Foundry Sand Facts 


for Civil Engineers
 

First Printing, May 2004 FHWA-IF-04-004 
Notice: This document is disseminated under the sponsorship of the US 

Environmental Protective Agency and the Department of Transportation in the 

interest of information exchange. The United States Government assumes no liability for its content or the use thereof. This report does not constitute a standard, 

specification, or regulation. The United States Government does not endorse 

products or manufactures. Trade and manufactures’ names appear in this report 

only because they are considered essential to the object of this document. 
Technical Report Documentation Page 

1. Report No. 2. Government Ascension No. 3. Recipient’s Catalog No. 

FHWA-IF-04-004 

4. Title and Subtitle 5. Report Date 

Foundry Sand Facts for Civil Engineers May 2004 

6. Performing Organization Code 

7. Author(s) 8. Performing Organization Report No. 

Foundry Industry Recycling Starts Today (FIRST) 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

TDC Partners Ltd. First 

417 S. St. Asaph St. PO Box 333 

Alexandria, VA 22314 Fall River, MA 01244 11. Contract or Grant No. 

13. Type of Report and Period Covered 

12. Sponsoring Agency Name and Address September 01 - September 03 

Federal Highway Administration 

Environmental Protection Agency 

Washington, DC 14. Sponsoring Agency Code 

15. Supplementary Notes 

16. Abstract 

Metal foundries use large amounts of sand as part of the metal casting process. Foundries successfully 

recycle and reuse the sand many times in a foundry. When the sand can no longer be reused in the 

foundry, it is removed from the foundry and is termed “foundry sand.” Foundry sand production is nearly 

6 to 10 million tons annually. Like many waste products, foundry sand has beneficial applications to 

other industries. 

The purpose of this document is to provide technical information about the potential civil engineering 

applications of foundry sand. This will provide a means of advancing the uses of foundry sand that are 

technically sound, commercially competitive and environmentally safe. 

17. Key Words 18. Distribution Statement 

Foundry Sand, Materials, Highway Construction, No restrictions. This document is available 

Asphalt, Concrete, Flowable fills, Embankment through the National Technical Information 

Service, Springfield VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 80 

Form DOT F 1700.7 (8-72) Reproduction of complete page authorized 

This form was electronically produced by Elite Federal Forms, Inc. 
SI* (MODERN METRIC) CONVERSION FACTORS 

APPROXIMATE CONVERSIONS TO SI UNITS 

Symbol When You Know Multiply By To Find Symbol 

APPROXIMATE CONVERSION FROM SI UNITS 

Symbol When You Know Multiply By To Find Symbol 

LENGTH LENGTH 

in 

ft 

yd 

mi 

inches 

feet 

yards 

miles 

25.4 

0.305 

0.914 

1.61 

AREA 

millimeters 

meters 

meters 

kilometers 

mm 

m 

m 

km 

mm millimeters 0.039 inches 

m meters 3.28 feet 

m meters 1.09 yards 

km kilometers 0.621 miles 

AREA 

in 

ft 

yd 

mi 

in 

ft2 

yd2 

ac 

mi2 

square inches 

square feet 

square yards 

acres 

square miles 

645.2 

0.093 

0.836 

0.405 

2.59 

VOLUME 

square millimeters 

square meters 

square meters 

hectares 

square kilometers 

mm2 

m2 

m2 

ha 

km2 

mm2 square millimeters 0.0016 square inches 

m2 square meters 10.764 square feet 

m2 square meters 1.195 square yards 

ha hectares 2.47 acres 

km2 square kilometers 0.386 square miles 

VOLUME 

in 

ft2 

yd2 

ac 

mi2 

fl oz fluid ounces 29.57 milliliters 

gal gallons 3.785 liters 

ft3 cubic feet 0.028 cubic meters 

yd3 cubic yards 0.765 cubic meters 

NOTE: Volumes greater than 10001 shall be shown in m3 

MASS 

mL 

L 

m3 

m3 

mL milliliters 0.034 fluid ounces 

L liters 0.264 gallons 

m3 cubic meters 35.71 cubic feet 

m3 cubic meters 1.307 cubic yards 

NOTE: Volumes greater than 10001 shall be shown in m3 

MASS 

fl oz 

gal 

ft3 

yd3 

oz 

lb 

T 

ounces 

pounds 

short tons 

(2000 lb) 

28.35 grams 

0.454 kilograms 

0.907 megagrams 

(or ”metric ton”) 

TEMPERATURE 

g 

kg 

Mg 

(or “t”) 

g grams 0.035 ounces 

kg kilograms 2.202 pounds 

Mg megagrams 1.103 short tons 

(or “t”) (or ”metric ton”) (2000 lb) 

TEMPERATURE 

oz 

lb 

T 

0

F Fahrenheit 

temperature 

5(F-32)/9 Celsius 

or (F-32)/.18 temperature 

ILLUMINATION 

0

C 0C Celsius 1.8C = 32 Fahrenheit 

temperature temperature 

ILLUMINATION 

0

F 

fc 

fl 

foot-candles 10.76 lux 

foot-Lamberts 3.426 candela/m2 

FORCE and PRESSURE or STRESS 

lx 

cd/m2 

lx lux 0.0929 foot-candles 

cd/m2 candela/m2 0.2919 foot-Lamberts 

FORCE and PRESSURE or STRESS 

fc 

fl 

lbf 

lbf/in2 

poundforce 

poundforce 

per square inch 

4.45 

6.89 

newtons 

kilopascals 

N 

kPa 

N newtons 0.225 poundforce 

kPa kilopascals 0.145 poundforce 

per square inch 

lbf 

lbf/in2 

* SI is the symbol for the International System of Units. 

Appropriate rounding should be made to comply with Section 4 of ASTM E380. 

(Revised September 1993) 
Forward 

Metal foundries use large amounts of sand as part of the metal casting 

process. Foundries successfully recycle and reuse the sand many times 

in a foundry. When the sand can no longer be reused in the foundry, it is 

removed from the foundry and is termed “foundry sand.” Foundry sand 

production is nearly 6 to 10 million tons annually. Like many waste 

products, foundry sand has beneficial applications to other industries. 

The purpose of this document is to provide technical information about 

the potential civil engineering applications of foundry sand. This will 

provide a means of advancing the uses of foundry sand that are technically 

sound, commercially competitive and environmentally safe. 

This document was developed by Foundry Industry Recycling Starts 

Today (FIRST), in cooperation with the U. S. Department of 

Transportation and the U.S. Environmental Protection Agency. The United 

States Government assumes no liability for its contents or use. Neither 

FIRST nor the Government endorses specific products or manufacturers. 

This publication does not constitute a standard, specification or regulation. 

Acknowledgements 

This Document was prepared based on the technical references and 

examples provided by a variety of sources, including the foundry 

industry, state departments of transportation, university researchers, 

and contractors. U.S. Environmental Protection Agency provided partial 

financial support of the preparation of the document. 

U.S. Department of Transportation, through the Federal Highway 

Administration, supports the expanded use of recycled materials in highway construction and provided overall technical review of the document. 

The authors appreciate the many agency and industry representatives 

who provided information and technical comments necessary to compile 

this document. 

Foundry Industry Recycling Starts Today (FIRST) is a non-profit 

501 (C) (3) research and education organization whose website 

www.foundryrecycling.org provides access to the technical references 

used in the preparation of this document. The American Foundry Society 

(AFS) is a metalcasting industry association which has sponsored 

research on foundry sand recycling options. 

Table Of Contents 

Chapter 1: An Introduction to Foundry Sand . . . . . . 1
 

Background Information . . . . . . . . . . . . . . . . . . . . . . . . 1
 

Foundry Sand Uses and Availability . . . . . . . . . . . . . . . . 3
 

Types of Foundry Sand . . . . . . . . . . . . . . . . . . . . . . . . . 5
 

Foundry Sand Physical Characteristics . . . . . . . . . . . . . . 6
 

Foundry Sand Quality . . . . . . . . . . . . . . . . . . . . . . . . . . 9
 

Foundry Sand Economics . . . . . . . . . . . . . . . . . . . . . . 10
 

Foundry Sand Engineering Characteristics . . . . . . . . . . 11
 

Foundry Sand Environmental Characteristics . . . . . . . . 13
 

Closing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
 

Chapter 2: Foundry Sand in Structural 


Fills and Embankments . . . . . . . . . . . . . . . . . . . . . 15
 

Engineering Properties for Embankments . . . . . . . . . . . 15
 

Construction Practices . . . . . . . . . . . . . . . . . . . . . . . . . 19
 

Chapter 3: Foundry Sand in Road Bases . . . . . . . . . 27
 

Background Information . . . . . . . . . . . . . . . . . . . . . . . 27
 

Purpose of the Road Base . . . . . . . . . . . . . . . . . . . . . . 28
 

Mix Design Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 30
 

Control of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 33
 

Construction Practices . . . . . . . . . . . . . . . . . . . . . . . . . 34
 

Marketing Fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
 

Chapter 4: Foundry Sand in Hot Mix Asphalt . . . . . 37
 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
 

Hot Mix Asphalt Aggregate Requirements . . . . . . . . . . 38
 

Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
 

Concerns of the Hot Mix Industry . . . . . . . . . . . . . . . . 41
 

Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
 

Chapter 5: Foundry Sand in Flowable Fills . . . . . . . 43
 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
 

Mix Design and Specification Requirements . . . . . . . . . 44
 

Mixture Proportioning Concepts for Flowable 


Fills with Foundry Sand . . . . . . . . . . . . . . . . . . . . . . . . 46
 

Closing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
 
Chapter 6: Foundry Sand in Portland 


Cement Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . 49
 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
 

