Abstract
Struvite (ST) recovered during wastewater treatment has been sparsely applied in cement-based composites. This study systematically evaluated the thixotropic behavior of cement-struvite (CST) pastes, a mix of 5–20 % ST by mass of cement, and proposed the interaction mechanisms leading to the pastes' thixotropy. The hysteresis loop area was used to establish the pastes' thixotropy and investigate its relationship with increased ST content, temperature, and yield stress. In the thixotropic behavior model used, the equilibrium shear stress was employed to examine the CST pastes' irreversible change; the characteristic time of deflocculation was used to study the flocs destruction process; and the incipient structure parameter and flocs structuration rate were used to evaluate the structure-rebuilding process quantitatively. The results revealed an enhanced CST pastes' initial structural parameter (early re-flocculation), above 1.8 times higher than the control. On the other hand, their long-term structuration rates (0.002–0.004 s−1) were lower than that of the control paste (0.006 s−1), depicting the retardation effect at the hydration products' growth stage and improved workability. The CST pastes' yield stress, plastic viscosity, and thixotropic loop area were 1.2–1.7, 1.8–8.1, and 1.1–3.6 times above the control, respectively. The results suggest the mechanism of CST pastes' thixotropy arising from the filler effects and attractive interaction that results in early flocculation and subsequent growth of hydration products at the bridge between cement and struvite particles. The increased short-term thixotropy of CST pastes suggests enhanced buildability, essential for 3D concrete printing.
Recommended Citation
U. Ewuzie et al., "Investigating The Thixotropy Of Fresh Struvite Cement-based Composite: Insights On Mechanisms Of The Pastes’ Thixotropic Behavior," Cement and Concrete Composites, vol. 160, article no. 106058, Elsevier, Jul 2025.
The definitive version is available at https://doi.org/10.1016/j.cemconcomp.2025.106058
Department(s)
Chemical and Biochemical Engineering
Publication Status
Full Text Access
Keywords and Phrases
Composite material; Flocculation; Portland cement; Rheology; Struvite; Thixotropy
International Standard Serial Number (ISSN)
0958-9465
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 Elsevier, All rights reserved.
Publication Date
01 Jul 2025
Included in
Chemical Engineering Commons, Civil and Environmental Engineering Commons, Materials Chemistry Commons, Materials Science and Engineering Commons
Comments
Materials Research Science and Engineering Center, Northwestern University, Grant 2239511