In a feat believed to be among the first of its kind, Webcor and its project partners successfully developed and placed a low-carbon concrete mix for drilled-shaft auger-cast piles.

• This isn't just another incremental gain; it is a solution to one of the most stubborn challenges in the construction industry.

The Tremie-crete Problem

Deep-foundation concrete, often referred to as tremie-crete, is notoriously difficult to decarbonize.

• Most green baselines (measured by Global Warming Potential (GWP)) don’t easily apply to drilled shaft foundations because of the specific physical properties required during the "fresh state" of the pour.
• While standard concrete is often judged by its final strength, tremie-crete is driven by rheology, or how the mixture flows.

To work at these depths, the mix must have high fluidity and strong resistance to "bleeding" and segregation under high hydrostatic pressures.

• Historically, achieving this meant using mixtures with very high Portland cement contents to increase paste density. As Webcor Concrete Director Eric Peterson points out, "The use of high amounts of cement in tremie-crete is not determined by strength. It is driven by the rheological requirements of the mixture."

Breaking the Status Quo

The project team was initially on the verge of abandoning the low-carbon approach.

• Early attempts did not perform well in terms of strength or fresh-state properties, and a traditional "back-up" mix carried a heavy carbon cost of 430 kg CO2-eq/m3.
• However, Eric — who chairs the ACI Committee 237, Self-Consolidating Concrete (SCC) — saw an opportunity to apply SCC principles to the foundation piles.

For four months, the team Keller, CEMEX, and Webcor Concrete worked at CEMEX’s laboratory in Livermore to develop and test a new mixture.

• One major hurdle was a site-added "fluidizer" that lacked an Environmental Product Declaration (EPD) and had not yet been used in the Project’s previous strength tests.
• Without an EPD, the total carbon impact could not be quantified, which is required by SFO.
• Webcor assisted the manufacturer of the fluidizer in obtaining a verified product EPD through Climate Earth and ASTM, allowing the team to confirm a GWP of 270 kg CO2-eq/m3—well below SFO’s requirements.

From Lab to Labor

In the lab, the mixture performed like a champion, but as any seasoned practitioner knows, the lab is a controlled environment.

• When early field results for the test piles appeared to differ from the trial batching in the lab, Eric spent the better part of two weeks in the field observing the batching, curing, and testing processes.
• He identified several critical issues, including the addition of water in the field and the handling of specimens before transfer to the lab. He also documented issues occurring at the lab related to preparation and testing procedures.

"There is a significant difference between the capability of a concrete mixture and how it performs during high-paced production," Eric notes.

• By resolving these field-level and testing gaps, the mix began to behave as it had in Livermore.
• It developed significant strength between 28 and 56 days, consistently exceeding 6,000 psi and demonstrating that the Code's "over-design" requirements were satisfied.

The Bottom Line

The success at SFO demonstrates that:

• It is often possible to satisfy both performance requirements and low-embodied-carbon goals.
• We have moved beyond identifying the problem to offering a performance-based solution for the rest of the industry.
• By understanding the challenges and applying a proven strategy, we’ve created a roadmap to decarbonize one of the difficult elements of our structures.

The bottom line: If you think deep foundations are a "necessary evil" in terms of carbon cost, think again.

• We have proven that even 90 feet down, sustainability is achievable with the right mix of expertise, materials, and persistence.

The goal now is to apply the lessons from this success to other projects in our pipeline with similar or more complex challenges.

In honor of Women in Construction Week (WiC Week), we’re spotlighting five outstanding women selected by the Women of Webcor (our employee resource group for women, open to ALL Webcorians) leadership committee who have made exceptional contributions to Webcor while embodying our core values.

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She was anxious to take on new challenges at a larger, more established GC and support more complex projects, but she wasn’t sure where. As she researched the companies behind some of her favorite buildings in San Francisco, however, the answer became clear: a California-focused commercial contractor called Webcor.

• “I knew I wanted to join a team with the talent and vision to build such iconic projects,” she says. “At the same time, I was nervous because Webcor’s projects and reputation were so impressive, and everything I’d done up to that point in my career was much smaller. I’d be taking a huge leap.”