Mixture Design and Specification Requirements . . . . . . 49
 

Gradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
 

Effect of Material Characteristics on Foundry 


Sand Concrete Quality . . . . . . . . . . . . . . . . . . . . . . . . 51
 

Other Constituents . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
 

Construction Practices . . . . . . . . . . . . . . . . . . . . . . . . . 53
 

Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
 

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
 

Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
 

Chapter 7: Foundry Sand in Other
 

Engineering Applications . . . . . . . . . . . . . . . . . . . . 57
 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
 

Foundry Sand in Portland Cement Manufacturing . . . . 57
 

Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
 

Foundry Sand in Grouts and Mortars . . . . . . . . . . . . . 60
 

Foundry Sand in Agricultural/Soil Amendments . . . . . . 61
 

Foundry Sand to Vitrify Hazardous Materials . . . . . . . 62
 

Foundry Sand as a Traction Material on Snow and Ice . 62
 

Foundry Sand for Smelting . . . . . . . . . . . . . . . . . . . . . 62
 

Foundry Sand in Rock Wool Manufacturing . . . . . . . . 63
 

Foundry Sand in Fiberglass Manufacturing . . . . . . . . . . 63
 

Foundry Sand for Landfill Cover or Hydraulic Barriers . 64
 
Figures 

Figure 1. Metal casting in a foundry . . . . . . . . . . . . . 2
 

Figure 2. How sand is reused and becomes 


foundry sand . . . . . . . . . . . . . . . . . . . . . . 3
 

Figure 3. Top ten foundry production states 


in the U. S. . . . . . . . . . . . . . . . . . . . . . . . . 4
 

Figure 4. Unprocessed foundry sand . . . . . . . . . . . . . 6
 

Figure 5. Foundry sand gradation . . . . . . . . . . . . . . 8
 

Figure 6. Green sands from a gray iron foundry . . . . 8
 

Figure 7. Embankment with foundry sand subbase . 15
 

Figure 8. Moisture density relationships for
 

green sand and chemically bonded sand . . 17
 

Figure 9. Foundry sand delivery . . . . . . . . . . . . . . . 20
 

Figure 10. Spreading foundry sand . . . . . . . . . . . . . . 21
 

Figure 11. Grading foundry sand . . . . . . . . . . . . . . . 22
 

Figure 12. Stepped Embankment . . . . . . . . . . . . . . . 25
 

Figure 13. Schematic of a flexible pavement structure 27
 

Figure 14. Schematic of a rigid pavement structure . . 28
 

Figure 15. Preparation of road base . . . . . . . . . . . . . 33
 

Figure 16. Asphalt pavement . . . . . . . . . . . . . . . . . . 37
 

Figure 17. Construction of HMA pavement . . . . . . . 40
 

Tables 

Table 1. Typical physical properties of foundry sand 7
 

Table 2. Foundry sand applications by volume . . . 11
 

Table 3. Engineered uses of foundry sand . . . . . . . 12
 

Table 4. Friction angle of foundry sands . . . . . . . . 31
 

Table 5. Cohesion of foundry sands . . . . . . . . . . . 31
 

Table 6. Permeability of foundry sands . . . . . . . . . 32
 

Table 7. Foundry sand mixes . . . . . . . . . . . . . . . . 45
 

Table 8. Recommended test methods for 


flowable fills . . . . . . . . . . . . . . . . . . . . . . 48
 

Table 9. Fine aggregate gradation . . . . . . . . . . . . . 50
 

Table 10. ASTM C144 sand gradation for mortars . 60
 

Chapter 1:
 

An Introduction to Foundry Sand 

Background Information 

What is a Foundry? A foundry is a manufacturing facility that produces metal castings by 

pouring molten metal into a preformed mold 

to yield the resulting hardened cast. The primary 

metals cast include iron and steel from the 

ferrous family and aluminum, copper, brass 

and bronze from the nonferrous family. There 

are approximately 3,000 foundries in the U.S. 

What is Foundry Sand? Foundry sand is high 

quality silica sand that is a byproduct from the 

production of both ferrous and nonferrous metal 

castings. The physical and chemical characteristics of foundry sand will depend in great part 

on the type of casting process and the industry 

sector from which it originates. 

Where Does it Come From? Foundries purchase 

high quality size-specific silica sands for use in 

their molding and casting operations. The raw 

sand is normally of a higher quality than the 

typical bank run or natural sands used in fill 

construction sites. 

The sands form the outer shape of the mold 

cavity. These sands normally rely upon a small 

amount of bentonite clay to act as the binder 

material. Chemical binders are also used to 

create sand “cores”. Depending upon the geometry of the casting, sands cores are inserted into 

the mold cavity to form internal passages for 

the molten metal (Figure 1). Once the metal 

has solidified, the casting is separated from the 

molding and core sands in the shakeout process. 

1 
In the casting process, molding sands are recycled and reused multiple times. Eventually, 

however, the recycled sand degrades to the point 

that it can no longer be reused in the casting 

process. At that point, the old sand is displaced 

from the cycle as byproduct, new sand is introduced, and the cycle begins again. A schematic 

of the flow of sands through a typical foundry 

can be found in Figure 2. 

Figure 1. Metal casting in a foundry 

How is it Produced? Foundry sand is produced 

by five different foundry classes. The ferrous 

foundries (gray iron, ductile iron and steel) produce the most sand. Aluminum, copper, brass 

and bronze produce the rest. The 3,000 

foundries in the United States generate 6 million 

to 10 million tons of foundry sand per year. 

While the sand is typically used multiple times 

within the foundry before it becomes a byproduct, only 10 percent of the foundry sand was 

reused elsewhere outside of the foundry industry 

in 2001. The sands from the brass, bronze and 

2 
copper foundries are generally not reused. 

While exact numbers are not available, the best 

estimate is that approximately 10 million tons of 

foundry sand can beneficially be used annually. 

 

Return Sand Storage New Sand Storage 

Excess Return 

Sand to Waste 

Sand 

Screen 

Waste 

Sand 

Mold 

Making 

Cores and Mold Lumps to 

Mechanical Reclamation 

Return Sand 

System 

Return Sand 

System 

Casting to Cleaning 

and Finishing 

Shakeout 

Molten Metal 

Cores from Core Making 

Additives 

Bentonite Sea Coal 

Figure 2. How sand is reused and becomes foundry sand 

Foundry Sand Uses and Availability 

What Makes it Useful? Foundry sand is basically 

fine aggregate. It can be used in many of the 

same ways as natural or manufactured sands. 

This includes many civil engineering applications 

such as embankments, flowable fill, hot mix 

asphalt (HMA) and portland cement concrete 

(PCC). Foundry sands have also been used 

extensively agriculturally as topsoil. 

What is Being Done With It? Currently, 

approximately 500,000 to 700,000 tons of 

foundry sand are used annually in engineering 

applications. The largest volume of foundry 

sand is used in geotechnical applications, such 

as embankments, site development fills and 

road bases. 

3 
Where is it Available? Foundries are located 

throughout the United States in all 50 states. 

However, they tend to be concentrated in the 

Great Lakes region, with strong foundry 

presence also found in Texas and Alabama 

(Figure 3). 

Figure 3. Top ten foundry production states in the U.S. 

How Does the Foundry Sand Industry Operate? 

Historically, individual foundries have typically 

developed their own customer base. But over 

time, foundries have joined together to create 

regional foundry consortia to pool resources 

and to develop the recycled foundry sand 

industry. FIRST (Foundry Industry Recycling 

Starts Today) is a national coalition of member 

foundries. FIRST focuses on market development of sustainable options for beneficial 

reuse of foundry industry byproducts. 

4 
Types of Foundry Sand 

How Many Types of Foundry Sand Are There? 

There are two basic types of foundry sand 

available, green sand (often referred to as 

molding sand) that uses clay as the binder 

material, and chemically bonded sand that 

uses polymers to bind the sand grains together. 

Green sand consists of 85-95% silica, 0-12% 

clay, 2-10% carbonaceous additives, such as 

seacoal, and 2-5% water. Green sand is the 

most commonly used molding media by 

foundries. The silica sand is the bulk medium 

that resists high temperatures while the coating 

of clay binds the sand together. The water adds 

plasticity. The carbonaceous additives prevent 

the “burn-on” or fusing of sand onto the casting 

surface. Green sands also contain trace chemicals 

such as MgO, K2O, and TiO2. 

Chemically bonded sand consists of 93-99% 

silica and 1-3% chemical binder. Silica sand is 

thoroughly mixed with the chemicals; a catalyst 

initiates the reaction that cures and hardens 

the mass. There are various chemical binder 

systems used in the foundry industry. The 

most common chemical binder systems used 

are phenolic-urethanes, epoxy-resins, furfyl 

alcohol, and sodium silicates. 

5 
Foundry Sand Physical Characteristics 

What is the Typical Particle Size and Shape? 

Foundry sand is typically subangular to rounded 

in shape. After being used in the foundry process, 

a significant number of sand agglomerations 

form (Figure 4). When these are broken down, 

the shape of the individual sand grains 

is apparent. 

Figure 4. Unprocessed foundry sand 

(Courtesy Lifco Industries) 

What are Some of the Physical Properties? 

Foundry sand has many of the same properties 

as natural sands. While one foundry sand will 

differ statistically from another, recently published properties from Pennsylvania provide 

fairly typical values. Pennsylvania foundry 

sands are classified in two categories: 

• Foundry sand with clay (5%) – FS #1 

• Foundry sand without clay – FS #2 

Table 1 shows the results for bulk density, 

moisture content, specific gravity, dry density, 

optimum moisture content and permeability 

measured using the applicable ASTM standard. 

