Carbonation depth prediction of fly ash concrete subjected to 2 and 3 dimensional CO2 attack

Based on accelerated carbonation tests, 1D, 2D and 3D carbonation of high performance concrete with different fly ash contents (0%, 20%, 40%, 60%) are studied. The interaction coefficients of 2D and 3D are defined; the time dependence coefficient n of carbon dioxide diffusion and the interaction coefficients K of 2D and 3D carbonation are analyzed. The mathematical model which includes n and K is deduced. The experiments indicate that 2D and 3D carbonation have obvious interaction; interaction coefficients obey the attenuation function through time t. The mathematical model of 2D and 3D carbonation life prediction based on Fick scattering law can be solved by Fourier expansion. The life prediction of concrete of Sutong Bridge beam shows that the 1D, 2D and 3D carbonation prediction life are 1595, 882 and 758 years, respectively, 2D and 3D carbonation life predicted are reduced clearly.