Photo courtesy Donley’s Inc.
Almost half of the concrete placed contained at least 40 percent slag cement, qualifying it for an ID point under LEED-NC. The average slag content was 19 percent of all cementitious materials used in the concrete, but cement with as much as 93 percent slag cement content was used for some mixes. Another sustainable benefit of using slag cement in this project is the resulting lighter-colored, high-performance concrete mix absorbs less heat from solar radiation and helps to lower the heat island effect. The pervious concrete used also stores less heat due to its relatively open pore structure.
Recognizing the unparalleled growth driven by construction of its Heart and Vascular Institute, the Cleveland Clinic built the largest and most sophisticated healthcare material-handling and order fulfillment system in the United States. With a concrete superstructure of more than 139,355 m2 (1.5 million sf), the East 89th Street Garage and Service Center stands as one of the largest concrete structures in Cleveland. Its construction used almost 76,455 m3 (100,000 cy) of concrete with a mix containing 20 percent fly ash.
To create the slab for the structure’s 96 by 168-m (315 by 550-ft) footprint, the first stage involved 415 truckloads of concrete and four pump trucks, with crews from Donley’s placing more than 3058 m3 (4000 cy) of concrete, covering 3066 m2 (33,000 sf). This was followed by three more large placements—totaling 8180 m3 (10,700 cy) of concrete—to complete the slab over the entire building area. Most of the building products used in the $192-million LEED Silver facility came from sources within 80 km (50 mi) of the site.
The concrete used for deep foundation and structural support elements, as well as the heavy concrete used for radiation bunkers and X-ray rooms, also typically include high levels of SCMs. A 34,474-kPa (5000-psi) self-consolidating concrete (SCC) containing slag cement and fly ash was used in the auger cast piles for the parking garage at the new Science + Technology Park at Johns Hopkins in Baltimore. At Holy Cross Hospital, one of the largest hospitals in Maryland, a proprietary flow mix containing about 75 percent fly ash is being used in sheeting and shoring applications to support a major campus expansion program.
Conclusion
The healthcare industry is making great strides in implementing sustainable design and construction practices for creating healing environments as healthy as possible, and green building certification has proven to be the best method possible to achieve this goal. Concrete and cementitious-based building materials offer extensive sustainable construction benefits and can help achieve LEED for Healthcare certification in many ways.
While the proper use of blended cements and supplementary cementitious materials can be more complex, the results achieved can provide higher-performance and more environmentally-friendly concrete mixtures. Various organizations, including the American Concrete Institute (ACI) and the Slag Cement Association (SCA), offer recommendations design professionals can consult on how to specify such substitutions. Additionally, manufacturers can provide technical assistance to help develop or modify specifications; most can provide detailed test results, and additional support.
Case Study: Slag Cement for Moses H. Cone
Photo courtesy Triad Business Journal
Slag cement is playing a key role in the construction of the new $200-million, six-story North Tower at the Moses H. Cone Memorial Hospital (Greensboro, North Carolina). The largest construction project in the hospital’s 58-year history, the tower takes advantage of natural light and passive energy, features noise-reducing design, relies on locally sourced building materials, and uses less energy and natural resources in its construction and operation.
The approximately 6700-m2 (263,713-sf) expansion specified 40 percent cementitious replacement to target credits under the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design for Healthcare (LEED-HC) program. The project, targeting LEED Silver, uses a portland-slag cement blend to achieve greater strength potential and long-term durability. By successfully combining these cements, the hospital is aiming to reduce its building’s carbon footprint. Completion is expected for June.
Andrew Pinneke, PE, LEED AP, is a construction and building system specialist at Lafarge. He serves as a consultant on a wide range of sustainable construction issues and coordinates the company’s sustainable construction efforts throughout the United States. Pinneke previously worked as a structural engineer for almost a decade. He sits on the National Ready Mixed Concrete Association (NRMCA) Sustainability Committee, the American Concrete Institute (ACI) Building Information Modeling Committee 131, and the ACI Foundation’s Strategic Development Council (SDC), as well as participates in the American Society of Civil Engineers (ASCE) and the U.S. Green Building Council (USGBC) local and national chapters. Pinneke can be contacted via e-mail at andrew.pinneke@lafarge-na.com.
