Insulfoam’s Regional Sales Director, Rick Canaday, joined Home Talk USA with Michael King to discuss insulation in your home, insulation properties, moisture concerns, energy leaks in and out of the home and more.
Originally posted online at Construction Superintendent
Understanding rigid foam insulation for foundation and under-slab applications
Up to one-quarter of a building’s energy loss is due to lack of insulation in below-grade areas, including the foundation and under slabs. Now that high-performance building envelopes are common above ground, the relative amount of total heat lost below grade will grow if these spaces are not addressed.
As a result, superintendents increasingly will encounter below-grade and under-slab insulation on all building types. To help increase understanding of how two common rigid-foam insulations perform in these settings, this article evaluates moisture absorption and thermal performance. It also discusses installation procedures for below-grade and under-slab insulation.
Rigid foam insulation
Two common rigid foam insulations specified for below-grade applications are expanded polystyrene (EPS) and extruded polystyrene (XPS).
An easy way to recognize EPS on the jobsite is that it is commonly white. This insulation is made of expanded polystyrene beads fused into sheet stock and blocks of various densities, compressive strengths and sizes. Historically used as a stable roof insulation, EPS has gained wide acceptance in wall, below-grade and under-slab applications due to its low-moisture absorption, strength and stable, long-term thermal performance. EPS insulation blocks can be custom-cut into a variety of shapes and sizes to meet wide ranging job specifications.
Building professionals have used EPS successfully in below-grade applications for decades. As of 2013, the International Code Council explicitly permits EPS throughout frost protected shallow foundations, under slabs and any other below-grade application.
To make XPS, manufacturers combine and melt polystyrene with blowing agents and additives, then force the liquid mixture through an extrusion die in a continuous feed, where it is shaped, cooled and trimmed to size. The product is most commonly available as boardstock of fixed size and thickness. Manufacturers often tint XPS a primary color for brand recognition.
Moisture absorption and thermal performance
There is much confusion in the marketplace regarding whether EPS or XPS insulation resists moisture better. This is a key point, as wet insulation has lower thermal performance. While manufacturers of both insulation types tout that their products have lower moisture absorption, in-situ tests indicate that EPS performs better in this regard.
For example, in 2008, Stork Twin City Testing – an accredited independent testing laboratory – examined sheets of EPS and XPS removed from a side-by-side installation after 15 years in service on a below-grade foundation in St. Paul, Minnesota. The XPS was significantly wetter on extraction, with 18.9 percent moisture content by volume compared to 4.8 percent for the EPS. After 30 days of drying, the XPS still had elevated moisture of 15.7 percent, while the EPS had dried to 0.7 percent.
The U.S. Department of Energy’s Oak Ridge National Laboratory also reports high moisture absorption levels for XPS. In a 2012 study, the lab reported “all samples of XPS insulation gained much more moisture during the 15 years of contact with soil moisture.” The resulting loss of energy savings performance was 10 percent for a full basement (“deep basement”) and 44 percent for a slab-on-grade installation.
By comparison, the U.S. Army Cold Regions Research and Engineering Laboratory found EPS buried in wetted soil for 1,000 days absorbed only 1.7 percent moisture by volume, which is substantially lower than the XPS rates noted above.
Installing rigid foam insulation below grade
On building foundations, the insulation (whether EPS or XPS) is installed over the damp/waterproofing, after that layer has adequately cured. Crews can use mechanical fasteners or polystyrene-compatible adhesive to attach the insulation. Applying a bead of polystyrene-compatible caulk or mastic to the top of the insulation board minimizes water infiltration behind it.
For under-slab applications, the rigid foam insulation typically should be installed over a gravel base, with a poly vapor diffusion retarder between the gravel and insulation. Additional insulation is applied along the edges of the slab, because that is a primary surface for heat loss. To avoid damage to the insulation, it is necessary to ensure removal of any jagged surfaces or irregularities in the substrate before installing the rigid foam panels.
In either case, it is important to confirm all details with the insulation manufacturer and local building department, and to ensure appropriate construction techniques to drain water away from the building.
In addition to its lower moisture absorption and better long-term thermal performance, EPS has the highest R-value per dollar among rigid insulations. As such, it provides a cost-effective way to insulate building foundations, and under slabs.
Ram Mayilvahanan is the product marketing manager for Insulfoam, which offers below-grade insulation under the Insulfoam and R-Tech brand names. For more information, visit www.insulfoam.com.
Contact Ram Mayilvahanan, Insulfoam’s Product-Marketing Manager
Originally posted online at Buildings.com in Buildings Buzz!
Wet insulation is ineffective insulation – rigid foams that retain high volumes of moisture lose about half of their insulating R-value. Because insulation installed on below-grade building foundations and under concrete slabs is often exposed to moist soil, it is crucial to choose an insulation that has minimal long-term moisture retention and the ability to dry quickly.
For facility professionals that are evaluating insulation for building retrofits or for new construction, paying attention to moisture performance helps ensure effective long-term thermal resistance. Because the insulation will be hidden from view, any problems with degraded materials will not be obvious, although the effect on higher energy bills will be very real.
One challenge in selecting insulation is cutting through the competing claims of insulation manufacturers. Producers of extruded polystyrene (XPS) and expanded polystyrene (EPS) – common below grade insulations – both claim that their products are superior at resisting moisture. In their own ways, each one is right, but it depends on whether one is looking at abstract, standardized tests or performance in actual installed conditions.
Claims that XPS insulation absorbs less moisture than EPS are based on ASTM 272, Standard Test Method for Water Absorption of Core Materials for Sandwich Constructions. This test calls for fully submerging an insulation sample in water for 24 hours, then weighing it for moisture absorption immediately upon removal from the water.
How does this test represent reality? The truth is it doesn’t reflect real-world conditions for two reasons:
1) Unless your building is in a lake or river or subjected to severe flooding, the insulation will not be fully submerged.
2) It doesn’t account for how much an insulation dries out or does not dry out between periods of moisture exposure.
Entire marketing campaigns have been built around this test, but when it comes to what really happens on your building, it’s necessary to look at actual exposure during in-situ tests. Studies of insulation exposure to moisture in actual field conditions show that EPS outperforms XPS by a wide margin, largely because EPS dries much faster than XPS.
For example, the independent lab Stork Twin City Testing evaluated the moisture content of EPS and XPS buried side-by-side for 15 years on a building foundation in St. Paul, MN. At the time the insulations were removed, the EPS was four times drier than the XPS – the EPS had only 4.8% moisture by volume compared to 18.9% moisture content for the XPS. After 30 days of drying time, the EPS had dried to only 0.7% moisture by volume, while the XPS still contained 15.7% moisture.
