Geopolymers: Synthesis, Characterization and Applications II

Dear Colleagues,

This proposed Interdisciplinary Topic is a continuation of the successful Special Issue “Geopolymers” in Minerals in 2018 and Interdisciplinary Topic “Geopolymers: Synthesis, Characterization and Applications” in 2021. Since its closure in September 2022, the 25 publications in the aforementioned Interdisciplinary Topic have had over 35000 views. Encouraged by the interest shown by readers, MDPI has decided to propose a second edition.

The term “geopolymer” was introduced in the early 1970s by Joseph Davidovits for inorganic polymeric materials, synthesized (by him) from natural (geo-) silicon and aluminum-containing sources, reacted with alkaline media (solvent). Geopolymers consist of repeating siloxonate (Na, K, Ca) (-Si-O-Si-O-) or sialate (Na, K, Ca) (-Si-O-Al-O-) units (oligomers), polycondensed into typically ceramic, covalently bounded, non-crystalline (amorphous) 3D networks. Further research widened their definition by adding ferro-sialate and alumino-phosphate oligomers, as well as acidic (using phosphoric or humic acids as solvent) geopolymerization routes.

The scientific interest in this innovative class of materials is driven by three main factors:

1. A series of features, making geopolymers applicable and even preferred for many industrial applications, including but not limited to:

• Geopolymer resins and binders;
• Geopolymer cements and concretes:
  • Low-tech building materials (geopolymer bricks, blocks and other cast elements);
  • Low-CO₂ cements and concretes.
• Fixing of potentially hazardous chemicals in water resistant (insoluble) geopolymers.

2. The possibility of employing in their synthesis a number of inorganic industrial waste products, such as blast furnace slags, thermal power plant fly-ash, mine tailings, etc., some of which are abundantly available all over the world.

3. Environmentally friendly industrial production. The use of industrial waste can enormously enhance the resource efficiency of industrial branches generating such waste, such as mining or metallurgy. On the other hand, the use of already-existing waste material can significantly diminish large waste dumps, directly improving the environmental status of affected areas.

4. The possible replacement (even partial) of ordinary cements and concretes by geopolymers (produced by carbon-free sources) is also a route to low-carbon production, diminishing the industrial tension on climate change.

In order to cover a wider area of geo-waste utilization, in this second edition, we aim to enhance the strict geopolymerization with studies on alkali activation and vitrification.

Considering the interdisciplinary character of the topic, we are launching it across a wider range of MDPI journals, in the hope of attracting papers that cover this subject from different points of view.

Prof. Dr. Thomas N. Kerestedjian
Prof. Dr. Alexander Karamanov
Topic Editors