A Canadian Patented system to densify weak and very weak base soils such as saturated clays and silts; peats and any other weak and compressible soils type.
A “POLY-PIER” is simply a designed and fabricated confinement unit (a bag) that is placed in and through the weak strata being treated through a drilled hole and filled with Poly-Mor’s expanding Poly-Mor 486 hydro-insensitive expanding foam system. As the containment unit(s) fill with the expanding material the soils are compressed and compacted thus densifying same as well as leaving a pile-like structure in place within the weak soils structure.
Under the auspices of Alberta Transportation and EBA Engineering a test project using Poly-Piers was undertaken to densify deep peat and organic soils deposits. The location of the test site was a portion of highway 1.5 km north of the junction of Hwy. 759 and Hwy. 39, in the Province of Alberta, which on a regular basis had settlement issues resulting in dips in the asphalt pavement.
Soils Report indicated the following:
Asphalt Concrete Pavement
0.0 to 0.3
Granular Base Course
0.3 to 1.2
0.9 to 4.9
3.0 to 8.2
3.3 to 13.7+
One of the initial challenges was what grid pattern to employ. It was proposed by Poly-Mor and agreed to by all parties that two different spacings were to be used for the foam injection. On the south half of the project, 1.2 m staggered spacing was chosen, and for the north section of the site, 2.4 m staggered spacing was used. The two different spacings were selected to determine if there was any benefit to having a denser spacing of foam columns.
The project engineers claimed the test to be a total success despite the fact that after about five months there was settlement of some 3” but after the initial settlement the road stabilized. Probable cause for the settlement was that some 6” – 6’ of asphalt was overlaid the on the test area which was never taken into account initially as this treatment was not known at the time. Of note both spacings were equally effective .
This technology is applicable in the industrial, commercial, residential, public works and institutional markets where water leaks are a problem.