Geofoam Intrusions

Geofoam Intrusions: Features and Utility

GEOFOAM INTRUSIONS

ABSTRACT

Cellular materials, whether open- or closed-cell, are very efficient in load bearing

because of their ability to support relatively large loads with relatively small amounts of

material. Polymeric (plastic) and glass foams have been used in geotechnical applications

since at least the 1960s as thermal insulation, lightweight fill, and for many other

functions. Since 1992, any type of foam used in a geotechnical application has been

considered to be a geosynthetic product called "geofoam." Now, there are two

geosynthetic families of non-planar (three- dimensional) cellular materials and products,

geofoams (closed cell) and geocombs (open cell) that bring the technical attributes and

cost effectiveness of cellular materials to geotechnical applications.

This new terminology coincided with a rapid expansion worldwide in the

knowledge and use of foams in geotechnical applications. The primary focus of this paper

is to list the various applications of geofoam in Geotechnical Engineering field. A brief

overview of geofoam materials and past and current uses of geofoam is also included to

provide background information for understanding the future of this technique and the

development needs.

National Institute of Technology Karnataka, Surathkal. 1


CHAPTER 1

INTRODUCTION

"Geofoam is a generic term that has recently entered the civil engineering

vocabulary to describe foam materials used in geotechnical applications. the most

commonly used geofoam materials are expanded polystyrene (EPS) and extruded

polystyrene (XPS) although geofoam also includes glass foam (cellular glass). in

geotechnical applications these materials have traditionally been used for thermal ground

insulation and construction of light weight fills for more than 30 years. However, the

range of geotechnical applications has grown to include compressible inclusions to

reduce lateral earth pressures against walls, and cushion materials for vibration

attenuation and noise damping. In some cases geofoam may provide two or more

functions and in other cases, it may be combined with traditional geosynthetics to form

drainage composites.

Christopher Columbus and Richard Buckminster "Bucky" Fuller were great

philosophers. The particular interest here was their broad conceptual appreciation for, and

inventive devotion to, making less material do more work. As a corollary to this was his

interest in working with, rather than fighting, the forces of nature.This is well

summarized in the following quote attributed to them.

"Don't oppose forces; use them."

And so the geosynthetic subject of this paper, geofoam, makes the points taken from

Columbus and Fuller that:

Not all geosynthetics are planar (two-dimensional) as has traditionally been

defined. Geosynthetics technology and society as a whole can only benefit from all

those involved with geosynthetics accepting and promoting three-dimensional

geosynthetic materials such as geofoam and geocomb.

Sometimes it is more effective technically and more efficient cost wise to reduce

forces on a structure (something geofoams and geocombs excel) rather than to

increase the strength of the structure as has been the traditional approach using planar

geosynthetics and, in fact, civil engineering materials in general.



Although most geotechnical engineers have heard the term geofoam,

misconceptions about its definition continue. Since the early 1990s, geofoam has been the

generic term for any synthetic geo-material created in an expansion process using a gas

(blowing agent) and resulting in a texture of numerous closed cells. Geofoam is the

generic family name for any closed-cell foam material or product used in a geotechnical

application. Geofoam is now recognized worldwide as a geosynthetic product category in

the same sense as geotextiles, geomembranes, geogrids, etc.

A geofoam material can be manufactured in a fixed plant or foamed in place,

which thus includes several types of foam grouts among geofoam materials.

1.1 MATERIALSThe experience has revealed that the vast majority of geofoam applications are

best satisfied using polymeric foam made of polystyrene. There are additional materials

that have been tried over the years but were found to be technically unacceptable. The

latter are not listed here but are discussed for their historical interest. Geofoam materials

can be divided into three major categories:

Polymeric (plastic),

Cementitious (typically using Portland cement) and

Cellular glass.

The polymeric category is further subdivided depending on the polymer chemistry and

specific manufacturing process used:

Rigid cellular polystyrene (RCPS), which can be either expanded polystyrene

(EPS) or extruded polystyrene (XPS);

Polyethylene (PE);

Polyethylene-polystyrene (PE-PS) blend; and

Polyurethane (PUR).