The high moisture absorption of XPS is further seen in a 2012 report from the U.S. Department of Energy’s Oak Ridge National Laboratory. Researchers found that XPS insulation installed below grade for 15 years had absorbed 67% or more moisture. The resulting loss of energy savings performance for the XPS was 10% for a full basement (“deep basement”) and 44% for a slab-on-grade installation.
Insulation manufacturers are well aware of how their products will perform over the years. Evidence of this is seen in the limitations stated in warranties they offer. This is why XPS manufacturers typically warrant only 90% of the insulating R-value of their products during time in service, whereas most EPS manufacturers warrant 100% of the R-value. Some XPS manufacturers will also void warranties in case of ponding or water immersion, which runs contrary to their highlighting of 24-hour, full-immersion testing.
There are many claims in the market about whether EPS or XPS offers the best moisture resistance. When evaluating such statements, it is important to consider the basis upon which the statements are made. Does the testing involve guys in lab coats dunking insulation into a fish tank for one day, or does it replicate how insulation performs on actual buildings over many years? If facility managers are making the investment in insulation, this is an important distinction to pay attention to, otherwise the product might not perform as desired.
Contact Ram Mayilvahanan, Insulfoam’s Product-Marketing Manager
Originally posted online at Constructor Magazine, Web Exclusive
USING GEOFOAM TO SIMPLIFY COMMON SITE PREP CHALLENGES
Contractors have successfully used expanded polystyrene (EPS) geofoam to simplify site preparation since the 1960s. Projects built with the material include road beds, bridge approaches, levees and other civil jobs. Now, geofoam is increasingly solving a host of construction challenges in commercial buildings and large residential applications.
Geofoam is an ultra-lightweight, engineered, closed-cell rigid foam. The material is about 100 times lighter than soil and weighs substantially less than other lightweight fills.
Even though it is very light, geofoam is high strength, with compressive resistance values of 317 to 2,678 lbs/ft2 at a 1 percent strain. Geofoam is suitable for a range of heavy loading conditions, including sub-base for pavements and railroads bearing jet aircraft and locomotives.
EPS geofoam changes the traditional soil compaction phasing method in which contractors mechanically compact soil to a percentage of dry density and pay for multiple samples and laboratory tests. Unlike other lightweight fills such as shredded tires or wood chips, EPS geofoam is homogenous, which provides uniform load transfer and eliminates differential settlement.
GEOFOAM APPLICATIONS AND BENEFITS
The combination of lightweight and high strength makes geofoam the ideal material for many building applications, including:
• Creating level building pads on steep-sloped lots
• Stabilizing steep slopes
• Remediating soft soils
• Forming swimming pools and pool decks
• Creating theater/stadium seating
Creating level building pads on steep-sloped lots
Given its lightweight, contractors can use geofoam to simplify construction of retaining walls needed to level steep-sloped lots. Geofoam drastically reduces or can eliminate the lateral load on retaining walls, so walls do not need to be as robust. Material and labor costs are much lower due to reducing forming, structural steel and concrete volume, and lessening or eliminating the need for geogrids or mechanical tiebacks.
Eckhart Construction Services, a Carolinas AGC member, used geofoam to create a level building site for a McDonald’s restaurant. There, a retaining wall was needed that could accommodate the change in grade, as well as reduce the load over extremely soft soils. Typical soil fill would have caused unacceptable settlement of the retaining wall. The use of EPS geofoam allowed for incorporation of a traditional keystone retaining wall while eliminating the need to use the typical geogrid material to reinforce the retaining wall.
Stabilizing steep slopes
Geofoam’s lightweight makes it an excellent option for stabilizing steep slopes, without the need to change the final slope geometry. Since the material is much lighter than other fills, it greatly reduces the weight of a slope’s driving block and lowers the risk of costly and dangerous landslides. An additional advantage of using lightweight geofoam blocks on slopes is that crews can move and place them by hand. This eliminates the need for heavy earth moving and compaction equipment on steep and uneven terrain.
Remediating soft soils
Ground with soft soils or soft clay makes building construction notoriously difficult. To eliminate or greatly reduce the need for time-consuming and costly surcharging of soft soils, EPS geofoam provides high load support at a low weight for projects of all sizes.
An example is the renovation of an existing office building into a city hall in the Pacific Northwest. Building codes required installation of new handicap ramps as part of the upgrade. The challenge was the project site is situated on extremely soft glacial till at the south end of a lake. As such, the ramps needed a very lightweight void fill to avoid post-construction settlement. After evaluating various lightweight fill options, the project team chose EPS geofoam. Crews installed 5,000 cubic yards of geofoam, which played a role in helping the project be completed two months ahead of schedule and nearly $600,000 under budget.
Forming swimming pools and pool decks
Contractors use geofoam to simplify construction of swimming pools in residential, commercial and institutional uses, including hotels, schools and community centers. Project teams can order the blocks pre-cut to precise dimensions or can easily cut them to size and shape on site. This simplifies the concrete forming process, and greatly reduces weight for construction of rooftop pools or on sites with poor load-bearing soils. Once crews form the pool basin and decks with geofoam, they can apply shotcrete directly to the foam.
Because crews can readily form geofoam into a host of shapes, the material provides a simple way to create landscape topography and berms. This is particularly beneficial when loads must be minimized on underlying structures and utilities. Examples include rooftop gardens and landscaped spaces with shallow buried utilities that cannot bear the weight of soil fills.
Creating theater/stadium seating
Geofoam provides contractors a fast and simple way to change slopes within buildings – either creating tiered seating as in auditoriums, movie theaters, churches or gymnasiums, or leveling out such a sloped space for other uses.
For stadium style seating, crews hand place row upon row of geofoam blocks to achieve the necessary profile. They can then either place concrete over the geofoam as shotcrete or as pre-cast panels. Using geofoam greatly simplifies the forming process and eliminates the need for complex tiered compacting of soil to form the stepped profile of stadium seating.
Crews can also use geofoam to quickly level an existing sloped elevation in a building. For example, a university wanted to convert a sloped floor lecture auditorium into a surgical suite at a hospital. The project engineers specified EPS geofoam as a structural void fill to reverse the slope. The EPS supplier cut the blocks to minimize field fabrication on the job site. Because the enclosed auditorium did not have space to accommodate heavy equipment, and as noise from mechanical compaction of soil would have disrupted hospital patients and staff, geofoam was an ideal alternative. The lightweight structural fill provides a strong, stable sub-base for the new, level concrete floor slab.