She decided to ask her former colleague, a retired union carpenter who knew her and her work history well, for his honest opinion: Did she have what it took to succeed at a large GC like Webcor? 

“He looked at me kind of sadly and said, ‘No, they’ll eat you alive,’” she recalls. She submitted her application anyway. 

Weeks later, she was standing at the Grand Hyatt at SFO project site as one of Webcor’s newest project engineers (PEs). After about a year, she was promoted to senior PE while wrapping up the Grand Hyatt, which went on to win the Design-Build Institute of America’s (DBIA’s) National Award of Excellence in 2020.

Shifting From Design to Construction

Cibele studied architecture at the California College of the Arts (CCA), an art school that emphasizes craft and delivery as much as design. After graduating with her Bachelor of Architecture, she worked for architecture firms as a designer for almost six years. 

Around that sixth year, she realized she was beginning to outgrow her career path. She wanted to do more than design—she wanted to bring those designs to life. 

• It was clearly time to move on, but she wasn’t sure about her next move. “I was becoming restless but didn’t know where to go, so I wandered a bit after leaving my old design firms,” she says. 

 She soon landed a job as a bench carpenter operating a computer numerical control (CNC) at a custom woodwork shop, where she stayed for a few years before pivoting to project management at a small GC. There, she realized that as much as she excelled at and enjoyed architecture and design, she clearly loved construction more.

“In architecture, we work inside our minds, which makes the work feel quiet and solitary,” she says. “Construction is more tangible and collaborative, and the energy from everyone working together on the project is livelier. It doesn’t hurt that construction pays better too! 

“However, I do think both fields attract people who see their work as a passion—not just a job.”

Of course, that’s not to say she isn’t still working her architectural muscles. Her design background has positioned her as a uniquely effective collaborator who understands and appreciates architects’ vision and goals. “Hopefully, they see me as a partner instead of an adversary!”

Lessons Learned at Webcor

As an assistant project manager, Cibele now approaches every issue knowing the best thing she can do is something—even if it’s not the perfect move. She no longer lets the fear of making a mistake intimidate her into freezing up. When faced with a problem, waiting around for a solution isn’t helping anyone.  

• “The path only becomes clear once you start moving,” she says. “Take action, even if it’s a small step. It might not be the right direction, but at least you’ll know which direction not to go in.”

She’s also learned the immeasurable value of listening and observing. When people take the time to truly absorb what others are saying instead of talking over one another, she says, a clear path forward often emerges.

• “I don’t think projects are successful because of a single ‘hero moment’ where one person saves the day,” she says. “It’s the million small problems caught and resolved because we’re actually listening to one another. Listening and observing more than I speak has become my default way of working with a team.”

These types of hands-on, real-life lessons learned on the job have been the most rewarding part of her Webcor experience. Fortunately, she knows plenty more are ahead at UCSF Health Helen Diller Hospital—a life-changing project that’s become the most gratifying accomplishment of her career.

“I’ll always be proud of my contributions to HDH,” she says. “It’ll be standing tall and taking care of people long after I’m gone.”

Building a Long-Term Career at Webcor

It’s been almost 15 years since Cibele left the architecture world to figure out her next move. Today, she’s grateful to say she’s never been more confident about the direction her career’s headed and hopes to stay with Webcor for many years to come. 

Beyond her own career advancement, though, Cibele recognizes that moving up in this industry is a win for all women who are underestimated, dismissed, and questioned for daring to work in construction.

“Being underestimated is a near-universal experience for us,” she says. “But our success is even more gratifying when it proves the doubters wrong!” 

Recently, she ran into the retired union carpenter who had once said Webcor would “eat her alive.” “When I saw him, he’d already heard I’d joined Webcor,” she says. “He was so proud of me!”

In honor of WiC Week, we’re spotlighting five outstanding women selected by the Women of Webcor (our employee resource group for women, open to ALL Webcorians) leadership committee who have made exceptional contributions to Webcor while embodying our core values.

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Her journey began in the world of fine arts and fashion design — a background that might seem a world away from a construction site, but one that provided the foundational creativity she uses every day as a Virtual Design and Construction (VDC) Manager at Webcor.

