Synthesis of geopolymers as sustainable materials for applications in Cultural Heritage

Recently, the studies on the possible applications of geopolymers as a sustainable alternative to the traditional concretes and consolidants increased considerably in many fields such as Cultural Heritage. The potentialities linked to their production concern the lower CO2 emissions, the possibility to reuse processing waste and the encouraging results in durability, chemical stability, and mechanical resistance. In this work, an industrial silt, a waste product of quarry rocks washing, was recycled in the synthesis of a series of Na-polysialate (siloxo) geopolymer concretes. The mechanisms of synthesis of metakaolin-based geopolymers were investigated, along with the influence of water content, described by the molar ratio H2O/Na2O, on the final product. The results obtained suggest that all the activating solutions effectively produced a reaction between the precursor and the activators, developing different geopolymers, but only the compositions with a low water content achieved the expected high compressive resistance qualities.