Accelareted Carbonation in Unsaturated Fractured Cement

Carbonation is the process during which dissolved inorganic carbon reacts with cement phases to form calcium carbonates. The consequences of carbonation are chemical (pH decrease), physical (porosity change) and mechanical (alteration of mechanical properties and induction of internal stresses). The most common consequence of carbonation related to concrete structures is the carbonation-induced corrosion of reinforcement bars. Recent literature indicates that carbonation progresses faster in the presence of microcracks which form continuous pathways to the available carbon. The carbonation rate may depend on the crack geometrical properties which determine, among others, water content and diffusivity of the gas phase. The outcome of this study will help to understand the mechanisms of carbonation in the presence of micro/macro cracks, the influence of crack properties and the relation between material properties and service life.

The objective of the project is to determine the effect of microcracks on the carbonation rate, with a focus on the interplay between the evolution of the crack properties and the microstructure of the surrounding concrete matrix during carbonation. Most of previous studies in the literature are limited to, from an experimental point of view, determination of carbonation fronts and rates using simple indicators (phenolphtaleine), or, from a modeling point of view, to a continuum scale or simple representation of cracks. The proposed study takes a step further towards a mechanistic understanding of the processes as a basis for physically-based simulations.