The current definition of geofoam as proposed is any manufactured material

created by some expansion process that results in a material with a texture of numerous,

closed, gas-filled cells. The cell walls are solid although permeable to gases. Most

geofoam materials are polymeric (plastic) but glass foam (cellular glass) has been and is



also used. Although gases (called blowing agents) other than air are typically used in

manufacturing geofoams, with time (which can vary widely depending on the geofoam

material, a fact that many fail to consider properly when designing) the cells eventually

become filled with air.

Polymeric materials have always dominated the geofoam market. Several

different polymers have been tried in geofoam applications but the one used most

commonly by far is polystyrene. There are two ways to manufacture polystyrene foam:

By the two-stage moulded-bead process, which produces moulded, expanded

polystyrene or, as it is more commonly called, expanded polystyrene (EPS). They are

prepared by Block moulding which give prismatic blocks or Custom shape moulding

producing pieces with specific shape.

By a continuous extrusion process, which produces extruded expanded polystyrene or

simply extruded polystyrene (XPS). It is produced in plank- shaped pieces.

An EPS and, to a much lesser extent, XPS have always dominated the geofoam

market, it is not surprising that the relatively few geofoam failures have been documented

in the literature involve only EPS and XPS. However, it should not be assumed that other

geofoam materials are problem free in their use.

There is simply no sufficiently documented published information to permit a

discussion of failures involving these other materials. However, the lack of documented

failures in other geofoam applications does not imply that failures in these applications

could not occur.



CHAPTER 2

GENERAL FUNCTIONS AND APPLICATIONS OF GEOFOAMS

2.1 INTRODUCTION.There are several aspects regarding the functions provided by geofoam that are of

particular interest:

Unique functions. With one exception (drainage), geofoam functions do not

duplicate those of any other geosynthetic product. Therefore, geofoam provides

the end user with new tools for solving geotechnical problems.

Multi-functionality. Depending on the material and product used, geofoam can be

inherently multi-functional. This increases its cost-effectiveness in many

applications because several technical and financial benefits can be derived from

using only one product.

Complementary. Geofoam products are rarely used alone. In most geofoam

applications, one or more other types of geosynthetics are used.

Synergy. Geofoam products allow the use of other types of geosynthetics

(especially geogrids and other tensile-reinforcement products) in applications

where these other geosynthetics were heretofore of little or no use. Therefore,

there are applications where geofoam and other types of geosynthetics can be

combined synergistically to produce new, unique results that would not be

possible otherwise.

Depending on the particular geofoam material and product used, geofoam can

provide a wide variety of geosynthetic functions. With one exception, geofoam functions

do not duplicate those provided by traditional planar geosynthetics.

2.2 GENERAL APPLICATIONS OF GEOFOAMS. 2.2.1 Thermal Insulation.

EPS and XPS were invented circa 1950 primarily to provide thermal insulation.

Foams in general are very efficient thermal insulators because they are approximately 98%



to 99% gas by volume and gases are typically very efficient thermal insulators. We use

geofoam as thermal insulation of roads, railways, and airfield pavements, the below-ground

portions of buildings (to reduce seasonal heating requirements); and beneath on-grade

storage tanks containing cold liquids.

Each of these applications was successful in its original goals.

2.2.2 Lightweight Fill.

Geofoams, especially polymeric ones, are unique materials in that they have a

density that is only about 1% to 2% of the density of soil and rock yet are sufficiently strong

to support many types of loads encountered in geotechnical applications. Thus one of the

earliest functions of geofoam that was developed was its use as a lightweight fill material in

a wide variety of "earthworks." The general benefit of using geofoam as opposed to other

materials in earthworks is the significantly reduced stresses on the underlying subgrade. This

can have multiple benefits in terms of reduced settlements, increased stability, etc.

Geofoam materials, EPS in particular, can have a density as low as 10 kg/m3

which is less than 1% of that of normal earth materials (soil and rock). Nevertheless, the

stiffness and strength of geofoam can be sufficient to support motor vehicles, trains,

airplanes and even lightly loaded buildings. Thus geofoam is useful as a lightweight fill

material.

2.2.3 Fluid Transmission.Typically, geofoam materials have very low permeability for fluids (both gases

and liquids). However, both EPS and XPS geofoam products can be factory cut or

purposely shape moulded to have geometry such that they readily transmit fluids

(especially ground water) along one face or side of the product.

