![Figure 1: Relationship between specific permeability coefficient and specific diffusion coefficient for concrete [2]](https://images.tandf.co.uk/common/jackets/crclarge/978042917/9780429176654.jpg "Figure 1: Relationship between specific permeability coefficient and specific diffusion coefficient for concrete [2]")
ABSTRACT
The law of frequently used in literature to describe the advance of the carbonation is not sufficient for quantitative assessment of the carbonation process. The increase of the diffusion resistance from the concrete exterior and a diffusion of Ca/OH/2 from the non carbonated interior towards the carbonated marginal zone of the concrete lead to a permanetly increasing deviation from the law of as the duration of carbonation increases. Using these two variables a law of carbonation was derived by Schiessl [3] which describes very well the actual advance of the carbonation:
/3/
/4/
where x=actual depth of carbonation /m/ x∞=final depth of carbonation /m/ D=diffusion coefficient /m2. s−1/ C1=concentration of CO2 in the atmosphere /g.m−3/ C2=concentration of CO2 in concrete at the carbonation front /g.m−3/ a=quantity of CO2 require d for the carbonation of 1 m3 of concrete /g.m−3/ b=retardation factor /g.m−2.s−1/; b=1,2 . 106 g.m−2 .s−1 t=carbonation time /years/.
