Demolition and Deconstruction: Review of the Current Status of Reuse and Recycling of Building Materials. Michael Nisbet, Principal, JAN Consultants, 428 Lansdowne Ave., Montreal, Quebec H3Y 2V2 George Venta, President, Venta, Glaser & Associates, 1436 Aldercrest Court, Oakville Ontario L6M 1X3 Simon Foo, Engineering Specialist, Architectural & Engineering services, Public Works and Government Services Canada, 11 Laurier St., Hull, Quebec K1A 0S5 Abstract Reuse and recycling of the main components of residential and commercial structures appear to be making continuous progress. The benefits of reuse and recycling of waste streams from building construction and demolition include diversion of waste materials from landfill sites and reduced depletion of natural resources. Both of these benefits contribute to sustainable development within building industry. The rate of progress is not easily quantified, particularly in North America, because of a lack of reliable information. The paper compares the current information base and extent of recycling in the United States and Canada to that of European countries, which in some cases are more advanced in construction and demolition waste recycling. The paper focuses primarily on recycling of concrete and steel but also considers other materials such as non-ferrous metals, gypsum and wood. Technical and economic factors and the relevant standards that contribute to the success of reuse and recycling are identified. The technical, and other barriers are presented and the research that is underway to remove these barriers is discussed. Economic barriers include the need for rapid demolition and clearing of the site, the cost of separating the material to be recycled from contaminating materials and the relative economic advantage of disposal versus recycling. These issues and the role of the market are as a driver for increased reuse and recycling of construction and demolition waste are addressed. Introduction It is estimated that about 146 million tonnes and 11 million tonnes of construction waste are generated annually in the United States and Canada1 respectively. Approximately 42% of the total quantity generated is typically reused or recycled. By comparison, as shown in Table 1, European countries such as the Netherlands, Belgium and Denmark have achieved recycling rates between 80% and 90%.2

Table 1: C&D Waste Generated and Recycled (Summary Table)2 Member State C&D Waste

Generated (million tonnes,

rounded)

% Reused or recycled

% Incinerated or landfilled

Germany 59 17 83 UK 30 45 55 France 24 15 85 Italy 20 9 91 Spain 13 <5 >95 Netherlands 11 90 10 Belgium 7 87 13 Austria 5 41 59 Portugal 3 >5 >95 Denmark 8 81 19 Greece 2 <5 >95 Sweden 2 21 79 Finland 1 45 55 Ireland 1 >5 >95 Luxembourg 0 n/a n/a

EU-15 180 28 72 The construction and demolition (C&D) recycling / reuse (R&R) industry in North America can generally be characterized as underdeveloped in comparison to other construction related industries. This is due, in part, to the following factors:

• Lack of legislation which mandates C&D waste reduction and diversion; • Design and construction practices which preclude efficient and effective

deconstruction and / or source separation; • A lack of material recovery/reprocessing facilities (MRFs) and end-use markets

for source separated materials; • A lack of acceptance of used materials by owners, designers, contractors and

regulatory agencies; • Specified construction schedules which are too short to allow deconstruction

and/or separation to occur; • Accessibility to landfills which have low tipping fees, such as private facilities,

rural sites and landfills located in the U.S.A. Concrete constitutes more than 50% of construction waste in Figure 1 and approximately 73% this material is reused in low value applications such as fill or road sub-grade. Metals, primarily steel, are subject to high recycling rates though they constitute only

about 4% of construction waste. Less than 3% of building related waste, materials like wood, gypsum, paper, etc., was reported as being diverted for proper R&R.3

Figure 1: Institutional, Commercial & Industrial Construction C&D Waste Stream [Source: Reference 3]

52%

20%

10%

4%4% 3% 7%

concrete/rubble wood gypsum plastics metals fiberglass other

Recycling Concrete Technology of concrete recycling Plants for producing recycled concrete aggregates are similar to plants for production of crushed aggregate from other sources. They incorporate crushers, screens, transfer equipment, and devices for removal of foreign matter, as shown in Figure 2, which is a simplified flow chart of a typical plant for processing recycled aggregate from concrete debris that is relatively uncontaminated. Technical issues Recycled concrete as reused in low value applications such as fill or road sub-grade is a well recognized application. However, there are some technical concerns about the performance of concrete made with recycled aggregate. The state-of-the-art is being monitored by the RILEM’s (The International Union of Testing and Research Laboratories for Materials and Structures) Technical Committee 37-DRC on Demolition and Reuse of Concrete. A report to the RILEM Technical Committee 37-DRC, covering the period 1945-1977 concluded:4

“There seems to be reasonable knowledge of the basic engineering properties of recycled concrete, and the main penalty in its use is a slightly lower compressive strength compared with a control mix made with the original, virgin aggregate. The main field in which more information on the behaviour of recycled concrete is required is its durability. Creep, wetting expansion, and porosity all need to be examined as does the effect of aggressive solutions.”

