• Introduction
• Matrix New!
• Glossary New!
• Notice

• Environmental and Engineering Evaluation New!
• State Contacts New!
• Cost Issues
• Standards/Specifications New!

• Baghouse Fines
• Blast Furnace Slag
• Coal Bottom Ash/Boiler Slag Updated!
• Coal Fly Ash Updated!
• FGD Scrubber Material Updated!
• Foundry Sand Updated!
• Kiln Dusts
• Mineral Processing Wastes
• MSW Combustor Ash
• Nonferrous Slags
• Quarry Byproducts
• Reclaimed Asphalt Pavement Updated!
• Reclaimed Concrete Material Updated!
• Roofing Shingle Scrap Updated!
• Scrap Tires
• Sewage Sludge Ash
• Steel Slag
• Sulfate Wastes
• Waste Glass

• General Descriptions
• Asphalt Concrete Pavement
• Portland Cement Concrete Pavement
• Granular Base
• Embankment or Fill
• Stabilized Base
• Flowable Fill

[ Material Description ] - [ Asphalt Concrete ] - [ Flowable Fill ] - [ Portland Cement ] - [ Embankment ]

FOUNDRY SANDMaterial Description

ORIGIN

Foundry sand is a high-quality silica sand that is used to form molds for ferrous (iron and steel) and nonferrous (copper, aluminum, brass, etc.) metal castings. The raw sand is normally of higher quality than typical bank run or natural sands used in construction.⁽¹⁾

The most common casting process used in the foundry industry is the sand cast system. Virtually all sand cast molds for ferrous castings are of the green sand type. Green sand consists of high-quality silica sand, about 5-10 percent bentonite clay (as the binder), 2 to 5 percent water and about 5 percent sea coal (a carbonaceous mold additive to improve casting finish).⁽²⁾ The term "green sand" is used because molten metal is poured into the mold when the sand is damp or "green".⁽³⁾ The green sand process constitutes upwards of 90 percent of the molding materials used.⁽⁴⁾

In addition to green sand molds, chemically bonded sand cast systems are also used. These systems involve the use of one or more organic binders (usually proprietary) in conjunction with catalysts and different hardening/setting procedures. Chemical binders include phenolic, furfuryl alcohol, and other inorganic binders.⁽²⁾ Foundry sand makes up about 97 percent of this mixture. Chemically bonded systems are most often used for "cores" (used to produce cavities that are not practical to produce by normal molding operations) and for molds for nonferrous castings.

Excess foundry sand is typically generated because varying amounts of the previously mentioned additives must continually be reintroduced to the foundry sand to maintain its desired properties, resulting in a larger volume of sand than is needed for the foundry process.⁽⁵⁾ In addition, heat and mechanical abrasion eventually render the sand unsuitable for use in casting molds, and a portion of the sand is continuously removed and replaced with virgin sand.⁽⁶⁾ The spent sand is either recycled in a non-foundry application or landfilled. Of the 6 to 10 million tons of spent foundry sand generated annually, less than 15 percent is recycled.⁽⁶⁾

Additional information on the production and use of spent foundry sand in construction materials applications can be obtained from:

American Foundrymen's Society, Inc.
505 State Street
Des Plaines, Illinois 60016-8399
http://www.afsinc.org/

Foundry Industry Recycling Starts Today (FIRST)
http://www.foundryrecycling.org

CURRENT MANAGEMENT OPTIONS

Recycling

In typical foundry processes, sand from collapsed molds or cores can be reclaimed and reused. A simplified diagram depicting the flow of sand in a typical foundry sand molding system is presented in Figure 1. Some new sand and binder is typically added to maintain the quality of the casting and to make up for sand lost during normal operations. ⁽⁷⁾

Figure 1. Schematic of foundry sand processes and material flows.⁽⁸⁾

The recycling of spent foundry sand can save energy, reduce the need to mine virgin materials, and may reduce costs for both producers and end users.⁽⁶⁾ EPA has found that spent foundry sands produced by iron, steel, and aluminum foundries are rarely hazardous.⁽⁶⁾ Despite the support from the EPA, only about 15 percent of spent foundry sands are recycled.⁽⁶⁾ This is mainly due to the lack of information on its possible beneficial uses.⁽⁹⁾ Beneficial reuse of foundry sand continues to become a more accepted practice as more end-users are introduced to the concept.

