Physical Properties for Ground Engineering
Physical properties of URETEK relative to increased density:
- Compressive strength
- Shear strength
- Flexural strength
- Tensile strength
Within certain limits the URETEK polymer demonstrates elastic characteristics. Hooke’s Law indicates that compression is proportional to the applied forces and will not exceed more than 2%-10% in deviation.
Only when force exceeds the elastic limit is the internal cellular structure permanently modified and will not recover its initial form. The elastic limit depends on the density of the material.
The four diagrams on the right indicate the effect of density on its resistance to forces of compression, shear, bending and tension.
The URETEK polymer is primarily used to consolidate ground and to re-level settled structures. It is clear that, from a practical point of view, the most important property is compressive strength. Diagram 6.1a relates the density of the material to its compressive strength. The usual surface density of the URETEK material, which is about 70kg/m3 when injected beneath flooring, can reach 300 kg/m3 in deep injection levels.
The elastic limit varies between 10 and 65 kg/cm2.
The URETEK polymer has considerable shear strength, which for a standard thickness to the ASTM standard, varies from 5 and 30 kg/cm2 according to the density of the material.
Resistance to aging
Long-term evaluation of a high density URETEK material indicates a design life of at least 33 years. Ongoing testing is indicating an extended design life well beyond this period. This is also typical of other studies provided both independently and by major raw materials suppliers indicating long-term stability and durability even in unfavorable environments.
The durability of Uretek material has been subjected to long-term testing at independent laboratories – including the University of Hanover, Germany – and by the raw material suppliers who are engaged in ongoing development of polymer resins.
The Uretek material performed well under demanding test conditions, which demonstrated a minimum life of 30 years at surface levels. Underground, the material is engineered to last up to 100 years.
Chemical Resistance of URETEK Material
The resistance of the expanded URETEK polymer to chemical agents has been evaluated as a function of loss of volume following prolonged exposure, and evaluated in the following categories:
- Excellent resistance (loss of volume < 3%)
- Good resistance (between 3% and 6%)
- Fair resistance (between 6% and 15%)
- Poor resistance (between 15% and 25%)
- Not recommended: Only concentrated nitric acid and concentrated sulphuric acid destroy the material upon contact.
|Methyl Ethyl Ketone
General description of the test
Samples of the URETEK material were subjected to immersion in various liquids and to cycles of thermal stress. After the test, variations in volume were measured by means of a high precision optical measuring instrument, and the degree of liquid absorption through variations in flow thrust examined.
There were 10 cycles, each one consisting of the following:
- 08 hours in air at 65˚C
- 16 hours in air at 23˚C
- 08 hours in air at 30˚C
- 16 hours in air at 23˚C
Immersion in liquids
The samples were completely immersed in various liquids at a temperature of 23˚C for 14 days. The liquids used were:
- Crude oil
- Fuel oil
- Gas oil
- High octane gasoline
Two of the samples already subjected to thermal stress were also subjected to this test by immersion in high octane gasoline.
The samples were immersed in 1.25m of water at 20˚C for 7 days to determine absorption through percentage variations in their flow thrust.
This test included samples which had been subjected to the two previous tests.
The 10 cycles of thermal stress described above have left no visible trace on the material, and its dimensions have shown no measurable variation.
The material is absolutely impermeable to water even after various immersions, and almost completely impermeable to the other liquids used in the tests. Thermal stress has had the effect of reducing its total liquid content, probably because of evaporation occurring during periods of high temperature.
Scientific studies show that rigid Uretek material does not have any detrimental effect on the environment.
Rigid and flexible Uretek materials were tested at a disposal site and evaluated after 3 and 5 years. The Uretek material, although discoloured, had not changed structure. Analysis of the leachate water did not show a noticeable deviation in composition from leachate water derived from waste which did not contain Uretek material.
The stability of Uretek material is well documented and a table of chemical resistance is given under Technical Info. The chemical and solvent resistance of Uretek material is good, and resistance to oil and grease is excellent. Rigid Uretek materials are stable in water solutions of common detergents, salts, acids and bases. The Uretek material can only be degraded by strong acids such as nitric and sulphuric acids.
Rigid Uretek material is inert to mildew and fungi and will not mould or decay. The Uretek materials do not nourish insects or rodents. They are chemically neutral.
When buildings have subsided due to external factors such as leaking or broken drains causing washout, insurance company engineers turn to Uretek to provide a solution that is non-disruptive and economical.
The Uretek processes are fast – most residential work is done in a day or two. There is minimum inconvenience to the household. Residents do not need to move out, and there is no excavation, and no mess, dust or water.
Uretek processes involve minimal disruption and are economical and permanent.
There are many international companies in the insurance industry that have used the Uretek process to handle insurance claims, such as Zurich Insurance UK, AIG, Aviva, Liberty, Royal Sun Alliance, Cunningham Lindsey and others.
- Little or no disruption
- Very cost effective
- Ten year warranty on Uretek Resin
- Clean, quest, dry, odorless
- Proven process
- Professional technicians
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