After a college internship in the fashion industry, Annie realized the environment lacked the steady, reliable atmosphere she was looking for. She shifted gears, taking a receptionist role at an interior design firm to test the waters in architecture. That move sparked a series of transitions: from receptionist to marketing coordinator, and eventually to a marketing role at Turner Construction in New York.

"I enjoyed marketing a lot, but the only challenge was the time — I was constantly cranking out proposals and graphics," Annie recalls. Seeking something more operations-based, she accepted an on-the-job training offer for VDC.

The Universal Language of Problem-Solving

Transitioning into VDC was a "tech challenge" of the highest order. Working in Revit and managing trade coordination on-site required Annie to master complex MEP (mechanical, electrical, and plumbing) systems without a traditional engineering background. "When I first started on-site, I really didn't have the engineering background a lot of people do," she says. "It was another level of 'wow.' But over time, I learned what I needed to."

Her strategy was simple and direct: she admitted what she didn't know and sought help from the experts in each trade. "My style was just to admit I didn't have the knowledge and to look for all the help I could get. I had experienced people from each trade helping me learn."

This humility led her to discover that the construction industry has a remarkable capacity to accommodate people with diverse skill sets. "What's very cool about this industry is that there's room for people with a lot of different educational backgrounds. Problem-solving,” she says; “anyone can be good at that."

Finding Culture and Stability at Webcor

Annie moved to Los Angeles seven years ago and joined Webcor four years later, after stints at other major firms. For her, the move to Webcor was driven by a desire for genuine connection. At previous firms where the home office was out of state, there was often a sense of isolation.

"I wanted to work somewhere more California-based. At my previous firm, the main office was in Arizona, and I felt disconnected," Annie explains. "Webcor is absolutely different. People are very friendly; it's a different culture."

That culture has provided a sense of stability that Annie found lacking elsewhere. "Coming to Webcor felt more like having a history with the company — with the leaders and the people I worked with on projects," she notes. Her current work extends into ACC (Autodesk Construction Cloud), where she is helping to build formal training programs. "SMEs get so busy with their day jobs," she says. "I'm working on a program for that. It allows me to meet more people and get involved with more workflows than the typical VDC tasks."

A New Normal for Representation

When Annie started her career in New York, women were a small minority—perhaps six out of a team of 70. Today, she often finds herself in meetings where women outnumber men. On the San Benito Student Housing project at UC Santa Barbara, for instance, the entire dedicated trade coordination team was composed of women. She has observed past industry attempts to "artificially" balance teams — such as assigning women specifically to hospital projects or women’s colleges — but Annie views the organic presence of women in leadership as the ultimate goal.

"At other GCs I worked at, there were no women in roles as senior as (Sr. VP) Allison McCue or (VP) Kamika Kilgore," she says. "It doesn't surprise me now; it seems par for the course.

“Women should be in these roles,” she says. “It should just be normal." For Annie, the focus remains on the quality of the work and the support found in the day-to-day environment. "It's important to be around women who are supportive every day."

Finding a Personal Style in the Field

As a self-described "shy and quiet" communicator, Annie has had to find her own voice in an industry often characterized by outgoing, assertive personalities. "I have to find my style for communicating with men who may not be expecting to see me there or are not used to working with a shy woman," she explains. This internal navigation is as much a part of the job as the software she masters.

Her advice to the next generation? Don't wait for a "roundabout path" if you can find your way to STEM early. "I wouldn't recommend that path if they could decide earlier," she admits. "There was a time I was questioning my decisions, wondering what my career path would look like." However, she has demonstrated that a background in art can be the perfect precursor to a career in digital construction. "When I was studying art, my dad tried to encourage graphic design because it was the 'practical' art, but I didn't like computers back then. Then I switched, and I started loving them."

Whether she is organizing luncheons for a hundred women in the trades or refining virtual models, Annie’s focus is on the human element of the build. "You have to find your own style to fit with the team and get along with people," she says. In the end, the most sophisticated software in the world is only as good as the communication between the people using it.