Damage of Concrete Parking Aprons from Auxiliary Power Unit (APU) Exhaust and Spilled Jet Oils.

摘要

The precise cause for concrete damage observed in the vicinity of parked B-1 and F/A-18 aircraft has been determined. The combination of downward-directed auxiliary power unit (APU) blast and spilled aircraft oils are responsible for the scaling observed at these sites. Laboratory tests confirmed that ester-based lubricating oils and hydraulic fluids are chemically reacting with the calcium hydroxide in the concrete and destroying the mortar-aggregate bonds. The cyclic heating of the pavement by the APU greatly accelerates the reaction and facilitates the mixing and refluxing of aircraft fluids with the aqueous calcium hydroxide present. A variety of sophisticated tests were conducted to verify these findings, including X-ray diffraction and mass spectroscopy. In addition, the damage observed at military installations was duplicated under controlled laboratory conditions. After five weeks of subjecting a test slab to cyclic heat and jet oils, damage similar to that observed in the field was produced.