SUSTAINABILITY IS A PRIORITY IN THE BUILDING AND CONSTRUCTION INDUSTRY. DESIGN PROFESSIONALS THROUGHOUT NORTH AMERICA ARE COMING UP WITH HIGHLY ENGINEERED STRUCTURES COMBINED WITH MANY SUSTAINABLE FEATURES, AND SPORTS FACILITIES ARE NO EXCEPTION.

Some of the notable sports venues that have earned the label ‘green,’ according to the U.S. Green Building Council (USGBC) include:• American Airlines Arena—home to the National Basketball

Association’s (NBA’s) Miami Heat;• Philips Arena—home to the NBA’s Atlanta Hawks and the

National Hockey League’s (NHL’s) Atlanta Thrashers;

Specifying Blended Cements

by Andrew Pinneke, PE, LEED APImages courtesy Lafarge

Constructing sustainable sports facilities

• Nationals Park—home to Major League Baseball’s (MLB’s) Washington Nationals;

• Target Field—home to MLB’s Minnesota Twins;• CONSOL Energy Center—home to the NHL’s Pittsburgh

Penguins; and• the training facility for the National Football League’s

(NFL’s) Detroit Lions.Sustainable construction aims to identify building materials and methods that are cleaner and more environmentally responsible while ensuring the highest quality in terms of aesthetics, durability, and strength.

It takes into account the structure’s entire lifecycle and aims to reduce the impact at every stage, from the initial choice of products through to the building’s eventual reuse.

Concrete is produced locally, is almost entirely recyclable, has a long life span, and has increasingly favorable carbon dioxide (CO

2) and energy footprints. All these attributes come

in addition to the properties of the material itself:

• unequalled durability;• almost entirely natural ingredients;• fire-resistant qualities;• thermal insulation qualities; and• acoustic insulation qualities.Concrete’s thermal inertia properties enable it to absorb heat during the day, store it, and give it back at night, creating substantial savings in terms of heating and air-conditioning. Daily heating and cooling requirements can be minimized, reducing greenhouse gas (GHG) emissions by using composite insulating properties of insulated concrete forms or prestressed concrete wall panels. In high-risk areas, concrete’s resistance properties enable structural designs that are highly resistant to natural disasters.

Advantages of SCMs and blended cementsThe most common supplementary cementitious materials (SCMs) used are fly ash (i.e. a coal combustion by-product from power plants and other industrial facilities), slag cement (i.e. a by-product of the iron-manufacturing process), and silica fume (i.e. a by-product of manufacturing silicon metals and ferro-silicon alloys). SCMs can be used in concrete mixes either as a separate component or as a constituent of blended cement. Binary blends contain portland cement and one SCM, portland cement and two SCMs are used to create ternary blends, and quaternary blends consist of portland cement and three SCMs.

SCMs and blended cements can offer more environmentally responsible and performance advantages for many concrete structures. The use of these repurposed by-product materials is due to several performance factors, including:• low permeability;

• resistance to chlorides and sulfates;• mitigation of alkali silica reaction (ASR);• greater strength;• lower temperatures for mass concrete; and• improved workability.Perhaps the greatest physical benefits imparted by SCMs can be seen in the properties concrete exhibits after hardening. Concrete gains strength at a decreasing rate over time, so varying the concrete mixture can significantly alter the rate and/or ultimate strength gain. Typically, using slag cement and fly ash will lower early strengths (i.e. one to 14 days), but significantly improve long-term strength development (i.e. 28 days and beyond), but this strength gain is dependent on the proportions and materials used (Figure 1). For example, Class F fly ashes tend to have a slow strength gain curve that contributes mainly to the strength beyond 28 days, whereas silica fume affects primarily the three-to-28 day strengths. Both compressive and flexural strengths can increase markedly at 28 days and beyond with the addition of SCMs.

SCMs can also significantly extend the concrete’s life by reducing the permeability of chlorides and other aggressive agents. Silica fume has a very profound effect on permeability; it can exhibit as much as a five-fold reduction. When used in the correct proportions, SCMs also effectively prevent excessive expansion due to ASR. The efficiency of slag cement in controlling damaging expansion due to ASR depends on the nature of the slag cement, the reactivity of the aggregate, and the alkali loading of the concrete.

