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<br />COAL REFUSE GRADATION <br /> Gravel (%) Sand (%) Silt or Clay (%) <br />Average 28 49 23 <br />Minimum 3 24 4 <br />Maximum 65 75 60 <br />The fines were generally non-plastic or showed very low plasticity. <br />Liquid Limits were less than 24 and Plasticity Indices less than 7. Most <br />samples classify as a silty sand with gravel (SM) according to the Unified <br />Classification System. Occasional cleaner or coarser samples classified a SP, <br />GP or GM. <br />Standard Proctor Testing. One standard Proctor moisture-density test <br />• (ASTM D 698) was performed for this investigation on a sample of coal refuse <br />from a composite sample of the Shelby tube samples. A total of 18 standard <br />Proctor moisture-density tests were reviewed. Five of the tests were on <br />samples that contained considerable gravel which resulted in relatively high <br />maximum dry densities. The 14 remaining tests were judged more <br />representative of typical coal refuse gradations and the results are <br />summarized below. <br />SUMMARY OF STANDARD PROCTOR TESTING (ASTM D 698) <br />• <br /> Maximum <br />Dry Density (pcf) Optimum <br />Moisture Content (%) <br />Average 93 11.5 <br />Minimum 87 9.5 <br />Maximum 98 14.0 <br />12 <br />