As of 2002, eighteen states had programs that regulated beneficial reuse activities for foundry sand,⁽¹⁾ most notably in Wisconsin, Michigan, Illinois, Iowa, Indiana, Minnesota, Pennsylvania, Ohio, California, Texas, and Louisiana.⁽²⁾ Other countries such as Canada, Spain, Japan, and New Zealand also beneficially use spent foundry sand.⁽²⁾ Beneficial applications of foundry sand include:

• Aggregate replacement in asphalt mixtures, Portland cement concrete.⁽⁶⁾
• Source material for Portland cement.⁽⁶⁾
• Sand used in masonry mortar mixes.⁽⁶⁾
• Embankments, retaining walls, subbase, flowable fills, barrier layers, and HMA mixtures.⁽³⁾

Currently, approximately 900,000 to 1.5 million tons of foundry sand are used annually in engineering applications.⁽⁶⁾

Disposal

Even though many states have developed beneficial reuse regulations for industrial byproducts, large quantities of foundry byproducts are still being landfilled in the United States.⁽³⁾ However, the scarcity of landfill space as well as an increase in tipping fees and transportation costs has stimulated the pursuit of beneficial reuse of the foundry sand.⁽¹⁰⁾

State Regulations and Specifications

State regulations of foundry sand reuse are guided by the concept of ensuring the protection of human health and the environment. Rules guiding foundry sand reuse vary from state to state. Some states have a single set of requirements for all industrial by-products, while others have rules specifically guiding the reuse of foundry sand. These rules typically include a requirement for risk assessment for each reuse project and/or developing general concentration thresholds for leachate and contaminants in the waste itself.⁽¹¹⁾

Links to regulations guiding the reuse of foundry sand in ten example states including: Illinois, Indiana, Louisiana, Maine, Michigan, New York, Pennsylvania, Texas, West Virginia, and Wisconsin, can be found in the State Toolkit for Developing Beneficial Reuse Programs for Foundry Sand⁽¹²⁾ published by the U.S. Environmental Protection Agency. The link to the toolkit is below.

http://www.epa.gov/sustainableindustry/metalcasting/toolkit.pdf

MARKET SOURCES

Currently, there are around 3000 active foundry operations in the United States that generate 6 million to 10 million tons of foundry sand per year.⁽⁶⁾ Ferrous industries account for about 95 percent of foundry sand used in metal casting. Spent foundry sand can be obtained directly from foundries, most of which are located in the Great Lakes region.⁽¹⁾ Foundries can also be found in Alabama, California, Louisiana, Tennessee, and Texas.⁽¹¹⁾

MATERIAL PROPERTIES

Physical Properties

Physical properties for spent foundry sand from green sand systems are listed in Table 1.

Table 1. Typical physical properties of spent green foundry sand.

The grain size distribution of spent foundry sand is very uniform, with approximately 85 to 95 percent of the material between 0.6 mm and 0.15 mm (No. 30 and No. 100) sieve sizes. Five to 12 percent of foundry sand can be expected to be smaller than 0.075 mm (No. 200 sieve). The particle shape is typically subangular to rounded. Waste foundry sand gradations have been found to be too fine to satisfy some specifications for fine aggregate. A comparison of typical grain size distributions of clean and used foundry sand in comparison with regular concrete sand is illustrated in Figure 2 below.