In most cases, 50 percent slag cement is sufficient for controlling expansion in concrete with highly reactive aggregates and high alkali content. The amount of fly ash required to mitigate excessive expansion typically is in the range of 15 to 55 percent, depending on the chemical composition of the ash, reactivity of the aggregate, and the alkali loading of the concrete. Generally, Class F ashes are much more effective in controlling expansion due to ASR than Class C ashes. Silica fume can be used to control ASR; however, the amount required generally results in poor constructability. Blends of SCMs have also been shown to be effective in controlling expansion due to ASR.

Figure 1

Test results comparing lower early strengths and higher later strengths of concrete with the use of supplementary cementitious materials (SCMs).

Many of the materials used to build Nationals Park, including the slag cement, were produced locally, which helped the stadium earn LEED Silver.Photo © Nymfan9. Photo courtesy Wikipedia.

National Master Specification (NMS) states that fly ash and other SCMs:

should be considered as partial replacement of portland cement in concrete in order to reduce greenhouse gas emissions, increase the conservation of raw materials, energy, resource recovery, and reduce waste.

As such, a number of Olympic venues were built with high-performance fly ash concrete.

The LEED Gold-certified Olympic Village was used to house the competitions’ 2800 athletes. Its construction to reach LEED certification involved reducing the buildings’ environmental footprint in terms of energy efficiency, water consumption, heating, use of local materials, and reuse of any surplus. Innovative concrete materials demonstrated their added value in achieving this.

Approximately 85,630 m3 (112,000 cy) of concrete was used in the award-winning project, with specified strengths ranging from 24,821 kPa (3600 psi) for the footings and walls to 49,987 kPa (7250 psi) for the support columns and shear walls. Several formulations of a high-volume fly ash concrete (developed using tests conducted in laboratories as well as LEED assessment calculations) made a strong contribution to meeting the cost, performance, and sustainability requirements. Maximizing recycled content, including 35 to 50 percent fly ash replacement of cement in the concrete, was a key strategy to achieve LEED certification.

With eight complexes distributed over a 36.4-ha (90-acre) former industrial waterfront property, the 55,741.8-m2 (600,000-sf) village containing over 600 dwelling units has now become Millennium Water—a fully integrated, socially inclusive community that will be home to 16,000 people. By

Across all sports and levels of play, high school, collegiate, and professional teams are increasingly setting high standards for sustainable design of stadiums, arenas, and ballparks, such as Kaufman Stadium in Kansas City.

Blends of slag cement and silica fume, as well as blends of fly ash and silica fume, seem to have a synergistic effect in mitigating expansion due to ASR, while producing a very workable concrete.

While the performance benefits of SCMs to plastic and hardened concrete are quite numerous, their effect on the worldwide trend toward more sustainable construction practices will continue to increase. High-performance blends represent a class of cement that can help designers and builders achieve stronger, more durable, longer-lasting structures, and they reuse by-products from other industries normally destined for landfills. They reduce use of nonrenewable natural resources, energy consumption, and GHG emissions. These environmental benefits are increasingly important to project developers and owners.

Building green with LEEDThe Leadership in Energy and Environmental Design (LEED) initiative has become the widely adopted guide for the design and construction of environmentally responsible structures. Concrete can contribute many points on a sustainable building project using the LEED system. For structural elements and pavements, concretes containing SCMs contribute to LEED credits in the following categories:• Sustainable Sites (SS);• Energy and Atmosphere (EA);• Materials and Resources (MR);• Indoor Environmental Quality (IEQ); and• Innovation in Design (ID).In the United States, nine professional sports stadiums have been granted LEED certification and at least five more professional organizations are considering going for a rating.

Many more green upgrades for professional sporting facilities are also in the works, along with new construction like a baseball stadium for the Florida Marlins and an $800-million sustainable stadium in Los Angeles in an effort to lure a professional football team back to the city.

Professional teams are not the only ones building sustainable structures. Seven other university and private sports facilities have earned LEED certification, including Penn State’s Medlar Field at Lubrano Park and the University of Minnesota’s TCF Bank Field. These are only a few of the teams implementing sustainability policies and realizing the many benefits that greener stadiums can produce. To date, according to USGBC, 139 sporting arenas have applied for LEED certification or are in the process of doing so.