WORKING WITH GEOFOAM
Although geofoam can be manufactured in many sizes and shapes, standard blocks are typically 4 feet wide by 8 feet long, and of varying thickness. If contractors do not order geofoam precut to specified dimensions, they can easily trim geofoam to size using a hot wire cutter (which some manufacturers will supply) or with a handsaw or a chainsaw onsite.
When placing geofoam, the blocks are staggered so their joints are not located in the same vertical plane. At times, the blocks are interconnected with either barbed plates or polyurethane adhesive, in accordance with engineering specifications.
Due to geofoam’s lightweight, crews can maneuver and place the blocks by hand or with small mechanical equipment. A typical installation is to place geofoam blocks on a level course over sand, pea gravel or any locally available permeable leveling course material.
Following are points to keep in mind when working with geofoam:
• Geofoam is subject to damage when exposed to certain hydrocarbon chemicals or solvents. If needed, crews can protect the material with hydrocarbon-resistant geo-membranes or concrete slabs.
• Manufacturers treat geofoam with a fire retardant to avoid the rapid spread of fire. However, the material is combustible at high temperatures, so it is important to be cautious when conducting hot work, such as welding, around geofoam.
• Exposing geofoam to sunlight for extended periods can cause superficial discoloration, which does not impact the product’s integrity and can be removed with a broom or very light pressure-washing, if desired.
• Because geofoam is lightweight, it is important to take care when stockpiling the material on job sites where windy conditions exist. Contractors should weigh or tie-down stockpiles, as necessary.
Soil fills will continue to factor prominently in construction given their ubiquity and familiarity, but for challenging projects, geosynthetics like geofoam are increasingly popular. Geofoam offers contractors a simple-to-use, engineered alternative to traditional earthen fills. The material solves a host of site preparation challenges in commercial and large residential building projects.
INSULFOAM GEOFOAM QUESTIONS:
Contact Nico Sutmoller, Below-Grade & Geofoam Specialist
Originally posted in Modern Contractor Solutions Magazine, June 2014 issue
Three tips for choosing the right material for your project
Which insulation is best for use on buried building foundations and under concrete slabs? Sales reps, naturally, will tell you that their company’s product is best. But, what does independent testing and research say?
These three tips will help your firm select a cost-effective and high-performance rigid foam insulation type for your next below-grade insulation job.
1. CONFIRM LONG-TERM THERMAL PERFORMANCE
Two of the rigid foam insulations most commonly used below grade and under slabs are expanded polystyrene (EPS) and extruded polystyrene (XPS). Although both are closed cell insulations, they perform very differently over the long term.
XPS has a higher initial insulating R-value than does a similar thickness and density of EPS, but the R-value of XPS degrades over time. EPS does not experience such “thermal drift,” and the reported R-value remains the same throughout years of installed service.
This is a crucial point when selecting insulation, as a decreasing R-value means lower thermal performance over time, and thus increased heating and cooling energy and costs for the building owner.
A simple way to confirm an insulation’s long-term thermal performance is to review the warranty. Established EPS manufacturers typically warrant 100 percent of the published R-value for 20 years. By comparison, most XPS warranties typically cover only up to 90 percent of the published R-value, to account for the R-value degradation that occurs in the field.
2. ENSURE MINIMAL LONG-TERM MOISTURE ABSORPTION
In addition to R-value stability, rigid foam insulations differ in their rates of moisture absorption and their ability to dry. Wetted insulation provides lower thermal resistance and can degrade over time. Since insulation installed below grade frequently contacts wetted soil, rates of moisture absorption and the ability to dry is key in these applications.
Independent laboratories have conducted extensive tests of moisture absorption rates for both EPS and XPS. Although XPS often rates better in laboratory short term, fully submerged tests, real-world long term tests show that EPS performs much better. The reason is that EPS has the ability to dry much faster than XPS. This ability to dry at a fast rate helps EPS remain drier during conditions of repeated exposure to moisture.
A 15-year in-situ test of EPS and XPS dramatically demonstrated this point. Stork Twin City Testing evaluated the moisture content of EPS and XPS buried side-by-side for 15 years on a building foundation in St. Paul, Minnesota. At the time the insulations were removed, the EPS was much drier than the XPS—the EPS had only 4.8 percent moisture by volume, compared to 18.9 percent moisture content for the XPS. After 30 days of drying time, the EPS had only 0.7 percent moisture by volume, while the XPS still contained 15.7 percent moisture.
The high moisture absorption rate of XPS in real-world settings is further seen in a 2012 report from the U.S. Dept. of Energy’s Oak Ridge National Laboratory (ORNL). Their researchers found that XPS insulation installed below grade for 15 years had absorbed 67 percent or more moisture.
3. TARGET AN APPROPRIATE COMPRESSIVE STRENGTH
One of the best ways to save money on rigid foam insulation installed under concrete slabs is to ensure the material is not over-engineered. A common design assumption leads to specification of rigid foam strengths that are many orders of magnitude higher than necessary, which can double the insulation material cost.
Without getting into extensive technical details and mathematical formulas, the problem is engineers often use an overly conservative approach for insulation under concrete slabs. Many designers assume that point loads applied to a slab, such as those from the wheels of a forklift, transfer to the insulation in a triangular load path. Yet, concrete slabs distribute loads more uniformly than this, which means the insulation does not need as high of a compressive resistance as when one assumes a concentrated triangular load path.
An overly conservative design approach often results in specification of a high compressive resistance XPS product, when a more cost-effective EPS would offer sufficient strength. Since XPS typically costs more per inch than EPS, this is wasted money that comes off the contractor’s bottom line.
A simple solution for contractors is to ask the designers if they are using a formula from the Theory of Plates on Elastic Foundations, which take into account how slabs and insulation behave together. A resource to point them to for example calculations is the article “Right-sizing Under-slab Insulation,” in the April 2014 issue of Structure magazine.
With building owners’ growing desire to save money on heating and cooling costs, and increasingly stringent energy codes, contractors will be installing below-grade and under-slab insulation on more of their projects. EPS insulation out-performs XPS for both long-term thermal resistance and long-term moisture absorption, and EPS comes in a variety of compressive strengths suitable for nearly all building projects. With the highest R-value per dollar, EPS is the cost effective insulation choice.