Figure 2. Grain size distribution for regular concrete sand and foundry sands.⁽¹⁶⁾

Spent foundry sand has low absorption, although reported values of absorption were found to vary widely, which can be attributed to the presence of binders and additives.⁽⁷⁾ The content of organic impurities (particularly from sea coal binder systems) can vary widely. This may preclude a specific foundry sand from being used in applications where organic impurities are important (e.g., Portland cement concrete aggregate).⁽¹⁷⁾ The specific gravity of foundry sand has been found to vary from 2.39 to 2.70. This variability has been attributed to the variability in fines and additive contents in different samples. ^(1;7)

In general, foundry sands are dry, with moisture contents less than 2 percent. A large fraction of clay lumps and friable particles have been reported, which are attributed to the lumps associated with the molded sand, which are easily broken up.⁽⁷⁾ The variation in hydraulic conductivity, listed in Table 1, is a direct result of the fraction of fines in different foundry sands.

Chemical Properties

Spent foundry sand consists primarily of silica sand, coated with a thin film of burnt carbon and residual binder (bentonite, sea coal, resins, etc.). Table 2 lists the chemical composition of a typical sample of spent foundry sand as determined by x-ray fluorescence.

Silica sand is hydrophilic and consequently attracts water to its surface. This property could lead to moisture-accelerated damage and associated stripping problems in an asphalt pavement. Antistripping additives may be required to counteract such problems.

Depending on the binder and type of metal being cast, the pH of spent foundry sand can vary from approximately 4 to 8.⁽¹³⁾ It has been reported that some spent foundry sands can be corrosive to metals,⁽¹⁹⁾ which can cause the deterioration of metal objects such as underground pipes, culverts, or reinforcing members. The presence of high acidity, pH of 5.5 or less, in soil is also considered a corrosive condition. Soil with a pH of 5.5 or less can react with the lime in concrete to form soluble reaction products that can easily leach out of the concrete. The result is a more porous, weaker concrete.⁽²⁰⁾

Few peer-reviewed studies have been conducted to determine organic residues in spent foundry sand or the leachates produced from spent foundry sand. It was found that all spent foundry sands contain polyaronmatic hydrocarbons (PAHs) in which naphthalene is made up about 30 percent of the PAH content.⁽²¹⁾ Laboratory studies indicate that organic compounds leach only at low concentrations.⁽²⁾ With the presence of phenols in chemically bonded foundry sands, there is a possibility that leachate from stockpiles could result in phenol discharges.^(13;17;22) Because of the high temperatures encountered during the molding process, residual organic compounds in spent foundry sands are found only in small quantities. Therefore, spent sand, after casting, typically does not contain organic contaminants above regulatory threshold levels, however, fresh casting mixtures and core sand that have not been in contact with hot metal may contain organic contaminants.⁽²⁾

Mechanical Properties

Typical mechanical properties of spent foundry sand are listed in Table 3. Spent foundry sand has good durability characteristics as measured by low Micro-Deval abrasion⁽²³⁾ and magnesium sulfate soundness loss tests.⁽²⁴⁾ The Micro-Deval abrasion test is an attrition/abrasion test where a sample of the fine aggregate is placed in a stainless steel jar with water and steel bearings and rotated at 100 rpm for 15 minutes. The percent loss has been determined to correlate very well with magnesium sulfate soundness and other physical properties. Studies have reported relatively high soundness loss, which is attributed to samples of bound sand loss and not a breakdown of individual sand particles.⁽⁷⁾ The internal friction angle of foundry sand has been reported to be in the range of 33 to 40 degrees, which is comparable to that of conventional sands.⁽⁷⁾

Table 3. Typical mechanical properties of spent foundry sand.

DESIGN CONSIDERATIONS

Although specifications for the foundry sand reuse depend largely on the application, general suggestions can be made for improved use of spent foundry sand in roadway applications. An increase in strength in highway subbases using foundry sand can be obtained in the field by compacting the foundry sand-based mixtures using higher compactive efforts. It is recommended that the subbase layer be compacted at dry of optimum for higher strength.^(9;26)

Compacted foundry sand used as a working platform and subsequently as a contributing subbase member in flexible pavement design has been studied.^{(27;26;28;29;30)} California Bearing Ratio percentages as well as regression coefficients for the power function model to calculate Resilient Modulus, MR, are shown in Table 7-3. Laboratory and case study results show that with proper design and construction, compacted spent foundry sand provides adequate support as a working platform or subbase material.^(27;26;28) Design charts for selecting the equivalent thickness of compacted foundry sand for working platforms are provided in reference 29, where a methodology for including the structural contribution of working platforms made from foundry sand or other alternative material is presented in 30.

