6-■-4 ■=4´5104.1 Experiment methodFig. 5 shows the pipe viscometer system25) used in the experiment which consists of the following devices: the sample container (airtight steel container with a capacity of 80 liters); a compressor made by company S (tank capacity 24 liters, maximum pressure 0.9MPa); a pump pipe (pipe inner diameter 100mm, length 1000mm); a diaphragm pressure gauge made by company K (capacity 0.2MPa); a receiving container for the discharged specimen (capacity 40 liters); a 10´-where y: water film thickness (cm); and, W: unit water content (kg/m3).With their relationship determined beforehand, it will be possible to estimate the water film thickness (y) corresponding to a desired pumping pressure level, and then the slip velocity by using the thus estimated value and Equation (2), and the pump load (pressure gradient) required for the desired amount of pumping by using Equation (6).The experiment used the same concrete materials, mix proportions and mixing procedure as those described in 3.1 and 3.2.80 liter sample containerPressure regulator valveDischarge pipeHorizontal support(7)weighing instrument made by company A for flow rate measurement (capacity 150kg, verification scale interval 20g); and, a data recorder made by company T which has been set to display the mass of the discharged specimen in unit of 50g for the mass analysis. The mass measurement results were saved and recorded in the data recorder every 0.1 seconds.The flow rate measurement was carried out as follows. Concrete was mixed and left to stand still for 3 minutes. About 65 liters of the specimen was fed to the sample container shown in Fig. 5, and the lid was placed to keep the container airtight. With the pressure gradient adjusted to about 100Pa/cm by operating the pressure regulator valve, the outlet shutter was opened to start pumping the concrete into the receiving container. After ensuring a stable flow line of the concrete at the discharge pipe outlet, the same operation was also performed at pressure gradients of about 150Pa/cm and 250Pa/cm to measure the amount of concrete discharged. In reference to the change over time in mass of the specimen in the receiving container shown on a monitor screen of the data recorder, the flow rate was calculated by dividing the difference in mass at a constant flow rate per unit of time with the measurement time and the concrete mass per unit volume.24 liter compressor, 0.9 MPa(inner diameter 100 mm, length 1.0 m)150 kg weighing instrument with a discharge rate Pump pipePressure gaugeOutlet shutterReceiving containerDataRecorder→4.2 Measurement resultsTable 3 shows the estimation results of the Bingham fluid flow rate which is necessary for the calculation of the Fig. 5 Pipe viscometer─ 5 ─4. Measurement of the rheological quantities using a pipe viscometer
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