Figure 2: Flowchart of basic plant for production of aggregate from C&D

concrete This conclusion applies to uncontaminated concrete from a known source. If recycled concrete aggregate were to be used on any scale, then the rubble from general building demolition would have to be exploited. Some progress has been made in the investigation of the effects of contaminants in the demolition debris passing into new concrete. Contaminants may be clay balls, bitumen joint seals, expansion joint fillers, gypsum, refractory bricks, chlorides, wood and other organic materials, chemical admixtures, steel and other metals, glass, lightweight bricks and concrete, weathered or fire damaged materials, industrial chemicals, reactive substances, high alumina cement concrete, etc. Studies have been made of the effect on concrete strength of various contaminants that were added independently and in various quantities to a natural and recycled aggregate.5,6 The table below shows the volume percentage of each of six common contaminants, which when added to the aggregate, gave 15% reduction in compressive strength compared with control concretes.

Dosing equipment

40 mm screen Primary crusher

40 mm screen Secondary crusher

Screens - fractions Product: recycled concrete

aggregate 0 – 40 mm

0-40 mm

0-40 mm 40-200 mm

40-600 mm

0-40 mm

Table 2: Volume percentages of contaminants that caused 15% reduction in compressive strength 5,6

Contaminant

Lime plaster

Soil Wood (Japanese cypress)

Gypsum Asphalt Paint (vinyl

acetate) Volume % of aggregate

7 5 4 3 2 0.2

On the basis of such findings, the proposed Japanese standard for the “Use of recycled concrete aggregate and recycled aggregate concrete” limits the amounts of injurious impurities contained in recycled aggregates to the values shown in Table 3.

Table 3: Allowable quantities of injurious contaminants according to the proposed B.C.S.J. standard. 5,6

Type of aggregate Plasters, clay lumps and other impurities of densities

< 1950 kg/m3

Asphalt, plastics, paints, cloth, paper, wood, and similar material

particles retained on a 1.2 mm sieve. Also other impurities of

densities < kg/m3 Recycled coarse 10 kg/m3 2 kg/m3 Recycled fine 10 kg/m3 2 kg/m3 Codes and Standards Most developed countries have standards for concrete aggregates, for example in Canada there is CSA Standard A23.1-00 and in the U.S. ASTM C33 and ASTM C125. Also, the US Army Corps of Engineers has changed its specifications and guides to encourage the use of recycled concrete as aggregate. Japan, a leader in this area, proposed B.C.S.J. standard for the “Use of recycled concrete aggregate and recycled aggregate concrete”. In addition to limiting amounts of injurious contaminants it specifies quality requirements for such aggregates and recommends the applications shown in Table 4. Table 4: Quality requirements for recycled aggregates according the B.C.S.J.

proposed standard.5,6

Test item Recycled coarse aggregate Recycled fine aggregate Oven-dry specific gravity Not less than 2200 kg/m3 Not less than 2000 kg/m3 Percentage of water absorption

Not more than 7% Not more than 13%

Lost substances in washing test

Not more than 1% Not more than 8%

Percentage of solid volume Not more than 53% -

B.C.S.J. also suggests uses for various qualities of recycled aggregate. They propose that the higher quality recycled material be used, for example in low-rise apartments, single-family residences and single-storey commercial buildings. Lower quality material could be used in foundations for concrete block construction, machinery foundations, etc. While recycled aggregate of the lowest acceptable quality could find use as foundations for wooden buildings, gates, fences, simple machinery foundations, and slabs on grade. Economics The capital investment in equipment to produce aggregate from recovered concrete is similar to that needed to process aggregate from natural sources. The competitiveness of recycled aggregate depends on its processing compared to that from natural sources. The economic aspects of recycling of concrete have been analyzed in a number of US, German and Dutch studies.1 Based on these studies, the RILEM report 4 draws the following conclusions:

1. Abundant and constant supply of demolition rubble; 2. High dumping costs for demolition rubble; 3. Easy access for heavy trucks; 4. Suitable industrial land available, preferably next to sanitary land fill; 5. Inaccessibility or scarcity, and therefore high cost of good quality natural sand

and gravel or crushed stone; 6. Ready market for the products.