Lime or cement treatment will have a beneficial effect on the strength of foundry sand mixtures. Addition of lime or cement will increase the unconfined compression and CBR of fully hydrated specimens.⁽⁹⁾ Moreover, foundry sand-based subbase specimens have been shown to resist winter conditions better than specimens of reference materials.⁽⁹⁾

ENVIRONMENTAL CONSIDERATIONS

Leachability

Leachate characterization suggests that foundry sand is generally safe to reuse in highway applications.^{(31;32;33;34)} Spent foundry sand often contains metals and core material containing partially degraded binder. Spent foundry sand may contain leachable contaminants, including heavy metals and phenols that are absorbed by the sand during the molding process and casting operations. Phenols are formed through high-temperature thermal decomposition and rearrangement of organic binders during the metal pouring process.⁽¹⁷⁾

Spent foundry sand from brass or bronze foundries, in particular, may contain high concentrations of cadmium, lead, copper, nickel, and zinc.⁽⁷⁾ However, studies have indicated that foundry sand is less contaminated with metallic elements than foundry dust and slag. Studies also suggest that the constituents in the bulk waste stream of foundry sand exist, but these constituents are not necessarily leachable.⁽²⁾

Five widely used standard leaching tests are outlined in Table 4.

Table 4. Extraction Conditions for Different Standard Leaching Tests.⁽³⁵⁾

A series of leachate tests conducted by the U.S. Department of Energy (DoE) including the TCLP, synthetic precipitation leaching procedure (SPLP), and shake extraction (ASTM D3987) methods indicated that leachates from foundry sand fell within the 95th percentile of metallic element concentrations, below the TCLP thresholds. Their report concluded that foundry sands are generally not hazardous.⁽³⁶⁾ In an independent study foundry sand specimens evaluated by the EPA Method 1311 and TNRCC Statistic Leaching Test Method showed that contaminants regulated by the EPA were well below regulation limits for hazardous material.⁽³⁷⁾

A laboratory batch water leach test, column leach test, and below subbase lysimeter study evaluated leachate from gray iron foundry sand. Leachates were analyzed for concentrations of cadmium (Cd), chromium (Cr), selenium (Se), and silver (Ag) and compared to groundwater quality standards for Wisconsin. Peak concentrations in the lysimeters below 84 cm of foundry sand were all above peak concentrations found from the laboratory water leach test and were above the peak concentrations from the laboratory column leach test for both Cr and Se. Peak selenium concentrations in the leachate from the field lysimeters exceeded the Wisconsin groundwater standard. However, with application of dilution factors to account for the reduction in concentration expected between the bottom of the pavement structure and the groundwater table, concentrations would not exceed the groundwater quality standards if the foundry sand layer is at least 1 m above the groundwater table.⁽³⁸⁾

The binder system is the primary source of organic contaminants in foundry sand, and green sand systems which generally do not involve organic binders have been shown to have lower potential for leaching organic compounds.⁽¹¹⁾ The primary organic contaminants from foundry sand are acetone and 1,1,1-trichloroethane.⁽¹¹⁾ In a DoE sponsored research project, it was found that most organic compounds are burned out during the casting process: 23 of the 37 organic compounds tested were 100 percent below detection limits and 7 were more than 80 percent censored.⁽³⁶⁾

Water leach tests on 12 green sands from iron casting foundries showed that leachate test results, when compared to the Wisconsin maximum permissible concentrations, which is the most stringent criteria for reuse of a material that will be placed below the water table, exceeded the limits. However, the concentrations exceeded the maximum permissible concentrations by a small amount and similar concentrations were observed in reactive medium barrier material that is commonly placed below the groundwater table for remediation of contaminant plumes.⁽³⁹⁾

