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Natural Aggregates—Foundation of
America's Future |
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Various
Uses of Aggregates
Growth
in Aggregates Demand
Growth
into the Next Century
Working
With Nature
USGS—Source
of Information
Special
USGS Projects
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Rocky
Mountain Front Range
Mid-Atlantic
Geology Case Study
Summary
References
Information
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Natural
aggregates, which consist of crushed stone and sand and gravel,
are among the most abundant natural resources and a major basic
raw material used by construction, agriculture, and industries
employing complex chemical and metallurgical processes. Despite
the low value of the basic products, natural aggregates are a major
contributor to and an indicator of the economic well-being of the
Nation. |
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U.S. counties producing natural aggregates.
Credit: U.S. Geological Survey |
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Various Uses of Aggregates |
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Aggregates
have an amazing variety of uses. Imagine our lives without roads,
bridges, streets, bricks, concrete, wallboard, and roofing tiles
or without paint, glass, plastics, and medicine. Every small town
or big city and every road connecting them were built and are maintained
with aggregates. More than 90 percent of asphalt pavements and
80 percent of concrete are aggregates. Paint, paper, plastics,
and glass also require sand, gravel, or crushed stone as a constituent.
When ground into powder, limestone is used as an important mineral
supplement in agriculture, medicine, and household products. Aggregates
are also being used more and more to protect our environment. Soil
erosion-control programs, water purification, and reduction of
sulfur dioxide emissions generated by electric power plants are
just a few examples of such uses. |
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Growth in Aggregates Demand |
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One way to understand and appreciate better the importance of
the aggregates industries is to look at their production in the
context of all mining. On the basis of either weight or volume,
aggregates accounted for more than two-thirds of about 3.3 billion
metric tons of nonfuel minerals produced in the United States in
1996. When coal mining is included, the amount of crushed stone
and sand and gravel produced still accounts for more than one-half
of the volume of all mining and more than twice the amount of coal
produced. In this century, the production of aggregates increased
from a modest total of about 58 million tons in 1900, when the
collection of production statistics began, to 2.3 billion tons
in 1996 (Bolen, 1996; Tepordei, 1996). The 1996 annual production
of crushed stone and construction sand and gravel was the highest
ever recorded in the United States for these mineral commodities.
It is important to note that of the total natural aggregates produced
in this century, more than one-half was produced and consumed in
the last 25 years.
Of the crushed stone produced in the United States, limestone
and dolomite account for 71 percent; granite 15 percent; and gabbro,
basalt, and diabase, also known as traprock, 8 percent. The remaining
6 percent of the crushed stone produced comprises sandstone, quartzite,
marble, calcareous marl, slate, shell, and volcanic cinder and
scoria.
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U.S. crushed stone production, by kind
of stone. Includes (in descending order of production) sandstone
and quartzite, miscellaneous stone, marble, calcareous marl,
slate, shell, and volcanic cinder and scoria.
Credit: U.S. Geological Survey |
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The production of natural aggregates is closely related to the
population and the level of industrial development of a specific
area. The major aggregates-producing States, based on 1996 data,
were Texas, California, Ohio, Pennsylvania, and Illinois, in descending
order. The 1996 U.S. per capita consumption of aggregates was 8.7
metric tons. The State per capita consumption of aggregates varied
from highs of 28.7 tons in Alaska, 20.7 tons in South Dakota, and
17.6 tons in Iowa, to lows of 3.8 tons in Connecticut and 3.3 tons
in Louisiana.
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Production of natural aggregates, crushed stone and sand and gravel,
by State.
Credit: U.S. Geological Survey |
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The production
of recycled aggregates, mostly from concrete and asphalt pavements,
has also been increasing in recent years. Replaced and reconstructed
old roads and buildings have become major sources of "recyclable
materials." In some applications, recycled aggregate can compete
with natural aggregates on price and quality. The increasing limitations
imposed on the use of landfills, as well as the higher costs imposed
on their use, are making the recycling of aggregates economically
viable. |
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Continuous Growth into the Next Century |
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As we
attempt to forecast the level of production of aggregates, we have
to look back first. During the past 25 years, production of crushed
stone has increased at an average annual rate of about 3.3 percent.
Production of sand and gravel, which until 1974 exceeded that of
crushed stone, has increased at an annual rate of less than 1 percent.
