Self-healing efficiency of unhydrated cement nuclei for dome-like crack mode in cementitious materials

Nuclei of cement particles left unhydrated in cementitious materials after maturation can provide self-healing capability to micro-cracked matrix under favorable conditions. In this present study under the assumption that self-healing is attributed to the rehydration of the unhydrated cement nuclei in cementitious materials, a model study is conducted to characterize the self-healing efficiency of the hydration reaction of unhydrated cement nuclei on crack. Based on a tortuous crack path around unhydrated cement nuclei in practical cementitious materials, a dome-like crack mode is presented to investigate the self-healing efficiency on cracks. Recurring to a generalized hydration reaction model of cement particles, the analytical self-healing efficiency model quantitatively considers the influence of the volume fraction and particle size distribution of unhydrated cement nuclei randomly distributed in cementitious materials based on the proposed dome-like crack mode. Meanwhile, the healing process of unhydrated cement nuclei in model cementitious materials is simulated and the reliability of these analytical models is verified via computer simulation. Furthermore, model applications suggest that volume fraction of unhydrated cement nuclei in matrix is a key factor and the particle size distribution is also very important for self-healing efficiency in the long time.