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 CaCO 3 (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 CaCO 3 . 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.
Insofar the cost of repairing concrete structures reaches the trillions of dollars, new technologies, such as concrete self-healing, are investigated continuously. Consequently, the main objective of this work is on the production of a cheap and easy-to-make material, which can be used in large-scale applications, besides presenting similar results as other ones more complex systems. In brief, a core-shell system is produced and investigated as a self-healing agent. Aiming this, a mix of gelatin and sodium silicate (Na 2 SiO 3 ) is used as the core, while poly(vinyl alcohol) (PVA) is the glutaraldehyde crosslinked shell. The obtained materials are characterized using several techniques, such as Fourier transform infrared spectroscopy (FTIR), as well as, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). FTIR proves the obtaining of the proposed system. In turn, TGA and DSC showed that the material could endure real-life applications. Also, granulometry tests show that the obtained materials are mostly in the micrometric scale. The Na 2 SiO 3 release is especially tested in aqueous media, proving the core-shell system swells, releasing its active agent. Thereby, the obtained results allow concluding that the presented core-shell material is useful to the self-healing applications.
This review intends to show how nanotechnology is currently being applied in concrete. Both organic and inorganic species can be used as nanoagents, producing materials with improved properties, promoting economic and environmental gains by extending the materials' lifetime. Thus, this paper covers nanotechnology applications to improve mechanical, thermal, and corrosive properties of concrete and shows bibliometric results, proving the increase of interest in these fields. Results have shown that organic agents are more commonly used than inorganic ones, and that nanotechnology is applied mainly to improve mechanical and thermal properties.
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