The construction of the Interstate Highway System, which became
the National Highway System, was one of the major reasons for this
growth. By using very conservative assumptions, we have projected
trends in the production of crushed stone and sand and gravel at
average annual growth rates of 1 percent and 0.5 percent respectively.
Based on these assumptions, by 2020 U.S. production of crushed
stone, which is expected to increase by more than 20 percent, will
be about 1.6 billion metric tons, while production of sand and
gravel will be just under 1.1 billion metric tons, an increase
of 14 percent. The amount of crushed stone to be produced in the
next 20 years will, therefore, equal the quantity of all stone
produced during this century, about 36.5 billion metric tons. Combined
with the projected cumulative production of sand and gravel, the
total amount of aggregates to be mined in the next 25 years will
be equivalent to almost all the mining that has taken place in
this country for these materials in the past 100 years. These projections
suggest that vast quantities of crushed stone and sand and gravel
will be needed in the future and that much of it will have to come
from resources yet to be delineated or defined. Therefore, interdisciplinary
scientific studies specifically relevant to the aggregates industry
will be needed even more in the future.
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National aggregates production in the United States with projections
to 2020, based on growth rate of 1.0% for stone and 0.5% for
sand and gravel.
Credit: U.S. Geological Survey |
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Working With, Not Against, Nature |
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Today,
we recognize that Earth's resources, however vast, are
finite. We also realize that everything we use must start with
raw materials that are grown or mined. We also understand that
wise stewardship of the environment is necessary to preserve
natural resources for future generations. To that end, the crushed
stone and sand and gravel producers have to meet all environmental
regulatory requirements, and are encouraged to exceed what the
laws and regulations require. Consequently, their work is planned
with a clear understanding of their role in conservation and
land reclamation. The results of successful reclamation projects
can be seen around the country in housing subdivisions, shopping
malls, community parks and lakes, golf courses, and wildlife
refuges.
Caring about the environment and providing essential products
are only part of today's aggregates producers' commitment
to their communities. More than 90,000 employees and their families
depend on the aggregates industries for their livelihood, and thousands
more work in related industries that use this valuable natural
resource or its byproducts.
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USGS—The Major Source of Information
on Natural Aggregates |
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For more
than 100 years, the U.S. Geological Survey (USGS) has been the
major source of information on the Nation's natural resources.
In 1996, the USGS's capabilities to provide relevant, objective,
and timely information on production, location, quality, and availability
of natural resources were enhanced by the addition of minerals
information specialists from the former U.S. Bureau of Mines. Today,
the USGS is uniquely positioned to assist Federal, State, and local
government organizations, schools and universities, private industry,
interest groups, and the general public by providing information
on the Nation's natural resources.
USGS mineral commodity specialists keep track of developments
in the U.S. and international mineral industries. Information about
the production, consumption, and recycling of minerals from U.S.
companies, mines, and mineral-processing plants is collected, processed,
analyzed, and published. Annual and quarterly reports on the production
for consumption of natural aggregates, as well as directories of
principal producing companies, are published and distributed in
print and electronic form. Most of this information is available
as printed reports and on CDROM. It can also be accessed immediately
through a fax-on-demand system, MINES FaxBack, or on the World
Wide Web. The geologic occurrences of potential sources of crushed
stone and sand and gravel that may be used as natural aggregates
in the conterminous United States are discussed in USGS Bulletin
1594 (Langer, 1988) and in USGS Circular 1110 (Langer and Glanzman,
1993).
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Special USGS Projects on Aggregates Resources
and Urban Growth Issues |
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Infrastructure,
such as roads, airports, utilities, and many other facilities,
is vital to the growth of any populated area. Much of the Nation's
infrastructure built during the 1950's and 1960's has
deteriorated. In many areas of rapid population growth, the infrastructure
is becoming inadequate, and new roads, streets, and sewage systems
must be built to meet the increased needs. Maintenance and development
of the infrastructure requires large volumes of natural aggregates.
As urban areas expand, local sources of these resources are becoming
less accessible. Resources that are unavailable locally must be
brought in from more distant sources, often at greater costs that
are passed on to the public as higher taxes or reduced services.
The successful integration of natural resource information into
land-use decisions is increasingly difficult as the competing needs
for lands and resources become more numerous, complex, and urgent.