Contact Ram Mayilvahanan, Insulfoam’s Product-Marketing Manager
More news coverage on the use of InsulFoam Geofoam in Chicago’s newest and biggest downtown attractions, Maggie Daley Park. When complete, the new park will have a distinctive presence with signature elements like rock-climbing sculptures, an ice-skating ribbon, and play garden. Read more in the latest and on-going news coverage on details and view the project’s job site camera:
Originally aired and published on ABC 7 Chicago News, by Paul Meincke
In the shadow of towers made of concrete and steel, there are building blocks of a different sort. Thousands of them are being layered together to give shape to what will be Maggie Daley Park.
“We’re going to transform what was a flat, sort of uninviting area into a gem for Chicago that compliments Millenium Park,” said Chicago Park District CEO Michael Kelly.
That transformation has a lot to do with topography. When this 20-acre park is done, its northeast corner will sit 30 feet higher than the southwest. That’s a lot of dirt. And dirt weighs a lot. And a lot of weight would not be welcome atop the two story parking garage that sits directly underneath. So, what do you use? Geofoam.
“Geofoam is essentially Styrofoam. It’s lightweight fill,” Kelly said
It’s 100 times lighter than soil. Geofoam isn’t a new concept. It was used here before, but there’s a lot more of it now, 75,000 cubic yards of it will be sculpted and tacked down to create a rolling terrain.
On top of the geofoam goes the dirt which will be deep enough in spots to accommodate the roots of one-thousand new trees. If you’d never seen the geofoam going in, you’d never know it was there.
“That’s essentially the best compliment we could get once this park is open and that is that people don’t realize that it’s a park constructed on top of a garage,” said project engineer Nichole Sheehan. “It’s a park that people are going to love and hopefully come to all the time.”
The park district has been recording its birth with time lapse camera, from barren garage roof to the building of baby hills, and when the park’s soft opening comes next fall, this is the vision. Three of the 20 acres devoted to a children’s playground. Just up the path, a 25 foot climbing wall, and when the cold months come, a feed of built in refrigerant will convert that path into a 400 meter ice skating ribbon – attracting old Hans Brinkers or perhaps young Blackhawks.
From debris dating back to the great Chicago fire to geofoam, this piece of Chicago has undergone remarkable change over the years.
In the late 40’s and early 50’s, there were lots of railroad, lots of parking that over the years goes went away or went underground.
“Somewhere way down there, there’s fill,” Kelly said. “There’s probably some old railroad scrap. Now we’re standing on geofoam and we’re building a green park. We’re building a 20 acre green roof is essentially what we’re doing with a thousand trees.”
The first of the trees come soon. The grand opening of Maggie Daley Park comes next Spring. Its birthing thus far carries four words welcomed in urban re-design.
Maggie Daley Park carries a roughly $55 million price tag. Most of that comes from parking garage lease money and private contributions along with five million in park district capital funds.
INSULFOAM GEOFOAM QUESTIONS:
Contact Nico Sutmoller, Below-Grade & Geofoam Specialist
Great story in the Chicago Sun-Times about the use of InsulFoam Geofoam in Chicago’s newest and biggest downtown attractions, Maggie Daley Park. This is a very large geofoam project, the new park will have a distinctive presence with signature elements like rock-climbing sculptures, an ice-skating ribbon, and play garden. Read more details and view the project’s job site camera: Geofoam Helps Mold the Construction of Chicago’s New Downtown Maggie Daley Park.
Originally published on Chicago Sun-Times, suntimes.com, by Tina SFondeles
Chicago’s shoveling days should be over, but the future Maggie Daley Park kind of looks like a winter wonderland, full of white building blocks.
Those giant blocks of Geofoam will transform flat land into a hilly landscape at the park site, which spans 20 acres and is bordered on the west by Columbus, the north by Randolph, the south by Monroe and the east by Lake Shore Drive.
Landscape architects say the lightweight, cost-effective, environmentally safe and recyclable fill material is key to creativity. The expanded polystyrene is being used around the world and locally to contour flat Midwestern land.
At Maggie Daley Park, crews are using old Geofoam — already part of Daley Bicentennial Plaza — and a lot of new blocks to shape the park. From various vantage points around the park, onlookers can watch as the foam is delivered every day — six truckloads — and crews have already filled the northeast and northwest corners of the park, and are moving south.
The foam installation will be done by early summer. By September, dirt will be placed over the foam. It’s even being used for the park’s ice skating ribbon.
“For the ice ribbon, you’ve got up and down. It’s not just flat,” said Lowell Zarzueta, of Walsh Construction, who is overseeing part of the second phase of the project. “For you to go up high, you almost have to skate super fast, just to get over that little hump.”
He said the foam is being used to create a hill that will be even with Randolph Street, making it easy for people to come into the park. There are also peaks at the northeast corner, where a picnic area is being built.
“With Maggie Daley Park, you’re going to have hills. The park will offer these beautiful vistas of Lake Michigan, which it never had there,” said Bob O’Neill, president of the Grant Park Conservancy. “In order to do that, to get these hills, and these rolling meadows over a whole flat area in Chicago, to get any topography, especially on top of a structure, you need Geofoam.”
Crews on Friday said deliveries of Geofoam are about half done. The mass quantity of snow Chicago received this year did slow work a bit, but crews said phase two of the park — earthwork, utilities, paving, architectural and program elements, soil placement and planting — is on schedule for completion in October.
Here’s how crews are layering the park: First it was excavated, the dirt placed in nearby Peanut Park to be reused. Tar was put over the garage, then a layer of black tarp. It’s then tested to make sure it’s waterproofed to prevent leaks to the garage below. Four inches of stone are placed on top, and then the foam is placed with yet another black tarp over it. Dirt will go over the foam.
Come next spring, the ground will become green again, as landscaping and planting will be in full swing.
This isn’t the first time the product has been used in Chicago. It was also used for the Daley Plaza renovation — where the trees are now planted, and for the Soldier Field remodeling, where Geofoam was placed as fill over the garage, creating a hilly and grassy landscape near Soldier Field and the Field Museum.
Peter Schaudt, the landscape architect behind both renovations, said Geofoam played a major role in the projects.
“I think it allows you the freedom to be creative,” said Schaudt, of Hoerr Schaudt Landscape Architects. “It allows you to really model the land in an artificial way, and the great thing is when you put the soil and lawn and trees on top of it, it’s an illusion.”
The product also is very strong, he said. “It never dematerializes. It stays the same size. At Soldier Field, it was used to support 18,000 pounds.
“It’s much more substantial than just putting a thin veneer over a roof, and it allows you to create a lot of great and dramatic changes,” Schaudt said.