6 
Property ASTM 

Standard 

Foundry Sand 

with Clay (5%) 

FS#1 

Foundry Sand 

without Clay 

FS#2 

Bulk density (pcf) C29 60 -70 80-90 

Moisture content (%) D2216 3-5 0.5-2% 

Specific gravity D854 2.5-2.7 2.6-2.8 

Dry density (pcf) D698 

Standard 

Proctor 

110-115 100-110 

Optimum moisture 

content (%) 

D69 8-12 8-10 

Permeability 

coefficient (cm/s) 

D2434 10-3-10-7 10-2-10-6 

Table 1. Typical physical properties of foundry sand 

Figure 5 compares the gradations of these 

materials to the ASTM C33 upper and lower 

limits (See Chapter 6). Foundry sand is 

commonly found to be a uniform fine sand, 

with 0 to 12% bentonite or minor additives. 

The quantity of bentonite or minor additives 

depends on how the green sand has been 

processed. 

7 
Figure 5. Foundry sand gradation, 

as compared to ASTM C33 

What Color is Foundry Sand? Green sands are 

typically black, or gray, not green! (Figure 6). 

Chemically bonded sand is typically a medium 

tan or off-white color. 

Figure 6. Green sands from a gray iron foundry 

(after processing and screening) 

8 
Foundry Sand Quality 

What Determines Foundry Sand Quality? 

The quality of foundry sand can be quantified by 

its durability and soundness, chemical composition, 

and variability. These three characteristics are 

influenced by various aspects of foundry sand 

production. 

Durability/Soundness of foundry sand is 

important to ensure the long-term performance 

of civil engineering applications. Durability of the 

foundry sand depends on how the sand was used 

at the foundry. Successive molding can cause the 

foundry sand to weaken due to temperature shock. 

At later stages of mold use, this can lead to the 

accelerated deterioration of the original sand 

particles. However, in civil engineering uses, the 

foundry sand will not normally be subjected to 

such severe conditions. In geotechnical applications, 

foundry sand often demonstrates high durability. 

Chemical Composition of the foundry sand relates 

directly to the metal molded at the foundry. This 

determines the binder that was used, as well as 

the combustible additives. Typically, there is some 

variation in the foundry sand chemical composition 

from foundry to foundry. Sands produced by a 

single foundry, however, will not likely show significant variation over time. Moreover, blended sands 

produced by consortia of foundries often produce 

consistent sands. The chemical composition of the 

foundry sand can impact its performance. 

Variability. Reducing the variability of the foundry 

sand is critical if consistently good engineering 

products are to be produced. Foundry sand 

suppliers should understand and control foundry 

sand variability so that they can provide customers 

with a consistent product. 

9 
How can I know I’m getting good quality? 

Methods to ensure foundry sands conform 

to specifications vary from State to State and 

source to source. Some States require testing 

and approval before use. Others maintain lists 

of approved sources and accept project suppliers’ 

certifications of foundry sand quality. More and 

more, foundry sand generators are determining 

the engineering properties of their sands. 

The degree of quality control necessary depends 

on experience with the specific foundry sand 

and its history of variability. Many purchasers 

require source testing and a certification document to accompany the shipment. 

How should foundry sand be handled? 

Foundry sand is most often collected and 

stockpiled outside of the foundries, exposed to 

the environment. Prior to use in an engineering 

application, the majority of foundry sand is: 

• Collected in closed trucks and transported to 

a central collection facility; 

• Processed, screened, and sometimes crushed 

to reduce the size of residual core sand pieces. 

Other objectionable material, such as metals, 

are removed. 

Foundry Sand Economics 

The success of using foundry sand depends 

upon economics. The bottom line issues are cost, 

availability of the foundry sand and availability 

of similar natural aggregates in the region. If 

these issues can be successfully resolved, the 

competitiveness of using foundry sand will 

increase for the foundries and for the end users 

of the sand. This is true of any recycled material. 

10 
Foundry Sand Engineering 

Characteristics 

What are the key engineering properties of 

foundry sand? Since foundry sand has nearly 

all the properties of natural or manufactured 

sands, it can normally be used as a sand 

replacement. It can be used directly as a fill 

material in embankments. It can be used as a 

sand replacement in hot mix asphalt, flowable 

fills, and portland cement concrete. It can also 

be blended with either coarse or fine aggregates 

and used as a road base or subbase material. 

Table 2 shows the relative ranking of foundry 

sand uses by volume. 

Ranking Application 

1 Embankments/Structural Fills 

2 Road base/Subbase 

3 Hot Mix Asphalt (HMA) 

4 Flowable Fills 

5 Soil/Horticultural 

6 Cement and Concrete Products 

7 Traction Control 

8 Other Applications 

Table 2. Foundry sand applications by volume 

11 
According to a recent survey of 10 states, 

foundry sand has been approved for use by 

various agencies within the state in the following 

engineered applications (listed in Table 3). 

It is expected that more states will be supplementing these uses as they become more 

familiar with the material. 

IA IL IN MI MN NJ NY OH PA WI 

Landfill 

daily cover X X X X 

Highway 

embankment X X X 

Roadway 

subbase X X X X X X X 

Parking lot 

subbase X X X X X 

Concrete 

and asphalt X X X X X X X X 

Foundation 

subgrade fill X X X 

Flowable 

fill X X X 

Generate fill X X X X 

Other X X X X 

Table 3. Engineered uses of foundry sand 

12 
Foundry Sand Environmental 

Characteristics 

What about trace elements in foundry sand? 

Trace element concentrations present in most 

clay-bonded iron and aluminum foundry sands 

are similar to those found in naturally occurring 

soils. The leachate from these sands may contain 

trace element concentrations that exceed water 

quality standards; but the concentrations are no 

different than those from other construction 

materials such as native soils or fly ashes. 

Environmental regulatory agencies will guide 

both the foundry sand supplier and the user 

through applicable test procedures and water 

quality standards. If additional protection from 

leachate is desired, mechanical methods such as 

compacting and grading can prevent and further 

minimize leachate development. 

In summary, foundry sand suppliers will work 

with all potential users to ensure that the product meets environmental requirements for the 

engineering application under consideration. 

Closing 

Do I need to know more about this technology 

to use it confidently? Foundry sand can be used 

to produce a quality product at a competitive cost 

under normal circumstances. The remaining chapters of this publication provide a general overview 

of foundry sand use in various civil engineering 

applications. It will familiarize highway engineers 

and inspectors with this technology. This publication is also designed to assist those individuals 

who have little or no previous experience using 

foundry sand or no experience in a particular 

application of foundry sand. 

13 
14
 
Chapter 2:
 

Foundry Sand in Structural Fills and 

Embankments 

Engineering Properties For 

Embankments 

How are embankment materials generally 

classified? Embankment materials used in 

construction (Figure 7) are generally classified 

on the basis of soil type, grain size distribution, 

Atterberg limits, shear strength (friction angle), 

compactability, specific gravity, permeability 

and frost susceptibility. 

Figure 7. Embankment with foundry sand subbase 

(Ohio Turnpike, sand from Ford Motor Company 

supplied by Kurtz Bros. Inc.) 

15 
Soil Classification. Foundry sand would 

normally be classified under the Unified Soil 

Classification System (USCS) as SP, SM or SPSM and under AASHTO as A-3, A-2, or A-2-4. 

It is a nonplastic or low plasticity sand with 

little or no fines. Some foundries or foundry 

sand suppliers will process the sand to remove 

the majority of silts or clays that may be 

present. The silt or clay content can range 

from 0 to 12%. 

Grain Size Distribution. Foundry sand consists 

of a uniform sand, with a coarse appearance. 

Typical gradations are provided in Chapter 1. 

Atterberg Limits (Liquid and Plastic). Typically 

foundry sand without fines is nonplastic. The 

plastic behavior can depend on the clay content. 

For foundry sand with 6 to 10% clay, a liquid 

limit LL greater than 20 and a plastic index PI 

greater than 2 are typical. 

Shear Strength (Friction Angle). Foundry sands 

have good shear strength. For foundry sands 

without clay, the direct shear test is used to 

measure its friction angle. It ranges from 300

-360 , 

which is comparable to conventional sands. Its 

shear strength is superior to silts, clays or dirty 

sands, showing that foundry sand is acceptable 

for use as an embankment material. The triaxial 

shear strength test can be used to measure the 

drained shear strength, friction angle and cohesion of foundry sands that contain clay. A 

typical value of the friction angle and cohesion 

for these sands is 280 and 3700 psf, respectively. 

But these properties can vary. Foundry sand used 

on the Ohio Turnpike had a friction angle of 350 

and cohesion of 6100 psf. 

16 
Compaction. Compaction of foundry sand 

is needed to increase its density during 

embankment construction. Moisture-density 

relationships have been developed for green 

sands with 0 to 5% fines, green sands with 

5 to 12% fines, and chemically bonded sands. 

They show the optimal moisture content for 

maximum dry density for a specified level of 

compaction. In Figure 8, there is a definite 

peak in the moisture-density curve for green 

sands with fines between 5 and 12%. The green 

sands with few fines and the chemically bonded 

sands produce a flatter curve. The influence of 

water is not as significant for them. However, 

both curves are relatively flat, when compared 

to plastic soils. Dry Unit Weight, pcf110 

100 

Water Content, % 

(a) Green sand with 5-12% fines 

0 10 20 

(a) Green sand with 5-12% fines Dry Unit Weight, pcf110 

100 

Water Content, % 

(b) Green sand with 0 to 5% fines 

or chemically bonded sand 

0 10 20 

(b) Green sand with 0 to 5% fines or 

chemically bonded sand 

Figure 8. Moisture density relationships for 

green sand and chemically bonded sand 

17 
Specific Gravity. Foundry sands will normally 

have a specific gravity of 2.50 to 2.80. 

