A new technique for the production of glass foams was developed, based on alkali activation and gel casting. The alkali activation of soda-lime waste glass powders allowed for the obtainment of well dispersed concentrated suspensions, undergoing gelification by treatment at low temperature (75 degrees C). An extensive direct foaming was achieved by mechanical stirring of partially gelified suspensions, comprising also a surfactant. The suspensions were carefully studied in terms of rheological behavior, so that the final microstructure (total amount of porosity, cell size) can be directly correlated with the degree of gelification. \ud A sintering treatment, at 700-800 degrees C, was finally applied to stabilize the foams, in terms of leaching of alkaline ions. Considering the high overall porosity (88-93%), the newly obtained foams exhibited a remarkable compressive strength, in the range of 1.7-4.8 MPa

The stabilization of inorganic waste of various nature and origin, in glasses, has been a key strategy for environmental protection for the last decades. When properly formulated, glasses may retain many inorganic contaminants permanently, but it must be acknowledged that some criticism remains, mainly concerning costs and energy use. As a consequence, the sustainability of vitrification largely relies on the conversion of waste glasses into new, usable and marketable glass‐based materials, in the form of monolithic and cellular glass‐ceramics. The effective conversion in turn depends on the simultaneous control of both starting materials and manufacturing processes. While silica‐rich waste favours the obtainment of glass, iron‐rich wastes affect the functionalities, influencing the porosity in cellular glass‐based materials as well as catalytic, magnetic, optical and electrical properties. Engineered formulations may lead to important reductions of processing times and temperatures, in the transformation of waste‐derived glasses into glass‐ceramics, or even bring interesting shortcuts. Direct sintering of wastes, combined with recycled glasses, as an example, has been proven as a valid low‐cost alternative for glass‐ceramic manufacturing, for wastes with limited hazardousness. The present paper is aimed at providing an up‐to‐date overview of the correlation between formulations, manufacturing technologies and properties of most recent waste‐derived, glass‐based materials. © 2016 The Authors.Journal of Chemical Technology & Biotechnologypublished by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.