Hydration Properties of Multi-sintered 12CaO·7Al2O3 by Recycling Waste Resources

초록

Low-temperature calcined cement is a required solution in the cement industry for reducing energy requirements and CO<inf>2</inf> emissions. 12CaO·7Al<inf>2</inf>O<inf>3</inf> (hereinafter C<inf>12</inf>A<inf>7</inf>) is a calcium aluminate-based mineral that has properties of rapid hardening, expansion, and ultra-high strength. C<inf>12</inf>A<inf>7</inf> is mainly produced by the high-temperature melting method, but applying the low-temperature synthesis method (the hydrate sintering method) of C<inf>3</inf>A can enable its low-temperature production without any melting process. In this study, C<inf>12</inf>A<inf>7</inf> was synthesized using waste limestone and waste alumina that was decarboxylated at 900°C for one hour and then calcined at 1,200°C for one hour (this process was repeated twice) to study the hydration properties of the synthesized C<inf>12</inf>A<inf>7</inf>. The synthesis yield of the synthesized C<inf>12</inf>A<inf>7</inf> was ≥70% and the setting time for the synthesized C<inf>12</inf>A<inf>7</inf> hydrates finished within one minute but the setting time of the synthesized C<inf>12</inf>A<inf>7</inf> substituted for 50% gypsum was 158 minutes. The compressive strength of the synthesized C<inf>12</inf>A<inf>7</inf> substituted for 20% gypsum was 8.2 MPa. © 2023, Korea Society of Waste Management. All rights reserved.

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