In addition, there are geofoam materials that have an inherent permeability

throughout their entire thickness. The most-common example is glued polystyrene porous

block.

2.2.4 Vibration Damping.

The relatively high stiffness to density ratio of most geofoam materials makes them

relatively efficient at damping the small-amplitude ground vibrations and even air-borne

noise from motor vehicles and trains. The inherent very low density yet significant stiffness



of geofoam can be beneficial in reducing ground-borne, small-amplitude waves that produce

noise or ground motion that may be disturbing to people and/or harmful to sensitive

equipment. It should be noted that for vibrations of large amplitude, such as from

earthquakes, where relatively large movement of the ground (i.e., soil particles) is involved,

the benefit of using geofoam appears to derive more from the compressible-inclusion

function rather than the damping function. As it damps Vibrations effectively, now it is

being used as a part of bearings in base isolation systems.

2.2.5 Compressible Inclusion. This is the function requiring the greatest research because there is perhaps the

greatest diversity of potential applications. Applications fall into two broad categories:

Earth retaining structures where horizontal arching is involved.

Pipes, culverts, and similar structures where vertical arching is involved.

With regard to earth retaining structures, there are numerous combinations of

variables that require evaluation and the development of analytical techniques suitable for

routine practice. Key variables are:

Soil type (traditional coarse-grained soils as well as fine-grained soils);

Loading (static, including compaction effects and surface surcharges, as well as seismic;

Geosynthetic tensile reinforcement in the retained soil (without [REP-Wall concept] and

with [ZEP-Wall concept]);

For reinforced fine-grained backfills, the effect of providing drainage with the

reinforcements.

Geofoam can be formulated to be highly compressible and thus efficient for use

behind or above rigid/non-yielding structures. This allows what is called controlled

yielding (movement) of the adjacent soil or rock which in turn reduces the load on the

structure. The classical soil mechanics phenomenon of arching above pipes and culverts

is one type of yielding that can be induced using a compressible inclusion as in the

development of the active earth pressure state behind an otherwise non-yielding wall. In

each of these applications the load on structure is significantly reduced.



2.2.6 Structural Applications. This is the newest geofoam function and its exact definition is, consequently, still in

the process of evolution. This function relates to some of the newest and still emerging uses

of geofoam such as panels of EPS as facing for mechanically stabilized earth walls

(MSEW), as facing panels for Segmental Retaining Walls (SRW) and a variety of EPS and

XPS products used as formwork for poured-in-place reinforced concrete foundations and

walls. The benefit of this may be particularly useful under seismic loading where the very

low density of EPS geofoam can be beneficial.

Insulated wall forms for cast-in-place (CIP) portland-cement concrete (PCC)

construction.

Lightweight facing panels for mechanically stabilized earth walls (MSEW).

Void formers for CIP PCC construction.

Crash barriers for motor vehicles and aircraft.

Impact cushioning for rock sheds in mountainous regions. And

Void filling and foundation remediation using foam grouts.

Also, there are miscellaneous applications that do not fit into any of the functional

categories mentioned above.

2.2.7 Drainage Applications.

The most significant activity in this functional area in recent years has been

specifically for ground-borne gas drainage such as methane and radon. The use of existing

drainage products, (specifically glued polystyrene porous block) as part of the new Geo-

inclusion and the use of sheet drains are widely accepted now.



CHAPTER 3

SPECIFIC PROPERTIES OF GEOFOAMS

3.1 LONG TERM INSULATION VALUE.

Thermal insulation is useful in any application where it is desired to restrict the

flow of heat. This may be either for conservation of energy consumption during operation

of the structure, construction-cost savings, or for improved geotechnical performance of

the structure. Contrary to many perceptions, geofoam thermal insulation can be used cost

effectively in any climate and not just those subjected to seasonal or permanent cold

weather. R-value is used as an indication of Thermal insulation. R-value means the

resistance to heat flow. The higher the R-value, greater is the resistance to heat flow. EPS

insulation (0.90 pcf) provides a typical R-value of 3.60 per inch at a mean temperature of

75 degrees F and a typical R-value of 4.00 per inch at a mean temperature of 40° degrees

F. When properly installed and protected from moisture, the thermal resistance or R-

value, of EPS may be used without any adjustment for age.