A soft opening for the $55 million park, named for the late wife of former Mayor Richard M. Daley, is scheduled for fall, and the park will be officially completed by spring 2015. A park district website, maggiedaleyparkconstruction.org features two webcams to view the construction.
INSULFOAM GEOFOAM QUESTIONS:
Contact Nico Sutmoller, Below-Grade & Geofoam Specialist
Originally published in Structure Magazine, Structural Economics section, April 2014
Structural Economics: cost benefits, value engineering, economic analysis, life cycle costing and more…
Applying the Theory of Plates on Elastic Foundations to Save Material Costs.
A common, simplifying assumption used for specifying polystyrene insulation under concrete slabs results in material costs that are significantly higher than necessary. Using a design equation based on a more rigorous analysis of the design conditions can help avoid over-engineering the insulation and save thousands of dollars on the project.
Rigid foam insulations, such as expanded polystyrene (EPS), have been used successfully under concrete slabs for more than 40 years. Such insulation helps reduce heat loss to the ground in residences, cold storage units, warehouses and other commercial, institutional and industrial structures.
The problem is that designers often do not adequately account for how the concrete slab and underlying subgrade interact. Many designers assume that a concentrated load applied to the slab transfers to the rigid foam subgrade through a triangular load path. This assumption, while not necessarily incorrect, can be very conservative.
Concrete slabs distribute loads in a more even fash- ion, which means that the insulation does not need as high a compressive resistance compared to the typical simplified approach. A more accurate approach to this problem is to use the Modulus of Subgrade Reaction (K) to determine the slab’s deflection and the resultant stress applied to the elastic insulation subgrade. The pressure beneath a given slab under a load can be determined using the following formula, found in the Theory of Plates on Elastic Foundations, as described by Timoshenko and Woinowsky-Krieger:
Pressure on the subgrade = (P/8)√(K/D) Where:
- P = concentrated load on concrete slab in pounds
- K = Subgrade reaction modulus of total EPS insulation in pounds per cubic inch (k/t)
- k = Stiffness of one inch of EPS insulation in pounds per square inch
- t = EPS insulation thickness in inches
- D = Eh3 / 12(1-u2)
- E = Modulus of elasticity of concrete in pounds per square inch (57000√ f’c)
- f’c = specified concrete compressive strength in pounds per square inch
- h = Thickness of concrete slab in inches
- u = Poisson’s ratio for concrete (0.15)
An example illustrates the significant difference in the calculated results.
Take the case of a warehouse with a 6-inch-thick, 2,500-psi concrete slab on 2 inches of EPS insulation with a rated stiffness of 360 psi for one inch. Forklifts to be used in the building impart 8,000 pounds of force at the wheel, which has a 6-inch by 10-inch tire footprint on the slab. If the designer assumes that this load distributes at a 45-degree angle through the slab, the 8,000 pounds ends up distributed over approximately 396 square inches [(6 + 6 + 6)(6 + 10 + 6)] of the insulation’s surface, for an average pressure of 20.2 psi.
Taking into account the fact that concrete slabs distribute loads more evenly, using the Modulus of Subgrade Reaction method, the pressure on the insulation is actually much lower – approximately 1.85 psi. Since EPS insulation rated for 1.85 psi costs about 50% less than other rigid foam insulations rated for the much higher value of 20.2 psi, using the more precise method reduces insulation costs substantially. In fact, the 20.2 psi value is beyond the elastic range of the EPS material, and long-term creep effects must be taken into account when using that design approach. With:
P = 8000 pounds, h = 6 inches, f’c = 2,500 psi,
E = 57,000√ 2,500 = 2,850,000 psi, u = 0.15,
k = 360 psi for 1-inch EPS
K = 360 psi / 2 inches = 180 pci
D = Eh3/12(1-u2) = 2,850,000 (6)3/12(1–(0.15)2) = 52,480,818 lb-in
Pressure on EPS = (P/8)√(K/D) =
8000/8 √(180 / 52,480,818) = 1.85 psi.
The k value can be found by consulting the insulation manufacturer. One EPS insulation brand available throughout the U.S. has k values ranging from 360 to 1860 psi for one inch of insulation thickness. The specific value depends on the product type selected. Note that increasing the thickness of EPS insulation decreases the overall subgrade modulus.
Using the above method to determine the pressure that a slab transfers to the subgrade allows for proper specification of rigid foam insulation and avoids over-engineering the insulation for compressive strength. In the example application discussed in this article, the simplifying assumption of triangular load transfer through a concrete slab results in a compressive force on the insulation 11 times higher than the result from the more rigorous (but not much more complicated) analysis. Specifying higher compressive resistance insulation than necessary not only is overly conservative for the given design, it also does not improve the insulation’s thermal performance, and the cost to the project is excessive and unnecessary. It is a lose-lose scenario.
Contact Joe Pasma, PE, Insulfoam Technical Manager
Useful references to support this article: NEW moisture absorption data regarding XPS, moisture absorption and the effects on R-Value was released in March 2014. Read more in the updated summary and in subsequent 2008 test program documents:
- XPS Insulation Extracted After Field Exposure Confirms High Water Absorption & Diminished R-Value, March 2014 (pdf)
- 15- Year In-Situ Research shows EPS Outperforms XPS in R-value Retention, November 2008 (pdf)
- Expanded Polystyrene Insulation: Below Grade Testing Confirms R-Value Retention, August 2008 (pdf)
Originally posted on Construction Specifier online, Author Response to Reader Question, February 18, 2014
After the feature, “Out of Sight, Not Out of Mind: Specifying Thermal Insulation Below-grade and Under-slab” ran in our December 2013 issue, we received a letter from retired architect, Joseph S. Bond. Mr. Bond wrote that the article in question “seems to reverse the findings” from both his personal and professional experience with expanded and extruded polystyrene (EPS and XPS):
I am a retired architect, and may not have the best current information on EPS and XPS, but when these two products were mistakenly used as ‘flotation’ for lake docks and later removed, the XPS bales were like new and had no water soakage beyond the first (1/8 in.). However, I remember the EPS bales were waterlogged to the extent it took two people to even carry the bales. On top of this, the EPS bales showed a lot of disintegration due to freeze-thaw.
My observations may have been on EPS that had much less density (1-1/2 -2 #) than implied by The Construction Specifier article, but many reading will probably have the same concerns and begin to question the piece’s validity.
We asked the article’s author, Ram Mayilvahanan, to respond.
