The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity. The theory states that excess water can surround the fl...The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity. The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film. Experiments on limestone powder pastes were conducted to verify the theory. The superplasticizer dosage （sp%） and the water-powder ratio by volume （Vw/Vv） were systematically varied. A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes. The water film thickness （WFT） of flocs was then calculated and shown to determine the paste fluidity. Based on this WFT of flocs, the effect of the sp on the paste fluidity was determined and then compared with the effect of water.展开更多
The sedimentation of a single circular particle between two parallel walls was studied by means of direct numerical simulation (DNS) and experiment. The improved implementation of distributed Lagrange multiplier/ficti...The sedimentation of a single circular particle between two parallel walls was studied by means of direct numerical simulation (DNS) and experiment. The improved implementation of distributed Lagrange multiplier/fictitious domain method used in our DNS is a promising new way for simulation of particulate flows. The settling behaviors of the particle are presented ranging in Reynolds number from 0 to about 700, which showed that our results for low Reynolds numbers agreed well with that reported before. Nevertheless, for higher Reynolds numbers our results were different from theirs. The long-term mean equilibrium positions in our results were all on the centerline, but not at off-center position as reported before. In order to validate our simulation, experiments were also conducted. The results showed that the sedimenting behavior simulated in this paper agreed well with our experiment result.展开更多
基金supported by the National High-Tech Research and Development Program of China("863" Project)(Grant No.2012AA06A112)the National Natural Science Foundation of China(Grant No.51239006)the National Key Laboratory in China(Grant No.2012-Ky-02)
文摘The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity. The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film. Experiments on limestone powder pastes were conducted to verify the theory. The superplasticizer dosage （sp%） and the water-powder ratio by volume （Vw/Vv） were systematically varied. A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes. The water film thickness （WFT） of flocs was then calculated and shown to determine the paste fluidity. Based on this WFT of flocs, the effect of the sp on the paste fluidity was determined and then compared with the effect of water.
文摘The sedimentation of a single circular particle between two parallel walls was studied by means of direct numerical simulation (DNS) and experiment. The improved implementation of distributed Lagrange multiplier/fictitious domain method used in our DNS is a promising new way for simulation of particulate flows. The settling behaviors of the particle are presented ranging in Reynolds number from 0 to about 700, which showed that our results for low Reynolds numbers agreed well with that reported before. Nevertheless, for higher Reynolds numbers our results were different from theirs. The long-term mean equilibrium positions in our results were all on the centerline, but not at off-center position as reported before. In order to validate our simulation, experiments were also conducted. The results showed that the sedimenting behavior simulated in this paper agreed well with our experiment result.
