-products in general, and natural cork particles in particular, have been used to manufacture new materials which not only provide good thermal insulation but also have a limited impact on the environment and a lower cost. Alkali-activated foamed materials have been introduced in the field of alkali-activated materials which have been produced from different raw and waste materials. It has been proposed as a new idea that involves the production of lightweight materials, thus combining the performance and the benefits of energy-saving (Carbon footprint) with the reduction of the cradle-to-gate emission obtained. Besides, in order to reduce the density of the alkali-activated materials holes or lightweight aggregates can be added for such purposes. Therefore, in this research, novel alkali-activated lightweight foamed materials (AALFM) from a combination of tungsten mine waste mud (TWM), waste glass (WG), and metakaolin (Mk) using alkali activators solution of Sodium Silicate (SS) and Sodium Hydroxide (SH) was developed and combined with natural expanded granulated cork (EGC) using aluminium powder (Al) as a foaming agent. The objective of this study is to develop a new alkali-activated foamed tungsten-based binder/mortar and to characterize the cork waste composite made from this binder/mortar and natural granulated aggregates (EG-Cork). Cork, which is the exterior bark of Quercus suber L., a natural, organic, and lightweight plant tissue with a high dimensional stability substance. Physical properties of tungsten-based alkali-activated binder/mortar such as bulk density, thermal conductivity and pore sizes distribution were provided. The formulations of the alkali-activated binders are based on a combination of tungsten waste mud (TWM), waste glass (WG), and metakaolin (Mk). The mechanical and thermal properties of alkali-activated foamed materials produced were then tested. The research work includes three main phases. The first part shows the feasibility to produce new improved lightweight foamed alkali-activated materials using Panasqueira tungsten waste mud (TWM) as major raw material incorporating expanded granulated cork (EGC). During this preliminary study, a series of mixes containing mining waste mud, milled waste glass, metakaolin and Ordinary Portland Cement, in different proportions, were prepared. The influence on porosity, density, and compressive strength of incorporating granulated expanded cork at different percentages was first studied with potential applications in artistic, architectural, and historical heritage restoration. The second part investigates the influence of different precursors’ particle sizes on the physical and mechanical properties, such as density, porosity, expansion volume, and pore size by image analysis. The design and development of tungsten-based alkali-activated foams (AAFs) were studied systematically. Moreover, the manufactured AAFs with enhanced compressive strength from non-calcined tungsten waste mud (raw material) by changing the precursor particle sizes showed results of the same level or even higher as other research results obtained with fly ash and MK. The third part of the research investigates the effect of the incorporation of expanded granulated cork (EGC) to produce alkali-activated lightweight foamed materials (AALFM) with thermal properties. The findings indicate that experimental research on different combinations of raw materials particularly tungsten mining waste mud (TMWM) contribute to the development of alkali-activated materials (AAMs) and alkali-activated foamed materials (AAFMs). These new improved materials can be used as building materials with enhanced properties such as compressive strength, density, thermal conductivity, and fire resistance. This doctoral research contributes to a sustainable development by promoting the complete recycling and use of mining wastes as construction materials.
- Alkali-activation of tungsten mining waste mud blended with waste glass: reactivity, performance and innovative applicationsPublication . Gomes, João Castro; Magrinho, Manuel; Sedira, Naim; Beghoura, Imed; Humbert, Pedro; Manso, Maria; Fernandes, Ana; Silva, RafaelMines and quarries waste accounts for about 29% of the total generated waste from industrial processes and households in Europe. The reuse of mud tailings as precursor materials for alkali-activated binders and applications are very promising from a technical and environmental point of view. The aim of the present study was to develop added-value solutions to reutilize tungsten mine mud tailings in alkali activated materials. Some potential uses of these new materials obtained from alkali-activation of tungsten mud waste and other precursor materials, as well incorporating expanded granulated cork, such us a high energy efficient panel for a vegetated surface and a foamed lightweight brick wall, are presented.