Department of Civil Engineering, Tsinghua University, Beijing 100084, China.
China Construction First Group Construction & Development Co. Ltd., Beijing 100102, China.
Molecules. 2021 Feb 14;26(4):1011. doi: 10.3390/molecules26041011.
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.
由于流变参数不可计算，修正的宾汉姆模型和赫谢尔-布尔克利模型都不能用于描述和计算高流动性砂浆的剪切增稠性能。本文建立了一种新的指数流变模型，用于解决混凝土泵送过程中润滑层（高流动性砂浆）剪切增稠的特性和计算问题。该新的指数流变模型具有三个流变参数，即屈服应力、稠度系数和稠度指数。它们可以定量描述高流动性砂浆的屈服应力、差示黏度和剪切增稠程度。对不同配合比砂浆新建立模型流变参数的计算结果表明，砂浆的稠度指数随着砂-胶比或胶凝材料中粉煤灰掺量的增加而降低，表明砂浆的剪切增稠程度降低。砂浆的稠度指数随着硅灰掺量或高效减水剂掺量的增加而先降低后升高，表明砂浆的剪切增稠程度先降低后升高。这些变化模式通过砂浆的流变实验得到了证实。
