22 January 2024

This is Part 2 of a five-part series.

… continued from Part 1.

Addressing historical challenges

Hajimiragha delved into the historical challenges faced by the construction industry, particularly the corrosion issues associated with black steel rebar dating back to the early 1900s. He highlighted the initial excitement surrounding steel rebar, only for concerns to escalate as corrosion became rampant. The subsequent attempts to combat corrosion through epoxy coatings and galvanisation were acknowledged, but their shortcomings were emphasised—once the protective layers wore off, corrosion would resume.

Glass Fibre Reinforced Polymer (GFRP) has a 30-year presence in the market. He highlighted the extensive research, development, and testing conducted by universities and end-users, solidifying GFRP’s credibility as a material of choice. The speaker underscored the need to shift the focus from mitigating corrosion to eliminating it altogether by replacing traditional steel rebar with corrosion-resistant GFRP.

Hajimiragha likened the manufacturing process to polishing a piece of rebar to a diamond-like finish. The result was illustrated by glass fibres enclosed in high-performance vinylester epoxy. The glass fibres, each about a third of a hair’s diameter, make up 80% of the material, with the remaining 15% serving as a binder. The corrosion-resistant nature of GFRP, coupled with its composition, positions it as a robust and durable alternative.

Acknowledging the slow pace of adoption in the construction industry, Hajimiragha explained that structural engineers often require substantial historical evidence before embracing new materials. He presented a case from the early 1990s, showcasing the first bridge constructed with GFRP in Virginia, still standing with zero signs of corrosion. The speaker emphasised the importance of time-tested examples to instil confidence in engineers.

Barriers to adoption and overcoming challenges

Identifying key barriers to GFRP adoption, Hajimiragha outlined three main challenges:

  • Firstly, structural engineers seek substantial historical proof of a material’s durability
  • Secondly, the construction industry is historically slow to adopt new technologies
  • Thirdly, engineering codes play a crucial role in determining material acceptance

The presenter emphasised the industry’s slow-moving nature and the significance of overcoming these barriers for widespread GFRP adoption.

Addressing concerns about costs, Hajimiragha indicated that the price of GFRP has significantly decreased, making it comparable to traditional black steel rebar. He highlighted the benefits of GFRP—lighter weight, corrosion-free, and increased service life. Owners increasingly expect longer service lives for structures, making GFRP an attractive and economically viable option.

Noting the growing support from the US Department of Transportation (DOT) for sustainable and resilient solutions like GFRP, the presenter says the endorsement from DOT signals a shift towards embracing innovative materials that can enhance the longevity and durability of bridges and structures.

The International Residential Code (IRC) and International Building Code (IBC) are the primary governing codes, and he expressed optimism that fibreglass rebar would be included in these codes by 2024. This foresight was presented as a pivotal step forward for the construction industry.

Continued in Part 3…

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