Revealing anti-corrosion behavior of Mg alloy concrete formwork coated with release agents in Cl−-containing Portland cement paste.

• Three kinds of release agents were attempted on the surface of AZ41 Mg alloy. • Corrosion resistance of AZ41 Mg alloy embedded in Portland cement paste was studied. • Oil-based release agent coated Mg alloy presents the best corrosion resistance. Anticorrosion performance of AZ41 Mg alloy coated with three different kinds of release agents was investigated embedded in Portland cement (PC) paste containing 0.6 M NaCl. Surface characterizations were employed to obtain the surface information after coated with release agents before and after embedment. Meanwhile, electrochemical methods were adopted to assess the corrosion resistance embedded in PC paste. Results demonstrated that water-based release agent led to the corrosion of Mg alloy while the oil-based release agent not only protected the Mg alloy but also exhibited the best demolding effect. Oxide films can be generated on the surface of Mg alloy after coated with release agents. The thin film after applying the water-based release agent was magnesium/aluminium oxide and hydroxide with some talcum (3MgO·4SiO 2 ·H 2 O) particles. Additionally, thin films on the surface of Mg alloy after coated with emulsified and oil-based release agents were magnesium/aluminium oxide and hydroxide. [ABSTRACT FROM AUTHOR]