3000 word assignment on EPS geofoam

8/3/2019 3000 word assignment on EPS geofoam

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B Eng (Ordinary) in Civil Engineering

Civil Engineering Construction

1.0 INTRODUCTION

Expanded Polystyrene (EPS) Geofoam is a lightweight fill used in geotechnical applications. In

the past, EPS Geofoam has mainly been used as a protective material in packaging. Only

recently has the use of Geofoam as lightweight fill been recognised as a faster and much more

inexpensive method of preventing instability and settlement, as well as providing resistance to

lateral pressures (ACH Foam Technologies, 2011; Geofoam research Center, 2011). Geofoam is

also used in several other geotechnical engineering applications, including thermal insulation

(i.e. in the form of frost blankets (Hanna, 1978) and as a vibration damper (Horvath, 1995).

Despite these alternative applications, the specific focus of this report remains the discussion of

Geofoam utilisation as lightweight fill.

Given the rapid advancement of building technologies and subsequent development of more

stringent EU directives on environmental regulations (DEPC-IPPC, 2008), consumers are

becoming more conscientious of the environmental repercussions of new technologies.

Consequently, utilisation of new technologies (e.g. Geofoam), must be evaluated in light of

potential environmental implications, being of considerable global importance. Thus, this report

not only aims to outline benefits of Geofoam as an innovative product, but also to explore

current developments in the domain of Geofoam- recycling protocols (i.e. in terms of what can

be done with Geofoam after it has completed the lifespan of its intended use).

Though this report is constrained given that it is a review of the topic area, lacking testing of the

product itself; it is based on the empirical findings of experts in the field of geotechnical and

civil engineering. More specifically, EPS Geofoam will be discussed in this report in terms of

its overall advantages, manufacture, cost, environmental implications and previous research.

2.0ADVANTAGES OF USING EPS GEOFOAM

The main advantage of EPS Geofoam is that it can replace the use of other more costly,

environmentally unfriendly, inert fill material (Elragi, 2006; see Figure 2.1). Further cost

advantages are discussed below. In addition, installation of Geofoam requires no machinery.

Avoidance of machinery installation also has environmental impacts as manual installation

significantly decreases oil and fuel usage, thus reducing air pollution. Additionally, Geofoam is

a more environmentally sustainable material because it is non-biodegradable, consequently,

once it is buried it will not have have any adverse effects on the soil or ground water quality

(Geofoam Research Centre, 2011).

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Figure 2.1: Typical Geofoam fill detail

Furthermore, Geofoam can greatly reduce the axial loads on weaker sub-soil while at the same

time will reduce or eliminate lateral loads on abutments and foundations (see Figure 1; ACH

Foam Technologies, 2011). Another advantage of Geofoam is that it has very low density,

good insulation, low hydraulic conductivity, as well as strength and deformation properties that

complement soil behaviour (Geofoam Research Center, 2011). Geofoam is not weather

sensitive and can be used in various weather conditions. Consequently, project time line may

not have to be extended due to adverse weather conditions. (Geofoam Research Center, 2011).

Figure 1.1: Elimination of lateral loads on abutments via use of Geofoam (adapted from ACH

Foam Technologies, 2011)

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As Geofoam is manufactured in an industrial plant it provides a material which has consistent

properties such as load bearing capacity, size and shape as opposed to other lightweight fill

material, such as soil, waste tyres and wood chips (Foam Control, 2011), which is important

to consider in terms of quality control.

3.0MANUFACTURING PROCESS

A Geofoam block begins its life as expandable polystyrene resin beads (i.e. less than 3mm

diameter) and contains microscopic cells filled with a blowing agent (i.e. pentanes or butanes).

They are then exposed to steam under a controlled pressure, where the blowing agent expands,

resulting in each individual bead expanding up to 40 times in volume to form pre-puffs.

Subsequently, there is a holding period at room temperature after which the pre-puffs are

poured into a rectangular mould. The mould is secured closed and more steam is injected

through small perforations in the walls of the mould. The pre-puff then expands further and

fuses together to form a block (Hotwire Direct, 2011). Notably, during the manufacturing

process of Geofoam, no known harmful gasses are used that could potentially damage the

environment (Geofoam Research Centre, 2011).

