This method uses a 26-g SPEEDY MOISTURE TESTER to determine the moisture content of soils, fine aggregates, sand, and clay. By using the SPEEDY tester, the moisture content can be determined in the laboratory or field in from 45 sec to 3 rein, depending upon the material being tested. The tester operates on the principle of a calcium carbide reagent (reactive agent) being introduced into the free moisture of the soil sample. The resulting chemical reaction creates a gas that is contained in a sealed chamber, the pressure of which can be measured with the built-in gas pressure gauge.

APPARATUS. The SPEEDY moisture test set (fig. 15-28) includes the SPEEDY tester, a balance, half-weight reagent, measuring scoop, brushes, cleaning cloth, and two 1 1/4-in. steel balls.

PROCEDURE. The procedure for determining moisture content using the SPEEDY MOISTURE TESTER is as follows:

2. Place the soil sample and two 1 1/4-in. steel balls in the large chamber.

3. Place three scoops (24 g) of reagent in the cap. Then, with the pressure vessel in a horizontal position, insert the cap into the pressure vessel and tighten the clamp to seal the cap to the unit. 4. Raise the moisture tester to a vertical position so that the reagent falls into the vessel.

5. Hold the moisture tester horizontally; vigorously shake the device with a rotating motion for 10 sec to put the steel balls into orbit around the inside circumference; then rest for 20 sec. Repeat the shake-rest cycle for a total of 3 min. Do not allow the steel balls to fall against either the cap or orifice leading to the dial; this may cause damage.

6. Holding the tester horizontally at eye level, read and record the dial reading as the percent of moisture by wet mass.

7. When the sample is dumped, examine it for lumps. If the soil sample is not completely broken down, increase the time limit (shaking unit) by 1 min on the next test.

8. To determine the percentage of moisture by dry mass (ovendry moisture percentage), read the direct reading obtained in No. 6 above into a calibration curve that is also supplied with the test set.