The extra cost for preparation, processing, inspection, storage, and sale of recycled aggregates may result in their production cost being higher than conventional aggregate. The landfill charges for demolition debris can make the difference between competitiveness of the recycled concrete aggregate and gravel or natural crushed stone. Production costs of marketable recycled demolition rubble depend on the required quality of the material produced. The least expensive is the aggregate produced by a mobile plant on the demolition site, where the product is only intended for use as fill or for road construction purposes. The U.S. study indicates that in order to realize economies of scale, a plant should process at least 110 – 275 tons of debris per hour, and in order to produce a reasonable return on investment, the plant should process and sell no less than 200,000 tons of recycled aggregate per year. This implies that urban areas of at least 1 million people are needed to support the operation of a concrete recycling plant in the United States. There are no reasons to believe that this requirement would be substantially different in other industrialized countries. In order to be competitive for concrete production, however, it appears that in the Netherlands recycled aggregates would have to sell for approximately 25% less, instead of 50% more than natural gravel to compete with natural gravel for concrete production. For comparison, in the U.S. it was found that for recycled aggregates to be competitive

there, they would have to sell for at least 50% less than natural gravel to compete on equal terms with natural gravel for concrete production. Incentives and barriers Economics Recycling of concrete waste is only attractive when the recycled product is competitive with natural resources in terms of quality. Because of concern over quality, buyers may demand that the price of recycled aggregates be considerably lower than that of the natural materials. Qualification of recycled materials There are no major technical barriers. Demolition and crushing techniques for production of recycled concrete aggregate are well known and based on existing technologies. However, changes in the demolition process to include sorting of the deconstructed debris on site, are required. Research and development No barriers exist due to lack of technical and engineering knowledge of recycling and Reuse of clean, unpolluted building and demolition concrete waste is technically proven. However, research and development is still needed into the treatment of contaminated building wastes. Education and information Use of recycled concrete from building and demolition waste is tied to an understanding of the problems, challenges and opportunities. Therefore, education and information within all parts of the industry, including architects, design engineers, specifiers, building inspectors, contractors, building owners, regulators and the general public, is urgently needed. RECYCLING AND REUSE OF STEEL AND NONFERROUS METALS FROM BUILDING CONSTRUCTION AND DEMOLITION WASTE Metals in the construction industry Construction materials are the single largest use category for steel, accounting for over 13% of steel products shipped.7 Modern building construction, industrial, commercial and institutional, and residential, is using metals for improved performance, durability and appearance. The construction of huge industrial assembly plants would not be possible without using steel columns, girders and plates. In recent years, steel studs have been gradually replacing a substantial portion of wood studs as structural framing elements in residential housing construction as well. Steel is also readily recyclable material because it can be separated from other solid wastes magnetically, and a large part of steel production in Canada, the USA and other developed countries comes from the remanufacture of recycled steel and iron. A number of nonferrous metals have found wide application in the building industry. Aluminum is used in window framing as well as cladding in both residential and

