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Driven by the need for sustainable construction solutions, there is renewed interest in earth-based materials. Biopolymer stabilizers can enhance the rheological and structural properties of these materials to facilitate their use in 3D printing. This research examined the influence of sodium alginate on the stability, particle interaction, rheology, and 3D printability of kaolinite, a commonly found clay in soils deemed suitable for construction. Findings revealed that sodium alginate could boost electrostatic interactions to enhance the stability of kaolinite suspensions. This rise in repulsive potential energy could reduce storage modulus and yield stress by orders of magnitude. However, as the alginate content increased beyond its critical overlapping concentration (0.12 %–0.6 %), a reverse trend was observed, which was attributed to the formation of a three-dimensional polymer network. Furthermore, alginate addition shifted the “printability window” of kaolinite mixtures to higher solid contents, which has positive implications on the strength and shrinkage of the printable mixtures.
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Understanding the rheology of kaolinite clay suspensions using Bayesian inference
Mud is a suspension of fine-grained particles (sand, silt, and clay) in water. The interaction of clay minerals in mud gives rise to complex rheological behaviors, such as yield stress, thixotropy, and viscoelasticity. Here, we experimentally examine the flow behaviors of kaolinite clay suspensions, a model mud, using steady shear rheometry. The flow curves exhibit both yield stress and rheological hysteresis behaviors for various kaolinite volume fractions (ϕk). Further understanding of these behaviors requires fitting to existing constitutive models, which is challenging due to numerous fitting parameters. To this end, we employ a Bayesian inference method, Markov chain Monte Carlo, to fit the experimental flow curves to a microstructural viscoelastic model. The method allows us to estimate the rheological properties of the clay suspensions, such as viscosity, yield stress, and relaxation time scales. The comparison of the inherent relaxation time scales suggests that kaolinite clay suspensions are strongly viscoelastic and weakly thixotropic at relatively low ϕk, while being almost inelastic and purely thixotropic at high ϕk. Overall, our results provide a framework for predictive model fitting to elucidate the rheological behaviors of natural materials and other structured fluids.
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- Award ID(s):
- 1720530
- PAR ID:
- 10440306
- Publisher / Repository:
- Society of Rheology
- Date Published:
- Journal Name:
- Journal of Rheology
- Volume:
- 67
- Issue:
- 1
- ISSN:
- 0148-6055
- Page Range / eLocation ID:
- p. 241-252
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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