Preface: Vitrification and geopolymerization of industrial wastes

This VIRTUAL TOPICAL ISSUE of MATERIALS LETTERS including 35 refereed letters from the international community is the response to a broad Open Call for papers published in 2017, which attracted contributions from Europe (Bulgaria, France, Germany, Italy, Poland, Portugal, Spain and United Kingdom), Algeria, Argentina, Bolivia, Brazil, China, Colombia, Ecuador and Ukraine. The idea of publishing this topical issue in Materials Letters originated from the success of a scientific meeting supported by the Technical Committee TC05 of the International Commission on Glass (ICG), focused on Industrial Wastes and their Vitrification, which was held at University ‘‘Miguel Hernández” in Elche, Alicante, Spain, in September 2017 under the general topic: ‘‘Vitrification and Geopolymerization of Industrial Wastes”. The scope of that ‘‘pioneering” meeting and indeed of this topical issue has been to increase the interactions and participation of scientists involved in glasses from wastes (vitrification processing) and those involved in geopolymers (alkali activation) from wastes, e.g. in both cases developing fundamental science and technologies to achieve the inertization or safe encapsulation of wastes in inorganic matrices. In both cases, the disordered nature of structures (amorphous or pseudo-amorphous) facilitates the hosting or immobilization of a wide range of industrial wastes. However, there are questions not yet fully solved such as: the proportion of ‘‘short or large range ordering” in both these types of materials; their capability, commonalities and differences to immobilize specific type of residues; the determination of the most efficient treatment by vitrification or geo-polymerization; the use of glasses and waste glasses as precursors for geopolymer production, among other open research topics.