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Title: Evaluation of Dow Chemical production extruded truss-web landing mat
Authors: United States. Army Materiel Command.
White, D. W. (Dewey W.)
Keywords: Dow landing mats
Landing mats
Traffic tests
Skid tests
Publisher: Soils and Pavements Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: The investigation reported herein was conducted to evaluate 2- by 9-ft, truss-web, heavy-duty landing mat supplied by the Dow Chemical Company. The mat was traffic-tested to evaluate its performance relative to the requirement that heavy-duty landing mat be capable of sustaining 1000 coverages of heavy-duty loading (50,000-lb, single-wheel load (SWL), 250-psi tire inflation pressure) when placed on a 4-CBR subgrade. Traffic tests were conducted to determine the performance of the truss-web mat. These traffic tests were conducted on prepared subgrades, with a rolling wheel load simulating actual aircraft conditions. A 50,000-lb SWL with a 250-psi tire inflation pressure was used. The first quantity of mat tested was designated initial production mat. This mat failed after 240 coverages due to tire hazards caused by splits which began at the female I-lock corners and extended along the female connectors. The subgrade was rated at 4.0 CBR. Several design modifications were studied, resulting in tapering of the female connectors at the panel corners. This consisted of cutting the corners of the female connectors off for approximately 2 in. along the connector at an angle with the panel corners. The contractor modified sufficient panels with the tapered corners for a traffic test in an effort to improve the performance of the mat. This traffic test, designated modified production test, was conducted under the srune loading conditions used for the initial test. In the first phase of this test, the mat was placed on a subgrade rated at 4.0 CBR and subjected to 1040 coverages without test section failure. In addition to this traffic, two additional phases of traffic were applied prior to mat test section failure. Phase 2 consisted of traffic conducted for the Aberdeen Proving Ground (APG, the agency responsible for engineering tests of heavy-duty landing mat). Since only one line of panel end joints in the standard traffic lane received 100 percent of the traffic coverages, APG requested that an additional line of panel end joints be subjected to 100 percent traffic coverage. Therefore, traffic was applied to achieve 1000 coverages on an additional line of panel end joints, and the mat successfully sustained these coverages on a subgrade rated at 4.0 CBR. Phase 3 traffic was a continuation of Phase 1 traffic until mat failure. A total of 300 additional coverages were applied to the mat on a subgrade with a CBR of 3.9 (equivalent to 336 coverages on a subgrade rated at 4.0 CBR). Therefore, it was determined that the mat will withstand 1376 coverages when placed on a 4-CBR subgrade (1040 plus 336 coverages). Skid tests conducted on this mat resulted in values for the coefficient of friction on wet (0.40) and dry (0.62) surfaces that meet the requirements of the revised Qualitative Materiel Requirement (runway condition reading of 13-25 or coefficient of friction of 0.40 to 0.80). Tensile strength was within specified requirements as revealed by laboratory tensile tests of mat panel samples. NOTE: This file is very large. Allow your browser several minutes to download the file.
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