Bioassay tests conducted on algae and Dapbnia (representing plant and animal life) included a mixture of pure foundry sand from a foundry in Wisconsin and deionized water produced at a ratio of 1 g of foundry sand for every 4 mL of water. The solution was filtered and the leachate used in the test. The results indicated growth inhibition and showed that in its pure form, foundry sand could be harmful to aquatic life.⁽⁴⁰⁾ However, the study concluded that environmental risks markedly decrease or disappear when the foundry sand is mixed with other materials.⁽⁴⁰⁾

Further bioassay tests conducted on 11 foundry sand samples obtained from gray and ductile iron foundries showed that seven out of the 11 foundry sands exhibited bioassay patterns which were equivalent to or better than virgin sand control samples. Four out of the 11 sands exhibited elevated bioassay response levels. The three highest levels of bioassay inhibition were observed in sands from foundries using hot box cores and chemically bound mold binders.⁽⁸⁾

Modeling

Models currently used to simulate leaching from pavement systems and potential impacts to groundwater include STUWMPP,⁽⁴¹⁾ IMPACT,⁽⁴²⁾ WiscLEACH⁽⁴³⁾, and IWEM⁽⁴⁴⁾. Examples of models in the public domain include WiscLEACH and IWEM. WiscLEACH combines three analytical solutions to the advection–dispersion–reaction equation to assess impacts to groundwater caused by leaching of trace elements from CCPs used in highway subgrade, subbase and base layers. WiscLEACH employs a user friendly interface and readily available input data along with an analytical solution to produce conservative estimates of groundwater impact⁽⁴³⁾.

The U.S. EPA’s Industrial Waste Management Evaluation Model (IWEM), although developed to evaluate impacts from landfills and stock piles, can help in determining whether leachate will negatively affect groundwater. IWEM inputs include site geology/hydrogeology, initial leachate concentration, metal parameters, and regional climate data. Given a length of time, the program will produce a leachate concentration at a control point (such as a pump or drinking well) that is a known distance from the source. In addition, Monte Carlo simulations can provide worst-case scenarios for situations where a parameter is unknown or unclear. In comparing IWEM to field lysimeter information, it was found that IWEM over predicted the leachate concentrations and could be considered conservative. Overall, however, it was found that IWEM performed satisfactorily in predicting groundwater and solute flow at points downstream from a source.⁽⁴⁵⁾ A byproducts module for IWEM will be offered by the EPA in the near future.

An excellent source for detailed information on assessing risk and protecting groundwater is the EPA's "Guide for Industrial Waste Management"⁽⁴⁶⁾ which can be found at:

http://www.epa.gov/epaoswer/non-hw/industd/guide/index.asp

According to the EPA, sands from iron, steel, and aluminum manufacturers are, in nearly all cases, non-hazardous. Sands from leaded copper-base facilities, however, may be considered hazardous for toxicity under EPA rules. Due to the general complexity in composition and character of spent foundry sand, appropriate leaching tests should be conducted on foundry sand from a particular source before reuse, although recent studies have suggested that it is not necessary to leachate and measure the full spectrum of metallic elements in the sand.⁽³⁶⁾

REFERENCES

A searchable version of the references used in this section is available here.
A searchable bibliography of foundry sand literature is available here.

