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Title: Evaluation of Dow Chemical Company extruded aluminum two-piece 2-by 12-ft. landing mat (MX18-D)
Authors: United States. Army Materiel Command
White, D. W. (Dewey W.)
Keywords: Dow Chemical Co.
Laboratory tests
Landing mats
Traffic tests
Publisher: U.S. Army Engineer Waterways Experiment Station.
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: The investigation reported herein was conducted to evaluate an extruded aluminum alloy landing mat (designated MX18-D) designed and extruded by the Dow Chemical Company, Midland, Michigan. The mat, which was fabricated by Dow's subcontractor, Washington Aluminum Company, Enterprise, Alabama, is a 2- by 12-ft, two-piece partially hollow 6061-T6 aluminum alloy panel. (Two 12-in.-wide extrusions are welded together along their longitudinal edges to form a 2-ft-wide panel.) The panels are interlocked along the sides by a hinge-type connector, the components of which are an integral part of the basic panel extrusion. Extruded aluminum edge connectors are welded to the basic panel and consist of an overlap and underlap section secured by a locking bar after individual panels have been joined together. This investigation consisted of engineering traffic tests to evaluate the design and performance of the Dow MX18-D mat for compliance with criteria specified in the Department of the Army approved Qualitative Materiel Requirement (QMR) for Prefabricated Airfield Surfacings dated 14 April 1966 (this QMR was subsequently revised, and the revised QMR was approved on 2 April 1968). The traffic tests were conducted with a rolling wheel load simulating actual aircraft operations on mat placed on a prepared subgrade. The tests were conducted with a single-wheel load of 25,000 lb with a tire inflation pressure of 250 psi on a mat-surfaced subgrade with a California Bearing Ratio (CBR) of 4.0 for both item 1 (mat oriented with internal ribs of extrusion perpendicular to the direction of traffic) and item 2 (mat oriented with internal ribs of extrusion parallel to the direction of traffic). Results of this investigation indicated that the Dow MX18-D mat on items 1 and 2 sustained 704 and 500 coverages, respectively, of traffic, thus exceeding the original project requirements of the 1966 QMR (200 coverages on a 4.0-CBR subgrade). The service life of the MX18-D mat placed with the internal ribs of the extrusion parallel to the direction of traffic was only 71 percent as long as the life of the mat placed with the internal ribs perpendicular to the direction of traffic. The longitudinal weld did not contribute significantly to mat failure. Laboratory tensile strength tests were conducted on samples taken from the top sheets, ribs, and bottom sheets of panels of MX18-D mat. Results of these tests revealed that the tensile strength was within the specified requirements. The revised QMR for expedient surfacings now specifies that a medium-duty mat must sustain 1000 coverages of a 25,000-lb single-wheel load on a 4.0-CBR subgrade and weigh no more than 4.5 lb per square foot of placing area. Since the MX18-D mat weighs 5.3 lb per square foot of placing area and did not sustain 1000 coverages, no further tests of this item are recommended. NOTE: This file is very 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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