English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The objective of this research was to understand the dehydration mechanism of technical dihydrate and the variation of the physical properties of  β -hemihydrate after the first hydration-dehydration process. In this study, the recycling mechanism of different hemihydrate types as raw material was investigated. The influence of the first hydration-dehydration process on the hydration rate, microstructure, and mechanical properties of recycled hemihydrate were characterized by differential calorimetric analysis (DCA), calcium ion-selective electrode (Ca 2+ -ISE), conductivity, particle size distribution (PSD), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the formed hemihydrate after the first hydration-dehydration process differs in its properties than the unrecycled hemihydrate in some characteristics such as the morphological structure, number of surface, and side defects due to the grinding process after the first hydration step. In addition to the grinding step, the calcination process was responsible for increasing the number of defects on the crystal surface, which leads to a change in setting time and the microstructure of the recycled hemihydrate. Therefore, after the 1st reaction cycle of  β -HH, the compressive strength decreases due to a decrease in the hemihydrate crystal size, an increase in the surface area, and an increase in the amount of water required to perform the hydration reaction. The obtained hemihydrate after the first hydration-dehydration process was in  β  form due to the applied calcination process after the first cycle.

The Mechanism of the First Hydration-Dehydration Cycle of Pure α- and β-CaSO4•0.5H2O