Testing a Novel Geopolymer Binder as a Refractory Material for Rocket Plume Environments at SSC Project

<p>The project involved the development and testing of a new alumina-silicate based multi-purpose, cost-effective, &lsquo;green&rsquo; cementitious binder (geopolymer) capable of acting as a high performance refractory material with both a low ablation rate and a high early mechanical strength. This work was built upon previous research undertaken by the research team in the areas of geopolymer binders. Full scale and laboratory controlled tests were performed to compare geopolymer performance to currently available commercial products (e.g. Sentinel, Greencast). Geopolymer&rsquo;s thermal shock resistance properties were tested on eleven different fly ash stockpiles specimens from around the world. The geopolymer specimens were subjected to ASTM C-1100 (Standard Test Method for Ribbon Thermal Shock Testing of Refractory Materials). Samples were subjected to incremental 5-5-5-15-30 second flame exposure durations and to a 15 or 30 accumulated exposure, depending on the sample performance (e.g., if the plume became detached). Field test durations were limited to prevent excessive erosion of the test panels and subsequent plume detachment. Laboratory testing also demonstrated that geopolymer could withstand thermal shock and exposure to flame. Additionally, a computational model was created to determine the optimal chemical ratios for geopolymer to be exposed to elevated temperatures. Additionally, due to their excellent adhesion to pre-existing surfaces geopolymer binders were proven to be good candidates for use in repair of existing structures upon which they were applied and retrofitted; this was demonstrated and observed via tests conducted on repaired tested panels. Overall, the demonstration testing program revealed that the geopolymer products had equal or superior performance compared to commercial refractories currently used by NASA.</p>

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