Permeability. Green sands with fines less than 

6% and chemically bonded sands have permeability values in the range of 6x10-4 to 5x10-3 

cm/sec. However, when fines such as bentonite 

clay are present and greater than 6%, 

permeability can be lower, between 1x10-7 

and 3x10-6 cm/sec. 

Frost Susceptibility. Soils that are not susceptible 

to frost and that do not produce heave are 

gravel and clean sands. Fine-grained soils are 

generally classified as frost susceptible. The fine 

content of the foundry sand determines its frost 

susceptibility. Foundry sand without fines can 

have low to negligible frost susceptibility. 

CBR (California Bearing Ratio). In foundry 

sand, a CBR between 11 and 30 is typical. 

The resistance to penetration of a 3 in2 piston 

in a compacted sample of foundry sand is compared to its resistance in a standard sample of 

compacted crushed rock. CBR is high when the 

water content is dry of optimum, and then drops 

after the optimum water content is reached. The 

CBR for foundry sand with fines is generally 

higher than it is for granular sands. 

18 
Construction Practices 

General. Many contractors have found 

that working with foundry sand is similar 

to working with conventional construction 

materials. Foundry sand has been used effectively in normal embankment construction with 

and without permeability and leachate control. 

Foundry sands have also been used in conjunction with geogrid systems and with reinforced 

earth retaining walls that use straps or grids as 

horizontal tiebacks. 

Standard construction procedures can be adjusted to account for using foundry sand. Many 

procedures have been developed as the result of 

the experience gained using foundry sand in trial 

embankment and construction projects. 

Stockpiling. Foundry sand can be stockpiled in 

a climate-controlled environment or exposed to 

the elements. The foundry sand stored under 

controlled climatic conditions can be delivered 

to meet narrow limitations on moisture content. 

Conversely, the moisture content of the foundry 

sand stored outside will vary, depending on its 

location within the stockpile. It is recommended 

that foundry sand stockpiled outside be tested at 

various locations within the stockpile. 

Site Preparation. The site should be prepared 

for foundry sand placement in the same way it is 

prepared for similar soil fill materials. It should 

be cleared and grubbed, and the topsoil should 

be retained for final cover. The normal precautions for draining the site to prevent seeps, pools 

or springs from contacting the foundry sand 

should be followed. Also, environmental restrictions may require that the foundry sand be 

encapsulated in layers of clay. 

19 
Delivery and On-Site Storage. As with any fill, 

foundry sand is hauled to the site in covered 

dump trucks (Figure 9). The water content of 

the foundry sand is adjusted to prevent dusting 

and to enhance compaction. Foundry sand can 

be stockpiled on-site if the sand is kept moist 

and if the sand is covered. 

Figure 9. Foundry sand delivery (sand supplied by 


Kurtz Bros., Inc., construction by Trumbull Corp.)
 

Spreading. Foundry sand is spread using normal 

construction equipment, such as dozers. Lifts are 

usually 6 to 12 inches thick. Many contractors 

then track the dozer for initial compaction. 

Ideally, the sand is at or near optimal moisture 

when placed; if not, water should be added. 

20 
Compaction. Compaction should begin as soon 

as the material has been spread (Figure 10) 

and is at the proper moisture content. Ohio 

experience has shown it to be preferable to 

place the foundry sand as close to the optimum 

moisture content as possible, within 1-2%. 

Too dry of optimum requires significantly more 

compactive effort than when the sand is properly 

moisture-conditioned. However, the required 

compaction can eventually be achieved. Foundry 

sands are not normally sensitive to over-rolling 

and can tolerate a wider range of moisture 

contents than natural sands. 

Figure 10. Spreading foundry sand (Ohio turnpike, 

sand supplied by Kurtz Bros. Inc.) 

Vibratory smooth drum rollers, pneumatic-tired 

rollers, and vibrating plates have all been used 

successfully. It is important to properly screen 

the foundry sand and to remove residual core 

pieces. In most cases cores are not a problem if 

they are less than 3 to 4” long. The compaction 

process will slow down if they are larger. 

21 
The lift thickness, the weight and speed of the 

compaction equipment and the number of passes 

should be determined for optimal compaction 

(Figure 11). Many contractors run test strips and 

relate construction practices to the foundry 

sand’s degree of compaction. When vibratory 

compaction equipment is used, lifts of 12 inches 

are acceptable. In fact, thicker lifts may be preferred. They provide greater confinement. If the 

lift is too thin, the sand may dry out too fast. 

Also, it will not offer enough confinement for 

proper compaction. 

Figure 11. Grading foundry sand 

In a recent project, dynamic compaction was used 

successfully to compact foundry sand. The moisture-conditioned foundry sand was placed in 10 

to 15 foot lifts, and then dynamically compacted 

by a 12 ton weight dropped from 40 to 60 feet. 

This height can be adjusted for the required level 

of compaction and thickness of the sand layer. 

22 
In some foundry sand embankment construction, 

a foundation of coarser material such as rock or 

shale is placed. The foundry sand is placed on 

top in uniform horizontal lifts not more than 8 

inches deep. It is then compacted according to 

normal density specifications. 

Moisture Control. As with any fill material, 

controlling its moisture is an important 

consideration in compaction. Be sure to 

compare hauling foundry sand that has been 

moistened to the desired water content at the 

plant to adding water at the site. Hauling moist 

foundry sand translates to higher transportation 

costs, while adding water on-site sacrifices 

productivity in field placement. 

Erosion and Dust Control. To prevent wind and 

water erosion of the surface of the foundry sand 

embankment, contractors use the same sediment 

and erosion control techniques commonly used 

on other earthwork operations. On a project in 

Ohio, the contractor installed organic filter socks 

or berms around the construction area. 

Dusting may occur when compacted foundry 

sand is placed in dry or windy weather, or due 

to traffic disturbance. During construction, the 

soil should be kept moist and covered. Clay 

layers have also been used to cover the face of 

the embankment to prevent erosion of the 

foundry sand in a heavy rain. The completed 

embankment should be covered with topsoil 

and vegetation. 

23 
Three Key Construction Steps. To ensure 

successful construction of an embankment 

(Figure 12), with foundry sand and its long-term 

performance it is important to: 

1. Assess availability. Contact the local foundry 

sand supplier and determine whether an adequate supply of foundry sand can be provided 

in the time frame required. 

2. Investigate site conditions. As with any 

embankment project, use standard geotechnical techniques to evaluate subsurface soil 

and groundwater conditions. The two most 

important subsurface characteristics affecting 

embankment construction and performance 

are shear strength and compressibility of the 

foundation soils. 

3. Evaluate the physical, engineering, and 

chemical properties of the foundry sand. 

The physical and engineering properties 

that will determine the behavior of a foundry 

sand embankment (or any embankment) 

are grain-size distribution, shear strength, 

compressibility, permeability and frost 

susceptibility. Laboratory tests designed for 

testing soil properties apply equally well to 

testing foundry sands. Most foundry sand 

distributors can provide information on 

the physical, engineering and chemical 

composition of the foundry sand and can 

provide details on any possible leachate 

that must be considered during design 

and construction. 

24 
Figure 12. Stepped embankment 

(Ohio turnpike, sand supplied by Kurtz Bros. Inc., 

construction by Trumbull Corp.) 

Environmental Impacts. The trace element 

concentrations in most clay-bonded and 

aluminum foundry sands are similar to those 

found in naturally occurring soils. The vast 

majority of foundry sands meet water quality 

standards for leachate. Additionally, State 

environmental regulatory agencies can guide 

you through applicable test procedures and 

water quality standards. The amount of leachate 

produced can be controlled by assuring adequate 

compaction, grading to promote surface runoff, 

and daily proof-rolling of the foundry sand layer 

to impede infiltration. When construction is 

finished, a properly seeded soil cover will reduce 

infiltration. For highway embankments, the 

pavement itself can be an effective barrier to 

infiltration. 

25 
26
 
Chapter 3:
 

Foundry Sand in Road Bases 

Background Information 

What is a Road Base? A road base is a 

foundation layer underlying a flexible or rigid 

pavement and overlying a subgrade of natural 

soil or embankment fill material. It can be 

composed of crushed stone, crushed slag, or 

some other stabilized material. It protects the 

underlying soil from the detrimental effects of 

environment and from the stresses and strains 

induced by traffic loads. 

Flexible Pavement Road Base. For flexible 

pavements, there are typically two bases underneath the pavement that comprise the road base, 

a stabilized base and an untreated or granular 

subbase (Figure 13). The two different base 

materials are usually used for economy. Local 

or cheaper materials are used in the subbase, 

and the more expensive materials are used in 

the base. 

Flexible Pavement 

Base 

Subbase 

Subgrade 

Figure 13. Schematic of a flexible pavement structure 

27 
Rigid Pavement Road Base. In contrast to 

flexible pavements, rigid pavements are typically 

placed on a single layer of granular or stabilized 

road base material (Figure 14). 

Since there is only one layer under the rigid 

pavement and above the subgrade, it can be 

called either a base or a subbase. 

Rigid Pavement 

Base or Subbase 

Subgrade 

Figure 14. Schematic of a rigid pavement structure 

Granular or Stabilized Road Base. The selection 

of a stabilized base course or a granular base 

course depends on the traffic loads. Pavements 

that are subjected to a large number of very 

heavy wheel loads typically use cement-treated, 

asphalt-treated, or a pozzolanic stabilized mixture (PSM) base. Granular materials may erode 

when the heavy traffic induces pumping. 

Purpose of the Road Base 

Five of the most important reasons for 

constructing a road base are to: 

• Control pumping, 

• Control frost action, 

• Improve drainage, 

• Control shrinkage and swelling of the 

subgrade, and 

• Expedite construction. 

