READY MAT US LLC

P.O. 231 Sulphur, La. 70664
337-528-3443
"Providing composite solutions to rapid runway and road repair."

Rapid Runway Repair Introduction

Concept

The Air Force flies and fights from its air bases. However, it is at the air base that air power is most vulnerable. They can be most immediate and lucrative targets for an adversary. After all, it is by far more effective to destroy aircraft while they are on the ground than to hunt them in the air. From a practical perspective, it is reasonable to say that during some phase of a conventional conflict, repair of airfield pavement damage will be one of the civil engineer's primary wartime missions. It is a complex and difficult tasking that requires the total commitment of all involved to succeed. Proper preparation must be accomplished prior to the moment of need…for time will not be available during the conflict to accomplish meaningful training.

Background

American military leaders recognized the vital need for airfields to support operations in all theaters of operation. This could mean repairing and maintaining existing airfields quickly and at times close to the front as possible. To provide this level of support, Aviation engineers experimented with several different runway materials. For example the attempt to construct and repair airfields with wooden planks proved too costly and labor intensive. Precast concrete was another alternative but after extended testing it was too heavy and not feasible. However, work continued and by the mid 1990's HQ Air Force Civil Engineering Support Agency (AFCESA) had perfected the Folded Fiberglass Mat (FFM) System that is the primary method now employed Air Force wide.

Description

The Folded Fiberglass Mat (FFM) is the current Airfield Damage Repair (ADR) method used for Rapid Runway Repair. The FFM is a 30 ft. by 54 ft panel. Each FFM panel consist of 9 independent 6 foot by 30 foot composite panels joined by rubber hinges. The NSN for this product is 5680-01-368-9032. Each FFM Kit consist of two 30 foot by 54 foot FFM's and two each 24 foot by 2 foot joining panels and two each 30 foot by 2 foot joining panels.

Application

After an attack the RRR team receives its order to proceed to the repair location. The damaged is then assessed. The upheaval and dunnage is removed. The bomb crater is back filled with crushed stone and the FFM assembly is towed over the filled crater and anchored to the airfield pavement. The FFM prevents the fill from becoming foreign object debris (FOD) . Once in place the FFM makes for a virtually flush pavement repair. The FFM's have been tested to be effective for all fighter jets and heavies up to the C-130. A detailed description of the crater repair and FFM installation is described below.

Airfield Damage Repair Part A: Filling the Crater

Crushed Stone Repair Procedures
  1. Clear debris from around the crater at least 6 meters (20 feet) in all directions to allow identification of the upheaved pavement surface. Identification and removal of all upheaval or damaged pavement is critical. It cannot be rolled down flush with the existing pavement and left. The upheaved pavement will eventually break up and create additional problems adjacent to the crater repair.
  2. Perform profile measurement and visual inspection to identify and mark upheaval around the crater.
  3. Remove upheaved pavement using an excavator with bucket or moil point attachment, and the front-end loader. The dozer may also be used, depending on the runway surface.
  4. All debris material in excess of 304 millimeters (12 inches) must be removed or reduced in size. Breaking the pavement into smaller pieces will minimize the potential for voids and settling problems in the future.
  5. Push unusable debris at least 9 meters (30 feet) off the Minimum Operating Strip (MOS) and pile no higher than 0.9 meter (3 feet).
  6. Place backfill material into the crater in accordance with the repair procedure chosen. Note: If settling problems are anticipated, placement of membrane fabric between dissimilar backfill materials is recommended.
  7. Fill and compact the crater with crushed stone material, placing it in lifts approximately 152 to 177 millimeters (6 to 7 inches) thick. For C-17 operations, limit the aggregate size to a maximum of 25 millimeters (1 inch) in the top 152 millimeters (6 inches) of the crushed stone repair. Overfill the crater by approximately 76 millimeters (3 inches) above the original pavement surface height. Compact each lift of crushed stone using a minimum of four passes of a single drum vibratory roller or two passes with a 10-ton vibratory roller. One pass of the roller means traveling across and back in the same lane. If the crushed stone material is placed upon soft subgrade materials, it may be beneficial to separate the material using geomembrane fabric and place the crushed stone material in thicker lifts. In any case, the crushed stone should be compacted with a minimum of four passes of a single drum vibratory roller or two passes of a 10-ton vibratory roller per each 152 millimeters (6 inches) of thickness. A 457-millimeter (18-inch) crushed stone layer should receive a minimum of 12 passes with a single drum vibratory roller or six passes with a 10-ton vibratory roller prior to cut for the final grade.
  8. Grade the compacted crushed stone to approximately 25 millimeters (1 inch) above the pavement surface.
  9. Compact the crushed stone using two passes of a single drum vibratory roller or one pass with a 10-ton vibratory roller. The crushed stone layer should have a minimum 15 CBR to support C-130 and fighter jet operations.
  10. Perform profile measurement. The repaired crater must not exceed the maximum RQC of ± 19 millimeters (± 0.75 inch). A repair outside this tolerance may still be useable, depending on its location, but will have a much shorter life before requiring additional maintenance to bring it back within this limitation.
  11. The crushed stone repair is complete at this point.