industrial, commercial and institutional buildings. Copper, is used in wiring and as the main component of water distribution networks, while lead piping was often used in older plumbing systems. Zinc is used in steel galvanizing as well as in brass alloys. Nickel is used in production of stainless steel. Other nonferrous metals are also used to produce various alloys and to modify / improve the properties of steel. All of these metals used in the construction industry enter the waste stream. Wastes are generated to a relatively small extent in the construction stage, and in larger quantities on demolition. While metals constitute only about 4 to 5% of construction waste, as shown in Figure 1, they represent one of its most valuable parts. A major attribute of ferrous and nonferrous metals is that they can be recycled indefinitely without any loss of their properties. Metals recycling technologies are well developed and practiced. Recycling is a significant factor in the supply of many of the key metals. Recycling provides environmental benefits in terms of energy savings, reduced volumes of waste, and reduced emissions. These reductions, in turn, result in reduced disturbance of land, reduced pollution, and reduced energy use. C&D STEEL RECYCLING The steel industry recycles millions metric tonnes per year of steel cans, automobiles, appliances, construction materials, and other steel products. The processing of scrap requires much less energy than the production of iron and steel products from iron ore and diverts material from landfill. While the primary source of scrap steel is the automobile, C&D steel waste represents a major source of iron and steel scrap as well. In the late 1990s, the Canadian crude steel production was about 15.5 million tonnes, while the U.S. raw steel production was in the vicinity of 98 million tonnes. The overall recycling rate of steel products in North America over the 1988 – 1999 years has been in the 63.8% to 68.5% range, the highest of any material.8, 9 Recycling of C&D Iron and Steel The current volumes of the C&D steel waste that are recovered and recycled, according to statistics from the Steel Recycling Institute (SRI), are 95% for the structural steel beams and plate, but only 45% for the reinforcement bar (rebar). A barrier to higher rates of recycling of rebar is the difficulty of removing concrete debris adhering to the surface of the rebar. The reasons for the steel industry not using concrete-contaminated rebars are twofold, both technical and economic. The presence of concrete debris can affect the ceramic refractory lining of the steel furnace and shorten its lifespan, thus causing early furnace shutdown and capital expenditure of its rebuilding. On the economic side, as the industry is buying the scrap iron and steel by weight, understandably it does not want to pay for the weight of the concrete waste still attached to the reinforcing bar. The SRI position is that: “Recycling of rebar is predicated on the actual physical recycling of the concrete in which it is encased. A good clean scrap rebar product must be recovered from the concrete crushing operation or a steel mill will reject the material. The driving force behind concrete recycling is the cost of C&D landfill, which varies

significantly. Making the rebar clean enough for recycling is driven in the same way although in some cases there may also be some legislative forces in play.” C&D and other Steel Sources Recycling Comparison The rate of structural steel recycling is high compared to steel from other sources while rebar recycling is relatively low.10

Steel cans: 57.9% Appliances: 77.3% Automobiles: 91.2% Structural construction beams and plates: 95% Reinforcement bar and others: 45%

It is clear that while significant improvements can be made in the recovery and recycling of the rebar, recycling of the structural construction elements is already the highest in the steel scrap industry, higher even than that of automobile scrap. Steel Recycling Technologies The steel industry in Canada and the U.S.A. has been recycling steel scrap for more than 150 years. There are two well-established processes for making steel. The basic oxygen furnace (BOF) process, which is mainly needed to produce the steel required for packaging, car bodies, appliances and steel framing, uses a minimum of 25% but not more than 30% of recycled steel. The electric arc furnace (EAF) process, which is used primarily to produce steel shapes such as railroad ties and bridge spans, as well as steel plate, rebar and structural beams, uses virtually 100% recycled steel. Due to this difference in the recycling capability of the BOF and EAF processes, the North American steel industry is gradually changing. In 1996, BOFs were used to produce 57% of total steel in the U.S., while using only 22% of the total scrap consumed. During the same period, EAFs produced 43% of total steel, while using 64% of total scrap consumed. Three years later, in 1999, EAF steel made primarily from recycled ferrous scrap was already 46% of the total steel produced. Energy and Materials Savings For the steel industry, using old steel products and other forms of ferrous scrap to produce new steel lowers a variety of steel-making costs and reduces the amount of energy used in the process. That is why more than 72 million tonnes of steel scrap is annually recycled in North America. More steel is recycled than paper, aluminum, glass and plastic combined. When one tonne of steel is recycled, 1.3 to 1.5 tonnes of iron ore, 700 kg of coal or 3.6 barrels of oil, and 60 kg of limestone are conserved. The benefits of iron and steel recycling are huge in terms of recovered resources and reduced environmental effects. The estimated benefits of using recycled iron and steel instead of virgin iron ore to produce new steel are:11

• 74% savings in energy; • 90% savings in virgin materials use; • 86% reduction in air pollution; • 40% reduction in water use; • 76% reduction in water pollution; • 97% reduction in mining wastes; and • 105% reduction in consumer waste generated.

