Modified self-healing cementitious materials based on epoxy and calcium nitrate microencapsulation

Abstract

Aim This study was conducted to utilise 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 characterised by Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetric, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cementitious samples were prepared by mortar mixing with various amounts of microcapsules (0, 1, 3 and 6% w/w). The healing potential of microcapsules was analysed 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 microcracks sealing to improve durability of cementitious materials.