chemistry

Geofoam

Geofoam is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Geofoam rather than just read about it. In short: Geofoam is expanded polystyrene (EPS) or extruded polystyrene (XPS) manufactured into large lightweight blocks. The blocks vary in size but are often 2 m × 0.75 m × 0.75 m (6.6 ft × 2.5 ft × 2.5 ft).

Key takeaways

Geofoam belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Geofoam to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Geofoam from memory before moving on to harder problems.

Reference excerpt

Geofoam is expanded polystyrene (EPS) or extruded polystyrene (XPS) manufactured into large lightweight blocks. The blocks vary in size but are often 2 m × 0.75 m × 0.75 m (6.6 ft × 2.5 ft × 2.5 ft). The primary function of geofoam is to provide a lightweight void fill below a highway, bridge approach, embankment or parking lot. EPS Geofoam minimizes settlement on underground utilities. Geofoam is also used in much broader applications, including lightweight fill, green roof fill, compressible inclusions, thermal insulation, and (when appropriately formed) drainage. Geofoam shares principles with geocombs (previously called ultralight cellular structures) which has been defined as "any manufactured material created by an extrusion process that results in a final product that consists of numerous open-ended tubes that are glued, bonded, fused or otherwise bundled together." The cross-sectional geometry of an individual tube typically has a simple geometric shape (circle, ellipse, hexagon, octagon, etc.) and is on the order of 25 mm (0.98 in) across. The overall cross-section of the assemblage of bundled tubes resembles a honeycomb that gives it its name. Presently, only rigid polymers (polypropylene and PVC) have been used as geocomb material.

History The first use of EPS Geofoam was in Oslo, Norway, in 1972. Geofoam was used in the embankments around the Flom Bridge in an effort to reduce settlements. Prior to installing geofoam, this area experienced 20–30 centimeters of settlement annually causing extreme roadway damage. Due to the success of the Oslo geofoam project, the first International Geofoam Conference was held in Oslo, Norway, in 1985 for engineers to exchange knowledge, research results, share new applications, and discuss case histories. Since then, two more conferences were held in Tokyo, Japan, and Salt Lake City, US, in 1996 and 2001, respectively. The most recent conference was held in June 2011 in Lillestrom, Norway. Between 1985 and 1987, Japan used over 1,300,000 m3 (46,000,000 ft3) of geofoam in 2,000 projects. Testing and use of geofoam in these projects demonstrated the potential advantages of geofoam as a lightweight fill. For example, Geofoam was placed beneath runways in Japanese airports, proving the material can sustain heavy and repeated pressure. Geofoam was first used in the United States in 1989 on Highway 160 between Durango and Mancos, Colorado. An increase in rainfall caused a landslide, destroying part of the highway. Geofoam was used to create highway side slope stabilization to prevent any similar issues. The use of geofoam versus conventional restoration resulted in an 84% reduction to the total cost of the project. The largest geofoam project in the United States took place from 1997 to 2001 on Interstate 15 in Salt Lake City, Utah. Geofoam was chosen to minimize that amount of utilities that would need to be relocated or remodeled for the project. A total of 3,530,000 ft3 (100,000 m3) of geofoam was used, and approximately $450,000 was saved by eliminating the need to relocate utility poles. Geofoam was also used in embankments and bridge abutments for base stability. Subsequently, because of the success of usage of geofoam for the I-15 Reconstruction Project, the Utah Transit Authority has used geofoam embankment for its light rail (i.e., TRAX) and commuter rail lines (i.e., FrontRunner). From 2009 to 2012, a Vaudreuil-based expanded polymer manufacturing company provided over 625,000 m3 (22,100,000 ft3) of geofoam for a new segment of highway 30 in the province of Quebec, in the Montreal area, making it the largest geofoam project in North America to date. Since 2016, Geofoam is extensively used in the construction of the new elevated highway 15 and Turcot interchange in Montreal.

Applications A brief summary of applications can be found at:

Slope stabilization

Slope stabilization is the use of geofoam in order to reduce the mass and gravitational force in an area that may be subject to failure, such as a landslide. Geofoam is up to 50 times lighter than other traditional fills with similar compressive strengths. This allows geofoam to maximize the available right-of-way on an embankment. Geofoam's light weight and ease of installation reduces construction time and labor costs.

Embankments

Embankments using geofoam allow for a great reduction in necessary side slopes compared to typical fills. Reducing the side slope of the embankment can increase the usable space on either side. These embankments can also be built upon soils affected by differential settlement without being affected. Maintenance costs associated with geofoam embankments are significantly lower when compared to embankments using natural soil.

Reduced digging

Some weak and soft soil cannot support the weight of the desired structure; an overpass bridge on the nearby picture. If it was built out of traditional earthwork filling, it would have been too heavy and deform the weak soil underneath and damage the bridge. To reduce costs by not digging into the bedrock, geofoam is used for the interior filling of the bridge

Retaining structures

Using geofoam for retaining structures provides a reduction in lateral pressure as well as preventing settlement and improving waterproofing. Geofoam's light weight will reduce the lateral force on a retaining wall or abutment. It is important to install a draining system under the geofoam to prevent problems with built-up hydrostatic pressure or buoyancy.

Utility protection Utility Protection is possible by using geofoam to reduce the vertical stresses on pipes and other sensitive utilities. Reducing the weight on top of a utility by using geofoam instead of a typical soil prevents utilities from potential issues, such as collapses.

Pavement insulation Pavement insulation is the use of geofoam under pavement where pavement thickness can be controlled by frost heave conditions. Using geofoam as a sub-grade insulation element will decrease this differential thickness. Geofoam is 98% air by volume, making it an effective thermal insulator. Proper installation of geofoam is especially important as gaps between geofoam blocks will work against geofoam's insulating effects.

Advantages Advantages of using geofoam include:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Geofoam

Start with the simplest possible case. Write down what Geofoam claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Geofoam before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Geofoam ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Geofoam

In research: Geofoam appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Geofoam in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Geofoam is common in secondary-school and first-year university syllabi. It links to neighbouring topics Building insulation materials, Building materials, Insulators, so understanding it makes those chapters shorter.
In everyday life: Look for Geofoam outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Geofoam in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Geofoam means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Geofoam out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Geofoam in simple terms?

Why does Geofoam matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Geofoam?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Geofoam.