Airfiled Damage Repair Part B: Installing the FFM

Air Force FFM

Air Force FFM is manufactured by ReadyMat US LLC Inc., 337-528-3443. The FFM is air-transportable, can be moved easily by vehicles, can be positioned at greater distances from airfield pavement surfaces, and can be stored indoors out of the elements.

A standard FFM weighs about 1360 kilograms (3,000 pounds) and consists of nine fiberglass panels, each 1.83 meters wide by 9.14 meters long by 12.7 millimeters thick (6 feet wide by 30 feet long by 0.30 inch thick nominally). Elastomer hinges 76.2 millimeters (3 inches) wide connect the panels. When folded, these mats are 1.83 meters wide by 9.14 meters long and 203 to 254 millimeters thick (6 feet wide by 30 feet long and 8 to10 inches thick). This repair system also includes joining panels and two support mat kits. The joining panels come in 7.32-meter and 9.14-meter (24-foot and 30-foot) lengths. One of each size is needed to connect two 9.14-meter by 16.46-meter (30-foot by 54 -foot) mats. The resulting 16.46-meter by 18.29-meter (54-foot by 60-foot) mat is the normal size suitable for most crater repairs. If larger FOD covers are required, additional mats may be spliced together. There are two types of support mat kits for the FFM. Mat Kit A contains all the necessary tools and hardware required to assemble, install, and maintain the system. Mat Kit B contains the anchor bolts required to attach the mat to the pavement surface.

  1. The mat assembly area can be any area near the crater repair. This area must be cleared of all debris and swept. It must be large enough to accommodate the unfolding of both mats, allow equipment operations around the mat, and not interfere with crater preparations. This area should be approximately 30.4 meters by 30.4meters (100 feet by 100 feet) square, and located a minimum of 30.4 meters (100 feet) from the crater and off the MAOS.
  2. Mats are placed end-to-end about 1.2 meters (4 feet) apart, with the first panel up and positioned such that both mats unfold in the same direction. Unfold the mats in preparation for being joined together. The top panel of the mat is attached to a tow vehicle with a nylon strap. A crew of four people, or a forklift positioned on the opposite side of the mat, lifting each successive panel as the mat is being pulled open, speeds the unfolding process.
  3. Join the mats together so they are aligned, the 9.14-meter (30-foot) edges are even, and the 16.46-meter (54-foot) edges are roughly parallel with each other. Lift one end of the 16.46-meter (54-foot) edge and slip either the 7.32-meter (24-foot) or the 9.14-meter (30-foot) section of joining panel underneath the raised edge. Align the holes in the mat with the joining panel bushing holes and lower the mat. Install the top joining bushings and tighten by hand. This process is repeated at the other end of the 16.46-meter (54-foot) edge of the same mat using the remaining joining panel. Hand-tighten these bushings; final tightening will be accomplished later.The second mat is then towed over to the first mat with joining panel attached. One of the holes near the end of the second mat is aligned with its counterpart on the joining panel and a top joining bushing is installed. This end connection acts as a pivot point when the second mat is moved into position so all the remaining holes on the joining panel are in alignment.
  4. Install the remaining top bushing and tighten the entire second mat bushing with an impact wrench. Revert to the first top joining bushings and tighten them with the impact wrench. All joining bushings should be tightened and the joined mats are now ready to be towed over the repaired crater.
  5. Before any towing operation can commence, the area between the mat assembly area and the repaired crater must be completely swept. Any debris that is picked up under the mat as it is being towed could damage the matting and affect the smoothness of the repair.
  6. With the mat in position over the crater, it must be anchored in place. Techniques for anchoring the FFM will depend on the type of pavement surface. The FFMs are predrilled for anchoring bolts. All three anchoring techniques use a 101.6-millimeter (4-inch) bushing through which the bolt passes to hold down the mat.
    Concrete Pavements.The concrete anchor is normally a rock bolt that is 127 to 152.4 millimeters long and 15.9 to 19.1 millimeters in diameter (5 to 6 inches long and 0.625 to 0.75 inch in diameter). At each predrilled hole in the leading and trailing edges of the mat, drill a hole into the pavement corresponding to the diameter of the bolt being used. Position an anchor bushing in the predrilled hole as a guide for centering the drill bit. The depth of the hole must be at least 12 millimeters (0.5 inch) longer than the length of the bolt. Clean out the drill cutting with compressed air and insert the bolt through the bushing. Stand on the mat and bushings and tighten the bolt with an impact wrench.
    Asphalt-overlaid Concrete Pavements. Asphalt-overlaid concrete usually entails using a rock bolt that is 241.3 millimeters long and 15.9 to 19.1 millimeters in diameter (9.5 inches long and 0.625 to 0.75 inch in diameter). The installation procedure is the same as those for all-concrete pavements. The key factor in this installation is to ensure the bolt has been set deep enough into the concrete layer for a firm grip.
    Asphalt Pavements. Anchoring in asphalt pavement requires a 241.3- millimeter (9.5-inch) bolt and polymer. A hole 254 millimeters deep and 38 millimeters in diameter (10 inches deep and 1.5 inches in diameter) is drilled at the center of each predrilled mat hole. A two-part resin polymer is mixed and poured into each hole to about 38 millimeters (0.5 inch) below the surface of the pavement. An anchor bushing and bolt are immediately placed into each hole and pressed firmly (standing on the bolt and bushing) against the mat. The polymer will harden in about three minutes. Unless extra people are available, there may not be time to drill all the holes before beginning to pour the polymer. Drilling and setting the bolts are usually accomplished concurrently.
  7. Surface Roughness. The final grade of the repair must be checked using line-of-sight profile measurement stanchions, upheaval posts, or string lines to ensure the repair meets surface roughness criteria contained in T.O. 35E2-4-1. Procedures are described in T.O. 35E2-5-1, Crushed-Stone Crater Repair and Line-Of-Sight Profile Measurement for Rapid Runway Repair. FOD covers should be no more than 5 degrees off parallel with the runway centerline.
  8. Check connection bolts and verify that all connections between panels are tight and secure. Check anchor bolts and verify that all bolts are secure and that the FOD cover is held snugly against the pavement surface. In taxiway and apron applications, the leading and trailing edges of the FOD cover must be anchored. The side edges must also be anchored if the cover is located in an area where aircraft will be required to turn.
  9. Clean-up. For all repair methods, verify that the repair and adjacent area is cleared of any excess repair materials.