Geofoam blocks intended for use in the construction industry are treated with fire resistant

additives; however, even treated Geofoam blocks should be handled and stored with fire safety

in mind, as it is a highly combustible material (Geofoam Research Center, 2011). When used in

construction, these EPS blocks have unit weights between 12 and 30kgforce/m3 (Lee-Kuo Lin et

al., 2010). For further properties of EPS Geofoam, see Appendix B. For a schematic of the

manufacturing process of Geofoam, see Figure 2.1.

Figure 3.1 Schematic of manufacturing process of EPS

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3.1 Cost

In relation to cost, the use of Geofoam as landfill material is substantially cheaper

than other inert landfill methods (Elragi, 2006). More specifically, utilisation of Geofoam

results in a reduced cost to the client, as in comparison with use of soil fill, as it takes

significantly less time to lay, requires no machinery and does not need to be compacted

(whereas soil does), resulting from its rapid and easy-to-install construction method.

Given its standard block shape and lightweight properties, there is a greater reduction in man-

hours during the laying of the material. Geofoam does not require machinery-based installation

(i.e. it can be laid manually - thus avoiding machine rental, operator and/or fuel costs (see

Figure 3.1). Compacting machinery is not needed as a property of the material dictates that it

does not require compacting. Due to the regular shape and light unit weights of Geofoam, the

cost in transporting the material to the site is greatly reduced.

Figure 3.2: Manual installation of Geofoam

4.0 RECYCLING EPS

To date, there has not been reason to contemplate recycling the material (after it has been

exhumed), given that Geofoam is a relatively new technology. As time progresses, along with

further development, investigation in this area will be necessary. The Geofoam Research Centre

(2011) has reported a case in Norway where Geofoam, unearthed from a construction site which

had been in situ for 20 years, were found to be in good condition and were reused. Re-use is

obviously the initial option when attempting to recycle Geofoam. However, it is worth noting

that the question remains as to what can be done when re-use as fill material is not an option.

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4.1 Soil-EPS Mixes

Soil-EPS mixes (i.e. a mixture of soil and EPS) are still in their developmental infancy. These

soil-EPS mixes provide a way of diverting used EPS away from land fill by means of

reprocessing the used EPS which then can be recycled as a soil modifier for expansive clays,

which cause considerable damage to structures due to unpredictable ground movement (Illuri,

2007). Though Illuri solely promotes the use of EPS from packaging boxes, despite the

alternative use of EPS as lightweight fill; theoretically, EPS that had been used as the latter

could also be reused as a soil modifier.

Currently, lime is most commonly used as a chemical stabiliser for expansive soils (Illuri,

2007). However, with repeated wetting and drying, the beneficial effect of using lime as a

stabiliser is virtually lost, due to the reduction in moisture content, cementation bonds and dry

unit weight (Rao et al., 2001). The resultant aim in reusing EPS Geofoam as a soil modifier

suggests that the EPS beads can control the swell-shrink property of expansive soils thus

enabling them to be recycled in geotechnical applications (Illuri et al., 2007)

5.0 CASE STUDY: USE OF EPS AS A LIGHTWEIGHT FILL

Given that the utilisation of EPS Geofoam is a relatively recent advancement in both

geotechnical and civil engineering, there has been a paucity of empirical evidence conducted on

its potentially beneficial outcomes. Nonetheless, a case-study conducted on the use of EPS

Geofoam as a lightweight fill for a stretch of road is presented below to exemplify such

beneficial outcomes.

5.0.1 Project Particulars

This case study was conducted on a road widening project (over a stretch of 10.86km) using

EPS Geofoam, undertaken by the Michigan Department of Transportation on Lake Michigan

Drive (M45) through the town of Allendale in Michigan, USA.

Project Completed: November 2002

Contractor: Nagel Construction Inc.

Project manager: Bruce Morren

The road widening project could not commence until the load on a nearby buried water

main was reduced. This water main supplied up to 45000000 gallons of water per day to the

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local area. Sand fill would exert 9764.84kg/m2 load on the waterline, resulting in collapse of the

pipeline. Consequently Geofoam was used as an alternative lightweight option; (see Figure 5.1).

Figure 5.1 Detail of EPS being utilised as utility protection.

For this project, Geofoam substantially reduced the loads exerted on the underlying water main.

16400000 Kg of sand was removed and the Geofoam that replaced it represented only 1.5% of

that, weighing in at 24,000kg. Geofoam blocks have the ability to carry a vast amount of weight

from the four-lane carriageway it carries. The blocks used in this project were a 1.54 pcf density

EPS. Notably, the density of EPS blocks can be adjusted according to specifications.

