Supercritical geothermal wells, capable of producing ten times more energy than low temperature EGS wells, offer a solution to the increasing energy demand in the United States. Most supercritical wells developed to date have failed and none currently supply energy to the grid because the materials used in well development fail under supercritical conditions, including Portland Cement which degrades quickly due in part to decalcification. In this study, an alkali-activated aluminate-based composite is tested for its suitability in supercritical geothermal wells. The composite is hydrothermally cured for 1 day at 300°C, 1 day at 400°C, and 7 days at 400°C. The mechanical properties of each composite are measured, and the composition and microstructure is determined using FTIR, XRD, and SEM-EDS. Compressive strength, Young’s modulus, and toughness increase with increasing temperature and exposure duration, which coincides with the transformation and ultimate disappearance of zeolites, and the development of paragonite. Overall, the composite cured at each exposure condition exhibits acceptable properties for well development.

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