At midnight on December 20, 2008, Baker Concrete, Monroe, Ohio, placed a 17,500-cubic-yard mat slab in 24 hours. As part of the new MD Anderson Office complex, this building consolidates their office locations in Houston's Texas Medical Center and provides ultimate protection from hurricanes and tropical storms that occasionally reach the area.
With the 60,000-square-foot mat ranging from 7 to 12½ feet in thickness, ready-mix trucks arrived every 40 seconds to supply the eight concrete boom pumps onsite. The placement required 100 crew members working in three shifts to place the concrete. Ready-mix producer TXI, Houston, brought in several trainloads of aggregate to five of their batch plants and dedicated 100 ready-mix trucks to service the project.
The mat slab will support three buildings joined together: one 26-story building, another with 21 stories, and a five-story structure. Garrett Benson, Baker's project manager for the construction, says the owner decided to use heavier structural concrete construction. So the floors are constructed with “long-pan” forms with beam pockets as deep as 30 inches. All the columns are cast-in-place concrete, while precast concrete panels are used to construct the curtain walls. The buildings will house office staff, computers and servers, and records and archives.
The health care construction forecast
The Texas Medical Center is a huge complex of constantly growing hospitals and research buildings, which is representative of continual growth of the health care industry. Ed Sullivan, chief economist for the Portland Cement Association (PCA), Skokie, Ill., predicted in its Spring 2009 “U.S. Cement and Construction Forecast” that hospital and institutional building construction will rise to $18 billion in 2009, a 1.9% increase from last year. That may not seem like much, but all other nonresidential building construction sectors are lower than last year—as is portland cement consumption. Sullivan says American health care has come through an era with a focus on fewer overnight stays in hospitals and increased outpatient services. “But long-term demographics are changing. More people are getting older and there will be increased demand for health care.”
As with most construction projects, funding remains a challenge. Tom Fromm, the health care construction leader for Skidmore Owings & Merrill (SOM), Chicago, says traditional funding for health care facilities comes from philanthropy, public funds, investments, and operating budgets. But given the present economy, none of these funding sources, other than federal funding, are strong.
Concrete vs. steel
The decision to use structural concrete or structural steel for hospital construction is much more complicated than you might expect, says Robert Klute, a partner in the firm Hosking Klute Healthcare (HKH), Chicago. As facility consultants, HKH provides defined functional and operational building program requirements for health care clients before design work begins. Klute says hospital projects involve multidisciplinary teams of architects, engineers, construction managers/contractors, owners, clinicians, financial advisors, and consultants. The recommendation about materials to be used for a building's structural frame, he says, often is made by the CM/GC well before the design process begins and is driven primarily by cost. Local conditions—such as the status of labor contracts, the availability of skilled labor and skilled contractors, and the competition between suppliers—all play a part in the decision. Fromm says SOM always considers both structural steel and concrete in their initial design work so clients can judge cost differences. Projects today often go to structural steel construction, he says, “But when clients want fast-track construction, concrete often wins out.”
The choice between structural concrete or steel-frame construction can come down to something as simple as floor penetrations. Hospitals typically require a tremendous number of them, both during construction and as buildings modernize over time. Steel frames with concrete on metal deck floors are easier and less expensive to core. However, structural concrete handles building vibration better. Fromm says concrete dampens vibration, and with medical equipment becoming more sensitive to movement, concrete is preferred.
Cost of construction
Morley Construction, Santa Monica, Calif., is the structural concrete contractor building the Palomar Medical Center West hospital in Escondido, Calif. The publicly funded project in San Diego County has a price tag of nearly $1 billion. It may sound like a lot of money for a 732,000-square-foot building with an adjacent central facilities plant, but this amount is now the average cost for new hospital construction.
Sean Fleming, Morley's project manager for Palomar Medical Center West, says the funding for the hospital was committed five years ago with the passing of a public bond measure. The bidders for the project included a small group of pre-qualified contractors evaluated on past work and their understanding of hospital construction. From an approved list, the low bidder won the job. This fast-track project will become a community hospital, touted as the most state-of-the-art facility in the nation. The building uses a moment-frame structural-steel superstructure with concrete floors over metal deck, and a structural concrete basement.
In spite of the high price tag of hospital construction and the difficult economic climate, a number of hospital projects are either in the planning stages or going through the construction process. It's a good time to build because bids today are very competitive.
Benson says the mix for the Texas Medical Center mass concrete mat slab uses a 50% fly ash replacement of portland cement. The mix had to reach 5000 psi within 112 days—while keeping concrete temperatures below 160° F and differential temperatures between the outside and inside of the slab less than 40° F. To help achieve this, they wrapped the placement with curing blankets to prevent the exterior from cooling too quickly.
Mixes for the building columns had to reach 10,000 psi in 28 days; concrete for decks had to reach 5000 psi at 28 days and 7200 psi at 128 days. The mixes also included fly ash replacements of up to 25%. Maturity meters helped the team determine when to post-tension the tendon reinforcement, Benson notes.