5.1 Specific design requirements and installation of Geofoam on the M45 project.

The blocks in this project were cut to size before they were transported to site. Further field

cutting of the blocks proved to be easily achieved on site (i.e. in the case of manholes), as

shown in figure 5.2, with the use of hot wire cutters, as shown in Figure 5.3. Blocks were

installed in trenches which had been cleared of any vegetation and sharp stones prior to placing

the sand-bedding layer. The blocks on the M45 project were 160kg and the dimensions of the

blocks were 82cmx122cmx244cm. Consequently, the blocks were easily manoeuvrable around

site and easily installed by two workers. Each Geofoam block was fastened in place by10.2cmx10.2cm galvanised steel connector-plates. Similar to building a block wall, each layer is

installed perpendicular to the last with the joints staggered, as shown in Figure 5.4.

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Figure 5.2: EPS Geofoam adjacent to storm drain

Figure 5.3: Workers cut Geofoam to size using hot wire cutters

Figure 5.4: Structural Installation of EPS Geofoam

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As the blocks were being utilised under a pavement, before the road could be surfaced, the top

and sides of the blocks were wrapped in a PVC liner, to prevent degradation of the blocks in the

case of a petrol spill. Soil was backfilled to the sides of the road to road level to prevent

movement. A layer of sand and gravel were placed on top of the blocks to a minimum of

900mm (to keep the blocks below the frost line).

5.2 Advantages of using Geofoam on this project

During the process of laying the EPS blocks, up to 45000000 gallons of water per day was

being delivered to the local city. A heavier fill material or soil moving equipment could have

damaged the line. In the case of this project, it would have taken up to 3 hours to shut off the

water. According to the project manager, Bruce Morren, When you put the foam over the line

you know you are not going to disturb it.

The management team claimed that Geofoam was the more cost effective choice of fill, while

sand fill requires long-distance transportation. According to Federal Highway Administration

officials, Geofoam provides a reduction in labour costs and also a reduction in project

schedules. The project manager believed that safety was the main advantage to using Geofoam

blocks.

6.0 CONCLUSION

There are various densities of Geofoam available so as to meet different project

requirements.

Geofoam is a manufactured product resulting in uniformity in shape and density.

Much faster installation time than any other inert land fill material.

As a result of a more rapid installation time the cost to the client is significantly

reduced.

Reduces the lateral or bearing loads due to the Geofoam block low unit weights.

Geofoam is not weather sensitive and can be installed in various weather conditions.

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Geofoam has no known adverse effects on the environment in which it is installed and

compared with using soil as a fill material is more environmentally friendly as a whole.

Geofoam which has been buried for 20 years has been found to still be re-useable.

Geofoam can be recycled and used in other geotechnical applications such as soil

modification. (EPS-soil mixes)

References

Elragi, A.F. (2006). Selected Engineering Properties and Applicationsof EPS Geofoam. Ph.D.

Thesis, State University of New York, Syracuse, NY .

Hanna, A.N. (1978).Expanded polystyrene concrete sub-bases. Transportation Research

Record, 875, 1-6.

Horvath, J. S. (1995). Geofoam Geosynthetic. New York: Horvath Engineering.

Fang, H.Y (1990).Foundation Engineering Handbook Second Edition. Kluwer Academic

Publishers

Directive 2008/1/EC of the European Parliament and of the Council of 15 January 2008

concerning integrated pollution prevention and control (Codified version) (Text with EEA

relevance )

Lin, L-K, Chen L-H, Chen R.H.L. (2010)Evaluation of Geofoam as a Geotechnical

Construction Material. American Society of Civil Engineers

Rao, S M., Reddy, B.V.V. and Muttharam, M. (2001) The impact of cyclic

wetting and drying onthe swelling behaviour of stabilised expansive soils.

Engineering Geology, Vol.60.

Illia, T. (2009). Geofoam blocks save time on Utah light-rail project. ENR Magazine

Websites

http://geofoam.syr.edu/ March 2011

www.geofoam.com/ March 2011

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www.zhongji.com/ March 2011

www.flickr.com/ March 2011

www.enrconstruction.com/ March 2011

www.softoria.com/ March 2011

www.atlaseps.com/ March 2011

www.foam-control.com March 2011

www.hotwiredirect.com March 2011

www.ebookbrowse.com

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Appendices

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APPENDIX A: Foam-Control EPS Geofoam Properties & Additional

Properties for Compressible Applications

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Documents

3000 word assignment on EPS geofoam