Title:
Role of Intercrystallite Phosphorus on the Properties of α-Hemihydrate Gypsum (Prepublished)
Author(s):
Dongmei Liu, Xinyu Li, Wanqing Zhou, Gang Xu, and Yi Qin
Publication:
Materials Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
α-Hemihydrate gypsum; hydration; intercrystalline phosphorus; microstructure; morphology; setting time; strength
DOI:
10.14359/51746806
Date:
5/8/2025
Abstract:
Phosphogypsum (PG) is often used to produce α-Hemihydrate gypsum (α-HH), but the impurities in PG, including intercrystalline phosphorus (IP), limit its reutilization. The objective of this paper is to study the effect of IP on the morphology, hydration, and hardening properties of α-HH, using XRD, XPS, SEM, FTIR, and the test of setting time, hydration heat, and strength. The results revealed that IP dissolved out from dihydrate gypsum (DH) and entered the lattice of α-HH during the preparation of α-HH, while there was little difference in the morphology of α-HH. When α-HH hydrated, IP dissolved and converted into Ca3(PO4)2, absorbed on the surface of DH. 0.04% IP had no effect on the hydration, setting time, and strength of α-HH, with 0.1% or more IP significantly prolonging the hydration of α-HH and deteriorating microstructure of hardened paste, thus reducing strength. Based on the results, IP content in PG should be controlled to less than 0.04%.