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.

It has been determined that by direct injection into weak and very weak compressible soils using expanding polymer resins that the soils are not compressed and compacted to increase bearing capabilities and in fact what happens is the expanding resin tends to migrate through the weak soils and form wing like structures along vertical planes thereby not densifyng the base soils being treated. To overcome this reality “POLY-PIERS” system was developed!!

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.

ADVANTAGES

• Fast application – simply drill small holes, insert
• Eliminates need for costly piling and inflate Containment Unit with Poly-Mor 400 resin
• Minimal mess and disruption
• Reduces the destructive impact of large auger piling
• Treatment depths of 50 feet plus
• Resins contained within water-tight textile
• Compressive strength of material – 100
• E-Modulus – 24.0Mpa (3.481 kips) – 50.0Mpa- (7.252 kips)
• Probes inserted at 3’ – 4’ centres provides up to 600% increase in bearing pressure in surrounding soils
• Provides an ideal solution for load transfer and ground improvement in peat lenses and horizons.

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:

Material Type

Asphalt Concrete Pavement

Depth Range (m)

0.0 to 0.3

Granular Base Course

0.3 to 1.2

Stiff Clay

0.9 to 4.9

Peat

3.0 to 8.2

Soft Clay

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 PROCESS

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 .

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This technology is applicable in the industrial, commercial, residential, public works and institutional markets where water leaks are a problem.