Fig. 1 Crater Fill


Fig. 2 FFM Kits in WRM storage


Installation time

The time associated with ADR procedures is dependent on the Rapid Runway Repair (RRR) team members. For a smooth operation the RRR team must thoroughly know the procedure and sequencing of RRR activities. The "knowns" must be mastered if the "unknowns" of wartime equipment losses and personnel attrition are to be faced with any degree of success. However, based on timeline studies published in Air Force Manual 10-219 a typical dual crater repair can be accomplished in approximately 4 hours.

Fig. 3


Fig. 4 Air Force Engineers preparing FFM's


Inclement weather effects

As with any outdoor activity ADR procedures are affected by inclement weather. The FFM product however is manufactured from Fiberglass materials and is not subject to premature deterioration by rain or other weather conditions.

FFM Manufacturing Specifications

In Novemeber of 2007 the Air Force published a new revised specification for the FFM. ReadyMat US LLC works closely with the U.S. Air Force to stay current with ADR specifications and procedures. See the table below for physical properties of the current Air Force FFM.




Procurement History

The United States is known for it's vast developments in Military operations. One such operation of military support is ADR. The current Air Force method for RRR is the FFM. In the mid 1990's the Air Force began procuring and training with this system and has many hundreds of FFM's in the WRM ready for use. In addition the U.S. Air Force conducts ongoing training at various air bases around the world to remain ready in the event of a crisis. Many other countries have either adopted or are considering this same FFM RRR system as their primary ADR method. These countries include but are not limited to the following:

  • U.S.A.
  • Taiwan
  • South Korea (currently purchasing FFM's on a 7 year program)
  • France
  • Israel
  • Egypt (purchased FFM's in 2006)
  • Turkey
  • Kuwait
  • Saudi Arabia
  • Poland

Approved Aircraft

The FFM Airfield Damage Repair (ADR) described above using the FFM fod cover is currently certified for use by the U.S. Air Force for use with but not limited to the following aircraft:
F-4, F-5, F-8, F-14, F-15, F-16, F-17, F-18, F-22, A-10, and C-130.

In summation the Air Force certifies the current FFM ADR procedure suitable for all fighter jet aircraft and cargo aircraft up to the C-130.


Folded Fiberglass Mat Specifications
A standard FFM weighs approximately 3,000 pounds and consists of nine (9) fiberglass panels. Each panel is 6 feet wide, 30 feet long, and approximately 3/8 of an inch thick.
Rapid Runway Repair System
Rapid Runway Repair System ~ Hinged Folded Fiberglass Mats (FFMs) were designed specifically to effect repair on runways damaged as a result of aerial attack.
Runway Edge Marketing System
Rapid Mat produces a Minimum Operating Strip (MOS) Runway Edge Marking System which includes: Edge Markers and Distance-To-Go Markers. This MOS Marketing System allows for.
Portable Helicopter Landing Pad System
Option1: Includes 2 each Operational Folded Fiberglas Mats (FFMs). Each FFM consists of 9 (6'x30') panels (1/4 inch thick) linked by elastomer hinges and weighs about 3,200 pounds.