Corrosion Awareness Day

It is a never-ending problem! Corrosion of rebar in concrete is the major cause of infrastructure deterioration worldwide. April 24th is the corrosion awareness day. So, here is an article in contribution to the challenges we have dealing with corroding concrete infrastructure

Get Your First SmartRock Concrete Sensor for FREE

Giatec SR demo kit_
Giatec SR demo kit_

Rebar Corrosion 101

Steel reinforcement is naturally protected against corrosion in the alkaline environment of concrete. In exposure to aggressive conditions the protective passive layer (that is only few nano-meters thick) breaks down and in the presence of oxygen and moisture, rebar corrosion is initiated by the formation of anodic and cathodic areas. The expansive iron oxide that forms in the anodic area eventually results in the cracking and delamination of concrete.

How Critical Is This?

It is estimated that billions of dollars is required annually to address these structural deficiencies. The main challenge however is how to prioritize and schedule the limited repair budget that government owners have.The Federal Highway Administration (FHWA) estimates that an investment of $20.5 billion is required annually to eliminate the US bridge deficient backlog by 2028.

Most of the current condition assessment methods involve visual inspection or sounding methods such as hammering and chain-dragging. These approaches are subjective and only identify the issues after the fact. In other words, they call for immediate actions without providing any insight on the long-term performance of the reinforced concrete structure. Therefore, it is not possible to accurately estimate the remaining service life of non-corroded areas for future planning.

Non-Destructive Testing (NDT) Methods

Various NDT techniques have been utilized to evaluate the state of rebar corrosion in concrete. Among these, the half-cell corrosion potential measurement (as per ASTM C876 standard specification) is most commonly used in detailed condition assessment projects. This test method only offers an indication of the probability of corrosion and does not provide any information on the state of corrosion or rate of corrosion propagation.

There are also polarization techniques that can be used to determine the rate of corrosion. These methods include:

  • Linear Polarization Technique
  • GalvanostaticPulse Technique
  • AC Impedance Analysis (Lab Technique)
  • PotentiostaticPulse Technique

These techniques provide good information in studies in the lab on small-scale specimens. But, the results obtained in the field can vary by as much as a couple order of magnitude. This is mainly due to the assumptions on the polarization area that are simply not applicable in the field on a large-scale measurement.

Recently a new method has been developed for fast and accurate corrosion rate measurement. This method which is called “Connection-less Electrical Pulse Response Analysis (CEPRA)” does not require rebar connection as a DC pulse is sent through the concrete surface and its response is analyzed to determine the polarization resistance.

20151019_144334

In addition to the improved efficiency due to the elimination of rebar connection, this method provides accurate corrosion rate results in the field due to the controlled polarization area. Moreover, the corrosion measurement is directional and the measured concrete electrical resistivity is not affected by the rebar presence.

References:

Related Articles

Level Up Your Project Reports With Giatec 360™ – Part 2

Let’s dive deeper into report generation to learn more about how Giatec 360’s reports help you make better decisions faster on the jobsite. For an introduction to Giatec 360, click to read Part 1 of this blog. Get Your First SmartRock Concrete Sensor for FREE Free Demo Kit Giatec 360 – An OverviewSome of the key features are as listed as follows:   Temperature Differential Analysis  Generating Full PDF/CSV Reports  Customizing the reports as per user’s preferences which includes   Generating reports for a specific data range  Selected…

Level Up Your Project Reports With Giatec 360™ – Part 1

Let’s learn about Giatec 360 and how to make the most of this advanced web-based dashboard for monitoring and managing concrete pours. Get Your First SmartRock Concrete Sensor for FREE Free Demo Kit The construction industry is one of the busiest, most challenging, and constantly evolving industries, globally. A series of activities beginning from the designing, planning, testing, maintenance, etc., are coupled with rising demand for industrial infrastructure. The requirement and expectations of the field are set high, and the demands are more augmented than usual.  Besides the…

Giatec Paper Award

Giatec Award for Best Paper 2022 

We are very excited to announce the launch of our annual sustainability in construction research paper award contest! This is a great opportunity for civil engineers to expose their research and development to a global audience of industry experts. Plus, the winner will receive a monetary award of $1,000 US. The “Giatec Award for Best Paper” is open to civil-engineering professors, students (undergraduate and graduate), and researchers across Canada and the U.S. As a leading innovator in sustainable concrete, Giatec looks to connect academic research and development in…

Claim Your Free Demo Kit

Get Your First SmartRock Concrete Sensor for FREE

Get Real-Time Data with SmartRock®

See how it works today

We use cookies to provide you with a better experience, analyze site traffic and assist in our marketing efforts. By continuing to use this website, you consent to the use of cookies in accordance with our Privacy Policy Page.