Road structure – process – or apparatus – Pavement – Modules or blocks
Reexamination Certificate
2002-08-05
2004-02-03
Hartmann, Gary S. (Department: 3671)
Road structure, process, or apparatus
Pavement
Modules or blocks
C403S408100
Reexamination Certificate
active
06685388
ABSTRACT:
FIELD OF THE INVENTION
The field is lightweight panels, connectors and tools used to construct mats that enable or enhance mobility across unstable terrain.
BACKGROUND
It is desirable to move heavy vehicles over unstable terrain during various events. These events may include environmental remediation, military maneuvers, or scientific exploration of environmentally fragile areas. Mat panels have been used successfully for applications that are similar to this, such as expedient aircraft runway repair. Mat panels of a preferred embodiment of this invention use fiberglass-reinforced plastic (FRP) material similar to that of a mat developed by the U.S. military for airfield pavement repair. Three U.S. patents resulted from development work on these military panels.
U.S. Pat. No. 4,404,244, System for Rapid Repair of Damaged Airfield Runways, to Springston, Sep. 13, 1983, describes a membrane of FRP prefabricated from several chopped fiberglass matting layers chemically bonded to woven fiberglass roving and impregnated with a polyester resin to yield a panel of a typical thickness of ⅜ in. The anchoring system comprised special bushings fitted to holes along the edges of the panels for use with torque set rock bolts anchored to the edges of undamaged runway.
U.S. Pat. No. 4,605,337, Expedient Runway Surfacing with Post Tensioning System for Expeditionary Airfields, to Springston et al., Aug. 12, 1986, describes a system for building a runway with FRP panels that also uses a self-contained hydraulic tensioning system and a deadman earth anchor at each end of the runway to allow for expansion and contraction due to temperature and dynamic loads thereon.
U.S. Pat. No. 4,629,358, Prefabricated Panels for Rapid Runway Repair and Expedient Airfield Surfacing, to Springston et al., Dec. 16, 1986, provided an panel improved over that of the '244 patent in that it was lighter in weight through the introduction of hollow inorganic silica spheres, commercially referred to as “microballoons,” in the plastic resin.
Much before the military panels were invented, the use of plastic for landing mats was patented. U.S. Pat. No. 2,653,525, Landing Mat, to McGuire, Sep. 29, 1953, provided an unusually configured mat made of “fibrous reinforced plastic” for use as a runway surface at an airfield.
U.S. Pat. No. 4,746,243, Apparatus and Method for Rapid Repair of Damaged Airfield Runways, to Perry, May 24, 1988, uses the concept of the military runway repair patents with a clamping system and a tapered edge to integrate the mat with existing undamaged runway.
Alternative materials for supporting heavy equipment include a board mat system detailed in U.S. Pat. No. 4,600,337, Board Mat System, to Sarver, Jul. 15, 1986, that uses wooden boards connected in a flexible strip to support heavy loads.
More recent inventions for supporting heavy construction equipment include mats of heavy tubular support designed to be emplaced by the vehicle they support as described in U.S. Pat. No. 6,007,271, Ground Pressure Distribution Mat, to Cole et al., Dec. 28, 1999.
Recent patents for mats that used FRP materials include two with novel means for interlocking the mat panels. U.S. Pat. No. 5,776,582, Load-Bearing Structures with Interlocking Edges, to Needham, Jul. 7, 1998, describes a series of pyramid-shaped elements along opposite edges of a panel designed to interlace with similar elements on an adjoining panel. U.S. Pat. No. 5,888,612, Load-Bearing Structures, to Needham et al., Mar. 30, 1999, describes a honeycombed rectangular panel having an L-shaped stepped down lip running nearly the full distance along a narrow end and only halfway along an adjacent longer side with a straight stepped down lip extending halfway along the side opposite the adjacent longer side but at the other end of that side.
