Optimizing hydration and performance of phosphogypsum based cementitious system through multiphase composites
Artikel i vetenskaplig tidskrift, 2025

Thermal treatment of phosphogypsum (PG) to produce construction-grade gypsum is a promising approach for large-scale utilization. However, the single-phase composition of calcined gypsum necessitates the addition of retarders to control hydration speed, often compromising material performance. To address this, we propose a multiphase gypsum system that leverages synergistic interactions among various gypsum phases to regulate hydration kinetics. This study examines the workability, mechanical properties, water resistance, hydration heat, and microstructure of multiphasic PG. We systematically analyze the interaction mechanisms between different gypsum phases, including II-anhydrite (AII), III-anhydrite (AIII), β-hemihydrate (HH), and dihydrate (DH), within the multiphasic PG system. Results indicate that incorporating optimal amounts of AIII and AII effectively adjusts PG hydration process, enhancing workability and water resistance. Specifically, a composite of 30 % AIII and 20 % AII yields significant improvements in mechanical strength and water resistance (with a softening coefficient reaching 0.81), extends setting time, and reduces water demand. Interactions among AII, AIII, HH, and DH effectively regulate hydration rates in phosphorus-based gypsum cementitious materials. Early-stage hydration of AIII releases substantial heat, promoting the hydration of HH and AII. In turn, AII modulates HH's hydration rate, providing a retarding effect that enhances early strength. At later stages, hydration of AIII and HH increases the exothermic rate of AII's hydration, while DH serves as a nucleation site for AII crystallization, producing a dense structure. Additionally, unhydrated AII absorbs infiltrated water molecules, further improving water resistance and enhancing long-term strength.

Hydration hardening properties

Physical phase regulation

Phosphogypsum

Författare

Shouwei Jian

Wuhan University of Technology

Xinxin He

Wuhan University of Technology

Bo Peng

Wuhan University of Technology

Xin Gao

Wuhan University of Technology

Jianxiang Huang

Wuhan University of Technology

Fei Dai

Wuhan University of Technology

Jiaxuan Chen

Wuhan University of Technology

Baodong Li

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi

Wuhan University of Technology

Construction and Building Materials

0950-0618 (ISSN)

Vol. 472 140848

Ämneskategorier (SSIF 2025)

Materialkemi

DOI

10.1016/j.conbuildmat.2025.140848

Mer information

Senast uppdaterat

2025-04-02