Mr. Bond raises a frequently discussed point about the long-term problems that arise when using rigid foam insulations that do not conform to ASTM standards.
Since insulation, especially below-grade, is out of sight, it can also be out of mind when it comes to ensuring the product being used at the job site matches the product that was specified. As with other building products, there are numerous companies making rigid foam insulations, often with varying degrees of quality. We building professionals share the responsibility in making sure the selected right-foam manufacturer can consistently deliver product that meets the specified performance.
To ensure performance on key factors, including moisture resistance, it is crucial to not only specify foam insulation that has been manufactured and tested to meet ASTM C578, Standard Specification fro Rigid, Cellular Polystyrene Thermal Insulation, but also to ensure the manufacturer supplying the foam insulation can consistently deliver quality product. A manufacturer’s longevity and track record with past projects should help in assessing this.
As an example, the floating green on the 14th hole in the world-famous Coeur d’Alene Golf resort in Idaho – considered on the of the coolest shots in golf- was built with EPS. It continues to be a testimony to well-engineered flotation insulation. Projects like this help establish the ability of manufacturers to deliver quality product.
Mr. Bond’s observation is a timely reminder for us building professionals that it pays to make sure the right product gets to the job site.
Contact Ram Mayilvahanan, Insulfoam’s Product-Marketing Manager
Originally posted on CE News online in Progressive Engineering
Geofoam: A lightweight fill alternative
Geofoam is a rigid, engineered, lightweight fill material typically made of expanded polystyrene (EPS). For fills, a key advantage of EPS geofoam is its low weight — approximately 1 to 2 percent the weight of soil. Typical densities for EPS fill are between 0.7 and 2.85 pounds per cubic foot, therefore maintaining a predictable compressive strength that is suitable for many structural applications (see “Geofoam physical properties”).
Today, geofoam is fully recognized and accepted as a lightweight fill alternative and has seen increased use in commercial and residential applications. Since the first installation of geofoam in 1965 (see “A short history of geofoam”), numerous projects around the world that have relied on the material to solve construction problems.
Given EPS geofoam’s low weight, strength, and ease of use, more project teams are using it to solve regular construction challenges in five basic applications. Read the full article featured on CE NEWS as our Geofoam Specialist, Nico, discusses:
- The five basic applications and specific project examples: 1.) Lateral load reductions on structures 2.) Soft soil remediation 3.) Slope stabilization 4.) Lateral and dead load reductions over buried utilities 5.) Lightweight structural void fill.
- Geofoam physical properties
- Short history of geofoam
- Construction considerations
- Cost saving advantages
INSULFOAM GEOFOAM QUESTIONS
Contact Nico Sutmoller, Below-Grade & Geofoam Specialist
Originally posted on SitePrep online, March 2014
Although greenfield site preparation can involve a host of geotechnical challenges, in urban areas the need to work around existing infrastructure presents its own costly and complex design problems.
A new freeway interchange at Valsayn on the Caribbean island of Trinidad provides a clear example of the potential difficulties. Traffic growth in the island nation required the development of a new grade-separated interchange between two primary highways – the Churchill-Roosevelt Highway (CRH) and the Uriah Butler Highway (UBH).
One challenge the project team faced was that the north and southbound lanes of the UBH needed to pass adjacent to (and on both sides of) a support column for an existing flyover ramp. The new lanes required pavement of 9.8 to 10.5 ft. of embankment fill on top of the pier’s pile cap on very soft soils. A concrete shaft of seismic activity. The concrete shaft also keeps the pier in depended for the the new fill.
Designing infrastructure to mitigate earthquake damage is crucial in Trinidad, which lies near the boundary of two tectonic plates. The island has been impacted by five earthquakes greater than magnitude 7.0 since the 1700s, including a 7.3 quake in 2007.
To reduce the load applied to the pile cap under the existing pier, and to avoid any modification of the pier’s seismic behavior, contractor Vinci Construction Grands Projects specified InsulFoam GF expanded polystyrene (EPS) geofoam as a lightweight fill. Goefoam offers high compressive strength and predictability, yet weighs up to 100 times less than traditional soil fills depending on the EPS density selected.
Vinci Construction Grands Projets crews placed 2,100 cu. yds. of EPS22 geofoam fill in an 80 by 89 ft. area surrounding the pier in only three-and-a-half days. “Because of the ease and speed of installation, using geofoam allowed us to build this fill two times faster than a regular sand fill, especially in Trinidad where heavy rains can interrupt back filling activities for days,” says Cecile Huillard, construction engineer with Vinci Construction Grands Projets.
Huillard notes the use of EPS geofoam fill provided a cost-effective and simple alternative to building a concrete slab founded on piles to support the load from the road and transfer it away from the pier pile cap. No heavy equipment was needed for the fill placement, as crews were able to install the geofoam blocks by hand. Additionally, the geofoam resulted in lower and smoother post-construction differential settlements of the roadway in both the transversal and longitudinal directions. The use of geofoam also eliminated the need for additional geotechnical investigation for potential additional piles.
EPS geofoam does not typically require surcharging, preloading or the staging often necessary with other fills. It resists moisture, freeze-thaw damage, insects, mold and decomposition. The product is inert, does not emit undesirable gases or leachates, and is reusable or recyclable. EPS geofoam is available in multiple strengths suitable for a wide range of engineered applications. The EPS22 geofoam specified in the CRH/UBH interchange project has a compressive resistance of 1,051 psf at 1-percent deformation.
In addition to soft soil remediation and reducing vertical loads on existing infrastructure and utilities, engineers have used EPS geofoam to solve a range of other geotechnical challenges, as outlined in the adjacent article, Applications for Lightweight Geofoam Fill.
Applications for Lightweight Geofoam Fill
Given EPS geofoam’s low weight, strength and ease of use, more project teams are using it to solve regular construction challenges in five basic applications:
1. Eliminate or reduce lateral loads on structures.
2. Create a zero loading factor for soft soil remediation.
3. Lighten the driving block of a landslide for slope stabilization.
4. Reduce lateral and dead loads over existing or newly buried utilities.
5. Use as lightweight structural void-fill for numerous concrete and landscaping applications.
STRUCTURE LOAD REDUCTION
EPS geofoam significantly reduces lateral loads on retaining walls and building foundations. The material has an extremely low Poisson’s ratio (.05) and high coefficient of friction (.6), which helps enable placement of blocks in a way that replaces the sliding soil wedge above the angle of repose. By replacing the active wedge with EPS geofoam, which can be completely freestanding and self-supporting, project teams can save up to 75 percent of total project costs compared to traditional concrete walls designed to retain soil.
