Modeling of carbonation, de-carbonation and re-carbonation processes of structural concrete subjected to high temperature

Abstract

This paper proposes a multi-chemo-physics model to incorporate carbonation, de-carbonation and re-carbonation processes under high temperature. Experimental validation of the proposed integrated model is conducted by using the thermo-gravimetry experiments of cement paste and the strength of mortar composites immediately after high-temperature heating and after post-fire-curing. The CO2 concentration and the humidity are experimentally changed as the thermodynamic boundary conditions for wide-range verification and validation. The compressive strength is treated not as the material property but the computed structural capacity of a cylindrical solid in which the temperature, hydration degree and carbonation develop non-uniformly. The proposed model allows practically reasonable assessment of fire-damaged and moist-cured concrete as a multi-scale composite.