28 
Control Pumping. For pumping to occur, three 

conditions must exist simultaneously. The material 

under the concrete slab must be saturated with 

free water, the material must be erodible, and 

frequent heavy wheel loads must pass over the 

pavement. These loads create large hydrodynamic 

pressures that transport untreated granular materials and even some weakly cemented materials to 

the surface. This loss of fines is termed pumping. 

Control Frost Action. Frost action is the combination of frost heave and frost melt. Frost heave 

causes the pavement to lift up, while frost melt 

causes the subgrade to soften and the pavement 

to depress. Both lead to the break up of a pavement. Three factors produce frost action: 

1. The soil must be frost susceptible in the depth 

of frost penetration. These soils generally have 

more than 3% fines or are uniform sands with 

more than 10% fines. 

2. Water must be available. 

3. Temperatures must remain below freezing 

for a sufficient period of time for water to 

flow from the water table to where the ice 

lenses form in the road base. 

Improve Drainage. A road base can raise the 

pavement to a desired elevation above the water 

table, acting as an internal drainage system. 

Control Shrinkage and Swelling of the Subgrade. 

If the subgrade shrinks and expands, the road base 

can provide a surcharge load to reduce its movement. Dense graded or stabilized base courses 

reduce the water entering the subgrade, and act 

as a waterproofing layer. Open-graded base 

courses serve as a drainage layer. 

Expedite Construction. A road base can serve 

as a working platform for heavy construction 

equipment. 

29 
Mix Design Evaluation 

The road base material should be made of a 

mixture of crushed rock and enough fine material 

to hold the rock in place and to provide good 

compaction. Foundry sand can be used as the fine 

material in a road base. Engineering properties that 

characterize foundry sand as a subbase material 

are plasticity, shear strength, compaction (moisturedensity relationship), drainage and durability. 

Plasticity (Shrinkage or Swelling). Green foundry 

sands without fines and chemically bonded sands 

are typically non-plastic. However, the presence 

of bentonite clay increases the foundry sand’s 

plasticity. The plasticity index is commonly used 

to indicate a soil’s tendency to undergo volume 

change (shrinkage or swelling). The plasticity index 

is typically less than 2 for green sands with no or 

few fines and chemically bonded sands, and greater 

than 2 when the clay content increases beyond 6%. 

Shear Strength (Friction Angle). A soil’s shear 

strength is its ability to resist deformation. This 

property is critical when determining a soil’s ultimate bearing capacity, which is the largest load 

that the road base material can support. Shear 

strength depends on several material properties, 

such as soil cohesiveness, and the interlocking 

ability and packing of the particles. 

The friction angle of green sands with 6 to 12% 

clay is higher than it is for chemically bonded 

foundry sands and green sands without clay. The 

friction angle φ in Table 4 represents the peak 

strength for dense samples and the ultimate 

strength for loose ones. The higher friction angle 

for the green sand with clay is attributed to its 

fines. Similarly, the cohesive strength of green sands 

with clay is higher than it is for the chemically 

30 
bonded sands (Table 5). Green sands without clay 

are non-plastic. Either ASTM D5311 or ASTM 

D3080 can be used to measure shear strength. 

Loose Dense 

Green sand with clay (6-12%) 32°-34° 37°-41°

Clean green sand without clay/ 

Chemically bonded sand 

30° 35°

Natural sand 29°-30° 36°-41°

Table 4. Friction angle of foundry sands 

Cohesion (psi) 

Loose Dense 

Green sand with clay (6-12%) 0.60-0.75 1.44-1.82 

Chemically bonded sand 0.06 1.04 

Table 5. Cohesion of foundry sands 

Compaction. The compaction characteristics of a 

granular base or subbase material depend on the 

soil’s moisture-density relationship. Most specifications require that the granular base be compacted 

to a specified density that is at least 95% of the 

Standard Proctor maximum dry density, with the 

water content near optimum. The Standard Proctor 

test (ASTM D698 or AASHTO T99) is commonly 

used to measure compaction. The Modified Proctor 

test (AASHTO T180) can also be used when the 

base must have a high shear strength or be dense. 

To ensure base stability, angular particles with 

rough surfaces are preferred over round, smooth 

particles. Foundry sands are round to subangular 

in shape, with both smooth and rough surface 

textures. 

31 
Drainage. Since a road base should provide 

drainage as part of a pavement’s structure, the 

base material’s permeability is very important. 

Materials that are free-draining typically have 

a permeability between 10-2 and 10-3 cm/sec. 

The permeability of green and chemically 

bonded sands are given in the table below 

(Table 6). The presence of clay reduces the 

permeability of the green sands. Higher permeabilities are associated with foundry sands that 

have fewer fines, such as green sands that have 

been processed to remove the clay and chemically bonded sands. Permeability of foundry sands 

can be measured using ASTM D2434, AASHTO 

T215 or ASTM D5084. 

Permeability k 

(cm/sec) 

Green sand with clay 2.8 x 10-5 to 2.6 x 10-6 

Green sand without clay 3 x 10-3 to 5 x 10-3 

Chemically bonded sand 4.5 x 10-3 to 5.9 x 10-4 

Natural Sands 10-3 to 10-4 

Table 6. Permeability of foundry sands 

Durability. Foundry sand has sufficient strength 

to resist excess breakdown when placed in 

road bases (Figure 15). They have good particle 

strength. Many States will specify minimum 

requirements for LA abrasion (ASTM C131 

or AASHTO T96) and sodium sulfate soundness 

(ASTM C88 or AASHTO T104). Foundry sand 

without clay is normally not susceptible to frost, 

and this should be assessed using AASHTO 

T103. 

32 
Figure 15. Supplying Foundry Sand for a road base 

Control of Materials 

Handling. No deleterious materials (plastic 

fines, organic matter, or extraneous debris) 

should be in the foundry sand. This will reduce 

its load carrying capacity and ultimately, the 

expected performance of the road base. Foundry 

sand should be screened prior to its use in 

engineering projects. 

Aggregate. To meet State specifications for road 

bases, blending the foundry sand with another 

aggregate may be necessary. The gradation of 

the road base materials influences base stability, 

drainage, and frost susceptibility. Likewise, the 

aggregate must be sound and able to resist environmental deterioration. 

33 
Construction Practices 

Blending of Materials. Aggregate used in the 

construction of road bases should be mixed and 

processed to produce a uniform blend of material prior to final placement. 

Construction Plants. Construction plants should 

collect and store foundry sand until use. Because 

of the importance of the fine aggregate moisture 

content, the foundry sand should have consistent 

moisture content. 

Hauling. Blended mixtures can be hauled to the 

site in open or covered trucks. The mix in an 

open truck can dry and dust when hauled long 

distances. 

Spreading. The placement of road base material 

shall conform to local grading ordinances and 

agency specifications. The typical road base is a 

uniform layer of base material that is 6-10 inches thick, without any segregation. The final 

thickness after compaction is 4-6 inches. 

Compaction. Road base material should be 

rolled to achieve the desired compaction and 

specified density. It is important that all waste 

materials be removed from the foundry sand, 

because it can become entangled in the compaction equipment and delay construction. 

Finishing. The final layer of road base shall be 

finished with equipment capable of shaping and 

grading the final surface within the tolerances 

specified by the agency. 

What if I can’t afford to buy specialized construction equipment? There is no need to! Most 

plants can be readily adapted to add the foundry 

sand to the road base mix. For spreading, it can 

be placed with a jersey spreader. 

34 
What advice do you have for a first time user? 

Using foundry sand can produce strong durable 

road bases, but attention should be given to the 

following precautions: 

• Mix design evaluation. Proposed mix designs 

should be evaluated for performance prior to 

construction. Good quality constituents do not 

always produce a mix that will perform as 

desired. 

• Moisture content. Moisture must be 

maintained in the mix to ensure optimal 

compaction. The moisture may be added on 

site or at the plant. 

Marketing Fill 

The project specific nature of the fill materials 

market makes it difficult to quantify the total 

amount of foundry sand that will be needed on 

a regular basis. Currently, the rates of foundry 

sand generation is sufficient to supply construction companies and other related industries 

with fill material. The marketability of the sand 

depends on the availability of other fill material 

at or near the construction site. Transportation 

costs may quickly offset the low initial cost 

advantage of foundry sand. Foundry sand use 

is more advantageous when it is stockpiled close 

to the construction site. 

35 
36
 
Chapter 4:
 

Foundry Sand in Hot Mix Asphalt 

Introduction 

Asphalt concrete is the most popular paving 

material used on our highways and roadways 

in the United States. Over 94% of all pavements 

in the U. S. are covered with asphalt. This translates to over 2,030,000 miles (Figure 16). 

Figure 16. Asphalt pavement 

(courtesy Asphalt Pavement Alliance) 

The most prevalent type of asphalt paving 

material is hot mixed asphalt (HMA). This 

consists of a combination of plant-dried coarse 

and fine aggregates. They are coated with hot 

asphalt cement, which acts as a binder. 

Foundry sand has been used successfully to 

replace a portion of the fine aggregate used in 

HMA. Studies have shown that foundry sand 

can be used to replace between 8 and 25% of 

the fine aggregate content. When mixes are 

properly designed using Superpave, Marshall, 

or Hveem techniques, foundry sand can be an 

effective sand alternative. 

37 
Hot Mix Asphalt Aggregate 

Requirements 

Hot mix asphalt production requires that all 

constituent products: 

• Have inherently good quality characteristics, 

• Come from consistent, reputable supply 

sources, 

• Meet all environmental requirements, and 

• Are economically competitive with similar 

materials. 