Using EPS geofoam also reduces labor and material costs without the need for over-excavation, and requires much less robust forming, reduced structural steel and concrete wall thickness, and fewer footings. The material can also reduce or eliminate the need for geo-grids and/or mechanical tiebacks. Project teams are able to construct a retaining wall with EPS geofoam paired with a lower-cost fascia (which acts more like a fence).
Another key advantage of using the material in retaining wall applications is the allowance for taller walls in narrower rights-of-way. This reduces time and cost spent on property acquisition, as well as minimizes lane closures and encroachment into wetlands or neighboring properties.
SOFT SOIL REMEDIATION
Ground with soft soils or soft clay makes construction difficult. These soft surfaces are notoriously poor foundations for many projects, and can require extensive remediation.
Instead of choosing costly (surcharging) and time-consuming remediation of soft soils, projects of all sizes can install EPS geofoam, which provides high load-support while maintaining a low weight.
EPS geofoam’s low weight makes it an excellent option for stabilizing steep slopes, without the need to change the final slope geometry. As the material is much lighter than other fills, it greatly reduces the weight of a slope’s driving block and lowers the risk of costly and dangerous slope failures.
Additionally, since slope stabilization generally happens on steep and uneven terrain, using EPS geofoam simplifies construction, because crews can move and place it without heavy earthmoving and compaction equipment, thus greatly speeding up the construction schedule.
UTILITIES LOAD REDUCTION
Throughout the world, existing buried utilities create challenges for new construction. Notably, utilities frequently are not designed to have additional loads placed upon them. So, utilities either have to be moved or upgraded at high expense.
Instead, geofoam can be an ideal option to reduce dead and lateral loads on underground pipes, culverts and tunnels, while at the same time providing high thermal insulation values that protect against temperature fluctuations.
Another advantage is geofoam can protect utilities during seismic activity by reducing in-situ vertical/lateral stresses.
STRUCTURAL VOID FILL
Given its low weight, EPS geofoam is also well suited as a structural void fill in concrete forming operations. Crews can easily fabricate virtually any shape or slope, and the material eliminates separate concrete pours for vertical wall sections and topping slabs.
Applications include bridge column formwork, stadium seating in auditoriums and sports arenas, stairways, podiums, loading docks and rooftop pool decks. EPS geofoam can be manufactured into custom-cut blocks in various shapes and sizes to enable contractors to quickly build up these and other similar features.
“Because of the ease and speed of installation, using geofoam allowed us to build this fill two times faster than a regular sand fill, especially in Trinidad where heavy rains can interrupt back filling activities for days.” – Cecile Huillard, Construction Engineer, Vinci Construction Grands Projects
INSULFOAM GEOFOAM QUESTIONS?
Contact Nico Sutmoller, Below-Grade & Geofoam Specialist
Originally printed in Architectural Products Magazine, On Spec, Insulation, Nov 2013
Design professionals typically want to use as much insulation as possible, not only to comply with building codes, but also to build to the highest standards. Building owners want enough insulation to keep heating and cooling costs down, without having to ‘pay through the roof’ in upfront costs. Performance vs. cost: where is the middle ground that makes sense for both parties?
To answer that question, it is important to look at how insulation is designed. For many years, the use of rigid foam insulation was based not the R-value per inch – the higher the better. Today, well-informed design professionals are cognizant of the design optimum and the realization that insulation suffers from the law of diminishing returns. Any insulation installed beyond the design optimum provides little additional energy savings, but costs a lot of money. Efficient insulation design comes down to choosing the product that balances upfront costs with the energy savings offered over the life of the building.
So, which insulation gives the best ‘bang for the buck?’ To understand performance vs. expenditure across different rigid insulations, it is important to consider the R-value per dollar spent on both materials and labor.
Because material and labor costs for insulation vary by market, specific R-value per dollar figures often shift, but EPS consistently rates highest when compared to other rigid foam insulations. Also, EPS comes in much higher thicknesses (up to 40 in.) in a single-layer than does XPS or polyisocyanurate, so higher R-values can be achieved with fewer layers, lowering on-job labor time and cost. Plus, EPS does not suffer any loss in R-value over the life of the building, so the design R-value for EPS is the long-term R-value.
With that in mind, here are some increasingly popular applications in which design professionals use EPS to comply with building codes while reducing material and labor costs for roof insulation. Read full article (pdf) to learn more about:
- Roof recovers requiring a separator board
- Metal roof recovers
- Bilt-up sloped roofs
- High-traffic areas
- Comparison of common rigid foam insulations
“In the end, the right insulation product is the one that offers the optimum balance of performance and economy. Such a product satisfies both the design professional and the building owner, leading to a building that is code compliant, built to high performance standards and economical enough to deliver lifetime energy savings that justify the upfront costs.”
Originally printed in Architectural Products Magazine, Features Special Report, Insulation, Nov 2013
By: Alan Weis, Contributing Writer
INSULATION- APPLIED AND INSTALLED PROPERLY- CAN BE AN INTEGRAL MEASURE IN CREATING AN EFFECTIVE AND EFFICIENT ENVELOPE.
When it comes to insulation, R-value- the measure of thermal resistance – seemingly rules. In other words, the higher the R-value the better the thermal resistance. But there’s more to the story than that according to industry experts. “An insulation product’s R-value is only a starting point for understanding how well it works, says James Hodgson, general manager for Premier SIPS.
In fact, Hodgson says it’s crucial to evaluate the whole-wall R-value of the assembly, since the insulation is only one part of creating a tight, well-insulated envelope. For example, he claims DOE research shows that a 4.5-in. structural insulation panel (SIP) wall rated at R-14, out-performs a 2×6 stud wall with R-19 fiberglass insulation. “It comes down to significantly less air leakage, thermal bridging and convective looping for a better performing assembly,” says Hodgson.
Insulation, unfortunately, is too often treated as an afterthought, as Hodgson says it ends up getting fit around the structural systems instead of being an integral part of them, making it difficult to seal leaks. SIPs, he notes, address this by incorporating both in one assembly.
NOW VS. LATER
Longevity is another consideration when it comes to R-values. “It’s common for building professionals to look at R-value per inch at the time of installation, “says Ram Mayilvahanan, product marketing manager with Insulfoam. “Yet, it makes more sense to evaluate insulation’s long-term thermal performance and the return on investment.”
