In a November 12 press briefing at the Greenbuild Conference and Exposition in Pittsburgh, Portland Cement Association members announced a proposal to change the manufacture of portland cement by revising ASTM C 150 in order to significantly reduce emissions and provide key environmental benefits. Tom Chizmadia, PCA board member and chairman of the association's Environment and Energy Committee, outlined the association's proposal to allow for the inclusion of up to 5 percent ground limestone in the portland cement standard designated as ASTM C 150.

Emphasizing the importance of this change, Chizmadia noted, “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.” He also confirmed that “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 in line with those used in both Europe and Canada where limestone has been added successfully to portland cement for decades. Environmental benefits of the revision include a significant reduction in each of three areas: use of raw materials; energy consumption; and, greenhouse gas emissions. Assuming an estimated 2.5 percent average use of limestone in practice, the annual benefits would be:

• 1.6 million-ton reduction in raw materials consumption;
• Over 11.8 trillion-Btu reduction in energy use;
• Over 2.5 million-ton reduction in carbon dioxide emissions;
• Over 190,000-ton reduction of cement kiln dust.

Such figures represent what would constitute 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.

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 primary 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 — Cement composition incorporating a lower proportion of calcined materials, thereby reducing carbon dioxide emissions per unit of product; and,

3. Product Application — Development and promotion of concrete products that provide sustainable solutions for the building, design and construction industry.

As outlined, the cement industry's goal is consistent with the Bush Administration's “Climate VISION,” a climate-change initiative that aims to reduce greenhouse gases through voluntary measures implemented via industry programs.

ENVIRONMENTAL STEWARDSHIP RECORD

Highlighting the cement industry's past accomplishments with respect to environmental initiatives, 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 the means 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.”

Affirming the cement industry's desire 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 promote the energy-efficiency of cement-based and concrete products by providing technical support on environmental issues and participating in the development of sustainability standards.

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.
— Information supplied by Ryan Puckett of the Portland Cement Association, 847/858-2672

Annual Reduction in Natural Resources and Emissions Using 2.5% Limestone in Portland Cement

		Per Million Tons Cement, Per 108 Million Tons Cement
Raw Materials Reduction (net)
	Limestone (tons)	7,000
		756,000
	Clay (tons)	8,000
		864,000
Energy Reduction
	Fuel (million BTU)	110,000
		11,880,000
	Electricity (1000 kWh)	1,750
		189,000
Emissions Reduction
	Particulate Matter, PM10 (lbs)	61,240
		7,014,000
	SO2 (lbs)	145,110
		15,672,000
	NOx (lbs)	145,060
		15,667,000
	CO (lbs)	25,880
		2,795,000
	Total Organic Compounds (lbs)	3,570
		386,000
	CO2 (tons)	23,570
		2,546,000
Waste Reduction
	CKD (tons)	1,820
		197,000

4 Cement Manufacturing: 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 1,450°C (2,640°F).
4. Once cooled, the clinker is ground with a small amount of gypsum to produce the fine gray powder known as portland cement.