Modeling of the induced chemo-mechanical stress through porous cement mortar subjected to CO2: Enhanced micro-dilatation theory and 14C-PMMA method

In the present paper, we focus on the modeling of the CO2 carbonation phenomenon through the cement mortars. The CO2 carbonation will modify not only the pH value of the cement mortars but also the mortar specimen size, i.e. mortar shrinkage. The aforementioned issue is driven via the chemical reactions and it affects the micro-structure and particularly the porosity. Based upon the micro-dilatation theory which was originally proposed by Cowin and Nunziato [1,2], one of the four material moduli dealing with the micro-structure especially, β–ξ relation, has been determined for the first time. To pursue this goal, the carbonation experiments on the cement mortar (CEMI) have been achieved to determine CO2 affected zones by the carbonation process and to measure the corresponding deformations caused by the shrinkage phenomenon. According to our proposed semi-empirical method, it is possible to compute the induced chemical stress as well as the porosity gradient through the mortar. The numerically-obtained porosity distribution across the cement mortar has been afterwards compared to the outcomes coming from the 3D-connected porosity profile which is extracted by means of 14C-PMMA experiments. The latter experiments allow us not only to evaluate the computations for the porosity, porosity gradient and the induced stress but also to determine the micro-dilatation material moduli (coupling number, N = −0.316), in conjunction with the pore stiffness or the so-called void stiffness of the cement mortars.