Modelling Rheological Behavior of Fresh Cement-Sand Mixtures

Author(s):  
Hooman Hoornahad ◽  
Eduard A. B. Koenders

In this paper, the effect of the mix composition on rheological behavior of fresh cement-sand mixture is studied by considering a mixture as a two-phase model that is decomposed into a granular and a paste phase. The paste itself is subdivided into void paste and excess paste. Void paste fills the void space between the grains when they are in a fully compacted state while excess paste will use the remaining paste to form a paste layer around each individual grain particle, with equal thickness. By considering each grain particle covered with the excess paste layer as a single element, the rheological behavior of cement-sand mixtures can be related to their inter-element interactions for all sets of particle combinations.

2011 ◽  
Vol 295-297 ◽  
pp. 2178-2184
Author(s):  
H Hoornahad ◽  
E. A. B. Koenders

Fresh granular-pasty materials are considered as an intermediate class between solid and fluid. These materials are capable of showing their rheological behavior which can be close to either a pasty or granular system depending on properties and proportion of ingredients in the mixture. Therefore, quantification of such dependencies is a crucial factor in order to be able to predict the performance of this type of material. In this study a two phase model is considered in which a mixture is decomposed into a paste and a granular phase. The relation between the aggregate grading and the consistency of the mixture has been investigated for a concrete in which the pasty behavior is dominant. It was found that if the volume and property of the paste that remains after filling the space in between the aggregates in compacted state is kept constant, the consistency of a mixture can be characterized by the number of aggregates corresponding to each grain size regarding the sieve analysis test. The paper presents a modelling approach and experimental results.


1968 ◽  
Vol 78 (3, Pt.1) ◽  
pp. 359-368 ◽  
Author(s):  
William F. Prokasy ◽  
Martha A. Harsanyi

1997 ◽  
Vol 35 (7) ◽  
pp. 139-145 ◽  
Author(s):  
Jiann-Yuan Ding ◽  
Shian-Chee Wu

The objective of this study is to quantify the effects of humic acid solution infiltration on the transport of organochlorine pesticides (OCPs) in soil columns using a three-phase transport model. From experimental results, it is found that the dissolved organic carbon enhances the transport of OCPs in the soil columns. In the OCPs-only column, the concentration profiles of OCPs can be simulated well using a two-phase transport model with numerical method or analytical solution. In the OCPs-DOC column, the migrations of aldrin, DDT and its daughter compounds are faster than those in the OCPs-only column. The simulation with the three-phase model is more accurate than that with the two-phase model. In addition, significant decrease of the fluid pore velocities of the OCPs-DOC column was found. When DOC leachate is applied for remediation of soil or groundwater pollution, the decrease of mean pore velocities will be a crucial affecting factor.


2012 ◽  
Vol 9 (1) ◽  
pp. 47-52
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Buzina

The two-dimensional and two-phase model of the gas-liquid mixture is constructed. The validity of numerical model realization is justified by using a comparative analysis of test problems solution with one-dimensional calculations. The regularities of gas-saturated liquid outflow from axisymmetric vessels for different geometries are established.


PLoS ONE ◽  
2011 ◽  
Vol 6 (10) ◽  
pp. e24934 ◽  
Author(s):  
Clive R. McMahon ◽  
Marie-Jeanne Buscot ◽  
Natasha L. Wiggins ◽  
Neil Collier ◽  
John H. Maindonald ◽  
...  
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