Foundry sand has the potential to be a very high 

quality material in hot mix applications (Figure 

17). However, it is important that the foundry 

sand be cleaned of clay, dust, and other deleterious materials. Additionally, metals present in 

the sands should be removed either manually or 

magnetically. Then, it may be blended with other 

sands, at 8-25% replacement, to provide equal 

or possibly better results than normal sands. 

Gradation. Fine aggregates in hot mixes 

generally are required to meet the specifications 

of AASHTO M29. This specification limits 

materials passing the No 200 sieve to between 

5 and 10%. Many foundry sands have a higher 

percentage, requiring screening prior to blending 

or a limit on the maximum amount of foundry 

sand that can be added to a mix. 

Particle Cleanliness. Hot mix asphalt is generally 

tested by the sand equivalent test (ASTM D2419) or by the non-plastic index test (AASHTO 

T-90). These tests detect clay portions, which are 

very detrimental to aggregate-binder adhesion. It 

is important that when qualifying foundry sand, 

38 
the clay content and organic-based additive be 

quantified and limited in producing an asphalt 

mix. For many foundry sands, the sand equivalent test is not applicable. According to research 

done at the University of Wisconsin at Madison, 

the methylene blue test (AFS 2211-00-S) is a 

better method for the clay content. The loss 

on ignition test (AASHTO T 267-86) is a good 

method for detecting the organic based additives. 

Soundness. Nearly all foundry sands meet the 

loss of soundness specification, AASHTO T104. 

Particle Shape and Texture. Many hot mix 

asphalt specifications now require a fine 

aggregate angularity test, using AASHTO TP33. 

Foundry sands typically fall within the specified 

40-45% range. 

Absorption and Stripping. Foundry sand is 

generally non-plastic and has low absorption. 

However, it is primarily silica, which in the past, 

has been linked to stripping. As with all silicabased hot mix asphalt mixtures, a foundry sand 

mix should be tested using standard stripping 

tests. The University of Wisconsin at Madison 

has tested foundry sand mixes for moisture 

damage and, depending on the clay content 

and the extent of organic-based additives used, 

foundry sands can have positive or negative 

effects on resistance to moisture damage. The 

University of Wisconsin at Madison is currently 

developing better methods to quantify clay and 

organic-based additives to predict how foundry 

sands influence moisture damage. 

39 
Figure 17. Construction of HMA pavement 

Case Studies 

Pennsylvania, Michigan and Tennessee 

Departments of Transportation allow the use 

of recycled foundry sand in HMA. Pennsylvania 

DOT allows the use of 8 to 10% of the total 

aggregate portion to be recycled foundry sand 

in the asphalt wearing course. One hot mix 

producer in Michigan consistently supplies 

HMA with 10-20% recycled foundry sand to 

replace the conventional aggregate, and it meets 

Michigan DOT specifications. Another hot mix 

supplier in Tennessee claims that hot mix with 

foundry sand replacing 10% of the fine aggregate compacts better and outperforms the 

HMA containing washed river sand. In addition, 

a hot mix producer in Ontario, Canada has used 

foundry sand as a fine aggregate substitute for 

the past 10 years in both foundation and surface 

HMA layers. 

40 
In Pennsylvania, 10 million tons of asphalt 

pavement are produced each year. Two million 

tons of fine aggregate are needed. Although 

foundry sand cannot be used to replace the total 

fine aggregate quantity, it can be used to replace 

up to 15%. This would allow a significant 

amount of foundry sand to be used each year 

in Pennsylvania. 

Concerns of the Hot Mix Industry 

To be used by the hot mix industry, foundry 

sand has to be a consistent product with adequate supply. The engineering characteristics 

of the foundry sand have to be relatively similar 

from batch to batch, especially in gradation, 

so that the resulting hot mix asphalt is also 

consistent. Once a proper hot mix asphalt 

design has been developed and calibrated 

with the foundry sand, it is not cost effective 

to change the mix design. This will result in 

additional costs. If the foundry sand supply 

changes during the construction season, the 

hot mix supplier will be responsible for any 

out-of-specification material, and will incur 

any consequent penalties. 

Economics 

Use of foundry sands can be cost effective 

for both the foundries and the HMA industry. 

Highway agencies and contractors could switch 

to the recycled material when it is geographically 

and economically competitive. 

41 
42
 
Chapter 5:
 

Foundry Sand in Flowable Fills 

Introduction 

Flowable fill has several names, but each is 

essentially the same material: 

• Controlled density fill (CDF), 

• Controlled low strength material (CLSM), 

• Fly ash slurry, 

• Lean mix backfill, 

• Unshrinkable fill, and 

• Soil cement. 

Flowable mixtures make up a class of engineering materials having characteristics and uses that 

overlap those of a broad range of traditional 

materials including compacted soil, soil-cement, 

and concrete. Flowable mixtures consist of sand, 

water, cement and sometimes fly ash. The mixtures are proportioned, mixed and delivered in 

a very fluid consistency to facilitate placement; 

they provide an in-place product that is equivalent to a high-quality compacted soil but without 

the expensive compaction equipment and related 

labor. ACI defines flowable fill as a cementitious 

material that is in a flowable state at the time 

of placement and has a specified compressive 

strength of 1200 psi or less at 28 days. 

Flowable fills have been used as backfill for 

bridge structures including abutments, culverts, 

and trenches. It has been used for embankments, 

bases, and subbases. It is commonly used as bedding for slabs and pipes. It has also been used to 

economically fill caissons and piles, abandoned 

storage tanks, sink holes, shafts and tunnels. 

43 
Flowable fill materials usually offer an economic 

advantage over the cost of placing and compacting earthen backfill materials. Depending on 

the job conditions and costs involved, significant 

savings are possible. The closer the project 

location to the source of the flowable fill, the 

greater the potential cost savings. 

Most foundry sands can be used in flowable 

fill mixtures. The foundry sand does not have 

to meet ASTM C33 gradation specification 

requirements as a concrete fine aggregate to be 

suitable for use in flowable fill mixes. ACI 229R 

reports that foundry sand with up to 20% fines 

produced successful flowable fill mixtures. 

Because low strength development is desirable 

in flowable fill, even foundry sand with organic 

binders may be suitable. Foundry sand for flowable fill can be used in a dry or moisture 

conditioned form. 

Mix Design and Specification 

Requirements 

Flowable fills typically contain portland cement, 

fly ash, sand and water. Foundry sand can be the 

major ingredient in flowable fills. The flowable 

character derives from its distribution of spherical and irregular particle shapes and sizes. When 

mixed with enough water, the fly ash and sand 

surfaces are lubricated, so that it flows. 

Water requirements for mixture fluidity will 

depend on the surface characteristics of all solids 

in the mixture. A range of 50 to 200 gallons per 

cubic yard would satisfy most materials combinations. As with most flowable fill applications, the 

wetter it is the better. The water acts as a means 

of conveyance for the solid particles in the mix44 
ture. Portland cement is added, typically in quantities from 50 to 200 pounds per cubic yard, to 

provide a minimal (weak) cementitious matrix. 

Table 7 shows mix proportions recommended in 

ACI 229R. However, contractors familiar with 

flowable fill and foundry sand have reported 

using lower quantities of foundry sand, approximately 1500 pounds per cubic yard. 

Component Typical Mix Design 

(lb/yd3) 

Range 

(lb/yd3) 

Fine Aggregate/ 2850 1850-2910 

Foundry Sand 

Cement 100 50-200 

Fly Ash 250 0-300 

Water 500 325-580 

Table 7. Foundry sand mixes (adapted from ACI 229R) 

According to the ACI definition, flowable fill 

should have an upper compressive strength limit 

of 1200 psi, but strengths can be designated as 

low as 50 psi. Most flowable fill mixes are 

designed to achieve a 28-day maximum unconfined compressive strength of 100 to 200 psi. 

The goal is to have the flowable fill support 

early loads without settling, and yet still be 

readily excavated at a later date. Flowable 

mixtures can be designed to allow for hand 

excavation as well. 

It is important to remember that flowable fill 

mixtures with a low ultimate strength in the 50 

to 70 psi range have at least two to three times 

the bearing capacity of well-compacted earthen 

backfill material. 

45 
Mixture Proportioning Concepts For 

Flowable Fills With Foundry Sand 

The following are the most important physical 

characteristics of flowable fill mixtures: 

• Compressive strength development, 

• Flowability, 

• Time of set, and 

• Bleeding and shrinkage. 

Strength Development in flowable fill mixtures 

is directly related to its water-to-cement ratio. 

Water is added to achieve a desired flowability 

or slump. Just like normal concrete mixes with 

a given cement content, increasing the water 

content will usually result in a decrease in 

compressive strength. The coarser the sand, 

whether natural or foundry, the higher the bearing capacity is of the hardened flowable fill. 

Flowability is primarily a function of the water 

content and aggregate gradation. The higher the 

water content and the more uniform and spherical the sand, the more flowable the mixture. It 

is usually desirable to make the mix as flowable 

as possible in order to take advantage of the 

self-compacting qualities of the flowable fill. 

46 
Time of Set is directly related to the cementitious 

materials content and type, sand content, water 

content and weather conditions at the time 

of placement. Within 24 hours, construction 

equipment is usually expected to move across 

the surface of the flowable fill without any 

apparent damage. The time of set has been 

found to depend on the type of foundry sand 

incorporated into the flowable fill. Green 

foundry sands with low clay content and 

chemically bonded foundry sands normally 

require less water in the mixture. The flowable 

fill also takes less time to harden. 

