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doi:10.2204/iodp.proc.308.205.2008

Hydrometer analysis (Penn State)

Prior to the start of each experiment, each cylinder was mixed for 2 min using a plunging rod. Once the rod was removed, the stopwatch was started and the hydrometer was inserted and steadied. Readings were made at 15 and 30 s without removing the hydrometer. After the 30 s reading (and each subsequent reading), the hydrometer was removed, rinsed in deionized water, and wiped dry before obtaining readings at 1, 2, 4, 8, 16, and up to at least 1024 min. Hydrometer readings were recorded to the nearest 0.1 g/L.

An example data sheet and plot are given in Figures F4 and F5, respectively. We made continuous hydrometer readings on the reference mixture, B, which contained distilled water and dispersing agent. Reading B was then subtracted from the suspension reading, R_h, in Equation 2. We continually monitored temperature in the laboratory and updated water viscosity, η, accordingly. The effective depth, L, in Equation 1, is hydrometer-specific and was calculated according to a prescribed calibration procedure (Lewis and McConchie, 1994).

Specific gravity of the sample, G_s, in Equations 1 and 2, was determined on a representative subset of 19 samples obtained at MIT in general accordance with ASTM Standard D854-06 (ASTM International, 2006). These measurements are presented in Table T4. Measurements ranged between 2.65 and 2.77. For samples where no specific gravity measurements were made, we used an average value of 2.70 for evaluating Equations 1 and 2.

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