3.2 MOISTURE RESISTANCE.

Water vapour transmission through insulation materials is the passage of water

through the material in the vapour phase. In comparison to other common building

materials, EPS insulation has moderate water vapour permeability per unit of thickness.

Recommended design practices for walls and foundations should be followed in the

selection of vapour and moisture barriers for severe exposures.

3.3 TEMPERATURE CYCLING.

EPS is able to withstand the rigors of temperature cycling, assuring long-term

performance. In a series of tests conducted by the Dynatech Research and Development

Co., Cambridge, MA, core specimens removed from existing freezer walls, some as old

as 16 years, demonstrate EPS withstands freeze-thaw cycling without loss of structural

integrity or other physical properties.



3.4 STRENGTH CHARACTERISTICS.

The resilience of EPS insulation board provides reasonable absorption of building

movement without transferring stress to the outer skins at the joints. In most roofing

applications, Type1 EPS insulation material provides the dimensional stability and

compressive strength necessary to withstand normal roof traffic and equipment weight. If

greater rigidity and strength are needed, then higher density EPS insulation products can

be made use.

3.5 COMBUSTIBILITY.

Like many construction materials, EPS is combustible. EPS products are

manufactured with a flame retardant; however, EPS insulation will burn upon exposure to

flame or heat sources, including, but not limited to, open flames, welder's torches, or

other sources of heat. EPS insulation should be covered with a thermal barrier or

otherwise installed in accordance with applicable building code requirements.

3.6 SOLVENT ATTACK.

EPS is subject to attack by some petroleum-based solvents. Care should be taken

to prevent contact between EPS and these solvents and their vapors. This should be taken

into consideration in case of Highway embankments, where a lot of hydrocarbon

products can penetrate into the Geofoam material. Some protective coating can be made

over the foam material to prevent the contact of solvents with the foam, which will be

effective for a small period.

3.7 APPLICATION TEMPERATURES.

In roof construction and pavement construction requiring hot asphalt,

temperatures should not exceed 250 F at the time of direct contact with EPS insulation.

Avoid contact between EPS and high-temperature equipment, asphalt kettles and flame

sealer scan be used.



3.8 INSTALLATION EXPOSURE.

Prolonged exposure to sunlight will cause slight discoloration and surface

dusting of EPS insulation. The insulating properties will not be significantly affected

under normal usage. EPS stored outside should be protected with a light-colored opaque

material.

3.9 STANDARDS COMPLIANCE.

EPS insulation may be manufactured to meet or exceed the requirements

and should be strictly following the manufacturing standards and applicable building

codes.

3.10 PHYSICAL PROPERTIES.

3 Physical Properties of R-Control EPS Geofoam

TYPE - ASTM D6817 EPS12 EPS15 EPS19 EPS22 EPS29

Density, min.kg/m3

(lb/ft3)11.2

(0.70)14.4

(0.90)18.4

(1.15)21.6

(1.35)28.8

(1.80)

Compressive Resistance @ 1% deformation, min.

kPa(psi)

15(2.2)

25(3.6)

40(5.8)

50(7.3)

75(10.9)

Elastic ModuluskPa(psi)

1500(220)

2500(360)

4000(580)

5000(730)

7500(1090)

Flexural Strength min.kPa(psi)

69(10.0)

172(25.0)

207(30.0)

276(40.0)

345(50.0)

Water Absorption by total immersion, max., volume %

4.0 4.0 3.0 3.0 2.0

Oxygen Index, min., volume %

24.0 24.0 24.0 24.0 24.0

Buoyancy Force(kg/m3)(lb/ft3)

952(59.4)

955(59.6)

958(59.8)

961(60.0)

969(60.5)

Additional Properties for Compressible Applications


kPa(psi)

35(5.1)

55(8.0)

90(13.1)

115(16.7)

170(24.7)


kPa(psi)

40(5.8)

70(10.2)

110(16.0)

135(19.6)

200(29.0)



CHAPTER 4

APPLICATIONS OF GEOFOAMS

4.1 INTRODUCTION.

The following are common geofoam application concepts. The sketches are

intended to convey some of the more important features to be considered for

implementation.

