Abstract: Aiming at the engineering problem of concrete easy to crack, difficult to repair, and fast corrosion of reinforcement after cracking, microcapsules with tung oil (TO) as the core material, sodium alginate (SA) and nitrite-modified magnesium-aluminum hydrotalcites (NO^-₂-LDHs) as the wall material were prepared in this paper by using the sharp-pore solid-bath method. Three factors, namely, different TO and SA mass ratios, SA concentration, and emulsifier concentration were optimized by response surface analysis using the encapsulation rate as the response index. The polarization curves of the reinforcement were tested and the strength recovery rates of mortar specimens with microcapsules dosed at 0% and 1% (mass fraction) were compared under dry and wet cured conditions. The results show that the maximum encapsulation rate of microcapsules on TO is 74.03% when the mass ratio of TO and SA is 9:1, the concentration of SA is 1.69% (mass fraction), and the concentration of sodium dodecyl benzene sulfonate (SDBS) is 0.95% (mass fraction). The prepared microcapsules have a certain degree of corrosion inhibition effectiveness, and the efficiency of corrosion inhibition at 6% dosing of solution mass is 93.35%. The results of self-repair experiments show that microcapsules can significantly improve the compressive strength recovery rate of mortar specimens, and the 28 d recovery rate of dry cured specimens (80%) is higher than that of wet cured specimens (76%).

Key words: microcapsule, corrosion inhibitor, hydrotalcite, tung oil, cement-based material, self-healing