PITTSBURGH, Pa. – Members of the Portland Cement Association announced the latest effort by their industry to significantly reduce emissions and provide key environmental benefits by proposing a change in the manufacture of portland cement. Tom Chizmadia, PCA board member and chairman of the association’s Environment and Energy Committee, outlined PCA’s proposal to allow for the inclusion of up to 5 percent ground limestone in the portland cement standard designated as ASTM C 150.

Speaking to the press gathered at the Greenbuild Conference and Exposition, Chizmadia underlined the importance of this change, “Such reductions could add significantly to the environmental gains already achieved by the cement industry, and are clearly in line with the nation’s global climate policy goal of reducing greenhouse gas emission intensities.” Chizmadia added, “with the addition of ground limestone, our industry can provide the same quality product as we do under current ASTM standards.”

The proposed change would bring U.S. standards into harmony with those used in both Europe and Canada where the addition of limestone has been used successfully for decades. The environmental benefits include a reduction in use of raw materials, reduced energy consumption, and reduced greenhouse gas emissions. Assuming 2.5 percent limestone as an estimate of the average use of limestone in practice, the annual benefits would be:

• Reduction in raw materials use of 1.6 million tons.
• Reduction in energy use of over 11.8 trillion BTUs.
• Reduction in carbon dioxide emissions of over 2.5 million tons.
• Reduction of cement kiln dust of over 190 thousand tons.

These reductions provide an opportunity for a positive and significant response to the call for voluntary reductions in greenhouse gas emissions. Carbon dioxide would be reduced by approximately 2.6 percent per ton of product produced.

Table - Annual Reduction in Natural Resources and Emissions
Resulting From Use of 2.5% Limestone in Portland Cement

U.S. Cement Industry Climate Change Program
Chizmadia reinforced the cement industry’s commitment to environmental progress by summarizing a three-part program to reduce carbon dioxide emissions per ton of product by 10 percent between 1990 and 2020. The cement industry’s plan addresses three areas:

1. Manufacturing Process – Reduced emissions through increased efficiency, decreased fossil fuel use, and greater use of alternative fuels and recycled materials.
2. Product Formulation – Formulate cements using a lower proportion of calcined materials, thereby reducing carbon dioxide emissions per unit of product.
3. Product Application – Develop and promote concrete products that provide sustainable solutions for the building, design and construction industry.

The industry’s goal is consistent with the Bush Administration’s climate change initiative, termed “Climate VISION,” to reduce greenhouse gases through voluntary industry programs.

Record of Environmental Stewardship
Highlighting past accomplishments by the cement industry, Chizmadia noted, “Through improvements in manufacturing, it now takes 33 percent less energy to manufacture a ton of cement than it did in 1975. Beginning in the mid-90s, we were one of the first industries to study the issue of climate change.”

“We developed a carbon dioxide emissions protocol and means by which to record emissions reductions through the Department of Energy’s 1605 (B) Greenhouse Gas Reporting Program. For these efforts, our industry received the EPA’s Climate Protection Award for our partnership within the EPA’s Climate Wise program.”

Noting the cement industry is eager to grow alongside the sustainable building movement, Chizmadia also introduced David Shepherd as PCA’s director of sustainable development. In this newly created position, Shepherd will communicate the energy-efficiency of cement-based and concrete products by providing technical support on environmental issues and participating in the development of sustainability standards.

Inclusion of Limestone Approval Process
In early 2003, PCA proposed a change to ASTM C150 to allow the use of up to 5 percent ground limestone in portland cement. To move a change through the ASTM system, a vote of 90 percent or greater is required. Late in October, this proposed change received 94 percent approval, thereby allowing it to move to the next level within the organization prior to adoption.

Cement Manufacturing Process – Four Basic Steps

1. Raw materials—limestone with small quantities of clay and sand—usually come from a quarry near the plant.
2. The materials are blended in the right proportions, then ground together.
3. The materials are heated in an industrial furnace—called a kiln—to form an intermediate product called clinker. Kilns reach temperatures of 1450 degrees Centigrade (2640 degrees Fahrenheit).
4. Once cooled, the clinker is ground with a small amount of gypsum in the fine gray powder known as portland cement.

About the Portland Cement Association
Based in Skokie, Ill., the Portland Cement Association represents cement companies in the United States and Canada. It conducts market development, engineering, research, education, and public affairs programs.