A synergetic self-sealing model for cement-based composite using granular expansive agent and crystalline admixture

• The randomness of expansion self-sealing model ensures the simulated reliability. • The two self-sealing models are all based on the plane hypothesis and k - ε model. • The model result verifies the synergy of expansive agent and crystalline admixture. • Expansive agent and crystalline admixture work at different stage of sealing process. The autogenous self-sealing model has been researched in previous work, which could help to characterize the self-sealing process with crystalline products. The model outcome was presented in the form of leakage water flow, which demonstrates the self-sealing capacity or the recovery of watertightness. While in the research area of cement-based material self-sealing, the expansive agent cannot be neglectable, for example the superabsorbent polymer (SAP). Especially for the building components exposed to free water, an efficient water flow blockage after cracking is crucial to ensure stable service. Hence in this study, the self-sealing process of a granular expansive agent inside the crack of cement-based material was simulated. The model outputs were compared with experimental results to verify the reliability. Additionally, the autogenous self-sealing model was incorporated into this model to simulate the “crystallization-expansion” synergetic self-sealing. The contribution of crystalline product and expanded EA to water flow blockage were compared during the crystallizing process. Overall, this model is of great use to evaluate the role of expansive agent on water flow blockage after the cement-based material cracking in hydraulic engineering or engineering components exposed to water.