Self-healing cementitious materials containing encapsulated epoxy-montmorillonite-calcium nitrate: evaluating crack-healing performance, mechanical and thermal properties

Propagating micro-cracks in a structure decrease its load bearing capacity and would lead to collapse the entire structure. By the aim of enhancing the microencapsulated self-healing cementitious materials performance, montmorillonite (MMT) is used as a component of ternary healing agent. Microcapsules were synthesized by in-situ polymerization of urea-formaldehyde as shell around the core materials inclusive epoxy resin, calcium nitrate and montmorillonite. Physicochemical characterization of microcapsules was conducted by Fourier transformation infrared spectroscopy, field emission scanning electron microscopy, particles size analyzer, atomic force microscopy, and thermal gravimetric analysis. The mechanical assessment of cementitious specimens with different dosages of microcapsules (0%, 1%, 3%, and 6%) was performed by three-point bending, and compressive tests. The addition of MMT (0.5 wt.% by epoxy) led to enhance thermal stability up to 472 degrees C, and showed a significant performance at flexural and compressive recovery rates up to 170.21%, and 152.02%, respectively.