Facile synthesis and optimization of reactive bunsenite for the production of thermally stable geopolymeric composite

作者：Mohsen, Alaa; Alharbi, Yousef R.; Abadel, Aref A.; Soliman, Ahmed M.; Kohail, Mohamed; Huang, Haoliang; Ramadan, M.^*

来源：Journal of Materials Research and Technology-JMR&T, 2023, 27: 876-893.

DOI：10.1016/j.jmrt.2023.09.304

• Calcination temperature
• Reactive NiO
• Geopolymer
• Compressive strength
• Thermal stability

In this investigation, the impact of texture characteristics and the degree of crystallinity of the bunsenite phase (NiO) on the mechanical performance and fire resistivity of the geo-polymeric composites is addressed for the first time. NiO with different characteristics is prepared by applying two calcination-temperatures (400 and 600 degrees C) to obtain NiO-400 and NiO-600, respectively. Seven mixes were prepared; the control specimen was fabricated by mixing 50% slag+50%fly-ash + NaOH-solution and the other six mixes contained the same component modified with 0.5, 1, 2% NiO-400 or NiO-600. The compressive-strength at 3 and 28-days and fire resistivity up to 1000 degrees C were studied. Also, the phase composition and micro-structure were examined using XRD and TGA/DTG as well as SEM, respectively. The results showed that increasing calcination-temperature leads to decreasing surface area and increasing the degree of crystallinity of NiO. The composites modified with NiO-400 significantly enhanced the strength and fire resistivity of the control specimen, while NiO-600 demonstrated a lower effect. This refers to increasing the calcination-temperature is accompanied by decreasing the degree of reactivity, which reflects on the properties of geopolymeric composites. Regardless of the NiO-type, 1 w.% exhibited the highest strength. Adding NiO induced the formation of NiAl2O4, CaNi(SiO3)2 and NaAlSi2O6.H2O, which is compatible with enhancing mechanical and fire resistivity results.