Leg.AT.i - legare i leganti: cemento, terra cruda e geopolimeri

Ordinary Portland cement-based concrete is the world’s leading building material, second only to water. The production of cement and clinker requires a massive use of energy, mainly coal, resulting in the generation of a considerable amount of CO2 emissions as an undesirable by-product. In order to move towards more sustainable development, it is fundamental to find alternative binders to make concrete “greener”. In this review, a new and a traditional binder are taken into the exam: geopolymer and clay (raw earth). Both are gaining momentum since are commonly labelled as eco-friendly materials. One of their most promising features is the ability to incorporate solid and liquid waste, even toxic ones, in their manufacturing process. In the first part of the document, recent research on geopolymers is presented and, in particular the relationship between raw material treatment (including additives and mineral admixtures) processing and properties of the final product. At the end of this section, the potential application as porous thermal insulation material and 3D building material is discussed. In the second part, the paper reviews the progress in the performance improvement of the raw earth technique, focusing on mechanical behaviour. The analysis of the different additives and stabilizers commonly use (lime and cement) also paved the way for the conclusion in which geopolymer and earth are treated together. Finally, some potential opportunities and development directions have been suggested for future earth and geopolymer concrete research.