Novel Core-Shell System Based on Gelatin and Hydrophilic Polymers Useful as Concrete Self-healing Systems

Concrete structures repair results in substantial economic and environmental issues. So, new technologies able to increase concrete lifetime are being developed. Among them, the self-healing mechanisms, which can be improved by using polymers. Thus, three different materials are synthesized to act as self-healing systems. They are: (I) cross-linked gelatin mixed with CaCO3 (the self-healing agent); (II) a core-shell system based on the material I layered by poly(hydroxypropyl methacrylate); and (III) a second core-shell structure based on the material I covered with poly(vinyl alcohol). Cross-linking and grafting are performed using glutaraldehyde. Fourier-transform infrared spectroscopy (FTIR) proves the structure obtaining. Thermogravimetric analysis and differential scanning calorimetry prove that the materials show thermal properties that allow their use in concrete applications. Swelling degree shows that all materials swell when in contact with water. Granulometry shows the materials are mostly in the millimeter scale. Last, an aqueous media release test shows that the three tested systems did not liberate significant amounts of CaCO3. Therefore, both the gelatin and gelatin + polymer systems can protect the healing material, avoiding the release of the self-healing agent before the concrete cracking takes place.

Automated summary

By utilizing polymers to enhance self-healing mechanisms, three different materials have been synthesized to act as self-healing systems.