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Capping Material for Compacted Runway Crater Repairs

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Develop a nontoxic technology that supports aircraft operations within an hour of application over a spall or compacted runway repair, completely suppresses escape of debris from the repair, and survives 2,000 landing-and-takeoff cycles over 30 days. 

DESCRIPTION: Capacity for prompt recovery of flight operations is an imperative for all installations that include an operating runway. Workable methods of restoring substructure in craters by compacting fill and aggregate materials or flowable fill are in place and initial clearance of spalled surface debris is a straightforward exercise, but an urgent need remains for a rapid-setting capping material that will contain potential debris from the compacted substructure, flowable fill, or surface remaining after clearance of the spalled fragments, and be able to support 2,000 landing-and-takeoff cycles and a month of flight operations by any combination of fighter or heavy-lift aircraft. Greatest lateral loads will be encountered in regions that experience touchdowns, mechanical braking, and slow turns. Environmental constraints imposed on the cap are extreme, to accommodate possible actual conditions—full exposure to sun, precipitation in all forms, freeze–thaw cycles—and operations will impose severe stresses—350-psi rolling loads, large horizontal vectors associated with touchdowns and braking of heavy-lift aircraft, and spills of hydrocarbon and hydraulic fluids. The coefficient of friction is to be ~0.5, compression under load may not exceed 0.5 in, storage lifetime at 140 °F must be 10 y or more. Current recovery methods employ direct labor, which imposes a constraint on toxicity of ingredients. A hand-applied material that meets all of the performance criteria, retains workability for 15 minutes after application, can be applied without respiratory PPE more effective than gloves and a particle mask, and remains stable in storage at environmental conditions from -40 to 150 °F is the primary target of this contract. If one or more of the criteria are not so met, the limitation on toxicity can be waived if the functional characteristics of the capping material provide enough improvement over the set times and functional properties of current procedures and materials to justify development of a robotic application system. 

PHASE I: 0.5 h after application to an intact concrete surface at -40, 25 and 140 °F, 1. apply 500 cycles of a 325-psi load rolling at 100 ft/s and 2. measure horizontal force at failure of a lamina between parallel concrete slabs under 350-psi compression. 

PHASE II: Establish conditions and any associated technology for application to runways to restore original contour and attain full operational capability 30 min after compaction/preparation of final repair site. 

PHASE III: Refine as necessary to deliver a packaged product with detailed installation/operators guidance/manual, suitable for implementation in deployed environments and at civilian and commercial airfields. 

REFERENCES: 

1: "Laboratory and Field Evaluation of Rapid Setting Cementitious Materials for Large Crater Repair," ERDC TR-10-4, US Army Corps of Engineers, Engineer Research and Development Center.

2:  "Airfield Damage Repair (ADR)

3:  Polymer Repair of Airfields Summary of Research," AFRL-RX-TY-TR-2007-4555.

4:  "Large-Crater Repair Exercise at Silver Flag Exercise Site, Tyndall Air Force Base, Florida," ERDC/GSL TR-15-27.

KEYWORDS: Asphalt, Concrete, Crater, FOD, Runway Repair, Spall 

CONTACT(S): 

Dr Alessandra Bianchini 

(850) 283-6251 

alessandra.bianchini@us.af.mil 

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