C&D NONFERROUS METALS RECYCLING Nonferrous metals, mainly aluminum and copper, and to lesser a degree also lead, zinc, tin and nickel, are essential to the modern building industry. Aluminum is used as cladding on many residential houses as well as on ICI buildings. Anodized aluminum is a primary material for the construction of windows and doorframes from prestigious institutional and commercial projects down to residential housing developments and single occupancy dwellings. Copper, due to its excellent conductive properties, is used for power and telecommunication cable and wiring, as well as water distribution networks. Tin and lead are the primary components of soldering alloys, and the now discontinued use of lead for pipes is centuries old. Other nonferrous materials are used, their primary application being in alloys and/or for modification of steel characteristics (zinc, nickel). As such, all these materials find their way into the construction and demolition waste streams, and more and more of them are being reused and recycled. The following are the percentages of U.S. raw material needs supplied by commonly recycled nonferrous metals:12, 13

Aluminum 39.0% Copper 35.1% Lead 66.8% Zinc 26.1%

Besides conserving virgin materials and landfill space when nonferrous metal waste is recycled to make new products, the amount of energy required to produce them is also greatly reduced. Estimated energy savings for the four of the most recycled nonferrous metals achieved by manufacturing products with their scrap are significant:13

Aluminum 95% Copper 85% Lead 65% Zinc 60%

Aluminum Use and R&R Aluminum is a comparatively new metal that has been produced in commercial quantities for only 100 years, but second only to iron and steel in world consumption today. The building and construction industry is the third largest market for aluminum, ranking

behind containers / packaging and transportation. While it was not always the case, today, it is the most recycled nonferrous metal. The primary driver for aluminum recycling is the energy savings associated with its reuse. Embodied energy of aluminum produced from the bauxite ore is very high, up to 240 MJ/kg. The aluminum industry accounts for 1.4% of the total global energy consumption. Aluminum produced from recovered scrap and recycled aluminum rather than bauxite ore saves up to 95% of the total energy consumption. It is the used (aluminum) beverage cans (UBC) scrap that it the success of the industry, accounting today for approximately one-half of all old aluminum scrap consumed in the U.S. According to industry statistics, 62.8 billion cans were recycled in the U.S.A. (and that includes Canadian imports) during 1996. The recycling rate, based on the number of cans shipped during that year, was 63.5%. Based on these numbers, it is estimated that aluminum beverage cans produced in 1996 had an average 51.6% postconsumer recycled content, the highest recycled content percentage of all packaging materials.14 Aluminum C&D Waste Recycling There are very scarce data available addressing specifically aluminum C&D waste and its recycling rates. According to the AIA Environmental Resource Guide, the construction industry contributes little to the scrap aluminum supply at this time. It has been estimated that about 200 million kilograms of aluminum could potentially be available from the construction industry every year. Yet only 15% (30 million kilograms) of all construction industry aluminum is ever recovered. The problem is that the building aluminum scrap is difficult to recover economically. Often, it is “bound” into building assemblies that are difficult to separate or disassemble. Extruded shapes that are part of precast or poured concrete assemblies and components of electrical and engineered building HVAC systems are examples. Although their R&R is possible through preplanned and careful deconstruction techniques to separate the aluminum demolition waste from its contaminants, it is not common practice at this time. On the other hand, in the residential housing industry, aluminum siding is a relatively new product, used extensively for only about 25 years. Little of it has reached the end of its lifecycle yet. As houses with aluminum siding are refurbished or demolished at the end of their useful life, it can be expected that the inherent value of the metal will increase the amount of aluminum recovery, as there is very little contamination associated with aluminum siding. Copper and Copper Alloy Use and R&R Copper, perhaps the oldest metal known and used by man, still finds many applications in modern world. In construction and housing applications, the primary use of copper is in electrical and utility wires and cables, tubing, as well as HVAC and electrical motors. Water and wastewater plumbing, pipes and plumbing fixtures represent another major field. In the U.S.A. and Canada, copper recovered from all old and new refined and remelted scrap comprised about 35% and 40% of total copper supply, respectively.