In response to these issues, the USGS has initiated special projects
to increase better understanding of the natural resource needs
and issues of urban areas.
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Aerial view of the Suzio York Hill crushed stone quarry located near
Meriden, Conn.
Credit: U.S. Geological Survey |
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Rocky Mountain Front Range Infrastructure
Resources Project |
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In rapidly
growing areas along the Rocky Mountain Front Range urban corridor,
resource use often competes with other land uses and may be preempted
by government mandates in response to local issues. The Rocky Mountain
Front Range Infrastructure Resources Project began in 1997 and
is being conducted in the urban corridor from Cheyenne, Wyo., to
Pueblo, Colo. Initially, the project is focusing on a demonstration
area in the northern part of the urban corridor and will address
problems of sustaining the availability of infrastructure resources
(natural aggregates, water, and energy) in rapidly growing areas
along the Rocky Mountain Front Range urban corridor.
The principal goals of the project are as follows:
- Implementing a multidisciplinary evaluation of the region's
infrastructure resources.
- Determining the region's projected needs for infrastructure
resources.
- Identifying the issues that may affect the availability of
resources.
- Providing decisionmakers with tools to evaluate alternate
methods for sustaining infrastructure resources.
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Mid-Atlantic Geology and Infrastructure
Case Study |
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Sand and
gravel and crushed stone used as construction aggregates are
mined near urban and rapid-growth areas because the marketplace
is the urban environment and the materials are costly to transport.
For example, the Baltimore- Washington urban corridor is one of
the Nation's fastest growing metropolitan areas, with more
than 7 million people spread over 39 counties and the District
of Columbia. This area, with historic high levels of production
of construction materials and significant changes in resources
and urban development, is typical of the mid-Atlantic region. It
also provides insights into the likely future trends in other areas
of the Nation. Consequently, this corridor was chosen for a USGS
case study to document the regional trends in the production and
the availability of aggregates and the development of infrastructure.
The objectives of the regional case study are as follows:
- Identification of the main geologic sources and locations
of quality construction resources in the region.
- Documentation, by county, of the amount of aggregates produced
and used in the region, who produces aggregates, who uses aggregates,
and how much is consumed.
- Analysis of aggregates production and demographic information.
- Development of a regional aggregates resource demand forecasting
tool.
- Analysis of anticipated availability of aggregates as reflected
in countylevel management planning.
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Study area for the Mid-Atlantic Geology and Infrastructure Case Study
in the Baltimore-Washington urban corridor.
Credit: U.S. Geological Survey |
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Summary |
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Natural
aggregates are widely distributed throughout the United States
and occur in a variety of geologic environments, however, they
are not universally available. Some areas lack quality aggregates,
or existing aggregates deposits cannot be mined for a multitude
of reasons; but economic factors require that pits or quarries
be located near the population centers. However, residential communities
usually require that mining of aggregates be conducted far from
their boundaries.Thus, competing land-use plans, zoning requirements,
and various regulations frequently prohibit extraction of aggregates
near populated areas.
Because the demand for aggregates will continue and, most probably,
will grow in the future, provisions to assure adequate supplies
will have to be made. Long-range planning and zoning regulations
will have to take into account current and future community needs
for this valuable natural resource. All groups and individuals
will need to work together to ensure adequate community and environmental
protection, while ensuring the availability of aggregates at a
reasonable cost that will allow growth and prosperity.
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References |
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Bolen, W.P., 1997, Construction sand and gravel: U.S. Geological
Survey Minerals Yearbook 1995, v. 1, p. 703-714.
Langer, W.H., 1988, Natural aggregates of the conterminous United
States: U.S. Geological Survey Bulletin 1594, 33 p.
Langer, W.H., and Glanzman, V.M., 1993, Natural aggregate—Building
America's future: U.S. Geological Survey Circular 1110, 39
p.
Tepordei, V.V., 1997, Crushed stone: U.S. Geological Survey Minerals
Yearbook 1995, v. 1, p. 783-809.
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Information |
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More information
on natural aggregates can be found on the Internet at:
http://minerals.er.usgs.gov/minerals
http://minerals.usgs.gov/minerals/pubs/commodity/aggregates/
or by fax from MINES FAXBACK at (703) 648-4999 |
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Written
by Valentin V. Tepordei, February 1999, U.S.
Geological Survey |
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