Slope Stability

Embankments

Retaining Structures

Pavement Insulation

Shallow Foundations

Utility Protection

4.1.1 Slope Stability.

Geotechnical engineers have long recognized the utility of lightweight fill to

reduce mass and associated gravitational driving forces. Lightweight materials that have

been used in embankment construction include chipped bark, sawdust, dried peat, fly ash,

slag, cinders, cellular concrete, lightweight aggregates, expanded polystyrene, shredded

tires, and sea shells.

EPS geofoam is up to 50 times less massive than other lightweight fills (see

table). To achieve a net reduction in driving mass of 100,000 kg within an embankment



having an in-place soil density of 2100 kg/m3 would require placing about 90 m3 of

lightweight fill of 1000 kg/m3 density or about 50 m3 of EPS geofoam.

Material Density for calculation (kg/m3)

Bark 1000-1100

Sawdust 1000

Cellular concrete waste 1000

Light expanded clay (Leca) 800-1000

Waste bricks of Leca 1000

Tires 700-950 (in-place)

Pumice 1225

Expanded polystyrene geofoam 15-120

Table: Density Comparison of Different Fill Materials

Advantages to using geofoam for slope stabilization may include:

Maximizing available right-of-way.

Reduced construction schedule and traffic impact.

Relatively clean construction adjacent to waterways.

Reduced labour and future maintenance

A conceptual scheme of slope stabilization with geofoam is shown below. A

potential sliding block can be divided into an upper and a lower mass. The upper mass,

contributing more to driving or instability, is referred to as a driving block. The lower

mass, contributing more to resistance or stability, is referred to as a resisting block. These



may include ground water lowering, removal of material mostly from the upper or

driving block, or increasing the size or influence of the lower or resisting block by

providing a berm. Except for ground water lowering, the overall effect of either

decreasing the driving block or increasing the resisting block is to change the geometry of

the slope by decreasing the average inclination.

As the density of geofoam is 50 to 100 times lower than soils, Acceptable

improvement in safety factor can be achieved by soil excavation and replacement with

geofoam in the driving block. Such improvement in stability occurs without requiring a

change in the final slope geometry. The excavation back slope would be sloped to be self-

supporting. Free draining material would be placed as transition between the natural soil

and the geofoam along the back slope and as levelling course along the base. The final

geofoam block configuration balances the amount of geofoam required (cost) with other

design and construction factors such as ease and quickness of construction, traffic and

environmental impacts, and construction space limitations. Provision of a concrete slab

cover may not be necessary.

Installing EPS geofoam into an embankment requires that existing soil fill

material be removed. Sloped excavations that roughly parallel the shape of the geofoam

fill and the existing failure surface facilitate construction. Sloped excavations may not be

possible in some cases due to construction right-of-way limitations, requirements related

to traffic, poor soil, or a combination of these factors.

Where inclined excavations are not an option, a temporary steel sheet-pile wall

may be installed to permit vertical excavation adjacent to the geofoam fill, as shown

below. In both sketches, the concrete slab and pavement are optional.

4.1.2 Embankments.



An application concept for geofoam use as light-weight fill for embankment

construction is shown in the figure. Construction would begin with placement of a

granular levelling course. Geofoam would then be placed in successive layers to

construct the embankment. A 10 to 15 cm thick reinforced concrete slab or a membrane

cover may be provided over the top of the geofoam. The concrete slab would help in load

distribution. Both the slab and membrane serve as protection against very rare spillage of

fluids that can damage geofoam. Guard rails can be tied to the concrete slab or supported

on separate footing.

The geofoam side slopes would be covered with soil, lightweight fill or protective

facing. A road structure suitable for the anticipated traffic, and with adequate cover to

minimize possibilities for differential icing can be constructed above the geofoam fill.

This technique does not require pre-loading and removal normally associated with

embankment construction on soft ground. Side slopes at 2:1 or even in vertical finish can

be developed as geofoam imposes very light loads on the foundation and can be

constructed to interlock. Geofoam embankments require less maintenance and develop

minimal post-construction settlements compared to embankments constructed with

natural soils.



