Alkali-bonded inorganic polymers: environmentally friendly and sustainable materials with various applications

Alkaly-aluminosilicate binders are synthetic inorganic polymers set at low temperature to produce ceramic type materials using an easier process than that usually required for ceramic production. Alkali-bonded devices can be produced by moulding while machining and finishing are generally not required. Additions of different inert fillers allow to reinforce or functionalize the materials for specific applications, such as thermal insulation and heat resistance in the field of building and infrastructures or transportation, etc. Actually, alkali-bonded composites have a high heat tolerance because they do not burn or ignite, they do not release gases or smokes and they do not "explode" because they do not incorporate waters of hydration within the structure as hydraulic cements do. Industrial wastes and by-products can be recycled as raw materials or inert fillers for this kind of application. An overview of composite materials prepared by exploiting the binder as a glue for other phases (SiC, Al2O3, non hazardous wastes) and showing porosity in the range nano-micro - ultramacro are presented for different applications.