What the Experts Say About Raising Concrete with Foam admin 2018-08-15T00:31:20+00:00
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The Pros and Cons of Lifting Concrete with Foam vs. Mudjacking
Sinking or fallen concrete is a common problem in cities such as Denver. Two techniques may be used to repair this issue: polyurethane foam concrete raising or traditional mudjacking, which uses a sand slurry to raise concrete and fill any voids. The question is, is one superior to the other?
The Authorities Weigh In
It may not seem readily apparent which of these two approaches is best, so it helps to learn what objective professionals have to say about it. One such professional is James Warner, professional engineer and guest lecturer at the Colorado School of Mines.
In his textbook, Practical Handbook of Grouting: Soil, Rock, and Structures, he states:
“However, [there] are several limitations [to poly foam raising], the greatest of which is probably lack of complete filling of the cavity.”
So, why does this happen? Mr. Warner goes on to explain:
“Because the injected material [foam] reacts and reaches its maximum volume in increments shortly following injection, significant voids remain after treatment.”
MSDS REFERENCED FROM http://docs-europe.electrocomponents.com/webdocs/07c3/0900766b807c383b.pdf.
This can result in continued settling over time, as Mr. Warner demonstrates with an example local to Colorado:
“This was found to be the case when a bridge approach slab near the Denver airport that had been so treated [with foam] continued to settle and was subsequently removed. The foam grout was observed to have developed into pedestals at the drill holes, leaving a large portion of the total area untreated.”
While Mr. Warner does say there are certain cases where foam injection solutions are appropriate (i.e. when the continued use of the area being raised is more important than a complete filling and correctly done job), these cases are few and far between.
Not only have academics acknowledged the inability of polyurethane foam injection to properly raise concrete, but the Environmental Protection Agency has also released a safety bulletin warning people about the hazardous chemicals from which polyurethane foam is made.
See the bulletin here: See what the EPA says about polyurethane foam:
Click on the following EPA page
The Alternative to Foam
Compared with the polyurethane foam method, traditional mudjacking, when done properly, provides a complete filling of the voids under your concrete, properly supporting it. It also avoids all of the risks associated with a product made from harmful chemicals. The dense, environmentally safe sand slurry mix used by traditional mudjacking contains no harmful chemicals and can fill all the voids under your concrete since it does not harden after a short time, as polyurethane foam does.
It is important to remember when choosing a traditional mudjacking contractor that bigger is better. The bigger the truck, the more material it carries, ensuring your contractor will have all the material he needs to raise your concrete and fully stabilize it.
Polyurethane foam raising, as well as many mudjacking contractors, only perform the first step in the mudjacking process – raising the concrete. Unfortunately, they either can’t or don’t complete the second step – completely filling the voids under the raised concrete to stabilize it – leaving you with a half-finished job.
Contact AAA Concrete Raising in Denver to learn more about a mudjacking solution for you.