Structural Evaluation of Fly Ash Based Geopolymer Composites for High Temperature Applications

Abstract

The current research work focuses on the enrichment of fly ashes to the geo-polymer composite for high temperature application to 800˚C-1200˚C. The goal of the research is to enrich fly ash in order to obtain a pure natural alumino-silicate pozzolan. Mild acid and thermal treatment of different grades of fly ashes is carried out followed by geo-polymerization in the presence of potassium hydroxide environment. The process is further refined with the addition of the fumed silica to reduce the process related porosities which can deteriorate the overall performance of the geo-polymer. Continuous fibers are added to study and evaluate the interfacial bonding. The flexural tests result of the different samples cured at different temperatures were analyzed to better understand the flexure strength of the geopolymer composite fabricated using glass fiber. Dynamic Mechanical Analysis (DMA) of the geopolymer was performed to evaluate its ability to withstand high frequencies and vibrations. Load Deflection patterns suggest that consolidation process continues as the temperature increases from 80 °C to 250 °C, which is reflected by the stiff load-deflection curves. As the temperature increases to 1200 °C sample gradually fails suggesting inter-laminar delamination. DMA results suggest that storage modulus increases with temperature rise upto 350 °C at or below 100 Hz frequency. Fire Test did not result any structural deformation or blistering on either the front or back face.