著者
山田 義智 東舟道 裕亮 上原 義己 崎原 康平
出版者
日本建築学会
雑誌
日本建築学会構造系論文集 (ISSN:13404202)
巻号頁・発行日
vol.84, no.756, pp.139-148, 2019
被引用文献数
4

&nbsp;In order to conduct flow analysis of cement paste, mortar and concrete, it is important to obtain rheological constants representing the flow characteristics of the material. In this study, we measured cement paste's rheological constants by using rotational viscometer. Here, it was measured in consideration of flow history on cement paste. Furthermore, in this study, we derived the flow constitutive equation of the cement paste and proposed a marker particle visco-plastic finite element method. Using this marker particle visco-plastic finite element method, simulation of flow test of cement paste was attempted.<br>&nbsp;The results obtained from the experimental study and analytical study of this research can be summarized as follows.<br>&nbsp;Using a rotational viscometer, the flow curve of cement paste was measured for various shear conditions. It was confirmed that the flow curves of all cement paste samples can be approximated by the Bingham model under all shear conditions. And the obtained flow curve was approximated by the Bingham model, and the rheological constants (yield value and plastic viscosity) of the paste sample was determined. Thixotropy was confirmed in the flow characteristics of the cement paste sample from the obtained flow curves and rheological constants.<br>&nbsp;The cement paste was regarded as a visco-plastic fluid and derived the flow constitutive equation of visco-plastic fluid using overstress theory. The obtained flow constitutive equation considers non-Bingham characteristic, flow history, and pressure dependency of yield value. It was confirmed that the flow curves of cement pastes differing depending on shear conditions can be expressed by the proposed flow constitutive equation.<br>&nbsp;Marker particle visco-plastic finite element method was used to analyze the flow test of cement pastes. The results obtained by the analysis agreed well with the experimental results. Therefore, the marker particle visco-plastic finite element method and the rheological constants are effective.
著者
東舟道 裕亮 山田 義智
出版者
日本建築学会
雑誌
日本建築学会構造系論文集 (ISSN:13404202)
巻号頁・発行日
vol.86, no.784, pp.860-870, 2021
被引用文献数
3

<p>With the improvement of earthquake resistance and large scale of buildings, the number of cases where it is difficult to fill the form work with conventional slump-managed concrete is increasing. In addition, slump flows 45 cm, 50 cm, 55 cm, and 60 cm have been added due to the JIS (Japanese industrial standard) revision made in March 2019. In the future, it is estimated that the use of slump flow managed concrete will increase. Furthermore, in recent years, new admixtures have been actively developed, and it is necessary to correctly grasp the flow characteristics of concrete using these admixtures from a rheological point of view. It is the cement paste in concrete that is most affected by the flow properties of the admixture. Therefore, it is useful to be able to grasp the flow characteristics of cement paste. </p><p>We have already examined the relationship between the rheology constants obtained from the rheology test and the flow characteristics obtained from the paste flow test, and we proposed a rheology constant estimation method. In this study, we reexamined the rheological constant estimation method based on the correlation analysis findings using the visco-plastic finite element method (FEM). </p><p>First, flow analysis was performed by FEM using any combination of rheological constant and paste density (yield stress: 10 patterns, plastic viscosity: 7 patterns, paste density: 3 patterns, total 210 patterns) as input values. Next, based on the analysis results, the relationship between the paste flow characteristics (flow value, each flow arrival time, flow stop time) and the rheology constant and paste density was examined by correlation analysis. </p><p>As a result, it was found that the yield stress can be estimated by the flow value, and the plastic viscosity can be estimated by the multiple regression equation of the paste density and the 150 mm flow arrival time. </p><p>Furthermore, we proposed a new rheological constant estimation equation using the actual test results of the cement paste for the relationship obtained from the correlation analysis. After that, the rheology constant was estimated from the actual paste flow test results using the rheology constant estimation equation. Finally, a paste flow simulation was performed using the MPS method, which can consider the influence of the flow cone, and it was compared and examined: the actual paste flow test results and MPS analysis results. </p><p>As a result, the actual paste flow test results could be reproduced by MPS analysis, and the validity of the rheological constant equation was confirmed. </p><p></p>