The other application of Geofoam in embankment construction is in the case of

embankments constructed in marshy soils, where the constructed road settles with time.

Adding more fill to tolerate the grade results in additional settlement as shown in the

figure. This problem is due to the additional weight came into the soil due to the

additional fill material. This problem can be overcome by introducing Geofoam fill over

the area. As the material is lighter, it will result in reduced surcharge to the soil, thus

reducing the settlements.

4.1.3 Retaining Structures

Placement of geofoam behind retaining structures and below-grade walls can

offer advantages of reduced lateral pressure, lower settlements, improved water proofing

and better insulation. The central concept in using geofoam as a retaining structure

backfill is to substitute as much of the soil in the active or at rest wedge with geofoam to

the extent desired. Since the geofoam density is low, vertical stresses that develop behind

the retaining wall or abutment will be much less than for comparable aggregate backfill.

This would imply reduced settlements and especially step settlements such as

between a bridge deck and an approach fill. The retaining structure would be designed for



the expected lateral pressure transmitted by the geofoam fill, which can be zero.

Adequate sub-drain should be provided to prevent development of hydrostatic pressure

and buoyancy. The finished grade behind the retaining structure can be developed with or

without a load distribution slab or plastic sheeting cover above the top surface of the

geofoam, as desired. An application scheme for a retaining wall or abutment backfill is

shown below.

It can also be used to retain soil in the case of Bridge abutments and it itself is

used in the abutments. It reduces the dead load transfer to the retaining wall drastically

and thus reduces the section and hence economy is achieved. Again it reduces the usage

of non-renewable natural recourses such as soil and aggregates in case of earth fill used

in road constructions as well as filling areas.

4.1.4 Pavement Insulation.

The design of highway or airport pavements may be governed by subgrade

stress/deformation criteria or frost heave protection requirements. Where the pavement

thickness is controlled by frost heave conditions, considerable savings can be realized by

installation of geofoam as insulation. In considering geofoam as a subgrade insulation

element, care should be exercised to minimize development of differential icing.

Available experience suggests that the performance of geofoam insulation depends on

tight construction control to ensure continuity of insulation without gaps. High density

geofoams provide higher initial R-values, deform less under load, and absorb less

moisture over time.



Care must be taken during the insulation of pavements as any supervision

errors may result in the total failure of the structure, ie. if proper care is not taken, there is

a chance of splitting of Geofoams at the joints which allows the ground water to creep

into the pavement and can damage the structure as a whole.

4.1.5 Shallow Foundations.

In cold climate regions, building foundations are required to extend below depths

of expected frost penetration. This usually requires construction with basements or crawl

space below floor grade. The design concept shown below can be used to construct

buildings with frost protected shallow foundations. With this scheme, homes can be built

in cold climates with slab on grade support.

Fig. Foundation insulation

Wing insulation, as shown, may be required in areas that experience extreme cold

temperatures. Frost protected shallow foundations may enable savings in construction



and offer additional benefits from energy efficiency. The thickness, density and

insulation properties of the geofoam as well as expected extreme frost penetration depths

are important considerations. Any portions of geofoam that remain above ground should

have protective cover.

Another type of foundation insulation is in such a way that the whole foundation

will be placed in a Geofoam material so that it is isolated from rest of the soil. This is

performed when the water table of the area is near to that of foundation. Here the design

of insulation should be done properly as buoyancy force comes into play at the time of

intrusion. After the construction of foundation, which adds a lot of dead weight on the

foam, will contribute to the stability.

Foundation insulations are done in four ways. They are listed below

Perimeter insulation.

Exterior Foundation walls.

Sub slab insulation.

Interior wall insulation.

4.1.6 Utility Protection.

Geofoam has been used to control loading on rigid buried pipes by development

of an induced trench condition. It is also feasible to consider reducing stresses on large

flexible culverts by placement of geofoam. Here the load coming over the buried pipes

and culverts can be reduced to a greater extent so that they will be structurally safe

against the external stresses. (Low stress)

CHAPTER 5



PROBLEMS ENCOUNTERED WITH FOAMS

5.1 INTRODUCTION.

Geofoams should be properly inspected and proper care should be taken at site

and storing to reduce the damages as well as to obtain a better performance. Geofoams

are made of polymer fibers and are not inert in nature, it can react with any chemical and

thus it should not be exposed at site and it should be covered at least with apolythene

cover. The probable damages, which can happen to geofoams, are explained below.