1. Federal Highway Administration. Foundry sand facts for civil engineers. Federal Highway Administration (FHWA); 2004 May 2004. Report nr FHWA-IF-04-004.
2. Winkler E, Bol’shakov AA. Characterization of foundry sand waste. Chelsea Center for Recycling and Economic Development, University of Massachusetts; 2000 Report nr 31.
3. Abichou T, Edil TB, Benson CH, Bahia H. Beneficial use of foundry by-products in highway construction. In: Geotechnical engineering for transportation projects: Proceedings of geo-trans 2004, jul 27-31 2004. Los Angeles, CA, United States: American Society of Civil Engineers, Reston, VA 20191-4400, United States; 2004.
4. American Foundrymen's Society. Alternative utilization of foundry waste sand, phase I. Des Plaines, Illinois: American Foundrymen's Society Inc.; 1991.
5. Goodhue MJ, Edil TB, Benson CH. Interaction of foundry sands with geosynthetics. J Geotech Geoenviron Eng 2001;127(4):353-62.
6. Foundry Sands Recycling, EPA530-F-07-018 [Internet]; c2007. Available from: http://www.epa.gov/epaoswer/osw/conserve/foundry/index.asp.
7. Javed S, Lovell CW. Use of waste foundry sand in highway construction. Department of Civil Engineering, Purdue University; 1994. Report nr C-36-50N.
8. Bastian KC, Alleman JE. Microtox™ characterization of foundry sand residuals. Waste Management 1998 7/1;18(4):227-34.
9. Guney Y, Aydilek AH, Demirkan MM. Geoenvironmental behavior of foundry sand amended mixtures for highway subbases. Waste Manage 2006;26(9):932-45.
10. Javed S, Lovell CW. Uses of waste foundry sands in civil engineering. Transp Res Rec 1995(1486):109-13.
11. EPA, U.S. Environmental Protection Agency (EPA). Beneficial reuse of foundry sand: A review of state practices and regulations. 2002.
12. EPA, Environmental Protection Agency. State toolkit for developing beneficial reuse programs for foundry sand. Environmental Protection Agency; 2006.
13. Johnson CK. Phenols in foundry waste sand. Modern Casting 1981:273.
14. Abichou T, Benson CH. Foundry green sands as hydraulic barriers: Laboratory study. Journal of Geotechnical & Geoenvironmental Engineering 2000 12;126(12):1174.
15. Abichou T, Benson CH, Edil TB. Foundry green sands as hydraulic barriers: Field study. J Geotech Geoenviron Eng 2002;128(3):206-15.
16. Naik TR, Singh SS. Performance and leaching assessment of flowable slurry. J Environ Eng 2001;127(4):359-68.
17. Emery J, Canadian Foundry Association. Spent foundry sand - alternative uses study. Queen’s Printer for Ontario: Ontario Ministry of the Environment and Energy (MOEE); 1993.
18. Du L, Folliard K, Trejo D. Effects of constituent materials and quantities on water demand and compressive strength of controlled low-strength material. J Mat in Civ Engrg 2002 November/December 2002;14(6):485-95.
19. Emery J. Mineral aggregate conservation - reuse and recycling. Queen’s Printer for Ontario: Ontario Ministry of Natural Resources (MNR); 1992.
20. CalTrans. Corrosion guidelines. California Department of Transportation Division of Engineering Services Materials Engineering and Testing Services; 5900 Folsom Blvd., Sacramento, CA 95819, 2003. Report nr Version 1.0.
21. Ji S, Wan L, Fan Z. The toxic compounds and leaching characteristics of spent foundry sands. 2001;132(3-4):347-64.
22. Ham RK, Boyle WC, Engroff EC, Fero RL. Determining the presence of organic compounds in foundry waste leachates. Modern Casting 1989.
23. Ontario Ministry of Transportation. Resistance of fine aggregate to degradation by abrasion in the MicroDuval apparatus. Ontario, Canada: Ontario Ministry of Transportation; 1996. Report nr LS-619.
24. AASHTO. Soundness of aggregate by use of sodium sulfate or magnesium sulfate, part II tests. Washington, DC 20001: American Association of State Highway and Transportation Officials; 1999. Report nr T104-99.
25. Goodhue M, Edil T, Benson C. Reuse of foundry sands in reinforced earth structures. Madison, WI: Dept. of Civil and Environmental Engineering, University of Wisconsin-Madison; 1998. Environmental Geotechnics Report 98-12.