There are no statistics available showing the contribution of copper and copper-alloys C&D waste to the total copper scrap quantities available and recovered. However, as similar conditions and difficulties exist for the recovery of copper from demolished structures for copper as for aluminum, discussed in more detail earlier, our estimate of the C&D copper waste being recycled would be similar, about 15%. BARRIERS AND OPPORTUNITIES FOR C&D METAL WASTES R&R Some of the reasons for the low recycling rates of steel reinforcing bars and of aluminum and copper are the same as those for other construction and demolition waste. Economics Recycling of building waste is only attractive when the recycled product is competitive with natural resources in relation to cost and quality. While the quality of new products made from recycled metal scrap is identical to the products made from virgin raw materials, the cost of collection and processing of metal scrap must be compensated for by other cost savings, such as lower energy consumption. Technical aspects of metals recycling There are no technical barriers to the use of products and materials made from recycled metals. Metal properties do not change with reprocessing and the same metal can be reprocessed multiple times. Demolition and crushing techniques for separation of metals from concrete and other debris are well known and based on existing technologies. However, some changes in the demolition process, compared with traditional demolition, such as sorting of the deconstructed debris on site, are required. CONCLUSIONS Concrete There are no major technical barriers to recycling construction and demolition concrete waste into fill applications or into recycled concrete aggregates. Plants for production of recycled concrete aggregate are not much different from plants for production of crushed aggregate from natural sources. Factors to be considered in the used of recycled aggregates for concrete production are costs arising from pre-soaking, extra inspection, and compensating for lower strength and higher creep, shrinkage, and elastic deformation. If economic conditions are favourable, the market should act as a driver for increased R&R of concrete. One of the main barriers is lack of awareness, which can be overcome by education and demonstration projects. Steel and non-ferrous metals Recycling rates for construction steel are expected to increase, not only in the developed world but also in the emerging economies. A 95% recycling rate for construction plate and beam steel from construction and demolition sites is already in the forefront of steel recycling. An increase in the recycling of the C&D reinforcing steel from the current 45%, however, will be highly dependent on the development and implementation of

modern, efficient means of separation of concrete and steel debris, as the steel industry will not use the concrete-contaminated steel waste. There are significant improvements that can be made in the recovery of reinforcing steel and non-ferrous metals. To accomplish that, the following are the steps and conditions that have to take place:

• Improved separation and recovery technologies, including preplanned, selective building deconstruction, will have to be implemented and used;

• Improved economies of metal recovery and price margin differences between the primary (virgin) and secondary (recycled) metals have to support metal recycling;

• Environmental regulations can support use of construction materials with higher recycled content through incentives.

General Planning demolition projects: A necessary condition for the recycling of building waste is careful sorting of the construction and demolition waste. Demolition has until now been regarded as a low technological process. Policies and strategies: It is important for the building industry to recognize the fact that the demolition and handling of resulting waste is an integral part of the building lifecycle. Management and handling of construction and demolition waste should be carried out by the construction industry itself. Market drivers: The progress of construction materials recycling will depend on economic factors and incentives rather than regulations. REFERENCES 1. G.J. Venta and M. Nisbet, “Waste Streams from Building Construction and Demolition, with

a Specific Focus on Concrete”, study prepared for Public Works & Government Services Canada (PW&GS), Ottawa, March 2001.

2. “Construction and Demolition Waste Management Practices and Their Economic Impacts”, a study prepared by SYMONDS Group (UK) in association with ARGUS (Germany), COWI Consulting Engineers and Planners (Denmark) and PRC Bouwcentrum (the Netherlands) fro The European Commission, 1999.

3. “Construction and Demolition Waste in Canada”, prepared by SENES Consultants for Environment Canada, Ottawa, 1993.

4. P.J. Nixon, “Recycled Concrete as an Aggregate for Concrete – a Review”, RILEM TC-37-DRC. Materials and Structures (RILEM),65,(1977).

5. Proposed standard for the use of recycled concrete aggregate and recycled aggregate concrete, Building Contractors Association of Japan (B.C.S.J.), Committee on Disposal and Reuse of Construction Waste, 1977 (English version published in June 1981).

6. T. Mukai et al., “Study on Reuse of Waste Concrete for Aggregate of Concrete”, presented at a Seminar on Energy and Resources Conservation in Concrete Technology, Japan-US Cooperative Science Program, San Francisco, 1979.

7. G.J. Venta and M. Nisbet, “Reuse and Recycling of Steel and Nonferrous Metals from Construction and Demolition Waste”, study prepared for Public Works & Government Services Canada (PW&GS), Ottawa, March 2001.

8. “Recycling- Metals”, 1996, U.S. Geological Survey-Minerals Information, Reston, VA. 9. “Iron and Steel Scrap”, 1999, U.S. Geological Survey-Minerals Information, Reston, VA. 10. “Fact Sheet”, Steel Recycling Institute, Pittsburgh, PA, 2001 11. “Recycling Scrap Iron and Steel”, Institute of Scrap Recycling Industries, Inc. (ISRI),

Washington, DC, 1993. 12. “Recycling-Nonferrous Metals”, U.S. Department of the Interior, Bureau of Mines,

Washington, DC, December 1995. 13. “Recycling Nonferrous Scrap Metals”, Institute of Scrap Recycling Industries, Inc. (ISRI),

Washington, DC, 1993. 14. “Recycling”, The Aluminum Association, Inc., 2001.