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|Title:||Membrane-envelope technique for waterproofing soil base courses for airstrips : bare base support|
|Authors:||United States. Air Force.|
Burns, Cecil D.
Brabston, W. N. (William Newell)
|Publisher:||U.S. Army Engineer Waterways Experiment Station.|
Engineer Research and Development Center (U.S.)
Abstract: The purposes of the investigation reported herein were to (A.) determine the techniques required to construct a waterproof fine-grained soil base course by encasing the soil layer in a protective membrane envelope, (B.) evaluate several types of membranes for use in this waterproofing technique, and (C.) determine the effects of aircraft traffic under a range of weather conditions on a base course so constructed. A test section was constructed having (A.) a highly compacted lean clay base course over a low strength subgrade of the same soil, and (B.) a heavy clay base course over a loose sand subgrade. During construction, various surface and subsurface membranes were bonded together to form a single watertight envelope encasing both base courses. The initial strengths of the top 6 in. of the lean clay and the heavy clay were approximately 32 and 31 CBR, respectively. The test section was trafficked with a simulated F-4C aircraft loading. Traffic was applied intermittently for a 7-1/2-month period during which time extremely high and low temperatures and wet and dry weather conditions occurred. A total of 580 coverages were completed, after which soil tests indicated that there had been practically no changes in soil moisture content during the test period. Strength of the top 6 in. of the lean and heavy clay base soils at the end of traffic measured 67 and 57 CBR, respectively. From the results of this study, it was concluded that: (1.) A fine-grained soil base course can be successfully protected from water intrusion by encasement in a protective membrane envelope. This can be accomplished in the field using the techniques and equipment described herein. (2.) T1 and T2 membranes are not satisfactory for use as surfacing on a tactical assault field of this type. T16, T17, or WX18 membranes will withstand the abrasive action of a free-rolling F-4C aircraft wheel. However, a recently completed comparison study indicated that only the WX18 has sufficient tear strength to sustain braking and short-radius turns of F-4C aircraft. (3.) All subsurface membranes used in the tests reported herein were effective in waterproofing, but the T16 was more durable than the lighter membranes and less subject to damage during construction. NOTE: This file is large. Allow your browser several minutes to download the file.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Miscellaneous Paper|
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