In an effort to conserve the Earth's nonrenewable resources, green building is becoming more commonly specified. To build using sustainable designs, engineers and designers have identified concrete as a viable resource because of its strength, durability, and resource efficiency. However, the predominant raw material for the cement in concrete—limestone—makes concrete plain and gray, not the ideal look desired for most buildings. Instead contractors must take a new and creative look at this well-known building product. By coloring or adding decorative elements to the mix, the decorative possibilities increase.
Green basics
Sustainable or green construction is not just a buzz word, it is here to stay. Governments have even signed on, especially for public and commercial buildings. Tax breaks are available in many states. Concrete contributes to green construction in many ways, including quieter rooms, recyclability. superior energy performance, better indoor air quality, and improved disaster resistance.
Leadership in Energy and Environmental Design (LEED) is a rating system designed by the United States Green Building Council to evaluate the environmental performance of a building. It is a credit-based system and allows projects to earn points for environmentally friendly actions taken during construction and use of a building. Detailed information on the LEED program and the certification process is available at www.usgbs.org. Certification levels include silver, gold, and the highest, platinum. Companies strive to reach one of the certification levels in order to meet sustainable characteristics, as well as obtain applicable tax breaks.
Now the use of an assortment of green concrete mixes and decorative techniques meet LEED requirements on a variety of levels.
Terrazzo concrete
Created centuries ago in ancient Rome to add beauty and variety to courtyards and villas, terrazzo flooring is one of the original recycled products utilizing waste chips from slab marble processing. Today, terrazzo continues to provide the same track record of durability and performance and typically lasts the life of the structure. This combination of low maintenance, durability, and beauty has led to a resurgence in the use of terrazzo, and it can be seen in commercial, industrial, recreational, institutional, and residential projects.
Terrazzo is a green product because it is composed of naturally occurring aggregates, post-industrial stone from slab granite and marble processing, post-consumer recycled glass or plastic, and cement or epoxy binders. And because terrazzo is manufactured onsite, it minimizes post-commercial waste and transportation costs. In addition to these pro-environmental benefits, terrazzo fits into projects that are working toward LEED certification by contributing points for Building Reuse, Construction Waste Management, Recycled Content, Local Regional Materials, and Indoor Emitting Materials.
Coastal Grand
Some shopping centers serve a local population, others predominantly tourists, and still others part-time residents. But the $200 million Coastal Grand, Myrtle Beach, S.C. is designed to appeal to all three. Named to suggest the nature of its immediate surroundings, the design also is intended to reflect the character of the area and please tourists and locals alike.
The building design reflects both the beach architecture and “low country” architecture that is known for wraparound porches and expansive windows. To capture the lure and leisure of the beach area, the coast-facing side features wood lattice, grillwork, and stucco with embedded oyster shells. The low country side of the project uses mottled brick and textured mortar joints.
The flooring was created to complement the building design. With custom molds and proprietary coloration systems, the concrete floors were imprinted and colored to resemble wood and evoke boardwalks and docks.
The seashore, surf, fauna, and fishing piers inspire the Center Court, which features a playful and bright terrazzo floor highlighting the region's natural beauty and indigenous animals. In addition to this artistic application, an open-air restaurant cluster features quarried stone and integrally colored concrete seeded with oyster shells, and Herringbone brick patterned fields set-off by 4-foot-wide bands of concrete in a stacked brick pattern. Because of the intricate terrazzo design work, the Coastal Grand project received honorable mention from the National Terrazzo & Mosaic Association.
Pervious concrete
Used since the 1970s for stormwater management—and more recently in decorative designs—pervious concrete is a mix of course aggregate, cement, and water. The mixture creates an open-cell structure with 15% to 25% being voids that allows rainwater to filter through to the underlying soil. Because pervious concrete allows rainwater to seep into the ground through the pavement, the amount of stormwater runoff is reduced and water quality is improved. By adding integral colors to the mix, pervious concrete can become a decorative element that complements other project components.
Developers also are using pervious concrete for parking lots to increase utilization of commercial properties. The land ordinarily devoted to costly stormwater management practices or compliance with maximum impervious areas ordinances can now be developed or preserved, enhancing the bottom line.
Pervious paving also contributes to enhanced air quality by lowering atmospheric heating through lighter color and lower density and decreasing the impact of heat island effects. Accepted by the EPA as an alternative to other stormwater pollution prevention best management practices, such as grassy swales and drain invert filtration systems, pervious concrete paving is eligible for LEED credits including SS Credits, Construction Waste Management, Recycled Content, and Regional Materials.
Del Sur Ranch
Designed and built with the intention of demonstrating that environmental concerns and earth-friendly ideas can be ‘stylish,' the Del Sur Ranch uses the latest technology of photovoltaic panels, energy-saving features such as low-emission windows, drought tolerant plants, and weather-based satellite controlled irrigation, and rapidly renewable resources.
