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Keywords
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Microcapsule, Urea-formaldehyde, Epoxy, Calcium nitrate, Self-healing.
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Abstract
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Aim: This study was conducted to utilize the effective self-healing system to regain the mechanical properties of the cementitious materials containing micro-cracks.
Methods: Storing epoxy and calcium nitrate as healing agents was performed by microencapsulation in the urea-formaldehyde shell. The microcapsules were characterized by FTIR, TGA, DSC, FESEM, and EDS. Cementitious samples were prepared by mortar mixing with various amounts of microcapsules (0, 1, 3, and 6% w/w). The healing potential of microcapsules were analyzed based on the recovery rate of the mechanical properties.
Results: The obtained microcapsules have an outer rough surface, suitable diameter (1-100 μm) and shell thickness (0.2-0.6 µm), and remarkable thermal stability (up to 260 °C). Mechanical test results exhibit that created micro-cracks were healed completely and regained the recovery rates over 100%.
Conclusion: The prepared microcapsules besides enhancing thermal stability, demonstrate a high performance in micro-cracks sealing to improve durability of cementitious materials.
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