Abstract
In this study the effect of thermomechanical treatments in chloride induced pitting corrosion is presented for carbon steel rebars exposed to synthetic fly ash (FA) pore solution. Due to the likely phase transformations that steel reinforcements in concrete experience during the event of a fire, the understanding of the corrosion behavior of such phases is key in predicting the stability of the structure. The motivation for this study arrives from the scarce literature regarding the corrosion behavior of thermomechanically treated steel reinforcements in FA environments and the need for further investigation to understand its mechanism. In order to better understand the effects on the corrosion behavior electrochemical measurements including cyclic potentiodynamic polarization curves (CPP) and electrochemical impedance spectroscopy (EIS) were used. It was found that quenched specimens showed enhanced corrosion kinetics as their icorr values were higher, being of 3.18 × 10−5 and 2.20 × 10−5 A/cm2 for water and oil quenched compared to 2.13 × 10−6 A/cm2 for the as-received. Furthermore, the effective capacitance of the double layer (Ceff,dl) showed the lower stability of the passive film for the quenched specimens, with values of 1.11 × 10−3 µF/cm2 for the as-receive sample that decreased to 8.12 × 10−4 µF/cm2 for the water quenched sample. The anodic charge transfer coefficient in the synthetic FA alkaline pore solution changes from 0.282 to 0.088, for the as-received and water quenched rebars specimens, respectively. These results indicate a lower energy barrier for the anodic dissolution reaction of quenched specimens, indicating that martensite and bainite microstructures promote corrosion process. Enhanced corrosion was found on quenched samples presenting martensite and bainite microstructure as showed by the increased pith depth, with values of 5 μm compared to 1 μm observed in the as-received samples.
Highlights
Due to the high greenhouse gas emissions of the construction industry, which account for 10% of the total CO2 emissions, new green cement alternatives are necessary [1,2]
It can be seen that the microstructure in the center of the rebar is similar to the as-received sample, showing more uniform and refined ferrite grains
Martensite was observed on the as-received sample near the edge of the rebar, whereas pearlite and cementite were found on the annealed sample with larger grain size
Summary
Due to the high greenhouse gas emissions of the construction industry, which account for 10% of the total CO2 emissions, new green cement alternatives are necessary [1,2]. Novel ternary ecological concrete mixtures made out of sugar cane bagasse ash and silica fume partially replacing OPC have proven to impart corrosion protection, offering an effective alternative for building a more sustainable concrete industry [13]. These new binders present a different microstructure that influences porosity and tortuosity, and the ingress and diffusion of corrosive species, in addition the precursor chemistry and the activation process modify the nature of the interfaces as well as the alkaline reservoir, which regulate the corrosion behavior [14]. Further research is needed for disentangling the electrochemical mechanisms that govern corrosion of steel in eco-friendly cements and fly ash geopolymer concrete
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
