Concrete goes green
New mix designs make ready-mix good environmental steward
From the cement plant to the onsite pour, concrete is being embraced by the construction industry as the environmentally friendly, green alternative to other products.
Throughout the South Central region, industry groups are recognizing contractors that strive to exceed current environmental standards and are offering training for contractors interested in up-to-date applications.
“We all want to be good stewards of our environment,” says Tom Carter, vice president of environmental health and safety with the Portland Cement Association’s Washington, D.C. office. “In terms of business, more and more people are looking at the life cycle of products and making decisions based on whether products are green or not. We as an industry are trying to spread the word on what we are doing to reduce negative impact.”
In May, PCA presented Holcim in Theodore, Alabama with its Industry Energy & Environmental Award for going above and beyond on environmental standards in two categories. The plant took first place in the outreach category and was recognized as a finalist for environmental performance, the category it won in 2005.
After Hurricane Katrina Mississippi received emergency federal funds to rebuild the two U.S. Highway 90 bridges over Biloxi and St. Louis bays. The two projects, at a combined cost of $604.8 million, represent the first design-build and two of the largest bridge projects MDOT has ever tackled.
“We still have some emergency repairs to do on Hwy. 90 in Harrison County, and we will be letting four contracts TheLocated on the Theodore Industrial Canal, Holcim had historically discharged as much as 88 million gallons of water annually into the canal. But in 2006 the plant began utilizing stormwater as cooling/conditioning water in its production process, reducing its reliance on city water and eliminating all canal discharges.
The Theodore plant also increased its use of alternative fuels by 53 percent and installed a selective non-catalytic reduction system in October, leading to a significant reduction in emissions.
The United States accounts for one-fourth of all greenhouse gases in the world, and the PCA is trying to do whatever it can to reduce manufacturing emissions of carbon dioxide, Carter says. Yet, he emphasizes that the problem requires a global solution, with participation by all manufacturing countries.
“One of the things we don’t want is regulation that will shut down or stymie growth in the U.S. cement industry, particularly regarding greenhouse gas emissions,” Carter says. “If you do that, two things will happen. People will just ship it in from other countries where emissions are higher and transportation costs are higher, thereby increasing emissions globally. You also run the risk of discouraging use of concrete in building, losing that opportunity to save on energy efficiency and the lifetime of the building.”
He adds the benefits of the product far outweight the negative impacts.
“Studies show that vehicles get better gas mileage on concrete than they do on asphalt,” he says. In metropolitan areas, concrete offers the added benefit of reflecting sunlight, reducing heat and consequently, reducing overall energy costs.
“A study in Atlanta found that if all the asphalt roads were replaced by concrete, the ambient temperature in the summer would drop by seven degrees,” Carter says. “Imagine how much energy that would save, how many emissions went into cooling that many houses and offices in Atlanta.”
He adds that concrete is also an important part of green buildings because it is a good insulating material and can be designed to manipulate the way light comes into a building.
Concrete’s excellent thermal storage characteristics allow it to heat up and cool off slowly, stabilizing the interior temperature of buildings, says Ted Fery, a partner for the southern region of VOA Associates Inc., a design firm in Orlando, Fla.
That aspect of concrete hasn’t traditionally been considered in the energy-efficiency equation, says Fery, whose firm designs LEED-certified buildings, including the recently completed Integrated Operational Support Facility at Maxwell (Gunter) Air Force Base in Montgomery, Alabama.
The $12 million building incorporates “green” strategies using sustainable techniques and materials to qualify for a total of 28 LEED points, a high level of energy efficiency that is becoming the norm for government buildings, Fery says.
“We have been seeing this as the minimum standard for almost every occupied building that we have been doing for the Department of Defense for the last several years,” he adds.
Concrete is only one component among many that are engineered together to make a structure environmentally friendly and energy efficient.
“The most challenging aspect of the green strategies is the coordination of the different engineering disciplines to achieve the lowest energy consumption along with the certification process to prove that each and every point was truly achieved,” Fery says.
Because it’s new, green building poses some challenges to the construction industry, but Fery says he is certain it will become as standardized as other, existing building codes.
“It is already becoming part of building codes through several other building standards such as the American Society of Heating, Refrigerating and Air-Conditioning 90.1 Energy Standard for Buildings, which defines a minimum standard for energy consumption for mechanical and electrical systems used in modern buildings,” he says.
Bear Brothers, Inc., the Montgomery contractor that joint ventured on the Maxwell (Gunter) Air Force Base project with VOA, says that building green is a simple enough matter of doing what it always does - build according to specifications.
Even though special materials and processes were necessary to make the IOS facility at Maxwell energy efficient, the primary challenge for Bear was meeting the criteria for waste disposal, says Rush Stallings, project manager.
“We’ve been used to recycling steel, but not boxes and concrete,” Stallings says. The contractor placed numerous dumpsters onsite to separate and store materials for recycling and was tasked with locating recyclers.
South Central contractors are also catching on to the fact that parking lot and road surface environmentally friendly applications will become increasingly popular and are trying to stay ahead of the learning curve.
In April, the Arkansas Ready-Mix Association hosted its first pervious concrete contractor certification course, has another scheduled for July 24 and plans to conduct the one-day seminar on an as-needed basis, says Rita Madison, executive director.