26. Kleven JR, Edil TB, Benson CH. Evaluation of excess foundry system sands for use as subbase material. Transp Res Rec 2000(1714):40-8.
27. Kleven JR, Edil TB, Benson CH. Mechanical properties of excess foundry sand for roadway subgrade. Madison, WI: Dept. of Civil and Environmental Engineering, University of Wisconsin-Madison; 1998. Report nr Environmental Geotechnics Report 98-1.
28. Edil T, Benson C, Bin-Shafique M, Tanyu B, Kim W, Senol A. Field evaluation of construction alternatives for roadway over soft subgrade. Transp Res Rec 2000;1786:36-48.
29. Tanyu BF, Benson CH, Edil TB, Kim W. Equivalency of crushed rock and three industrial by-products used for working platforms during pavement construction. Transp Res Rec 2004(1874):59-69.
30. Tanyu BF, Kim W, Edil TB, Benson CH. Development of methodology to include structural contribution of alternative working platforms in pavement structure. Transp Res Rec 2005(1936):70-7.
31. Boyle WC, Ham RK. Assessment of leaching potential from foundry process solid wastes. In: Proceedings Purdue Indiana waste conference. Purdue Indiana ed. 1979.
32. Ham RK, Boyle WC. Leachability of foundry process solid wastes. Journal of Environmental Engineering 1981 107(1):155-170.
33. Ham RK, Boyle WC, Engroff EC, Fero RL. Organic compounds in ferrous foundry process waste leachates. J Envir Engrg 1993;119(1):34-55.
34. Ham RK, Boyle WC, Traeger P, Wellender D, Lovejoy M, Hippe JM. Evaluation of foundry wastes for use in highway construction. Wisconsin Departments of Natural Resources and Transportation; Madison, WI: 1993.
35. Bin-Shafique S, Benson CH, Edil TB. Geoenvironmental assessment of fly ash stabilized subbases. University of Wisconsin – Madison, Madison, Wisconsin 53706: Geo Engineering Department of Civil and Environmental Engineering; 2002. Geo Engineering Report No. 02-03.
36. Tikalsky P, Bahia H, Deng A, Snyder T. Excess foundry sand characterization and experimental investigation in controlled low-strength material and hot-mixing asphalt. U.S. Department of Energy; 2004. Contract No. DE-FC36-01ID13974.
37. Wang S, Vipulanandan C. Foundry sand for highway applications. 2000.
38. Sauer JJ, Benson CH, Edil TB. Metals leaching from highway test sections constructed with industrial byproducts. Department of Civil and Environmental Engineering, University of Wisconsin-Madison; Madison, Wisconsin 53706: 2005 Geo Engineering Report No. 05-21.
39. Lee T, Benson C. Leaching behavior of green sands from gray-iron foundries used for reactive barrier applications. Environmental Engineering Science 2006;23(1):153-67.
40. Harrington-Hughes K. Primer environmental impact of construction and repair materials on surface and ground waters. Transportation Research Board, National Research Council, 2101 Constitution Avenue, N.W. Washington, D.C. 20418: National Cooperative Highway Research Program; 2000. Report nr NCHRP Report 443.
41. Friend M, Bloom P, Halbach T, Grosenheider K, Johnson M. Screening tool for using waste materials in paving projects (STUWMPP). Office of Research Services, Minnesota Dept. of Transportation, Minnesota; 2004. Report nr MN/RC–2005-03.
42. Hesse TE, Quigley MM, Huber WC. User’s guide: IMPACT—A software program for assessing the environmental impact of road construction and repair materials on surface and ground water. NCHRP; 2000. Report nr NCHRP 25-09.
43. Li L, Benson CH, Edil TB, Hatipoglu B. Estimating groundwater impacts from coal combustion products in highways. November 2006 2007;159(WR4):151-63.
44. EPA, Environmental Protection Agency. Industrial waste management evaluation model (IWEM) User’s guide. Washington, DC: US EPA; 2002. Report nr EPA530-R-02-013.
45. Melton JS, Gardner KH, Hall G. Use of EPA’s industrial waste management evaluation model (IWEM) to support beneficial use determinations. U.S. EPA Office of Solid Waste and Emergency Response (OSWER); 2006.
46. EPA, Environmental Protection Agency. Guide for Industrial Waste Management [Internet]; c2006. Available from: http://www.epa.gov/epaoswer/non-hw/industd/guide/index.asp.

[ Material Description ] - [ Asphalt Concrete ] - [ Flowable Fill ] - [ Portland Cement ] - [ Embankment ]