Geofoams may catch fire during construction as they contain inherently

inflammable materials. As the Oxygen Index of some of the materials forming

geofoams is less than 21%, it is necessary to make the geofoam flame retardant.

A gas is used as blowing agent, to create closed cell texture, during manufacture

of geofoams. During thermal cooling of geofoams this gas is replaced by air in a

process known as out gassing. It may take years to complete the process . Hence

care should be taken against open flames for insufficiently seasoned geofoam

blocks.

Premature pavement failure may occure under static as well as dynamic loads due

to block shifting. Hence at least two layers of geofoams blocks should be used for

fills that will be subjected to dynamic and cyclic load.

As the density of geofoam material is very low, it is extremely buoyant in liquids

such as ground water. In the areas of possible submergence there must be a dead

load stress on geofoams sufficient to counteract uplift force due to buoyancy.

Any water absorbed in to a geofoam will increase the thermal conductivity and

thus reduces thermal insulation effect.

The geofoam layer of sufficient thickness is used in pavement construction so that

the soil subgrade beneath the geofoam would not freeze and thus prevent froast

heaving of subgrade. This will also prevent potholeas in pavement due to thaw

weakening of soil subgrade. During construction of road or airfield paved surface,

the heat balance is disrupted and this would retard the thermal insulation property

of the geofoams. Care must be taken in both design and construction in such

situations.



Differential icing will occur in pavement as insulated pavement develops surface

ice quickly. This happens due to escape of naturally stored heat from the insulated

surface quickly. This differential icing causes serious safety problems to drive

vehicles.

Geofoams, used as thermal insulation adjacent to wood framed residential

structures, may get damaged as insects attacks them as part of their attack on

wood. On the other hand no other known evidences that insects damage to

Geofoams occurred as they are non-nutritive and will not be consumed as food

source.

CONCLUSION



Geofoam is a new terminology in Geotechnical Engineering, which was added to

the literature only in 1992. But the intrusions of these less density polymer finds much

application in Geotechnical engineering compared to any other fill materials. It can be

effectively used as for reducing the dead load stresses in road and rail embankments,

retaining structures, stabilization of natural slopes etc. It can also be used in pavement

insulation and foundation insulation. Moreover, it can be used as sound absorbing

barriers in highways. The Geofoam intrusions can also stop the problem of Land sliding.

Intrusions of these low-density polymer materials can solve some of the problems

encountered with Geotechnical Engineering, if properly worked with. It can indirectly

resist Earthquakes as Newton’s second law of physics reminds us that force and mass are

directly proportional, so it is possible to reduce earth loads under both gravity and

seismic loading by a factor of about 100 when EPS geofoam is used to replace normal

earth materials as backfill and fill.

REFERENCE



John S. Horwath, Ph.D., P.E., Geofoam Geosynthetic:Past, Present and Future, EJGE

GeoFoam by John S. Horvath, Ph.D., P.E. Lecture Notes, International Geosynthetics

Society.

John S. Horvath1, Ph.D., P.E., CELLULAR GEOSYNTHETICS IN

TRANSPORTATION APPLICATIONS American Society of Civil Engineers.

http://www.ejge.com/

http://www.ascelibrary.org/

http://geofoam.syr.edu/

http://www.fhwa.dot.gov/

http://www.geosyscorp.com/

http://www.truefoam.com/

http://www.rewardwalls.com/

http://www.carpenter.com/Divisions/eps_Geofoam.htm

http://www.insultech-eps.com/


http://www.insultech-eps.com/

http://www.carpenter.com/Divisions/eps_Geofoam.htm

http://www.rewardwalls.com/

http://www.truefoam.com/

http://www.geosyscorp.com/

http://www.fhwa.dot.gov/

http://geofoam.syr.edu/

http://www.ascelibrary.org/

http://www.ejge.com/

Documents

Geofoam Intrusions