AS 1289.3.8.1:2017 pdf free.Methods of testing soils for engineering purposes Method 3.8.1: Soil classification tests—Dispersion—Determination of Emerson class number of a soil.
5 REAGENT
Distilled water.
NOTE: The test may be performed using other water sources if required by the specifier.
6 PROCEDURE
Figure 1 provides a flow chart of the method of determination of the Emerson class number.
The procedure shall be as follows:
(a) Obtain about 5 g of air-dried soil and screen through 4.75 mm and 2.36 mm sieves. Select three soil crumbs that are not individual particles retained on the 2.36 mm sieve.
(b) Put about 200 mL of water in a beaker. Carefully place three air-dried crumbs into the beaker of water, spaced around the base. Do not stir or otherwise disturb.
(c) Record the time of placing the crumbs in the water and allow a time period of ten minutes to elapse.
NOTE: Most dry soil crumbs slake (break up and run out along the bottom of the beaker in a flat pile) when immersed in water, owing to the stresses induced both by the compression of air as the negative pore water pressure attracts water into the soil, and by swelling. Release of compressed air may cause particles to fly off the crumb.
(d) Observe whether slaking occurs. If after two hours slaking does not occur, observe the crumbs to determine if swelling occurs. At the determination of a class number, measure and record the water temperature to the nearest 1°C.
(i) If the crumb does not slake and swelling does not occur classify the soil as Class 8.
(ii) If the crumb does not slake and swelling does occur, classify the soil as Class 7.
(iii) If a colloidal cloud covers the bottom of the beaker within 10 minutes (strong dispersion) or all the water in the beaker becomes cloudy leaving only a coarse residue in a cloud of clay (extreme dispersion), classify the soil as Class 1.
(iv) If a recognizable cloud of colloids in solution spreads as a thin streak on the bottom of the beaker (moderate dispersion) or there is a bare hint of a cloud in the water on the surface of the crumb (slight dispersion), classify the soil as Class 2.AS 1289.3.8.1 pdf download.