Resistance of different geopolymer formulations in several environments: Evaluation based on zeta potential

In recent years, geopolymer materials have been increasingly sought for nuclear applications. This work focused on developing geopolymer formulations for nuclear repairs, in which samples are exposed to acid fumes, require the use of geopolymer materials that efficiently meet both temperature and acid resistance properties simultaneously. To achieve this, four metakaolin-based geopolymer formulations were prepared from two alkaline silicate solutions with different concentrations (K 5 and K 11 ). Temperature resistance tests were carried out. Moreover, the samples were cast in water and immersed in acid (H 2 SO 4 and H 3 BO 3 for 7 days). Compressive strength and SEM observations were performed before and after the samples were immersed in acids. Zeta potential measurements were performed on the geopolymers by titration with H 2 SO 4 and H 3 BO 3 acids. The results revealed that all the samples have shown well thermal resistance at temperatures of up to 1200 °C. The K 5 based samples exhibits a good thermal resistance up to 1700 °C due to the presence of refractories additives. The K 11 based samples are pourable and undergo consolidation in water due to high alkaline concentration leading fast polycondensations reactions for better cross-linked materials. The compressive strength and SEM observations showed no change before and after immersion. Zeta potential measurements revealed values of −90 and −80 mV for the K 11 and K 5 samples, respectively. Finally, the zeta potential makes it possible to control the acid attack on geopolymers and predict their usage properties such as resistance at T °C, in acidic environments, and when cast in water