Evaluation the mechanical and electrochemical anti-corrosion properties of polydimethylsiloxane/SiO2 gel coated carbon steel rebar in concrete pore solution

The aim of the current study was to evaluate the mechanical and electrochemical anti-corrosion properties of carbon steel rebar in concrete pore solution after the steel was coated with polydimethylsiloxane/SiO2 (PDMS/SiO2) hybrid material as an organic–inorganic hybrid coating. PDMS/SiO2 hybrid material was prepared using a base-catalyzed sol-gel process with different SiO2 contents (0 wt%, 5 wt%, 10 wt%, 15 wt% and 20 wt%). Mechanical studies showed that the synergetic effect of PDMS and SiO2 increased the values of yield stress and Young's modulus and decreased the elongation at break. Electrochemical studies using EIS and polarization tests showed that the coated steel rebar samples had higher corrosion resistance than the uncoated steel sample, illustrating that the PDMS/SiO2 coating exhibits great barrier properties in corrosion reactions and indicates more corrosion resistance in the CPS corrosive media, and increasing the SiO2 content in the hybrid coating from 5 to 15 wt% promotes corrosion inhibition effectiveness. The steel rebar sample coated with the PDMS/SiO2 hybrid sample with 15 wt% SiO2 content as the optimal amount of SiO2 showed the highest corrosion resistance and inhibition efficiency (95.81%) values. SEM micrographs of the surface morphology of uncoated and PDMS/15SiO2 coated steel rebar surface samples immersed in CCP solutions for 24 h revealed that the PDMS/15SiO2 coating effectively inhibits steel corrosion in CCP solution due to less corrosive ion penetration to the steel surface.