Abstract
Despite the promising inherent properties of reinforced cementitious structures, there is still no viable solution for mechanical and corrosion issues other than a complete replacement, and the maintenance techniques are almost impractical. Here, a self-healing method is introduced based on restorative microcapsules having a phosphate-based corrosion inhibitor that operate on both matrix-porosity and metal-passivity to achieve sustainable protection. Microcapsules are synthesized through an interfacial polymerization technique and characterized by FE-SEM, FT-IR, NMR, and LPSA. The matrix was embedded with different contents of microcapsules, artificially damaged by a certain mechanical load, and healed for a specific period. EIS analysis showed more than 70 % anti-corrosion efficiency for every specimen, 78 % for 7C by reaching 67180 Ω.cm2, which is the result of the formation of FePO4/Fe3(PO4)2 precipitates that act as a barrier on the rebar. In addition, expanding Ca5(PO4)3OH products reduced the porosity of the composite by growing into the cracks and blocking the voids. As a result of the more compact structure, mechanical strength recovered to 30.5 MPa, almost 76 % of the initial amount, by the end of the healing period. Chloride Permeability of the samples with microcapsule improved by nearly 50 % compared to the blank ones. EDS confirmed the presence of the pore-blocking product among the cracks. Finally, the matrix porosity and PBP distribution were investigated by the μ-CT. PBP volume fraction of cracked sample was multiplied by almost 5, which confirms the successful release of healing agent. As a result, pore-blocking index improved by 30 % in the presence of microcapsules.
Published Version
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