Fly ash—a gold medal at the Winter OlympicsThe push to make each successive Olympics more environmentally responsible than the last has practically become a medal-worthy event itself, and the 2010 Winter Olympics hosted by Vancouver was no exception. Canada’s

design, LEED-certified sustainable buildings have operational efficiencies that make the facilities less expensive for the community to operate as a legacy to be enjoyed for generations. Now being hailed as the greenest in the world, Millenium Water is only the second neighborhood ever to achieve LEED Platinum certification.

Slag cement—a hit with Major League BaseballAs the demand for environmentally responsible design and building practices continues to grow, slag cement is making a strong contribution to the construction and renovation of sustainable sports facilities.With research and development efforts, this high-quality, innovative product has become a key ingredient in high-performance concrete used in such projects as:• Oriole Park at Camden Yards;• Washington Redskins’ FedEx Field;• Baltimore Ravens’ M&T Bank Stadium; and• Wells Fargo Center (home of the Philadelphia 76ers and Flyers).Engineered for long-term durability, the slag cement is widely specified to help achieve greater strength potential, reduced permeability, and increased resistance to chemical attack in concrete. It is also a strong contributor to sustainable design, as using slag cement in concrete saves virgin raw materials, consumes less energy, and makes use of an industrial by-product material that might otherwise be disposed of in landfills. The result is high-performance concrete with an extended service life, lower lifecycle costs, and less environmental impact.

Constructing green facilities for MLB, and professional sports in general, marks a watershed in the history of the sustainable construction movement. The league’s Nationals

Maximizing recycled content, including 35 to 50 percent fly ash replacement of cement in concrete, was a key strategy to achieve LEED certification of Vancouver’s Olympic Village.Photos courtesy Lafarge

Park in Washington, D.C., and recently renovated Kauffman Stadium in Kansas City, Missouri, are just two examples of ballpark construction projects that relied on slag cement to achieve durability and environmental goals.

With panoramic views of the Anacostia River and the U.S. Capitol, the $611-million Nationals Park is the first MLB stadium to earn LEED certification. To earn its Silver rating, the Washington Nationals’ baseball stadium—a 97,550-m2 (1,050,000-sf) facility with a seating capacity of 41,546—features numerous environmentally responsible elements, including high-efficiency lighting, low-flow plumbing fixtures, low-emitting finishes, a 585-m2 (6300-sf) green roof, and building materials with high levels of recycled content.

Many of the project’s construction materials were produced locally, including the slag cement that was used in all of the structural concrete and some of the architectural concrete. In addition to its sustainability benefits, the cement was selected to enhance the hardened and plastic characteristics of the concrete delivered to the job, and it provided the contractor with a consistent, high-quality concrete with excellent placing and finishing properties. The result is a beautiful ballpark that is respectful of its environment and will stand the test of time.

Even some of the more mature facilities have retrofitted green additions to their existing structures. Opened as Royals Stadium in 1973, Kauffman Stadium has always been one of the crown jewel ballparks of MLB. Slag cement played a key role in the recent multi-year major renovation of the stadium, home to the Kansas City Royals baseball team. The facility, which has a capacity of 40,775 seats, was renovated to include the addition of administrative offices, new seating and suites,

Innovative ternary blend—a winning strategy for the Big HouseHigh-performance blended cement played a key role in the $226 million renovation and expansion of Michigan Stadium in Ann Arbor. The three-year construction project, which began after the last Michigan Wolverines’ home game in 2007, included preservation of the existing historic structure as well as stadium enhancements that improve the game-day experience for fans.

Known as the “Big House,” the University of Michigan football stadium is the fourth largest stadium in the world. The recent renovation and expansion project involved replacing bleachers, widening seats and aisles, adding 83 luxury boxes and 3200 club seats, and constructing a new press box, restrooms, concession areas, and concourses. Seating capacity now tops 108,000.

One of the major construction projects involved removing the existing bowl floor and replacing it with concrete containing blended cement. This contained excellent uniformity, finishability, and superior hardened properties.

