Atmospheric corrosion of low carbon steel in a coastal zone of Ecuador: anomalous behavior of chloride deposition versus distance from the sea

Significance 

Atmospheric corrosion, especially in the coastal regions, has been a great problem in various structural components. In particular, low carbon steels are more susceptible to atmospheric corrosion due to favorable coastal climatic conditions. Generally, low carbon steels exhibit excellent mechanical strength making them preferable for use as reinforcement steel in concrete structures. As such, their atmospheric corrosion performance is a great concern amongst researchers. Despite several studies conducted in different climatic conditions, atmospheric corrosion of low carbon steels in coastal regions have not been fully explored. This should, however, take into consideration the influence of climatic factors on the corrosive behavior such as the relationship between the chloride deposition rate and the marine aerosol penetration.

Recently, different researchers have investigated the atmospheric corrosion of low carbon steels in different regions including Colombia, Ecuador, Chile, and Pakistan. Even though some good results have been obtained, various drawbacks have impeded the formulation of more accurate results. For instance, in different scenarios, accurate models for analyzing the influence of various factors such as the distance from the sea on the corrosion rate and chloride deposition rate have remained a challenge. Alternatively, in regions such as the Manabí province in Ecuador that has high construction potential, the existing structure has been built without taking into account the atmospheric corrosion protection knowledge, that is a key tool in deciding the corrosion protection criteria. This has led to less durable and low-quality structures. Prediction of corrosivity categories has been recently identified as an important aspect of studies involving the atmospheric corrosion of low carbon steels in coastal regions. From research and technical point of view, it has the potential of addressing the aforementioned drawbacks.

An international collaborative research among Professor Juan Carlos Guerra Mera (from the Technical University of Manabí), Professor Abel Castañeda Valdés (National Center for Scientific Research, Cuba), Professor Francisco Corvo (University of Campeche in Mexico) and Professor Juan José Howland (Technical University of Havana), and Dr. Joelis Rodríguez Hernández (Center of Research in Applied Chemistry in Mexico) investigated the atmospheric corrosion of low carbon steel exposed in coastal atmospheric condition. Specifically, the experiment was conducted in the coastal regions of Manabí province in Ecuador. The work is currently published in the journal, Materials and Corrosion.

Low carbon steels specimens were exposed at six different outdoor sites located at different distances from the sea. Corrosion by weight loss was evaluated for one year to classify the corrosion categories of the atmosphere concerning the low carbon steels. Based on the monthly chloride deposition rate, the environmental factors influencing the marine aerosol penetration and atmospheric corrosion rate were determined. Additionally, the authors also evaluated the monthly and annual changes in the corrosion rate and chloride deposition rate at different distances from the sea.

The research team noted that the deposition of the marine aerosol was anomalous with respect to the distance from the sea owing to the presence of estuary in the Manabí coastal region. Additionally, high chloride deposition rate, wind speed, temperature, and the coastal atmosphere were identified as the main factors influencing the marine aerosol penetration. For example, an increase in the wind speed and temperature highly influenced chloride deposition rate in the regions under shield conditions while a decrease in the RH-temperature complex exhibited significant influence in the zones without the shielded conditions. Therefore, both wet and dry periods showed almost equivalent corrosivity rate. In general, atmosphere high (C4) was identified as the predominant corrosivity category for approximately 20 years to come. The study will, therefore, provide the required knowledge such as corrosion protection measures required to build high-performance structures.

About the author

Juan Carlos Guerra Mera. Civil Engineer. Professor in Materials Resistance, Structures and Building Materials at the Faculty of Physical and Chemical Mathematical Sciences, Technical University of Manabí, Ecuador.

Director of the Hydraulic Engineering Degree in Pontificial Catholic University of Ecuador, headquarters Manabí, (until 2012). Master of Science and working toward PhD in Technological University of Havana, Cuba. In the last years has performed investigations concerning atmospheric corrosion and deterioration of structures. President of the College of Civil Engineers of Manabí. He has published several papers in national and international journals. He has presented several works in national events.

About the author

Abel Castañeda Valdés. Chemical Engineer, Tecnological University Havana (2007). Head of the Materials Protection Group, Research, Development and Innovation Department of the National Center for Scientific Research, Havana, Cuba. Senior Researcher and Assistant Professor, Master in Materials Science and Technology (2007). PhD in Technical Sciences (2013). Since 2002 has worked in the fields of atmospheric corrosion, deterioration of structures and application of electrochemical techniques in corrosion. Published around 45 articles, 20 of them in journals of high impact factor and the rest in journals of high international prestige. He has presented around 20 works in international events. Among his distinctions and awards the following stand out: Special Distinction of the Minister of Higher Education (2008). Two Annual Awards of the Academy of Sciences of Cuba (2009 and 2014). Relevant Awards in the Havana Forum of Science and Technology in 2014, 2015, 2018 and 2019. National Award for Technological Innovation in 2018.

About the author

Francisco Corvo. Chemist, PhD in Technical Sciences, National Center for Scientific Research, Havana, Cuba (1981). Head of Corrosion Department (2000-2005), National Center for Scientific Research, Havana, Cuba. Senior Researcher Institute of Materials, University of Havana (2005-2009), Professor at Centro de Investigación en Corrosión (CICORR), Campeche Autonomous University, México (2009 to present).

Project leader and participant in Cuban, Mexican and International projects, Director of several PhD and MSc Thesis. Author of articles in Corrosion specialized journal such as Corrosion Science, Materials and Corrosion, Corrosion (NACE) and others.

About the author

Juan José Howland Albear. Civil Engineer. PhD in Technical Sciences. Associate Professor and Principal Researches in Tropical Construction and Architectural Study Center, Technological University of Havana, Cuba. He has developed several research projects in the field of concrete and mortar. Author of several books and more than 40 papers published in national and international journals. He has several awards for his research work, including: the Relevant Award with Special Distinction at the XIII National Forum of Science and Technology (2001). Nationals Cuban Awards for Technological Innovation in 2014 and 2018. Annual Award of the Academy of Sciences of Cuba in 2014. Several awards granted by the Council of State of Cuba among them: Order Carlos J. Finlay for his research work (2013). Commemorative plaque for the 495th Anniversary of Havana, in 2015.

About the author

Joelis Rodríguez Hernández received the Ph.D degree in Physical Science from Universidad de la Habana, Cuba (2007). Since 1998 is working as a researcher in the area of Materials Science, gaining experience in structural characterization and in the relationship of crystalline structure and physical properties of materials. He have gained experience in the use of the X-ray Diffraction technique in powders; especially in the development of new methods and procedures for resolution and structural refinement by the Rietveld method from powder diffraction data.

Researcher at Centro de Investigación en Química Aplicada (CIQA), CONACYT, Saltillo, Coahuila, México.

Reference

Guerra, J., Castañeda, A., Corvo, F., Howland, J., & Rodríguez, J. (2018). Atmospheric corrosion of low carbon steel in a coastal zone of Ecuador: Anomalous behavior of chloride deposition versus distance from the sea. Materials and Corrosion, 70(3), 444-460.

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