Portland cement is the basic “glue” material in concrete. Mixed with water to create a paste, cement typically constitutes from 10 to 12 percent of the entire concrete mix. The remainder is aggregates, such as sand, gravel and stone. According to the World Business Council for Sustainable Development, “Concrete is the most widely used material on earth, apart from water, with nearly three tons used annually for every man, woman and child.” China produces about 45 percent of the world’s cement, followed by India at 6 percent and the United States at 5 percent.

The rule of thumb in the green building industry is that about one ton of CO2 is released in the production of every ton of portland cement. Worldwide, cement manufacturing contributes between 5 and 6 percent of total manmade CO2 emissions. In the United States, however, the cement industry’s aggressive efforts to reduce emissions and increase the use of supplementary cementitious materials in concrete (SCMs—primarily fly ash and slag cement) have had a positive impact. Currently, less than 1.5 percent of manmade U.S. carbon dioxide emissions are attributable the cement industry.

The cement industry has made major strides in reducing CO2 emissions and increasing the energy efficiency of manufacturing plants during the past 30 years. Since 1972, energy efficiency has increased by 33 percent to where, according to the Department of Energy, U.S. cement production accounts for only 0.33 percent of U.S. energy consumption. In 2006, the amount of energy required to produce one ton of cement averaged 4.649 million BTUs/ton, a decrease of 1.1 percent from 2005 levels. Recently, PCA member companies pledged to reduce carbon dioxide emissions per ton of product by 10 percent from 1990 levels by 2020.

Despite the progress that has been made, cement manufacturers worldwide are committed to doing more. In a 2006 interview in Concrete Construction magazine, Gilberto Perez, president of CEMEX’s U.S. operations said, “Managing sustainability is one of the greatest challenges the cement manufacturing industry faces all over the world. At the end of the day, we need to be conscious of sustainability. All of us are environmentalists, and we are living for our children and grandchildren.”

Cement Industry Activities

CEMEX plants won two awards from the PCA, for land stewardship in Davenport, Calif. (shown), and in Knoxville, Tenn., for innovations that led to reducing NOx emissions by 15 percent.

Nice words, but how is the cement industry backing that up? Many of the world’s major cement manufacturers operate around the world and have the reach and resources to make important environmental impacts. Several have developed programs to encourage environmental awareness and improvements in the industry. The following are a few of the more notable efforts.

Lafarge has developed a partnership with the World Wildlife Fund (WWF) to reduce CO2 emissions, improve quarry rehabilitation practices, and implement key performance indicators. This partnership was launched in March 2000 for a five-year period and has been renewed for a further three-year term. A part of this program is to set targets and report on progress. For example, 80 percent of Lafarge’s 800 quarries now have rehabilitation plans in place to ensure biodiversity restoration. They have also made significant progress in reducing CO2 emissions and have committed to finding solutions that will enable emerging countries to pursue their development while ensuring that the growth in their CO2 emissions is contained. “We are delighted at the success of our cooperation,” said Dr. Claude Martin, director general of WWF International. “It shows environmental groups can play a key role in working with the private sector to achieve positive change, rather than just calling for it.”

The Cement Sustainability Initiative of the World Business Council for Sustainable Development is a global alliance of 18 major cement producers who recognize that sustainable development is good business. The CSI has explored what sustainable development means for the cement industry and has identified actions cement companies can take towards that goal. The member companies have so far contributed about $6 million to develop an agenda for action and to encourage implementation.

The Holcim Foundation promotes innovative approaches to sustainable construction mainly through awards competitions and an international forum. The objective is to encourage sustainable responses to the technological, environmental, socio-economic and cultural issues affecting building and construction, both regionally and globally. The second Holcim Awards competition to promote sustainable construction is now accepting entries The prize money for the five regional competitions and the global awards totals $2 million.

Concrete Thinking, a website developed by green building consultants for the Portland Cement Association, provides solutions for sustainability issues, shows how specific concrete applications can—and have—successfully addressed sustainability, and provides an extensive library of documents on the issue. More than 40 case studies demonstrate sustainable concrete construction and interviews with leading thinkers on the topic provide insight.

Sidebar: Environmental Performance Measures

Supplementary cementitious materials. From left to right, fly ash (Class C), metakaolin (calcined clay), silica fume, fly ash (Class F), slag and calcined shale. (Portland Cement Association)

To put its commitment to sustainable development into consistent, tangible actions, PCA has developed the Cement Manufacturing Sustainability Program. The goal of the program is to balance society’s need for cement products with stewardship of the air, land and water; conservation of energy and natural resources; and maintenance of safe work places and communities. The Environmental Performance Measures translate the Cement Manufacturing Sustainability Program Principles into action. A long-term reduction target is identified for each key performance measure, and then progress toward that target is measured against a baseline. Currently, there are four goals approved by the PCA members:

Carbon Dioxide (CO2)—The U.S. cement industry has adopted a voluntary target of reducing CO2 emissions by 10 percent per ton of cementitious product produced or sold from 1990 levels by 2020.

Cement Kiln Dust (CKD)—The U.S. cement industry has adopted a voluntary target of a 60 percent reduction in the amount of CKD disposed per ton of clinker produced from 1990 levels by 2020.

Environmental Management Systems (EMS)—The U.S. cement industry has adopted a voluntary target of least 40 percent of U.S. cement plants to have implemented an auditable and verifiable EMS by the end of 2006, 75 percent by the end of 2010, and 90 percent by the end of 2020.

Energy Efficiency—The U.S. cement industry has adopted a voluntary target of increasing energy efficiency—measured as BTU per ton of cementitious product—by 20 percent from a 1990 baseline by 2020.

PCA has conducted an annual survey of members since 1970 to collect data and compare it against a baseline to measure performance toward reduction targets on energy use and labor practices. This tool has been modified to collect information on the targets identified above.

Sidebar 2: Energy & Environment Awards

Talk is cheap, but the cement industry is putting rhetoric into action. Since 2001, the Portland Cement Association and Cement Americas magazine have annually recognized those individual cement-industry facilities that “exemplify the spirit of continuous environmental improvement and back up this spirit with action.” Awards are presented for environmental performance, land stewardship, outreach, innovation, energy efficiency and overall environmental excellence.

The St. Marys Cement plant in Charlevoix, Mich., won the 2006 award for overall environmental excellence. In the past year, the plant installed a new indirect firing system that reduced both fuel consumption and emissions. It also replaced power plant fly ash with on-site shale and purchased bottom ash to reduce mercury emissions. Close to a residential area, the facility installed silencers that resulted in less noise. Working with the Michigan Department of Natural Resources, St. Marys maintained a fish-stocking program for the Chinook salmon fingerlings and worked to encourage the regional resurgence of the bald eagle by constructing nesting platforms on its property.

Other 2006 winners included another St. Marys facility in Bowmanville, Ontario, for environmental performance, and the California Portland Cement Company’s Mojave, Calif., plant for energy efficiency. CEMEX plants won two awards, for land stewardship in Davenport, Calif., and in Knoxville, Tenn., for innovations that led to reducing NOx emissions by 15 percent. Finally, the Holcim plant in Theodore, Ala., won for outstanding outreach activities.