Several versions of a funnel test are used to measure the workability of pastes and grouts. These devices differ in dimensions and intended uses; however, they all work on the principle of measuring the time for fresh paste or grout to flow through the opening of a funnel.
The flow cone test (Scanlon 1994) is intended for use in measuring the flow properties of grout for preplaced-aggregate concrete, but can also be used for other highly flowable grouts. The test is standardized in ASTM C939 and is considered appropriate for use in both the field and the lab. To perform the test, grout is poured into the flow cone, which is shown in Figure 29. The level indicator is used to ensure that a standard volume of grout is used for each test. The opening at the bottom of the cone is opened and the time for the grout to flow out of the cone is recorded. The test is not considered applicable to grouts that become clogged in the cone and do not continuously flow out the opening. Test results for such mixtures should be discarded.
The Marsh cone test (Zhor and Bremner 1998; Ferraris, Obla, and Hill 2001) is a non-standard test most typically used for oil well cements. The Marsh cone is a funnel with a long neck and an opening of 5 mm. A stand holds the Marsh cone in place above a glass graduated cylinder. After one liter of cement paste is placed in the cone, the orifice at the bottom of the neck is opened. The time for various volumes of paste to flow out of the orifice is measured. Since the weight of the cement paste in the funnel should be sufficient to overcome the yield stress, the time of flow should be related to viscosity. However, Ferraris, Obla, and Hill (2001) showed that the flow time from the Marsh cone test was not correlated to the viscosity measured with a laboratory parallel plate rheometer and hypothesized that the lack of correlation was related to factors such as friction and sedimentation in the Marsh cone.
The flow cone test has been adapted for measuring concrete (Ferraris 1999). The larger funnel used for concrete is 615 mm long with a 150 mm long outlet. The upper diameter of 230 mm narrows to 75 mm at the orifice. The device can be used for concretes with aggregate up to 20 mm.