Can grout really help hold up a high-rise?
Structural grout is a key element in many commercial buildings, but improper use can lead to building collapse.
We all benefit from grout. Just think of your bathtub and kitchen backsplash. But grout goes way beyond household use. It's also used to hold up concrete buildings and parking garages, and if used improperly the results can be catastrophic.
Zurich North America Construction Risk Engineer Craig Durgarian discovered an issue and is committed to making an impact with customers and the entire construction industry. In a Q&A, he explains the issue.
Q: In layman's terms, what is the issue?
Durgarian: Just as bolting/welding is integral to the stability of structural steel-framed buildings, grouting is equally critical to connect column and wall elements in structural precast concrete buildings and parking garages. Grout is a cement-based mortar or paste used for filling gaps between building materials. This critical building element is fundamental to the long-term strength of structures.
For a variety of reasons over many years in the construction industry, the verification of proper installation and quality of grout has not been given the attention it critically demands – especially as prefabricated/modular concrete building construction continues to gain popularity.
Q: What impact is improper grouting having on the construction industry?
Durgarian: In 2016, localized building failures occurred on two Zurich-insured projects (one under construction, and one recently completed), where missing and poor-quality grout caused certain connection joints to become highly overstressed. Thankfully, and miraculously, no one was hurt. The subsequent localized crushing of these isolated building elements ultimately caused millions of dollars in submitted claim damages including investigation costs of all remaining intact connections, schedule delays and business interruption impacts.
In recent years, several non-Zurich insured projects experienced similar misfortune. For instance, the 2012 collapse of a six-story precast concrete parking structure in Miami killed four individuals and injured three others, and the Occupational Safety and Health Administration (OSHA) cited missing or poorly installed grout as the culprit.
Q: What is your expertise in this area?
Durgarian: Prior to Zurich, I worked in structural engineering and construction project management, including the design, fabrication and erection of concrete structures such as multi-story office buildings and parking garages – and the installation of structural grout. As part of my role with Zurich North America Risk Engineering, I work with the Claims department in the reconciliation of complex professional liability and construction defect claims.
Q: What have you done to rectify this issue from a customer and industry perspective?
Durgarian: As a registered professional engineer, I have an ethical duty to address any potential threat to public safety. By late 2016, it was clear that this type of deficient construction was likely not limited to a single geographic area. In concert with my claim reconciliation efforts, I began to inform risk engineering teams, construction underwriters and claim handlers of the potential danger in this type of deficient construction so they could educate their customers.
In 2017, I joined our customer's executive team at a local chapter meeting of a structural engineers group, where we explained to attendees that newfound design analysis attention must be given to this grouting issue. We were initially met with resistance, but in the weeks that followed, the group issued a grout warning memo and began drafting new grout specification language for local designers to use in their upcoming project contract documents.
In 2018, with the help of Zurich Risk Engineer Rick Zellen, I got my foot in the door with one of Zellen's Construction customers and began stressing that new and unprecedented grouting quality controls were necessary in the industry. Over the course of site inspections and consultations on their projects, they too revamped their existing grout quality control procedures.
These consultations convinced me to create an 18-category and 70-question risk engineering field grouting inspection checklist, which we are deploying via Zurich Onsite for all project site inspections that involve structural grouting.
In 2018, I joined two committees within the national Precast/Prestressed Concrete Institute (PCI). We are now raising this issue with 400 U.S. precast concrete member companies.
An article in the September 2019 edition of Structure Magazine identified these same grouting risks and the need to change requirements. This magazine is the premier forum for advancing structural engineering knowledge in the U.S.
Q: What kind of reaction have we received from customers?
Durgarian: Both of our customers sent me formal correspondences sharing gratitude for helping them develop robust grouting installation quality control procedures and thanking Zurich for the partnership in difficult times. I have heard from several underwriters and risk engineers across the country explaining how they share grout stories with customers and prospects. And several companies informed me that they are developing more formal and measurable structural grouting quality control procedures. We are making a difference, and in the process, we will save lives.