A Consistency Model of Fresh Concrete under In-Stable Condition

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It is well known experimentaly that the flowability of fresh concrete will be changed not only with elapsed time but also pressure and shear stress in the conveying pipe. The effect of pumping on the consistency changing is different on each mixture condition or pumping condition. Some concrete becomes large consistency after pumping and some concrete becomes small one. There are no consistency model which express the behavior of concrete before and after pumping.In this study, a computer simulation method which express the behavior of concrete in the conveying pipe was proposed, and changing of fresh concrete consistency was discussed from rheological point of view to propose a model which express the changing of consistency by pumping. An experiment was carried out to compare with the analytical result and appropriately of analysis was discussed.Several concrete was prepared to examine the changing of consistency with elapsed time to discuss the behavior of fresh concrete with elapsed time. It was clarified by the experiment that the changing of consistency with elapsed time is related with mixproportion. A model which express the behavior of fresh concrete with elapsed time was proposed using this experimental result.On the other hand, an analysis of pumping under high pressure and high shear stress and stress distribution and pressure loss was discussed. Two type of simulation was carried out, one was used a model in which the consistency was not changed and the other was used a model in which the consistency was changed with proceeding the pumping. It is clarified with analysis that the quantity of flow of slip will be changed with proceeding the pumping used by the model in which the consistency changing.