Fleming says the Palomar Medical Center West project will use approximately 43,000 cubic yards of concrete. But even with a lot of mass concrete, the most challenging aspect is the lightweight concrete for the decks from the fifth floor to the building's top. The lightweight must achieve 3000 psi compressive strength, with a dry unit weight of 110 pounds/cubic foot. Southern California suppliers can readily reach 115 pcf but 110 pcf is difficult, he says. Also, the floors must be placed and finished to meet a minimum FF35 specification; the average so far is FF45. Ten different concrete mix designs were developed for the project, none of them being exotic.
Special concrete construction
ProCure Treatment Centers, Bloomington, Ind., has plans to build several proton therapy centers at locations around the country. A facility in Oklahoma City, Okla. is nearly complete, and one in Warrenville, Ill., has just achieved a milestone with the completion of its mass concrete placement. Concrete Structures, Carol Stream, Ill., is forming and placing the concrete for Gilbane Construction, Chicago, the project's general contractor.
ProCure provides patients with proton therapy—an advanced form of radiation therapy currently only available at five locations in the country. Protons can be controlled precisely so that most of the radiation is deposited directly in the tumor and virtually none of the healthy tissue behind the tumor.
Limited patient access to this therapy is due in large part to the expense of building a cyclotron, which is at the heart of each proton therapy center. Weighing as much as 200 tons, the cyclotron is placed in a highly reinforced concrete structure where it delivers protons traveling almost at the speed of light to four treatment rooms. As a precaution, thick mass concrete walls and ceilings surround the cyclotron and patient treatment areas to contain the radiation.
Concrete turns out to be an ideal medium to contain radiation. Mark Leuschner, ProCure's director of physics research, specifies local materials for concrete mixes based on their ability to block radiation; other individuals work out the details for mass concrete designs. Concrete with high concentrations of calcium aggregates, such as limestone, work very well for shielding radiation. But in areas where wall thickness must be restricted, iron aggregate mixes are chosen. The room housing the cyclotron requires the greatest amount of shielding.
At the Warrenville construction site Barry Coleman, Gilbane's general superintendent, says the thickest wall is a 12-foot-thick in the cyclotron room.
To limit the thickness of one wall to 7 feet, a 2-foot-wide section sandwiched in the middle of the wall was filled with iron aggregate concrete. Because it weighed twice as much as regular concrete, it was batched 4 cubic yards at a time. “It cost approximately $2000 per yard,” adds Coleman.
There are 870 tons of rebar and 13,300 cubic yards of concrete in the building's 20,000-square-foot treatment area.
As previously mentioned, many factors are considered when deciding between steel or concrete as the primary structural material for health care facilities. Jamie Farny, market manager for low-rise commercial buildings at PCA, offers the following advantages for building with concrete for the health care industry:
- Structural concrete doesn't need fire-proofing.
- Concrete buildings are stiff, so there is little vibration—increasingly important for sophisticated hospital equipment.
- Steel beams can affect the performance of MRI imaging equipment.
- Concrete effectively shields radioactive treatments.
- Building air quality is generally better.
- Adding on to a structure at a later date is easier and less costly.
- Concrete buildings are quieter.
- Fire spread is limited.
- Concrete can serve as the floor finish, eliminating the VOCs associated with other floor coverings.
- Concrete construction is sustainable.
Our aging population leads to the need for more health care facilities now and in the future. So even during these hard economic times, we will continue to build hospitals, health care facilities, and exotic buildings such as ProCure's cancer treatment centers. Concrete plays a vital role in the health care industry and as the economy and funding for facilities improve, you can expect to see continued growth.
Are We Safe in the Hands of the Millennial Generation?
At age 26 Garrett Benson is responsible for Baker's construction of the MD Anderson office center. A $280 million fast-track project that employs 150 workers, Benson says the schedule is critical because the client is giving up their office leases to move into the first nine stories of the new building in 2011. “To meet this schedule, we're placing 2000 cubic yards of concrete each week, using three tower cranes, and working 24 hours a day,” he adds.
Benson graduated from Houston University in 2007 with a degree in construction management. While attending school, he spent a couple of summers working on construction sites as a laborer, worked part time for a year and a half as an estimator for Baker, worked as a project engineer during his senior year, and was an assistant project manager for two years after graduation. Then he persuaded Baker to make him the project manager for this construction. He says he sought the position because of the job's many complexities.
Moving ahead, Benson wants to be part of a Baker project in Port Arthur, Texas, that will double the production size of a refinery. He thinks the additional experience in industrial construction will help pave the way for him to secure the many certifications needed for nuclear reactor power plant construction (he's hoping Baker will get the concrete work—and he will be project manager—for a reactor project coming to southern Texas).
Benson's father also works for Baker, as their chief operating officer; his first mat slab was a 5000-cubic-yard placement in Houston in 1982. Not that he's competitive, but Garrett likes to remind his dad that his first mat slab was 17,500 cubic yards.
Our industry wonders where tomorrow's leadership in the construction industry will come. If there are many millennial generation folks out there like Benson, our worries are over.