His company manufactures HD composite roof insulation, which bonds expanded polystyrene (EPS) foam to a high-density polyiso cover board, a combination that has high thermal efficiency and provides significant field labor savings. Plus, Mayilvahanan says it can be used to achieve UL Class A fire ratings on combustible roof decks without the use of gypsum or other cover boards.
“Many rigid foam insulations experience thermal drift, which is a loss of R-value over time as insulating gases within them dissipate and are replaced by air,” Mayilvahanan continues. “Some materials lose up to 20% of their insulating capacity during their time in service.” One the other hand, EPS insulation, he explains, not only offers a high initial R-value, it also doesn’t lose R-value with time. And, it can be used in wall, roof, below-grade and under-slab applications.
Continue to read FULL article (pdf) where further insulation consideration and types are described by industry experts.
“The push toward comprehensive green design has raised awareness that many building systems must work together for optimum performance,” says Mayilvahanan. “It’s not just insulating the structure appropriately, but also right-sizing the HVAC systems and educating owners and occupants on how to operate the building for high energy efficiency.”
Originally posted in Concrete Construction
As a specifier, architect and contractor….you must make well-informed decisions when it comes to below-grade, under slab, and cavity wall insulations in your projects. Below are two informative articles listing the similarities and differences between both EPS (expanded polystyrene) and XPS (extruded polystyrene) insulations.
Insulation Choices: Whether to use EPS or XPS can be a matter of cost.
What’s the difference between XPS insulation and EPS insulation, other than a single letter? For installation on concrete foundations and under floor slabs, the rigid foam insulation you choose can make a difference of tens of thousands of dollars on a project. A careful evaluation of these materials’ performance attributes against the project’s needs can dramatically shrink labor and material costs. The savings could mean the difference between a profitable job and one you just have to chalk up to experience.
When it comes to concrete and insulation, contractors tend to be most familiar with extruded polystyrene (XPS). Yet, expanded polystyrene (EPS) performs as well or better than XPS, and at a substantially lower cost. Below are three important factors to consider when comparing these two insulations for any belowgrade or under-slab applications, read FULL article to see more side by side comparisons of EPS and EXP for these insulation factors: 1.) Compressive strength 2.) Moisture retention 3.) Insulating capability.
EPS vs XPS: Insulation industry advances with EPS developments
There is much competition among polystyrene insulation manufacturers for the below-grade, under slab, and cavity wall insulation market. Claims made by the XPS (extruded polystyrene) industry are conflicting with that of EPS (expanded polystyrene) manufacturers. The validity of some claims is debatable. Specifiers, architects, and contractors must make well-informed decisions.
Read FULL article to thoroughly understand the similarities and differences between EPS and XPS insulations. Key differences include: 1.) Moisture resistance 2.) Environmental impact 3.) Long-term R-value 4.) Compressive strength 5.) Panel sizes 6.) Cost per R-value.
Contact Ram Mayilvahanan, Insulfoam’s Product-Marketing Manager
Originally posted on Better Roads Magazine
The Federal Highway Administration (FHWA) has promoted the use of expanded polystyrene (EPS) geofoam as a lightweight embankment soil alternative for a number of years. In a 2006 report, the agency’s Technical Service Team described the material as a “field-tested, budget-friendly winner.” Why? FHWA engineers list the following benefits:
- Accelerated construction
- Payroll, transportation and equipment cost savings
- Reduced labor time for construction
- Exerts little or no lateral load on retaining structures
- Easily constructed in limited right-of-way situations
- Allows application in adverse weather conditions.
The material is approximately 100 times lighter than soil, which save time. Additionally, a single truck can carry approximately 120 cubic yards of goefoam versus 12 dump truck loads needed for an equivalent volume of earthen fill. This reduces hauling costs, both in fuel and labor. Geofoam is easy to install by hand, so it reduces expenses for heavy equipment.
Following is a discussion of tangible benefits derived from geofoam usage in real-world applications such as:
I-80 / I-65 interchange, Gary, Indiana: FHWA recommended a net-zero load methodology for the roadbed to prevent post-construction settlement.
To reduce the amount of excavation of the high-organic content soils, the contractor, Walsh Construction, used EPS geofoam blocks. A six-member crew installed 700 cubic yards of geofoam in one week working four- to five-hour days. The geofoam was delivered to the job site on 32 flatbed truckloads, whereas traditional fills would have required more than 400 dump trucks in the highly congested project area leading into and out of metro Chicago.
Highway Interchange, Valsayn, Trinidad: The project team for an interchange between Trinidad’s Churchill-Roosevelt Highway (CRH) and Uriah Butler Highway (UBH), the island nation’s primary highways, used an EPS geofoam sub-base to solve an engineering challenge and save time in the process.
Highway geometry required placing new lanes adjacent to both sides of an existing fly-over ramp’s support pier. The grade for the lanes required placement of about 10 feet of embankment fill on top of the pier’s pile cap. Engineers determined that traditional fills would have caused unacceptable settlement of the compressive layers located below the fill.
To build the embankment while keeping loads down on the pile cap, Vinci Construction Grands Projets specified EPS geofoam as a lightweight fill, which provided an alternative to building a concrete slab founded on piles to support the load from the road and transfer it away from the pier pile cap. No heavy equipment was needed for the fill placement, as crews were able to install the geofoam blocks by hand.
The geofoam resulted in lower and smoother post-construction differential settlements of the roadway in both the transversal and longitudinal directions. It also eliminated the need for additional geotechnical investigation for potential additional piles. The ability to place the EPS geofoam during the rainy season was crucial to keeping the project on schedule. Crews placed 2,100 cubic yards of EPS geofoam in only 3.5 days.
Lake Cataouatche Pump Station Bridge, New Orleans, Louisiana: The U.S. Army Corps of Engineers used EPS geofoam when it needed to build a service bridge over above-ground outlet pipes at the Lake Cataouatche pump station near New Orleans.
The bridge abutments are over extremely soft soil (compressible peat). A traditional soil embankment would have added substantial load to the underlying soils. To minimize loads on the soft soils, the project team used EPS geofoam under the bridge abutments.
In addition to being lightweight, EPS geofoam has predictable elastic behavior and will not decompose. Further, unlike other lightweight fills such as shredded tires or wood chips, EPS geofoam blocks are homogenous, which provides uniform load transfer and eliminates differential settlement. All of these factors combine to make the material an ideal choice in many road sub-base applications at the federal, state and local levels.
INSULFOAM GEOFOAM QUESTIONS?
Contact Nico Sutmoller, Below-Grade & Geofoam Specialist