Concrete Corrosion Restoration 101

The Benefits of a Detailed, Owner-Led Restoration and Engineering Assessment Approach in Combating Concrete Corrosion

By Byron Evetts, PE & Grace Morris / Published January 2023

Concrete Corrosion

     Concrete is one of the most common building materials used in the construction of buildings and infrastructure worldwide, with over one cubic yard (two tons) for every man, woman, and child on earth. Concrete is a proven building material that provides stability, durability, and longevity to its structures. However, all materials eventually degrade and corrode over time, concrete included. Concrete corrosion is often most prevalent in coastal environments, but there is no part of Florida that is free from corrosion. 

     Although some may believe that moisture is the cause of corrosion in concrete reinforcing bars (rebars), this is not entirely accurate. The true culprit is the presence of marine salts that contain chlorides, which can penetrate the concrete and break down the protective layer on the steel. The result is rust and an expansion of the rebar that leads to cracking and spalling of the concrete.

     The presence of cracks and spalling on concrete surfaces necessitates immediate attention to prevent the onset of rapid, progressively deleterious effects. The failure to address these issues can result in water intrusion and exacerbation of the damage, culminating in the need for more and more costly repairs. The spalling of concrete, the chipping or flaking of the surface layer, presents a safety hazard when pieces dislodge and debris falls, posing a potential danger to those nearby. The unchecked progression of spalling can even lead to the structural failure of the concrete. Therefore, it is imperative to act promptly upon observing these issues to ensure that the required repairs are conducted in an orderly, timely, and meticulous fashion.

Historical Approaches to Concrete Corrosion

     Historically, the most popular approach to combat this issue was the “ostrich” approach, where individuals would attempt to “wish away” issues by neglecting them and anticipating a resolution without acting. However, it is imperative to note that such a course of action is no longer permissible under Florida law or by insurance companies. Another popular approach included seeking assistance from unqualified parties, such as friends or family members, to speculate on the issue, which is not advisable and may exacerbate the situation.

The Best Way Forward For A Concrete Restoration Project

1. Owner-Led Restoration
2. Owner-Led Restoration
3. Owner-Led Restoration

     To efficiently handle these repair projects, an owner should hire an engineer to conduct a systematic engineering assessment, followed up with a well-designed repair plan that qualified contractors can bid on and implement. To ensure successful execution, qualified engineers can assist owners in overseeing the construction process, while the selection of experienced construction administrators can further guarantee that the project is completed to the owner’s satisfaction. An example is discussed below.

Castaway Cove Condominium Concrete Restoration and Remediation Plan Case Study

     Existing Structures Engineering, acquired by Osborn Engineering in 2021, conducted a condition survey in support of a planned restoration project at Castaway Cove Condominium located in Palm Bay, Florida. The condition survey was designed to support follow-on production of a project manual for the implementation of recommended restoration work.

     Assessment of the building revealed that the existing conditions of the condominium consisted of many features such as coatings, railings, balconies, walkways, etc. that were either in poor condition, not code compliant, or at the end of their life cycle. After a careful and detailed inspection and survey, Existing Structures concluded that the following recommendations be incorporated into the condominium’s project manual:

     The balconies have some small areas of corrosion on the walls, overheads, and edges. Most of the balconies have an acrylic coating that is in fair condition, but there are several in need of a new acrylic topcoat. Since several of the coatings are at the end of their life cycle, it will be beneficial to recoat all the balconies. 

     The balcony guardrails are not up to code and consist of aluminum rails and pickets with embedded stanchions. They are in fair to poor condition, with failed coating, perforation, and pitting. It is recommended to incorporate new guardrails.

     The walkways have patching to bridge the expansion joints, which is a common problem. We recommend routing out the expansion joints and installing a new backer rod and urethane system.

     The current acrylic coating on the walkways and stairways is damaged and should be removed and replaced. The guardrails on the walkways are not up to code and have embedded aluminum stanchions, which allows water to enter the planks. It is recommended to incorporate new flush-mount guardrails. 

     Finally, it is vital to undertake a painting and waterproofing project after completing concrete repairs. Additionally, the fenestrations (door and window openings) should be thoroughly waterproofed.

Figure 1 (left) Condition of balcony guardrail during inspection • Figure 2 (right) Condition of balcony guardrail after repairs

     During the inspection process trained professionals conducted most of the inspection through visual and hands-on methods. To supplement this effort, sounding wheels and chains, sounding hammers, hand tools, and tape measures were used. The inspection was designed to be non-invasive, and no destructive methods were utilized.

     Incorporating the recommendations from the engineers proved to be an effective measure for Castaway Cove Condominium in combating concrete corrosion within its facility. The condominium successfully implemented an owner-led restoration and engineering assessment approach, which proved to be efficient in resolving the concrete corrosion issue in a manner that was lawful under Florida legislation and was duly approved by insurance companies. Further, the remediation resulted in a “clean” milestone inspection report.

     This proactive approach highlights the importance of engaging with professionals in the field, and their invaluable expertise in identifying and addressing structural issues. By taking this approach, Castaway Cove Condominium was able to mitigate risks associated with concrete corrosion and ensure that its facility adhered to current codes and regulations.

     The former president of the Castaway Cove Condominium Association, Susan Connolly, shares,

Figure 3 (left)Condition of walkway/deck during inspection • Figure 4 (right) Condition of walkway/deck after repairs

     For Castaway Cove Condominium, concrete corrosion started as a small issue; but due to the nature of condominium boards, the issue was not properly addressed because of the complexity of repairs and the common tendency to defer decisions. As a board we collectively and collaboratively incorporated an owner-led restoration project and engineering assessment approach. Through meticulous interviews with various firms, Existing Structures emerged as a partner committed to understanding our condominium board personally while offering a detailed solution. Their dedication to constant and clear communication stood out. This partnership resolved our long-standing issue and established a solid and professional working relationship with our condominium board. I wholeheartedly recommend the owner-led restoration approach and Existing Structures, extending my endorsement to other condominium boards seeking the best quality of work and professional excellence.

     Due to its marine environment, many buildings throughout Florida are prone to concrete corrosion and will likely require restoration. For safety, legal, and financial reasons, the timely and efficient repair of corrosive concrete is in the best interest of the community. When encountering corrosive concrete, it is vital that owners conduct a thorough engineering assessment, create a repair plan, and engage qualified contractors. This approach ensures that the repair work is carried out successfully, in compliance with Florida legislation, and to the satisfaction of all parties involved. 

 

 

Byron Evetts, PE, Director, Restoration Engineering
Grace Morris, Marketing Associate

Osborn Engineering

     Byron Evetts, PE, is the director of restoration engineering and is an industry-recognized expert in evaluation, preservation, and remediation of damaged and corroded structures. Grace Morris is a marketing associate. Both are with Osborn Engineering in Cape Canaveral, Florida. For more information, email inspections@osborn-eng.com, call 321-784-5811, or visit www.osborn-eng.com.