2024 Award Winners and Nominees
Project Name
Seattle Storm Center for Basketball Performance
Description
Project: The Seattle Storm Center for Basketball Performance
The new state‐of‐the‐art professional basketball performance center in Seattle, WA will serve as the dedicated practice facility for the WNBA’s Seattle Storm. Its design is sustainable with low carbon concrete as a primary design feature of the structure.
The Seattle Storm facility is being built on a 50,000‐square‐foot parcel in Seattle’s Interbay neighborhood. The project involved tilt-up construction with sandwich panels. The project is designed to achieve LEED® Gold certification, featuring all‐electric operations and a rooftop photovoltaic array. Construction began in Spring 2023 and is expected to be completed in time for training camp ahead of the 2024 WNBA season.
Project Details
Producer: NRMCA Member Stoneway Concrete
Contractor: Sellen Construction
Design Architect: Shive-Hattery
Architect of Record: ZGF
Structural: Holmes
This project had numerous technical challenges to meet low CO2 requirements, design challenges, maintain the construction schedule and achieve LEED® Gold certification.
Stoneway was initially approached by the contractor with the request for white cement concrete for the exterior tilt up walls. The requirements from the specifier included limits on embodied carbon and maximum cement limits. The alternatives: white cement (carbon reduction and cost) and pigments (cost) could not achieve. Sellen Construction had placed an 80% slag cement mix on a previous project (Amazon Spheres) and was aware that it produced a very light color after curing.
In addition to maximizing slag cement content and ASTM C595 type IL cement for various applications on the job, the design and construction team worked collaboratively to identify areas, like foundations and tilt-up walls, where concrete could be specified with 56 day design, rather than 28 days, further reducing the required amount of cementitious ingredients and GWP to achieve required strength.
Stoneway utilized Lafarge slag cement, Ashgrove type IL cement, CHRYSO & GCP’s admixture and fiber technologies to help exceed the specified embodied carbon limits and overall performance. The teams collaborated to identify the best low carbon mixes for the intended application.
Evidence
Stoneway was able to propose concrete mixtures that met the architect’s requirement for color, and that met the structural and design requirements that included:
• 6,000 PSI @ 56 days (500 PSI Flexural @28 days)
• Tilt panels required 4,000 PSI to tilt. Giatec Smart Rock maturity sensors were able to show the contractor they met the requirement in 3 days
• 3,000 PSI @ 28 days (500 PSI Flexural) for the exterior “beauty panels” required Macro fibers to replace WWF and make ease of consolidation easier.
• All concrete required .040% drying shrinkage at 28 days
Working with our admixture supplier Chryso/GCP
• STRUX® 75/32 MACRO FIBERS: Used in the panels to improve durability and long- term crack control
• CONCERA®, and ADVA enabled the use of local materials —helping to boost sustainability and minimize need for vibration due to high flow, making it easy to place and finish and produce high strengths.
Meetings were held with Sellen to discuss the challenges of the low carbon concrete and to discuss the finishing and curing methods required for these unique mix designs. This was followed up by several mockup pours that allowed the construction team the ability to place and finish the 80% slag mixes and practice the sandwich panel installation required by the design team.
During the construction process, Sellen & Stoneway worked together to overcome the challenges these mixes gave to the placing and finishing team, while only needing to make minor adjustments to the concrete mix.
Recently included in the January 17th Seattle Times article, “Northwest Innovators Chase the Dream of Greener Concrete,” the design of the Seattle Storm Center for Basketball Performance is a leading example of an eco-innovation approach to reduce the amount of carbon in concrete throughout the product lifecycle.
• 3,000 PSI @ 28 days “beauty panels” Concera/ADVA/STRUX – GWP of the mix 118 (kg CO2e/m3) specified 291 (kg CO2e/m3)
• 6,000 PSI @ 56 days Adva/VMAR 3 – GWP of the mix 155 (kg CO2e/m3) specified 429 (kg CO2e/m3), 4,000 PSI @ 3 days (using maturity sensors)
• 27% of the concrete on the project utilized 80% slag cement, 64% of the concrete utilized 50% slag cement.
• Overall, the project exceeded a 40% reduction compared to typical average mixes in the region, and achieved 80%* of the 2030 targeted reductions of the First Movers Coalition for concrete (for reference, here: WEF_FMC_Cement_Concrete_Commitment.pdf (weforum.org)
• GWP requirements & Stoneway GWP #’s are attached
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