The cement used was a high-performance blend of slag cement, silica fume, and portland cement. It is formulated for high strength, improved durability, and superior placing and finishing qualities. It provides performance benefits, including improved 28-day strengths, reduced permeability, higher rheology and pumpability of concrete (especially in hot weather), less concrete bleeding, and better resistance to alkali-silica reaction.

The cement blend uses less energy and reduces CO2

emissions compared to straight portland cement, helping projects earn LEED certification.

The trend is clearAcross all levels of play, teams are increasingly striving to achieve high standards in environmental design of their sporting facilities. The environmentally responsible building movement in general, and the LEED program in particular, will continue to provide a strong incentive for developing and specifying even more innovative, sustainable construction solutions.

Considering the fact concrete is the most widely used construction material, SCMs and blended cements can have a major impact on the environment. They can also help construction professionals and owners meet sustainable building objectives, as in the case of LEED.

Finding new ways to further improve environmental performance are continually being developed. In response to growing pressures to reduce the CO

2 footprint of cement,

the Canadian Standards Association (CSA) introduced a new classification of cement in 2008 (CSA A3001-08), this being portland limestone cement (PLC) containing up to 15 percent limestone.1 Limestone can be used up to this level in all types of cement, except for sulfate-resisting cements. Considerable laboratory and field testing demonstrates that PLC with up to 15 percent limestone can produce equivalent performance to a portland cement in terms of concrete strength and durability.

expanded concourses, and two new stair towers. Various new fan amenities were incorporated, including a children’s activities area, additional retail shops, a Hall of Fame building, restrooms, and concessions.

The $250-million renovation, completed by opening day last year, used a total of 16,820 m3 (22,000 cy) of concrete containing a 60-40 mix of Type I/II cement and slag cement with specified strengths of 27,579 and 34,474 kPa (4000 and 5000 psi). The higher than expected early strength gain helped the contractor remain on schedule and complete the project on time and within budget. By using slag cement, the contractor also achieved better consistency and performance from the mixes used throughout the project and met a goal percentage for recycled material.

As the demand for environmentally responsible design continues to grow, slag cement is making a strong contribution to sports venue construction and renovation, such as the Kansas City Royals’ Kaufman Stadium.

Combined for high strength and durability, a high-performance ternary blend of slag cement, silica fume, and portland cement played a key role in the renovation and expansion of the University of Michigan football stadium.

With this new class of cement, design/construction professionals can use similar percentages of SCMs (slag, fly ash, and silica fume) in their mix while also replacing 15 percent of the portland cement with limestone, compared to five percent now. As such, PLC has the potential to bring about an additional 10 percent reduction in GHG emissions associated with the production of portland cement clinker. When combined with 40 to 50 percent SCMs, the effective reduction in the CO

2 footprint of concrete is highly significant. cs

Notes1 There is currently no ASTM portland limestone cement (PLC) classification. However, PLC has been used in the United States under ASTM C 1157, Standard Performance Specification for Hydraulic Cement. Due to the recent establishment of a Canadian standard for PLC, a similar move is anticipated for the United States.

High-performance slag cement was used for the M&T Bank Stadium.

ADDITIONAL INFORMATION

AuthorAndrew Pinneke, PE, LEED AP, is the technical marketing coordinator for Lafarge North America’s cement division. In this role, his primary focus has been on sustainable construction and coordinating the sustainable construction efforts throughout the four business units of Lafarge in North America’s cement division. Pinneke worked as a structural engineer for almost a decade before joining Lafarge. He sits on the National Ready Mixed Concrete Association (NRMCA) Sustainability Committee, as well as participates in American Society of Civil Engineers (ASCE) and U.S. Green Building Council (USGBC) local and national chapters. Pinneke can be contacted via e-mail at andrew.pinneke@lafarge-na.com.

AbstractDesign professionals throughout North America are coming up with highly engineered structures combined with many sustainable

» features, and sports facilities are no exception. Many franchises are increasingly striving to achieve high standards in environmental design of their stadiums and arenas, and concrete is increasingly standing out as a responsible choice for sustainable development.

MasterFormat No.03 00 00–Concrete03 05 00–Common Work Results for Concrete

UniFormat No.A10–FoundationsB10–Superstructure

Key Words

Division 03Blended cementFly ashSlag cementSupplementary cementitious materialsSustainability

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