For repair, one type of military mats are emplaced over craters filled with crushed-stone to effect rapid runway repairs. In these applications, the compacted crushed-stone layer carries the load of the aircraft and the FRP mat-serves as a debris cover and wear surface. These military mats are constructed of an array of rigid FRP panels connected via flexible elastomer hinges. The individual panels are typically approximately 9 m×2 m (30 ft×6 ft. and the hinges are approximately 7.5 cm×9 m (3 in×30 ft.). A military mat is comprised of nine of these panels, thus it is approximately 9 m×16 m (30×54 ft) when unfolded. The mats are folded in an accordion (fanfold) fashion for shipment and storage. In use, the mats are unfolded, placed over the repaired pavement, and bolted to undamaged pavement. The material for the mats is a FRP resin composite. Two layers of a woven fiberglass material are embedded in a polyester resin filler to form a mat panel approximately 0.6 cm (0.22 in) thick. The perimeter of the panels is reinforced with an additional narrow strip of FRP material. The upper surface of the mat has a texture defined by the woven roving weave pattern of the FRP material. This effect is obtained by not smoothing over excess resin on the top laminate, thus yielding a non-slippery surface. The folded mat sections are heavy and require heavy equipment and substantial manpower to deploy.
Under a research work unit, several lightweight matting materials were investigated for use to build expedient roads over sands, not just for repair. AT40-MM-005, Advanced Materials for Construction of Contingency Pavement, Waterways Experiment Station (WES), U.S. Army Corps of Engineers, Vicksburg, Miss., 1997. Flat sheets of fiberglass-reinforced mat (1.2 m×3.6 m (4×12 ft), similar to the U.S. Military's Rapid Runway Repair Mat but less bulky, were tested with truck traffic over various types of sand. In order to construct a roadway for test purposes, four smaller sheets of the same mat material were placed under the edges of the larger sheets of mat and each of the larger sheets were bolted to the smaller “joiner” sheets. This mat system showed promise under truck traffic but was difficult as well as labor intensive to construct. Results of this work along with recommendations for improving the mat were reported. Webster, S. and J. Tingle, Expedient Road Construction Over Sands Using Lightweight Mats, WES Technical Report GL-98-10, U.S. Army Corps of Engineers, Vicksburg, Miss., Jun. 1998.
Subsequently, the fiberglass mat design was changed to yield a square 1.8 m (6 ft) on a side after emplacement. A variety of plastic “pop-in-pop-out” connector pins were developed and tested for use with this design. The best plastic pin design was able to withstand 7.6 cm (3.0 in) of rutting in sand-under the mat before failing. Road demonstration tests with the fiberglass mat and plastic “pop-in-pop-out” pins were conducted. Santoni, R. et al., Expedient Road Construction Over Soft Soils, ERDC/GSL TR-0107, U.S. Army Corps of Engineers, Vicksburg, Miss., May 2001. The plastic pins failed in these tests.
What was needed was a simple system for effecting repairs in areas where suitable heavy equipment and materials are not readily available. Also, use of expensive hydraulic tensioners and heavy deadman apparatus was impractical to deploy to areas of varying terrain and limited accessibility. Thus, improvements in connectors for simple lightweight panels led to a preferred embodiment of the present invention. Connector pin assemblies, spacer guides, and mat hole alignment tools were designed and developed for use with the mat panels. A demonstration test road was constructed at the Waterways Experiment Station, Vicksburg, Miss., using an embodiment of this invention further described in detail below.
SUMMARY
A preferred embodiment of the present invention uses lightweight FRP mat panels, preferably in multi-layer laminates, to fabricate a durable surface for applications such as a path, road, equipment or material pad, etc. that generally is intended for temporary use. Each mat panel comprises a flat surface area with L-shaped downward folded sides, or tabs, on two adjoining edges only
Smith Carroll J.
Webster Steve L
Baugher Jr. Earl H.
Hartmann Gary S.
The United States of America as represented by the Secretary of
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