Hydrothermal Synthesis of CaAl-LDH Intercalating with Eugenol and Its Corrosion Protection Performances for Reinforcing Bar
Ang Liu, Haohua Gu, Yongjuan Geng, Pan Wang, Song Gao, Shaochun Li
Abstract
Layered double hydroxides (LDHs) intercalating with a corrosion inhibitor for slowing down the corrosion of a reinforcing bar has attracted considerable attention. However, achieving high-loading capacity of organic inhibitor in LDH with high efficiency and long-term protection characteristics remains an important challenge. In this work, the CaAl-LDH intercalating with eugenol (EG) was synthesized via a continuous hydrothermal method. The prepared LDHs were characterized by SEM, XRD, UV-vis absorption spectra and TGA. Additionally, the corrosion protection performances of LDH-EG for steel bar were studied in detail via the electrochemical method. The results show that the loading amount of EG in LDHs was about 30% and about 80% EG could be released from LDH-EG within 4 h in SCPs containing 3.5% NaCl. The electrochemical test results show that the Rct value (105~106 Ω · cm2) of steel-mortar incorporated with LDH-EG has increased by 3–4 orders of magnitude compared to the specimen without LDHs (102~103 Ω · cm2) after 16 dry–wet cycles corrosion test. The significantly improved protection capability is mainly derived from two aspects: one is the filling effect of LDH, which can fill the pores of mortar and improve the impermeability; another reason is that the intercalated EG can slowly diffuse out of the inner structure of LDHs in a controllable way and result in a relatively long-term effect of corrosion inhibition.