04/07/2025
ASTM D6910/D6910M-09 5. Significance and Use5.1 This test method allows for the assessment of an apparent viscosity of clay slurries in the laboratory and in the field. Viscosity is a fundamental characteristic for slurries in construction applications. The Marsh Funnel Viscosity test can be used for field quality control of slurries. Relative changes in slurry viscosity can be identified using Marsh Funnel measurements and modifications can be made to mixing and handling procedures.5.2 In this test, it is assumed that the apparent viscosity of a slurry is directly related to the flow duration through a specially shaped funnel (the Marsh Funnel).5.3 In slurry wall construction and other applications, the viscosity of a slurry must be maintained at a level high enough to assist in stabilizing the trench walls. Slurry viscosity is also directly related to filter cake permeability.5.4 The Marsh Funnel Viscosity has been widely used in drilling soil and rock for water wells, oil, gas, soil stabilization, and the application of hydraulic barriers.5.5 Inert suspended solids such as fine sands and additives affect the viscosity of slurries. This test may be used to determine the relative effects of this and other such materials on the viscosity of a slurry.6. Apparatus6.1 Marsh Funnel (see Fig. 1)—The Marsh Funnel will comply with the following:6.1.1 Funnel Cone—A cone with a length of 305-mm [12-in.] and a diameter of 152-mm [6-in.] equipped with a screen at the top and an or***ce tube at the bottom. The capacity of the cone from the or***ce opening to the bottom of the screen shall be 1500 mL [1.6 qt]. It may be manufactured from plastic, metal, or other rigid and durable material, and may be provided with handles or stands.6.1.2 Funnel Orifice—An or***ce tube of 51-mm [2-in.] in length, with an inside diameter of 4.75-mm [3⁄16-in.]. The diameter of this outlet directly affects the Marsh Funnel test results and has been standard with the test since the inception of this method.6.1.3 Screen— A screen with openings of approximately 3.2 mm [0.125 in.]. The screen is normally placed at the 1500 mL [1.6 qt] level of the funnel; approximately 19 mm [0.75 in.] below the top of the funnel. The screen is used to separate larger particles that could plug the or***ce during the test.6.2 Graduated Cup— A metal or plastic graduated cup with a 946-mL [1-qt] marking.6.3 Timer— A stopwatch or equivalent timer with a resolution of 0.5 s or better.6.4 Thermometer— A thermometer with a range of 0 to 105°C [32 to 220°F] with a resolution of 1°C [2°F].6.5 Sampling and Cleaning Equipment.7. Hazards7.1 Appropriate eye and hand protection is recommended for direct work with the slurries.8. Sampling8.1 Obtain a 7.5 L [2 gal] representative sample of the slurry to be tested using dippers, buckets, mud or slurry samplers, or equivalent equipment from a field construction operation (for example, from a hydrated mix pond) or from a laboratory slurry mix. A specimen 1500 mL [1.6 qt] in volume is required for a test.9. Calibration Checks9.1 Periodically check the Marsh Funnel and the graduated cup for damage or wear. For the Marsh Funnel pay special attention to the or***ce tube. Verify that the graduation marks are present and readable in the funnel and the cup. In particular, make sure that the 946 mL mark is readable in the cup.9.2 Fill the Marsh funnel with 1500-mL [1.6-qt] of water while holding a finger over the or***ce. If the water surface is at the screen, no further marking is required. If the surface is above or below the screen, a mark should be placed inside the funnel for reference when running the test.9.3 Verify that the flow duration for 946 mL [1 qt] of water is 26 6 0.5 s at a temperature of 21 6 3°C [70 6 5°F]. 10. Procedure10.1 Verify that the funnel and cup are both clean and dry.10.2 Cover the Marsh Funnel or***ce with a finger and pour the freshly sampled slurry through the screen into the upright funnel.10.3 Holding the funnel over the graduated cup, remove the finger and start the timer.10.4 Measure the time for the slurry to fill the graduated cup to the 946 mL [1 qt] line.10.5 Determine the temperature of the slurry.NOTE 3—Repeating the test several times and averaging the results may reduce the chance for error and provide more reproducible results.11. Report11.1 Test data forms or test reports will include the following:11.1.1 The source of the sample.11.1.2 The date and time of the test.11.1.3 The elapsed time to the nearest second for 946-mL [1-qt] of the slurry to flow into the graduated cup. This value to be recorded as the Marsh Funnel Viscosity.11.1.4 The temperature of the slurry.
