Numerical simulation of the evolution of carbonation process in aerial lime mortar

Abstract

Aerial lime is one of the oldest binders discovered and used in mortars. In different regions of the world, there is a substantial number of historic masonry constructions comprising binders based on aerial lime. The carbonation process has essential relevance on the behaviour of this material. In this sense, an experimental program done by the research group is adopted to support the numerical simulation of the evolution of carbonation phenomenon. Initially, a strategy modelling presented in literature is adopted. In sequence, an iterative process is done to achieve the set of parameters to fit the experimental data using the results from cylinders tested at three different depths with thermogravimetric analysis at four different ages. With a new set of parameters and functions, the numerical model could reproduce reasonably the data from the thermogravimetric analysis. Then, the modelling strategy with the fitted parameters is used to study the evolution of the carbonation in five series of specimens with different sizes, tested with phenolphthalein indicator. Various values of equivalent reaction degree (R∼20% to R∼60%), in terms of numerical results, were obtained for the phenolphthalein test.