The association has been holding presentation seminars and promoting pervious concrete for years but recently began offering courses approved by the National Ready Mixed Concrete Association.
“The use of pervious is really taking off because architects and engineers are seeing on the national level the benefits and I want to make sure that Arkansas contractors and ready-mix suppliers are able to get the work,” Madison says.
Pervious concrete is an EPA best management practice that is used to control stormwater runoff. A pervious mixture includes controlled amounts of water and cementitious materials that form a thick, pasty coating around aggregate particles, creating a system of highly permeable, interconnected voids that drains quickly, according to the NRMCA.
Pervious is slow and stiff, takes a lot of work to get out of the truck and requires different tools, says Shauna Young, salesperson with Smith’s Ready Mix, the concrete producer for a pervious mix job in Hot Springs, Ark.
“You have to have the proper void spacing, so when you consolidate there is space for the water to run through,” says Young, adding that “placement is everything.” Because it’s not finished like regular concrete, contractors have the tendency to want to seal it off and make it look nice and neat, she says.
Brian Cook, owner of Ozark Patterned Concrete of Lowell, Arkansas, was one of the first to sign up for the certification training.
“Green building is becoming the trend, and you’ve got to be cutting edge to stay competitive,” says Cook, whose company delivered 230,000 square feet of decorative concrete last year to its primarily residential customer base. “I have one builder in particular that is marketing himself as green,” Cook says. “We have a little slow down in housing and that’s his approach, to make a niche out of being a green builder.” >>
Cook says he is looking forward to the pervious concrete training as a way to branch out more into commercial construction, at least as a consultant, if not the builder. “Before I signed up for the class, I talked to my concrete salesman and he said he is seeing more and more pervious,” he adds.
In spite of the nationwide sluggish residential building market, a lot of concrete home builders are opening up shop in New Orleans, where an estimated 200,000 homes will be rebuilt in the coming years. Global Green USA has set up an office there in an effort to guide standards for rebuilding more energy efficient and green housing than what was damaged or destroyed in the 2005 hurricane season.
“We have a resource center here with product boards, project information, cost information and manufacturers lists to help individual homeowners, residential builders and architects,” says John Moore, Global Green program assistant. “We do have some examples of concrete-built homes in our office.” Building with concrete increases strength and durability, as well as diverts possible components, like fly ash, from the landfill stream, Moore says.
“That’s why we support Green Sandwich (Technologies of North Hollywood, Cal.) and companies that do insulated concrete forms or structural concrete insulated panels to sustain high R values under high pressure winds and resist water.”
Roadbuilding. It’s no news to road builders that concrete is greener than asphalt because of its greater strength and durability, lower maintenance and fuel resistance.
The increase in the cost of petroleum products has made concrete even more appealing for roads.
“It’s been cost competitive with asphalt for several years now, but it’s even a better bargain because we can get it 6-10% cheaper than asphalt in some areas,” says Al Crawley, director of the Mississippi chapter of the American Concrete Pavement Association.
It is especially competitive for contractors willing to apply concrete using the roller compacted, or RCC, method.
“In Mississippi, regular paving grade asphalt installed will be $55-65 a ton, and that translates into $130 a cu yd,” Crawley says.
RCC has been an option for at least two decades, but its use was confined to heavy industrial applications like ports, where contractors use the expensive, high-density pavers required for installation.
“We haven’t had all the pieces of the puzzle,” Crawley says. “We’ve had people wanting it, but didn’t have contractors to place it and producers to make it.” Roller compacted concrete is difficult to make in a regular concrete truck because it’s very dry and hard to get out, Crawley says. Concrete trucks can’t carry as big a batch, so contractors are forced to use a central mix plant.
Contractors in Mississippi and Tennessee got “jazzed up” about RCC, thanks to a shoulder project in Georgia in 2004 on the Interstate 285 loop around Atlanta, says Lori Tiefenthaler, executive director of the Southeast Cement Association.
“They milled it on Friday, placed road compacted on Saturday and opened it on Sunday.” Both the Mississippi and Tennessee chapters of SECA conducted RCC demonstration seminars recently to get the word out to interested contractors.
The Chattanooga (Tenn.) Public Works Department started 2007 by placing more than 4,200 sq yd of RCC, which was recognized by Chattanooga officials as the economical solution for some of their public works facilities, as well as heavy industrial access routes.
“We think it’s the wave of the future,” Crawley says. “We’ve got the right ingredients here to make it work for small and medium-sized projects, and we’re excited about promoting it.”
Since highway department budgets seem to be tight everywhere, pavement rehabilitation is “really hot,” says Bill Davenport, vice president of communications for ACPA. “We are seeing state departments of transportation making funding go as far as they can,” Davenport says. “In a healthier economic climate, you may see more new construction or large-scale reconstruction, but given funding challenges, we are seeing a lot of pavement preservation contracts going on now.”
In response, the ACPA recently published a field reference manual guide to assist contractors in common repair and preservation techniques for concrete pavements, including joint and crack sealing, dowel bar retrofit, cross-stitching, full-depth repair, partial-depth repair and diamond grinding.