دانلود رایگان مقاله اثر درجه حرارت بالا در بندهای ژئوپلیمر قلیایی در مقایسه با پرتلند بندهای مبتنی بر سیمان

Abstract

This research focused on developing thermally-stable materials based on alkali-activation of slag, fly ash, and metakaolin compared to portland cement mixtures by using a hierarchical approach to material design. At lower length scales, X-ray diffraction (XRD) characterized the mineralogy that coupled to higher length scale experiments using thermogravimetric analysis (TGA) for determining the materials thermal stability. Additionally, high-energy X-ray computed microtomography (μCT) determined the best-performing material formulation that minimized thermal damage when exposed to high temperatures (650 °C). The thermal loading was ramped up to 650 °C from ambient temperature in 60 s and then held for a total of 10 min. The μCT identified that the alkali-activated fly ash mortar had less initial porosity than the ordinary portland cement mixtures, with more than 66% of the pores between 20 and 50 μm in diameter. Consequently, the alkali-activated fly ash mortar was able to dissipate approximately 565 °C in just 50 mm of material, outperforming all the other mixes studied in this paper with μCT confirming minimal damage after the temperature exposure.

4. Conclusions

This study evaluated the performance of three different alkali-activated mortars and compared them to two different portland cement control mixtures under direct elevated temperature exposure. Findings of this study confirmed that both of the PC/M and the C109/M suffered catastrophic damage under the elevated temperatures, contrary to the alkali-activated mortars (FA/M, M/M and S/M). The FA/M resulted to be the top performer under the specified boundary conditions of 650 °C at a 60 s ramp established for this study. The FA/M did not exhibit any damage after the exposure test. However, both the S/M and M/M out-performed the PC/M and C109/M, even though both S/M and M/ M sustained cracks and internal damage. All three alkali-activated mortars demonstrated a greater ability to dissipate heat, but only the FA/M showed up to 565 °C of temperature dissipation in approximately 50 mm of material without thermal cracking.