Abstract
A conceptual phase-field model is proposed for simulating complex microstructural evolutions during the self-healing process of cementitious materials. This model specifically considers carbonation healing mechanisms activated by means of dissolution of soluble {hbox {Ca(OH)}_{2}} mineral and precipitation of the {hbox {CaCO}_{3}} self-healing product. The system is described by a set of conservative and non-conservative field variables based on a thermodynamic analysis of the precipitation process and realised numerically using the finite element method (FEM). As a novel concept for modeling self-healing of cementitious materials, the evolution of multiple interfaces was investigated and demonstrated on a simple experimental test case of a self-healing mechanism consisting of carbonating calcium hydroxide. Parametric studies were performed to numerically investigate the effect of chemo-physical conditions. Two representative practical examples of cementitious materials were numerically implemented. It is demonstrated that the simulated evolution of the crack morphology is in good qualitative agreement with the experimental data.
Highlights
The problem of cracks in cementitious materials is a widespread and thorough engineering problem [1]
By day 14 it can be seen that the carbonate ions diffuse through the porous CaCO3 layer generated at the crack surface into the Ca(OH)2 matrix and undergo precipitation reactions, which allows the interface IsÀp to continue to move deeper into the matrix
We analysed the different depths of the cracks in combination with stereo microscopy and found that in the 21-day sample, the deeper areas of the cracks were completely filled with calcium carbonate
Summary
The problem of cracks in cementitious materials is a widespread and thorough engineering problem [1]. The presence of cracks affects the permeability of building structures and reduces their freeze–thaw resistance, and many enhance the chloride attack of concrete [3,4,5,6]. A variety of self-healing mechanisms have been developed for cementitious materials [7,8,9,10,11], which has led to concrete materials becoming intelligent and capable of detecting the damage and repairing themselves. According to the report RILEM TC-221-SHC, the self-healing mechanism can be classified into ‘‘autogenic’’ and ‘‘autonomic’’ [12]. The autogenous self-healing is mainly based on the original composition of cementitious materials, which consists of three
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