Of course we meant density as it relates to EPS foam density, not a learning challenge. This is the type of question that isn’t asked enough. Some people would take offense at such a question. In fact, they would consider it an insult, and immediately question their relationship with you. But that isn’t we’re focusing on today. What we’re speaking of is the density of your lightweight fill used in your construction projects. Specifically, about our main product, EPS Geofoam.

All EPS Geofoam is not equal and not all EPS foam density is either. Expanded Polystyrene (aka Geofoam) comes in several levels of density. The problems that have befuddled contractors when EPS Geofoam installation fails, is NOT due to the product, but most often with the human elements involved.

When architects specify a particular EPS Geofoam with a particular density ratio, it must conform to proven standards of performance by way of the ASTM library. Although spec sheets are available from the manufacturer, design professionals are to ensure government standards are met.

EPS Foam Density matters

Defining Failure in EPS

There are two types of failures; “avoidable” and “unexpected.” Avoidable failures typically occur when upon investigation, insufficient knowledge or improper human interaction. By that we mean this type of failure could have been avoided, due to the action/inaction of the design professional, contractor, molder or property owner(s). They might be caused by improper specification/use of inferior load-bearing products, mishandling, improper installation or failure to comply with design specifications. Human interaction is the primary culprit in most “avoidable” failure cases.

“Unexpected” failures of EPS Geofoam in Geo-technical projects that have no clear interaction or liability on the part of any of the project participants. Not only were failure issues ignored, but issues affecting proper performance were hidden, outside of the scope or other issues that could not have been planned for. Stuff happens.

The failure of Geofoam on construction sites is nothing new, however, there have been controlled experimental studies to identify any specific failure. Controlled environments yielded reliable conclusions to form said ASTM standards. However, specifications, which should prevent any failure of the EPS block have not been followed as much as anyone would think.

A surprising commonality in the United States design process for Geo-technical projects was/is to sub-contract the selection of EPS to a consultant rather than the architect. It would make perfect sense for a professional architect to know the codes (ASTM). As to why such a practice is prevalent is anybody’s guess.

From a white paper, circa 2010, by John S. Horvath, Ph.D., P.E., yields the following excerpts:

There is growing evidence that, in the United States at least, there has been an increase in the number of failures involving EPS block geofoam used for its most common functional application as lightweight fill, primarily for roads……
……The design professional alone is responsible for all aspects of design, including, but not limited to, selecting the minimum grades of EPS necessary to support the design loads. From a design perspective EPS grades are comparable to different yield strengths of structural steel or unconfined compressive strengths of PCC. ……..
……..However, it should be understood that the project design professional must still be sufficiently familiar with the EPS-block geofoam design process to be able to knowledgeably review shop-drawing submittals by the contractor and their consultant. This is because if there are any problems related to the performance of a fill incorporating EPS-block geofoam the project design professional will inevitably be drawn into the ensuing legal process…….
……The design professional alone is responsible for developing a complete project-specific material-and-construction specification for the EPS. A detailed guideline standard for this has been publicly available for use since ca. 2000 Stark et al. 2004b. This standard has already been used successfully for several major road projects such as the well-known Big Dig in Boston……
…..Unfortunately, experience indicates that the majority of U.S. road projects involving EPS-block geofoam fills in recent years have relied not on this standard but on either a specification developed by the local DOT or one downloaded from an EPS molder’s website on the world wide web. This was likely done because the project design professional was not sufficiently expert or experienced with specifications for EPS block geofoam so they simply used a document that was readily accessible or perhaps even provided to them.


EPS density is not widely recognized

Far too often it is a sad state of affairs to see what many architects reflect on their knowledge of the specification of the EPS block, often in the form of communication shared with consultants. Rather than dig into the ASTM library, the easy way out is to not be responsible, although the easy explanation is that the level of expertise is not available to the design professional. This trend is changing as more and more DoT construction sites demand the proper specs be used. Mind you, this white paper was written in 2010, and there are still failures occurring from former projects, although becoming less and less frequent.

As you can see, EPS foam density matters. Here at Poly Molding, we pride ourselves as maintaining the utmost in quality standards, as proven by the number of projects in which we have participated. Although we do not specify which type of EPS Geofoam be used for a project, we do supply a specification sheet with every inquiry.

Having been in business for more than 59 years, we are known and respected by nearly every commercial construction firm in the Tristate area.

From Yankee Stadium Garage to Freedom Tower, Raritan Medical Center to Stoney Brook University, our Geofoam is an integral part of these magnificent and functional projects. Because EPS foam density matters, and there is a difference.

Working on an upcoming project? We’ll be more than happy to discuss your EPS Geofoam needs.

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