Thermo-micromechanical damage modeling for airfield concrete pavement

Airfield concrete pavements are subjected to extremely high temperature loadings. The failure of airfield concrete pavements can be in the form of scaling or explosive spalling damage. This damage occurs in the upper surface and results in debris which can severely damage the aircraft engines.;The objective of this study is to understand the damage mechanism of airfield concrete pavements caused by the high temperature loadings, and to prolong the usable lifetime of the concrete pavements. The pores in concrete are usually partially or fully saturated with water. When the temperature increases, the water will become vapor. This will result in high pore pressure, which makes some contribution to the damage of concrete pavement besides the effects of thermal stresses.;First, a 1-D thermo-micromechanical damage model is proposed. The temperature distribution is solved numerically by utilizing the Duhamel's theorem, or explicit finite difference method. Pore pressure distribution is predicted based on the ASME Steam Tables and the temperature distribution. The stress-strain relationship accounting for void effects is derived. A dynamic crack growth model due to high pore pressure is proposed to predict the delamination of concrete pavement.;Second, an axisymmetric thermo-micromechanical damage model is proposed. The 3-D thermoelastic stress-strain relationship with void effects is derived. Temperature distribution is numerically calculated by the explicit finite difference method. And pore pressure distribution is predicted based on the ASME Steam Tables and temperature distribution. The stress distribution is calculated by finite element method. Further, Newman's crack growth model is applied to estimate delamination time of the concrete pavement.;Finally, coupled governing equations of heat and mass transfer in concrete pavement are derived. Dehydration of water in concrete at high temperature is considered. Explicit finite difference scheme is applied to calculate temperature and pore pressure distributions. Moisture migration is also investigated.