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Views: 7 Author: Site Editor Publish Time: 2022-07-23 Origin: Site
Item | ASTM D4716 | DW1370 | Comply or not |
Water head applying method | Water reservoir, whose length shall be at least equal to the total length of the specimen and have provision for maintaining a constant water level at any of several elevations. The total length of specimen is at least 350mm, which means the water reservoir shall apply at least 350mm water head difference | Water tower, able to apply water head difference up to 400mm | Different water head applying method, but the maximum water head difference meets the requirements of ASTM D4716 |
Water head | Use three gradients selected from the following values: 0.05, 0.10, 0.25, 0.50 and 1.0. The effective length of specimen is 305mm, so water head differences required are 15.25mm，30.5mm，76.25mm，152.5mm and 305mm with the accuracy of ±1mm | Water head difference of 0~400mm, continuously-adjustable and with the accuracy of ±1mm | Yes |
Loading mechanism | Capable of sustaining a constant normal compressive stress on the specimen ranging from 10kPa to at least 500kPa on a 305 by 305mm loaded area with an accuracy of ±1% Perform flow rate testing using a minimum of three applied normal stresses selected from the following values: 10, 25, 50, 100, 250 and 500kPa | Applied by air pressure surrounding the test specimen with maximum pressure up to 600kPa
The above is the pressure meter of DW1370 with measuring range up to 1Mpa; with the air pump of enough capacity, at least 500kPa air pressure can be reached. But the division of the pressure meter is 50kPa, so 10kPa and 25kPa can not be read from the pressure meter. | |
Specimen size | For geosynthetics whose width is not less than 305mm, take specimens of 305mm in width; For geosynthetics whose width is less than 305mm, take specimens of full width | PVD with 100mm in width DW1370 is only suitable to PVD with 100mm in width. There are also PVD of other widths; if any, please inform us. | |
Rubber substrate | Used to model soil adjacent to the geosynthetics on one or both sides or the specimen if desired; Compare the uncompressed thickness measured prior to use with the thickness measured at least one hour after use. If the thickness decreases by 20% or more, or if permanent indentations or damage are evident in the sheet, discard the sheet and retest using a new sheet. | Air pressure surrounding the specimen, not need of rubber substrate |
