A Rheological Model for Evaluating the Behavior of Shear Thickening of Highly Flowable Mortar

Abstract

Neither the modified Bingham model nor the Herschel–Bulkley model can be used to characterize and calculate the performance of shear thickening of highly flowable mortar because of their incalculability of the rheological parameters. A new exponential rheological model was established to solve the characterization and calculation of shear thickening of the lubrication layer (highly flowable mortar) during the pumping of concrete in this paper. This new exponential rheological model has three rheological parameters, namely, yield stress, consistency coefficient, and consistency exponent. They can quantitatively describe the yield stress, differential viscosity, and shear thickening degree of highly flowable mortar. The calculating results of the rheological parameters of the newly established model for the mortars with different compositions showed that the consistency exponent of mortar decreased with the increase of its sand-binder ratio or the dosage of fly ash in the binder. This indicates that the shear thickening degree of mortar decreases. The consistency exponent of mortar initially decreases and subsequently increases with the increase in silica fume content or the dosage of the superplasticizer. It illustrates that the degree of the shear thickening of mortar initially decreased and subsequently increased. These varying patterns were confirmed by the rheological experiment of mortars.

Rheological model of cement-based material slurry with different water-cement ratio and temperature

“…In the present study, the Bingham model gives a linear relationship between shear stress and shear rate (Bingham, 1922). The modified Bingham model applies quadratic functions to discuss the nonlinear parts of the shear stress-shear rate (Sun et al, 2010;Li et al, 2021). The Casson model (Peng et al, 2014;Aghighi et al, 2020) adds a square root function of the shear rate to the Bingham model, and the Ostwald model (Tao et al, 2020) uses a power law to obtain the whole constitutive relation between shear stress and shear rate.…”

“…The modified Bingham model applies quadratic functions to discuss the nonlinear parts of the shear stress–shear rate (Sun et al. , 2010; Li et al. , 2021).…”

Research on the flow characteristics of blasthole stemming slurry in open-pit mining

“…Both the modified Bingham model and the Herschel-Bulkley model can describe fluids with yield stress and shear thickening or shear thinning features (Song et al, 2023;Zhaidarbek et al, 2023). Several studies (Savage and Sayed, 1984;Chen and Ling, 1996;Feys et al, 2009;Li et al, 2021) have indicated that the quadratic term in the modified Bingham model lacks practical physical significance when describing shear thickening behavior in fluids. Additionally, in this study, the use of the modified Bingham model to fit the rheological The fluidity test of slurry.…”

Which Is an Appropriate Quadratic Rheological Model of Fresh Paste, the Modified Bingham Model or the Parabolic Model?

“…With the comprehensive use of mineral admixtures and chemical admixtures, the rheological behavior of fresh cementitious materials deviates gradually from those described by the Bingham model [7][8][9][10][11][12]. In recent years, many studies [13][14][15][16] have shown that fresh cementitious materials exhibit shear thickening or shear thinning. Shear thickening or shear thinning describes the increase or decrease, respectively, in the apparent viscosity of a fluid with the increase in the shear stress [6,17].…”

“…This means that the rheological parameters based on Herschel-Bulkley model cannot be calculated. In order to study the nonlinear rheological properties of cementitious materials, a new exponential rheological model was proposed to replace Herschel-Bulkley model [13].…”