Let the walls speak. A brief history of binders in architecture.

The use of binders and ligands in architecture played an important role in the development of human societies. Everybody is aware of the importance of Portland cement and concrete in modern construction industry, as a matter of fact there would be no urban or long-range modern infrastructure without the systematic technological use of high performance binders. However the huge volumes of cement and concrete produced at present, making them the materials that are produced the most in terms of weight, are raising serious concerns in terms of emitted carbon dioxide and energy requirements. Active research is ongoing to optimize low-energy and low-carbon footprint alternative materials, such as geopolymers, alkali activated materials, and calcined clays. In the past, it is argued that the success of the Roman Empire was solidly built on the clever and widespread use of hydraulic mortars. The long history and development of binder technology is reviewed, with an eye on chronological and geographical patterns.