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.
“Foam Injection Into Containment Units In A Highway Embankment Foundation – Pilot Study"
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.
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.
This Patented technology was ostensibly developed for northern climes where perma-frost is a reality and where infrastructure is often constructed above grade on piers.
The Polymer Pile concept is a methodology of backfilling around the pier that would support a structure above ground. A hole is drilled to a specified depth, filled with a granular material (gravel) and injected with our expanding hydro-insensitive expanding polyurethane resin. As the resin expands, voids between the granular spaces are filled and a controlled mold pressure is exerted to completely bind the gravels within the confined space of the bored hole and surrounding the pier within the hole with resultant break points exceeding 1600 psi. for the back-filled conglomerate. It is of note that the process to set up and cure literally only takes minutes before work on the piers can continue. Additionally, cold weather does not impact the reaction of the polyurethane system. Although the polyurethane system is exothermic in its reaction the amount of heat generated in the process is so minimal that it does not contribute to melting of perma-frost, ice or ice lens’ as the total amount of heat energy within the foam generated is minimal.
Testing undertaken at the University of Alberta and stated in an Engineering Masters Program Thesis confirmed,” The foam will travel readily through a gravelly medium and produce a concrete equal in strength to light weight Portland cement concretes. The foam injection can be customized to achieve the best quality product for specific environmental conditions. The mechanical behavior fulfills the requirement of being stronger than native frozen soils (0.5 – 1.0 MPa).”
A closer look at reinforced polymer base
Reinforced Polymer Base
Our internationally patented process for construction of reinforced polymer bases employs a variety of reinforcing materials such as polymer mesh, rods or geo-webs or other course geo-textiles which are placed on a roughly graded sub-grade. A high density, closed cell hydro-insensitive expanding polymer resin is applied over the grid of reinforcing material to a specified thickness thereby providing a contiguous base which will bridge any current and future weak areas in the base soils while at the same time providing a base which will prevent liquids, vapors, gases or other leachates to permeate through the reinforced base.
The excellent thermal characteristics of our polymer resins inherently provide a high degree of insulative protection which is a particularly important characteristic when working with base soils located in perma-frost and ice-lensed locales. The polymer resins employed are resistant to petroleum products and most other environmentally unfriendly liquids although our resins will eventually slowly break down if constantly exposed to ultra-violet light. Accordingly, whenever a reinforced Polymer base is constructed a wear surface such as gravel, clay, etc. is required.
This process is a unique combination and application of three components: a geo-grid; covered with a high density polyurethane foam and capped with a polyurea to provide a bullet-proof seal to prevent water from eroding embankments along ocean fronts, river fronts, earthen dams; around culvert openings under roads; or any other embankment where water erosion may be a threat.