Production of low-chromium steels as reinforcement for cementitious matrices cured by carbonation

• Grant number: 19/19909-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2019
• End date: July 14, 2021
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Guilherme Yuuki Koga
• Grantee: Matheus Henrique Ambrósio Santiago
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Concrete is the most widely used material in the world. The success of concrete lies on its affordability and mechanical performance, especially when reinforced with steel. Once embedded in concrete, mild steel is naturally protected by the formation of a passive film. This is possible thanks to the alkalinity of the interstitial pore solution which results from the hydration of the Portland cement. However, Portland cement manufacturing is responsible for about 5 to 7% of the global anthropogenic CO2 emissions. Different alternative low-carbon cement has been proposed, being those cured by carbonation a promising one. However, any alternative cementitious alternative to Portland cement must be able to passivate inexpensive steel reinforcement. Because the novelty of cement cured with CO2, little is reported about the steel aimed to be used as reinforcement. The aim of this project is to produce and to evaluate the passivation of steel containing small additions of chromium in an electrolyte simulating the interstitial pore solution of cementitious matrices cured by carbonation. Steels containing 2, 4 and 6 wt.% of Cr will be produced from commercial-grade precursors by using an arc-melter furnace. The resulting microstructure will be evaluated by x-ray diffraction and optical microscopy. Non-destructive electrochemical measurements such as open-circuit potential recording and linear polarization resistance will be performed along 48 hours to study the passivation. Potentiodynamic polarization tests will be used as a compliment. At the end of the project, it is expected to identify if low-Cr steels are promising to reinforce innovative low-carbon cementitious matrix cured by carbonation. (AU)