MOISTURE-INDUCED PRESSURES IN CONCRETE AIRFIELD PAVEMENTS

The author develops a mathematical model to estimate pressures generated by water and air in the pores of airfield concrete being heated by jet exhaust. The basis of the model is a constitutive relationship to characterize the flow of high-velocity, compressible, heated gases through a high-resistance porous medium. The key premise is that the resistance to flow can be modeled with friction coefficients analogous to the technique employed for simpler geometries. Pore pressure predicted using the model indicates that moisture in the pores of the cement paste is a likely cause of material failure when the pavement is being heated by aircraft exhaust. With an initial pore saturation of 90 percent or greater, high pore pressures and pressure gradients result from air being compressed by the expansion of liquid water. Concrete temperatures can reach 300 deg C in approximately 2 minutes. And even with a low saturation, the water vapor pressure could be sufficient to cause a tensile failure in portland cement concrete.

Language

  • English

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Filing Info

  • Accession Number: 00719278
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 16 1996 12:00AM