Novel Ca-Sls-Ldh Nanocomposites Obtained Via Lignosulfonate Modification For Corrosion Protection Of Steel Bars In Simulated Concrete Pore Solution

A novel nanocomposite (Ca-SLS-LDH) of Ca-Al-layered double hydroxides (Ca-LDH) modified with sodium lignosulfonate (SLS) was synthesized using hydrothermal synthesis method. Mechanistically, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis revealed that SLS modified the nanocomposite by adsorbing onto the surface of Ca-LDH. The specific surface area of Ca-SLS-LDH was larger and the average particle size was smaller than that of Ca-LDH. This enabled the Ca-SLS-LDH to bind chlorides more effectively and is hence suitable for application in reinforced concrete. Ca-SLS-LDH binds to chlorides through ion exchange and surface adsorption, which is similar to the binding mechanism of Ca-LDH to chlorides. Ca-SLS-LDH efficiently controlled the corrosion of carbon steel in simulated concrete pore (SCP) solution and had a stronger inhibitory effect compared to unmodified LDHs at equal concentrations. Ca-SLS-LDH improved the resistance to corrosion by binding more chlorides in SCP solution. In addition, it may be due to the anticorrosion effect of SLS on steel bars, thereby delaying the initiation of corrosion.