Bleeding and Settlement are possible in high 

water content flowable fill mixtures, since evaporation of the bleed water often results in 

settlement. As with any cementitious material, 

plastic shrinkage cracks on the surface of the fill 

can occur in high water content mixtures as 

well. The main concern with plastic shrinkage 

cracking is that water can infiltrate at a later 

date. Flowable fill mixtures should be checked 

for settlement and plastic shrinkage. 

Structural design procedures with flowable fill 

materials containing foundry sand are no different than standard geotechnical design procedures 

for conventional earth backfill materials. The 

design procedure uses the unit weight and shear 

strength of the flowable fill to calculate bearing 

capacity and lateral pressure of the material for 

given site conditions. 

47 
Closing Comments 

Although most foundry sands will meet ASTM 

C33 gradation requirements, it is not a controlling factor in the flowable fill mix design. If the 

flowable fill meets the general ASTM test 

requirements shown in Table 8, the flowable 

fill should be fine for most applications. 

ASTM Title 

C39 Standard test method for compressive strength 

of cylindrical concrete specimens 

C88 Standard test method for soundness of 

agregates by use of sodium sulfate or 

magnesium sulfate 

C138 Standard test method for density (unit weight), 

yield, and air content (gravimetric) of concrete 

C232 Standard test methods for bleeding of concrete 

C403 Time of setting of concrete mixtures by 

penetration resistance 

C827 Change in height at early-ages of cylindrical 

specimens from cementitious mixtures 

D2166 Unconfined compressive strength of cohesive 

soils, used where minimal or no cement is 

added to the blend 

D4219 Highly fluid grout-like mixes 

D4832 Standard test method for preparation and 

testing of controlled low strength material 

(CLSM) test cylinders 

D5971 Standard practice for sampling freshly mixed 

CLSM 

D6023 Standard test method for unit weight, yield, 

cement content and air content (gravimetric) of 

CLSM 

D60624 Standard test method for ball drop on CLSM to 

determine suitability for load application 

D6103 Standard test method for flow consistency of 

CLSM 

Table 8. Recommended test methods for flowable fills 

48 
Chapter 6:
 

Foundry Sand in Portland Cement Concrete 

Introduction 

Portland cement concrete (PCC) is a mixture of 

approximately 25% fine aggregate, 45% coarse 

aggregate, 20% cement and 10% water. Foundry 

sand can be used beneficially in concrete production as a fine aggregate replacement. 

Mixture Design and Specification 

Requirements 

Aggregates are classified based on particle size. 

Fine aggregates consist of natural sand or 

crushed stone with particle diameters smaller 

than 3/8 inch. Coarse aggregates are gravel or 

crushed stone with particle diameters ranging 

between 3/8 inch and 2 inches. 

The selection of aggregate used in concrete is of 

great importance. Aggregate properties strongly 

influence the concrete’s freshly mixed and hardened properties. Aggregate must be: 

• Clean and free of objectionable materials, 

including organic material, clay and deleterious 

contaminants, which can affect bonding of 

the cement paste to the aggregate, 

• Strong, hard and durable, and 

• Uniformly graded. 

49 
Gradation 

Specifications governing the selection and use of 

aggregates in concrete mixtures generally relate 

to the particle size distribution or gradation of 

the aggregates. The recommended gradation 

for fine aggregate is given in Table 9. This 

specification is geared towards plain concrete 

and concrete structures, pavements, sidewalks, 

and precast products. 

Sieve Sieve Size Percent Passing 

No. (mm) by Weight 

4 4.75 95-100 

8 2.36 80-10 

16 1.18 50-85 

30 0.600 25-60 

50 0.600 10-30 

100 0.150 2-10 

Table 9. Fine aggregate gradation (from ASTM C33) 

Generally foundry sand is too fine to permit 

full substitution. The percentage of materials 

passing the No. 30, 50 and 100 sieves is too 

high. To meet the specification, it is necessary 

to remove the fines or to blend the spent 

foundry sand with coarser sands. The foundry 

sands will then comply with the specification. 

In some areas, natural sands lack finer material. 

Foundry sand can be blended with them as a 

partial replacement to satisfy the specification. 

50 
Effect of Material Characteristics on 

Foundry Sand Concrete Quality 

Various characteristics of foundry sand can 

significantly affect the quality of concrete produced. The material characteristics of greatest 

importance and their effects on the product are 

discussed below. Foundry sand properties vary 

in samples taken from one foundry, and there 

is increased variation from foundry to foundry. 

This necessitates testing the sand every time 

prior to use to ascertain its quality. 

Particle Size Distribution. The fine aggregate 

particle size distribution can affect cement 

and water requirements, as well as concrete 

workability, economy, porosity, shrinkage and 

durability. Too many fine particles can lower 

the concrete strength and adversely affect 

durability. ASTM C33 requires that the fine 

aggregate used in concrete have a fineness 

modulus, an index of aggregate fineness, in the 

range of 2.3 to 3.1. The fineness modulus of 

foundry sand typically ranges from 0.9 to 1.6. 

The sand has to be blended with a coarser material to meet this specification. 

Dust Content. ASTM C33 allows a maximum 

of 5% fine aggregate particles to pass the No. 

200 sieve. These particles include clay and other 

dusts. A large dust content can interfere with the 

bonding of cement to the aggregate surface, and 

they can also increase water demand. These factors reduce the durability of hardened concrete. 

This is a concern when using foundry sands. 

Density. Density must be a minimum of 75-110 

lbs/ft3 (1.20 to 1.76 g/cm3

), according to ASTM 

C330 for general fine aggregate. A higher density aggregate is required when the concrete will 

be subjected to high compressive loads. 

51 
Organics Content/Deleterious Materials 

Content. According to ASTM C33, the maximum amount of clay lumps and friable particles 

allowed is 3%. Organic content is restricted 

because it interferes with hydration of the cement 

and its subsequent strength. The organic content 

of aggregate can be measured by a color test. 

Grain Shape. Round particles need less water 

and cement to coat their surface, and they produce a mixture that is more workable. 

Angularity increases water demand and cement 

content to maintain a workable mix. Foundry 

sand particles are typically angular to rounded. 

Specific Gravity. Although specific gravity does 

not directly relate to concrete quality, it can be 

used as a quality control indicator. The specific 

gravity of foundry sand varies from 2.5 to 2.8, 

depending on the source. This compares very 

favorably to natural sands. 

Other Constituents 

Coarse Aggregate. Coarse aggregates used in 

the concrete mixture should be appropriately 

sampled and tested to ensure good quality. 

Some aggregates of marginal quality have 

been observed to adversely affect the matrix 

of hardened concrete. 

Cement. Foundry sand can be used in combination with all types of cementitious materials. 

Chemical Admixtures. In general, foundry sand 

can be used with any concrete containing chemical admixtures. Retarders and water reducers 

are compatible with most foundry sands. As 

with natural sands, any organic material in 

the foundry sand may affect the dosage and 

52 
effectiveness of air entraining agents. Trial mixtures should always be examined for any 

potential compatibility problems. 

Construction Practices 

General Considerations. Foundry sand must be 

processed prior to reuse, i.e. screened, crushed, 

and magnetic particles should be separated. This 

will remove waste and deleterious materials, 

such as tramp metal and core pieces, preventing 

technical problems at the mix plant. 

Plant Operations. A separate bin should be 

reserved for the foundry sand at the plant, as is 

done for fly ash. Foundry sand can be handled 

in typical aggregate holding bins. It is important 

to keep the bins clean and the foundry sand dry 

to help eliminate any bulking problems at the 

gate opening. 

Case Study 

Laboratory Use of Foundry Sand in Concrete. 

An American Foundry Society (AFS) study in 

Illinois investigated foundry sand as a substitute 

for fine aggregate in concrete. When foundry 

sands without fines replaced a portion of the fine 

aggregate, the concrete produced had compressive strengths, tensile strengths and modulus of 

elasticity values comparable to mixtures composed of natural sand. 

On the other hand, when green foundry sands 

that had not been processed replaced 33% of 

the fine aggregate, the resulting concrete compressive strengths at 28 days were between 2600 

psi and 4000 psi. These low strength concretes 

53 
can be used in applications not requiring structural grade concrete, such as buried applications 

like sewer pipe or below grade concrete. The 

decrease in concrete compressive strength, as 

well as in tensile strength and modulus of 

elasticity, were attributed to too many fines 

and organic materials (clay and dust) in the 

foundry sand. 

Likewise, foundry sand has been used to make 

paving blocks and bricks. For these applications, 

foundry sand replaced 35% of the fine aggregate. If the fineness modulus was not exceeded, 

the concrete product was acceptable provided 

they met the ASTM specifications for minimum 

compressive strength, absorption, and bulk density. It is recommended that proper testing be 

performed to establish the appropriate limits on 

foundry sand addition prior to using it in commercially produced products. 

Applications 

Concrete can be used for cast-in-place or 

pre-cast products such as pipes, ornamental 

concrete units, load bearing structural units (i.e., 

beams, girders, etc.), utility structures and concrete blocks. The ultimate use, shape, and size 

of the product will govern the type and gradation of the aggregate required in the concrete 

mixture. For example, the final dimensions of 

the precast block will determine the maximum 

aggregate size. For this reason, when marketing 

spent foundry sand to precast producers or to 

a ready mix plant, the particle size distribution 

requirements should be requested ahead of time. 

54 
When the required concrete compressive strength 

is between 50 psi and 2500 psi, a 50% fine 

aggregate substitution with foundry sand has 

been successful. As with regular concrete, trial 

mixtures should always be tested prior to production for any potential compatibility problems. 

Limitations 

Foundry sand is black. In some concretes, 

this may cause the finished concrete to have a 

grayish/black tint, which may not be desirable. 

