Thermo-Micromechanical Damage Models of Airfield Concrete Pavement Under High Temperature Loading.
Abstract
Ordinary Portland Cement (OPC) is a widely used construction material. In airbase facilities, it is used to construct the runways and parking aprons. During the takeoff and landing of aircrafts, the high temperature exhaust has splashed to the concrete pavement from the modem vectored thrust engines (VTE) or auxiliary Power Unit (APU). The APU is a low-power has turbine that provides compressed air, from a load driven compressor, for starting the main engines and for operating auxiliary systems during ground maintenance. In particular, the exhaust gas temperature of a VTE could rapidly reach over 700 deg C, and the corresponding exhaust velocities could go beyond 1800 ft/s. The pavement is subjected to extremely rapid transient high temperature loadings as well as thermal cycles of heating and cooling. Figure 1.1 shows a typical damaged area in an F/A-18 parking apron. The origin of the problem is the F/A-18 auxiliary power unit, which is located at the bottom of the fuselage near the tail section. The exhaust gas temperature isotherms on the pavement top are almost circular and show a decrease along the radios. Chemical degradation of concrete due to hydraulic fluid, lubricating oils also contribute to the damage of concrete pavement. The U.S. Department of Defense has seen an increase in airfield concrete apron distress in the form of surface scaling when the aprons are exposed to cyclic heat, spilled lubricants, and/or hydraulic fluid (McVay, Smithson and Manzione, 1993). Chemical analysis of the damaged concrete reveals that the spilled fluid from the engines are undergoing hydrolysis (breakdown) accompanied by the consumption of calcium hydroxide, plus hydrated silicate and aluminate phases.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1998
- Accession Number
- ADA367097
Entities
People
- Hongwei Gong
- J. W. Ju
Organizations
- University of California, Los Angeles