The study on the hydration and hardening mechanism of high-calcium geopolymer cement

Making use of the ways such as DTA, hydrate velocity, this paper discusses principally the high-calcium geopolymer cement's hydration and hardening mechanism and compares with the traditional cement and slag cement. The result indicates that this material, in initial hydration stage, the metakaolin dissolves a lot of the [SiO4](4-) and [AlO4](5-) which compose the network. With the hydrating, pH value decreases, C3S starts to hydrate quickly and the soluble CaO concentrate and the number of the C-S-H around the C3S are increasing. Ca2+ takes the place of Na+ of the network. The network disaggregates and forms C-S-H with lower alkali. Later stage is most of the clinker and slag hydration. The products are similar with the slag cement. When the network disaggregates completely, Na+ will be doped,in the C-S-H gel.