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C <br />TABLE A -DESIGN TffiCKNESS -GRAVEL & CRUSHED ROCK <br />Maximum <br />Wheel Load <br />(IQPS) Total Pavement <br />Thickness <br />(Inches) Pit Run Gravel <br />CBR z 50 <br />(Inches) Coarse Crushed <br />Rock (Inches) Fine Crushed <br />Rock (Inches) <br />12 24 15 6 3 <br />25 31 20 8 3 <br />40 38 26 8 4 <br />As can be seen, even the lowest total pavement thickness would be 24 inches, resulting <br />in a high economic impact of bringing the material to the site. We have provided an alternative, <br />using the native clays as a subbase by improving their engineering characteristics with <br />amendment. The site clays, if oversized materials are removed, can be mixed with lime to <br />greatly decrease their plasticity index and thus their moisture sensitivity. An added benefit is <br />• the compressive strength that develops in this material upon curing and compaction. The crucial <br />aspect of lime-treatment is getting a finely-divided mixture, which is only possible with the use <br />of a reclaimer-pulverizer. A proprietary process, known as "Ports-Batch" where a freshly <br />slaked quicklime slurry is applied to the clay has been used for pavements over moisture- <br />sensitive clays for some time with good results. Usually, an impervious surface is applied to <br />the completed subbase to protect it from freeze-thaw and wet-dry cycles. We chose cement- <br />treated road base for the surface treatment. Because the Bureau of Mines Cvcular does not <br />consider this material combination, we used recent experience, combined with the CDOT design <br />procedure to generate the following table. <br /> <br />• <br />31 <br /> <br />