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Table 2.7-2 cont. <br />Page 3 <br />Physical Determinations Procedure or Reference <br />Emission Spectrographic Scan 0.75 meter spectrograph, 10 mg sample, 10 mg <br />graphite, Harvey -type electrode, burnt to <br />completion. <br />Artificial Weathering The samples (crushed to a nominal 1/2 -inch) <br />were subjected to 40 freeze -thaw cycles in a <br />controlled -temperature chamber to provide an <br />artificial weathering condition. At the <br />start, the samples were covered with deion- <br />ized water. Closed plastic containers were <br />used. Each freeze -thaw cycle consisted of 12 <br />hours of thawing and 12 hours of freezing. <br />The maximum temperature was 65°F and the min- <br />imum was 100F. <br />Particle Size Distribution <br />• Water Holding Capacity <br />Hydraulic Conductivity <br />Settling Characteristics <br />jb 1/87 <br />U <br />Dry sieving was employed on samples prior to <br />artificial weathering and wet sieving was <br />carried out after artificial weathering. <br />Eight -inch diam W.S. Tyler Inc. screens of 4, <br />14, 65, and 270 mesh were used. <br />ASA Agronomy Monograph No. 9, method 8-2.3, <br />pp. 134-137. After artificial weathering, <br />the sample material was air-dried and crushed <br />to pass a 10 mesh (1.68 mm) screen. Deion- <br />ized water was used to saturate the samples. <br />Two levels of suction pressure were tested, <br />1/3 bar and 15 bar. <br />ASA Agronomy Monograph No. 9, method 13-3.3, <br />pp. 215-220. After artificial weathering, <br />the sample material was air-dried and crushed <br />to pass a 10 mesh (1.68 mm) screen. Deion- <br />ized water was used as the fluid. <br />Method worked out by Dr. S.R. Olsen: 15 g of <br />air-dried -10 mesh sample material was mixed <br />with 1000 m1 deionized water containing 3 gpl <br />CaCl2 as a deflocculant. The slurry was <br />allowed to settle for 30 min in a 1 -titer <br />graduate and the settled slurry volume <br />recorded. <br />2-360 <br />