A 15% fine aggregate replacement with foundry 

sand produces a minimal color change. Also, 

the foundry must be able to meet the quantity 

requirements of the precast manufacturer. 

55 
56
 
Chapter 7:
 

Foundry Sand in Other Engineering Applications 

Introduction 

Other engineering applications of foundry sand 

will be presented in this chapter. They include 

using foundry sand in: 

• Portland cement manufacturing, 

• Mortars, 

• Agricultural / soil amendments, 

• Traction material on snow and ice, 

• Vitrification of hazardous materials, 

• Smelting, 

• Rock wool manufacturing, 

• Fiberglass manufacturing, and 

• Landfill cover or hydraulic barriers. 

Foundry Sand in Portland Cement 

Manufacturing 

Portland cement reacts chemically with water 

when hydrating, causing it to set and to harden. 

When mixed with fine and coarse aggregate, 

concrete is formed. There are several specifications for portland cement, as designated by 

ASTM C150 and ASTM C1157. 

Production of Portland Cement. Portland 

cement is manufactured using materials with the 

appropriate proportions of calcium oxide, silica, 

alumina, and iron oxide. These ingredients are 

found in natural rock, like shale, dolomite, and 

57 
limestone. It is the chemistry of the foundry 

sand as a silica source that is more important 

in cement production than is its grain size or 

shape. The requirements that must be met for 

foundry sand to be used in portland cement 

production are: 

• Its silica content equals or exceeds 80%, 

• It is a low alkali material, 

• A large quantity of sand is available, and 

• It has uniform particle sizes. 

Foundry sand may be one of the highest quality 

sources of silica available to the cement industry. 

The major chemical constituents of raw portland 

cement available in foundry sand include silica 

and alumina and iron oxides. By using foundry 

sands to replace virgin sands, the quantity of 

mined virgin sands can be reduced. 

Blended Cements. Blended hydraulic cements 

are of particular interest in the beneficial use of 

foundry sand, since these cements are produced 

by blending together two or more types of fine 

materials. Historically, blended cements have 

included portions of blast furnace slag or fly ash. 

Foundry Sand Acceptance by Portland Cement 

Manufacturers. The cement manufacturer has 

to evaluate the foundry sand to confirm its 

compatibility with other raw materials. In 

addition, cement producers need a chemical 

oxide analysis, TCLP results, annual volume 

and a sample. The chemical oxide analysis 

shows the amount of silica contained in the 

sand, while the TCLP shows whether or not 

the sand is hazardous. Also, because limestone, 

silica and clay are all common materials, the 

cement manufacturer has to be willing to use 

foundry sand. 

58 
Limitations. Factors that may limit foundry sand 

use in portland cement manufacturing involve 

limits on the quantity of foundry sand available 

and cost issues. Cement manufacturers require 

significant quantities of silica, 10,000–40,000 

tons annually for a plant. It is unlikely that a 

single foundry can provide that much sand. 

The sand from several foundries should be 

pooled at a community storage site to meet the 

demands of a single cement plant. 

Cement manufacturers will pay nominal fees to 

foundries for the use of their spent sand, but will 

consider it waste disposal. Additional charges 

may be levied for handling fees and shipping. 

However, there is potential for cost savings. 

Case Studies
 

Laboratory Study of Foundry Sand in Cement.
 

The American Foundry Society (AFS) in Illinois 

studied using green sand from a gray iron 

foundry in portland cement manufacture. First, 

a chemical analysis of the sand was performed 

to see if it met AASHTO specifications. Based on 

the chemical content, the foundry sand appeared 

to be an attractive alternative to raw material for 

cement kiln feed. Four mixtures were designed 

using 0%, 4.45%, 8.9% and 13.36% of foundry 

sand. The chemical characteristics of the resulting clinkers showed little difference between 

those made with and without foundry sand. 

The cement produced with the foundry sand 

met all the relevant chemical specifications. The 

properties of the cement, namely set time and 

compressive strength, were not affected by the 

presence of foundry sand. There was even a 

slight increase in compressive strength. 

59 
Commercial Study by Frazer & Jones. In January 

1994, a green sand manufacturer (Frazer & Jones) 

in up-state New York shipped 15,000 tons of 

foundry sand to a cement manufacturer in Ontario, 

Canada. It was used successfully as a replacement 

for excavated silica materials in the manufacture of 

low-alkali portland cement. The finished product 

was a high quality portland cement. 

Foundry Sand in Grouts and Mortars 

Mortars primarily consist of sand, cement and 

other additives, and are used in masonry construction. Its primary uses are to joint and seal concrete 

masonry units, to strengthen masonry structures 

by bonding with steel reinforcing, and to provide 

architectural quality. Approximately one cubic foot 

of sand is used to make one cubic foot of mortar. 

The cement paste occupies the space between the 

sand particles and makes it workable. 

Sand used in masonry mortar mixes is generally 

specified based on grading. ASTM C144 recommends the following gradation (Table 10). Sands 

that are deficient in fines make a coarse mix 

and ones that have too many fines produce a 

weak mortar. 

Sieve No. Sieve Size 

(mm) 

Percent Passing 

by Weight 

4 4.75 100 

8 2.36 95-100 

16 1.18 70-85 

30 0.600 40-75 

50 0.300 20-40 

100 0.150 10-25 

200 0.075 0-10 

Table 10. ASTM C144 sand gradation for mortars 

60 
A well-suited aggregate will fall into the middle 

of this range. Adequate gradation reduces mortar 

segregation and bleeding and improves mortar 

water retention and workability. Foundry sand is 

generally finer than the ASTM gradation requirements, but it can be blended with coarser sands 

to meet the specification. 

In addition to aggregate gradation, the aggregate 

should be clean and free from wastes, and also 

have a consistent moisture content. Likewise, the 

color of the foundry sand can impart a dark tint 

to the mortar, so it should be deemed acceptable 

prior to its use in architectural projects. 

Foundry Sand in Agricultural/Soil 

Amendments 

Foundry sand can be used as an additive in topsoil 

and compost materials. It is ideal for topsoil manufacture because of its uniformity, consistency, and 

dark color. Since a high sand content is required in 

topsoil, it is an essential ingredient. In composting, 

foundry sand reduces the formation of clumps and 

prevents the mix from compacting. This allows air 

to circulate through the material and to stimulate 

decomposition. Ohio nurseries have been blending 

foundry sands with soils and compost for use on 

ornamentals. Kurtz Bros. of Ohio has also used it 

successfully as golf green topdressing. For these 

applications, the presence of clay is beneficial, since 

it promotes the retention of nutrients. 

Regulatory issues for foundry sand use in agricultural applications vary from State to State on a caseby-case basis. 

61 
Foundry Sand to Vitrify Hazardous 

Materials 

Because of foundry sand’s high silica content, 

it is an ideal candidate to encapsulate, vitrify or 

neutralize hazardous materials. Preliminary tests 

show that this is a feasible option. 

Foundry Sand as a Traction Material 

on Snow and Ice 

Another possible use of foundry sand is as an 

anti-skid material on roads covered with snow 

and ice. Particularly its angular particles 

improve traction on highways in the winter. 

Likewise, its black color (ex. green sand) will 

hold the heat longer and will melt the ice faster. 

To be used as an anti-skid material, the foundry 

sand must meet each State’s requirements. 

Typically, foundry sand is too fine to comply 

with anti-skid regulations, but when mixed with 

a coarser material, it does comply. Trial mixes 

should be formulated and evaluated prior to 

use. In addition, the foundry sand should be 

free from glass, metals, or other substances that 

could be harmful to cars and vehicles. 

Foundry Sand for Smelting 

Another potential use for foundry sand is as 

a raw material in zinc and copper smelting. 

Foundry sand can be used in place of virgin 

sand. Guidelines for using silica sands in zinc 

and copper smelting are that the sand should 

be relatively pure silica (minimum 99.0%), 

have a maximum particle size of 2 mm and a 

bulk phenol content of less than 2 mg/kg (ppm). 

62 
The foundry should demonstrate to the smelting 

plant that the foundry sand meets these criteria 

and will produce quality zinc and copper. 

Case Study. A smelter in California has been 

using recycled foundry sand for some time. All 

of the foundry sands used in area brass and steel 

foundries were deemed acceptable due to their 

high silica content. 

Foundry Sand in in Rock Wool 

Manufacturing 

Rock wool fibers are commonly used to 

reinforce other materials, such as building 

material insulation, and are similar to fiberglass. 

Foundry sand can serve as a source of silica in 

the rock wool production process. They are 

produced by combining blast furnace slag with 

silica or alumina in a cupola furnace and then 

fiberizing the molten material. To be used in 

production, the foundry sand has to be pretreated and formed into briquettes. 

Foundry Sand in Fiberglass 

Manufacturing 

Foundry sand can be used in the manufacture 

of fiberglass. Fiberglass is produced by melting 

silica sand and straining it through a platinum 

sieve with microscopic holes, thereby forming 

the desired glass fibers. Manufacturers of fiberglass, such as Owens-Corning and CertainTeed 

Corporation, have specifications for silica content and particle size distribution, so to be used 

in this application, the foundry sand has to have 

the needed properties. 

63 
Foundry Sand for Landfill Cover or 

Hydraulic Barriers 

Foundry sand has been used for some time as 

a daily cover soil on municipal waste landfills 

and as a landfill liner. Foundry sand containing 

clay (> 6%) and the following Atterberg limits 

(liquid limit greater than 20 and plastic index 

greater than 3) has a low permeability. It is an 

ideal material for final or top cover. It is also 

expected to be resistant to permeation by 

brines and leachates in the short term. 

Each State may have different requirements 

placed on landfill materials and foundry sand 

usage should be decided on a case-by-case basis. 

64 
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66
 
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69