Unveiling the high strength and ductile character of reinforced CNT/geopolymer paste subjected to elevated temperatures

A significant challenge in developing suitable advanced materials in the construction sector is urgent face to the natural disasters affecting our infrastructure and endanger the world population. At this stage, geopolymers renowned as a green and low-carbon material has received considerable attention. Here, novel properties are revealed for Na-based and K-based metakaolin geopolymer paste reinforced by carbon nanotubes with various dosage, exposed to high temperatures. Results show that adding 1.08 wt% of CNT makes the geopolymer matrix thermally stable and resistant up to 1327 °C. It comes out that geopolymer nanostructure with low CNT concentration became tough to shear deformation along (001) plane up to 1127 °C and is easier to shear along (100) plane for highest CNT content. Calculations predict that low CNT dosage double the ductility of Na-based and K-based geopolymer matrix at room temperature. Heating up to 1327 °C enhances the stiffness of both nanostructures. The micro-hardness doubles at 800 °C for Na-based rather than K-based geopolymer matrix when adding low CNT dosage.