Hydration process of interfacial transition in potassium polysialate (K-PSDS) geopolymer concrete Available to Purchase

Environmental scanning electron microscopy (ESEM) was used to study the hydration process of the interfacial transition zone (ITZ) between coarse aggregate and potassium polysialate (K-PSDS) geopolymer under an 80% relative humidity environment. An energy dispersion X-ray analysis (EDXA) was also used to distinguish the chemical composition of the hydration products. The ESEM micrographs and corresponding EDXA results show that the development of the microstructure of ITZ is quite different from that of matrix. At the beginning there were many large voids filled with water (about 50 μm) in the fresh ITZ, but these voids were not found in the bulk matrix. As hydration proceeded, gel products gradually precipitated on the edges of these voids and extended outward. Eventually these voids were completely filled with hydration product. At this stage, the difference in the micrograph between the ITZ and the matrix was hardly distinguishable. However EDXA results showed that the contents of K/Al and Si/Al in the ITZ were higher than those in the bulk matrix. This indicates that K and Si accumulate in the ITZ, which results in a difference in chemical composition between the ITZ and the matrix. In addition, well-developed crystals were not found in the ITZ at any stage and sponge-like amorphous gel was always observed instead.