The Del Sur Ranch building used recycled wood from an old barn for its flooring and the same earth-friendly approach was used in the outdoor parking lot.
Workers placed 10,270 square feet of 8½ inch custom integrally colored pervious concrete over a 6-inch class II subbase. With this alternative pavement system, the construction of the parking space contributed to the water-saving irrigation system by eliminating the interference of local hydrology and drought stress for trees and plants. Additionally, the pervious system allows rainwater to seep directly into the ground so the stormwater runoff can be reduced and water quality improved. The parking lot achieved the same structural capacity and maintenance as most traditional pavements.
Because of its earth-friendly design, Del Sur achieved San Diego's first Platinum LEED award with a point score of 59 out of 69 points.
Grass/concrete porous pavement
This cast-in-place, monolithic, continuously reinforced grass/concrete porous pavement system is constructed with colorful paving blocks designed as an eco-friendly alternative to classic building materials. It can be used as an alternative to the impervious paving method. Recently, there's been an influx of projects in the commercial building industry that incorporate this type of system as a decorative element. Landscape architects use it in their designs to soften areas in between buildings and plazas that are generally reserved for paving. The result quite often is a landscape design that provides an aesthetically pleasing space, replacing a stark landscape.
Typical applications now include emergency access areas, driveways, plazas, overflow parking areas, delivery access routes, embankments, drainage ditches, and storage areas for heavy materials and vehicles. Part of the reason for the increase in usage is due in large part to the positive environmental benefits, including controlling erosion, softening hard surfaces, reducing stormwater runoff, and meeting greenspace zoning requirements. Projects can expect to achieve LEED points for SS Credit, Construction Waste Management, Recycled Content, and Regional Materials.
Pacific Corporate Center
Twenty acres provides the setting for the Pacific Corporate Center—an office complex consisting of one 10-story building and four mid-rise buildings with three parking structures. Mike Peltz, lead landscape architect on the project, wanted to create a landscape design that would provide a special and memorable setting for the site's future tenants. Peltz sought to weave all the buildings and amenities together with enriched pedestrian paving and lush gardens.
The 6- to 10-story structures that make up Pacific Corporate Center required fire lanes to encircle the buildings, greatly compromising the landscape design Using a reinforced grass/concrete porous pavement system was the only system, besides paving, approved by the City of San Diego for fire lane access, so it was chosen to soften the plaza space while still providing the required access for the fire department.
The central spine of the landscape design is formed by an arched walkway that spans from one corner of the site to the other. The journey along the 1000-foot-long crescent shaped spine is designed to emulate a river's run from its mountainous origins, through the foothills, into the prairie, and to its ultimate end at the delta.
The site features eclectic concrete finishes and sawcuts, ranging from natural concrete with exposed seeded aggregate, antique cork colored concrete with a sandblast finish, blue concrete, architectural paving, and reinforced grass/concrete porous pavement. An example of how decorative concrete can enhance a building's design, the Pacific Corporate Center won the Concrete Flatwork Project of the Year Award from the American Concrete Institute.
Architectural concrete paving
The structural properties of reinforced concrete can be combined with the aesthetic quality of exposed aggregate concrete finishes surface seeded with select aggregates such as granite, recycled glass, marble, pebbles, and shells to create beautiful architectural concrete paving systems.
A system like this is superior to veneer-type paving finishes such as granite, slate, tile, and brick because the process consists of a single, structural monolithic placement, making delimitation of the paving surface nonexistent, increasing longevity, and reducing future maintenance costs. Because recyclable materials are used, projects can achieve LEED points for SS Credit, Construction Waste Management, Recycle Content, Regional Materials, and Low-Emitting Materials: Paints & Coatings.
National City Library
When Carrier Johnson set out to find a flooring finish to complement their design for the new National City Library in National City, Calif. The original choice was terrazzo, however, it turned out to be too expensive for the budget, but they still desired a finish that would offer “durability in a civic presence.”
A high-density architectural concrete paving was chosen as a cost alternative to terrazzo. The high-density seeded exposed aggregate finish selected made a much harder, more impermeable surface while the look went along with the concept of the building.
With decorative architectural concrete bands on the exterior flatwork of the building and heavy-duty applications on the inside, the architects were able to take the same flooring they used on the exterior and continue their design within the interior of the library. The designers chose a mixture of Indonesian green rock, tumbled beach glass, pyrite, and abalone shells. The cementitious nature of the material also allowed for the inclusion of a reactive chemical stain system to create decorative bands on the interior pattern without having to create separate pours. The result is a monolithic, structurally sound, and durable surface that should serve its purpose well. The library won the 2005 AGC Build San Diego, Design-Build award.
Byron Klemaske is vice president of T.B. Penick & Sons, San Diego. For more information on T.B. Penick or to learn about decorative concrete mixes, visit www.tbpenick.com.
