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Comparisons with concrete underpinning and mud jacking

Supplier: Mainmark
20 May, 2010

Uretek resin injection underpinning and concrete pavement leveling avoids the draw-backs of traditional concrete underpinning and 'mud jacking' by hydraulic injection of cement slurry.

Traditional Underpinning: 

In reactive clay conditions, foundation clay soils expand and contract with changes in the moisture content of the ground. ("Shrink-swell." ) 

Concrete or masonry underpins, unless installed along every part of a building's footing system, often contribute to future differential movements in the structure. This is because underpinning is generally used to re-support a footing down onto a different strata not susceptible to movement.

The problem is that whilst the corrected section is then effectively rigid, the adjacent sections that have not been underpinned will continue to move with future shrink-swell of the ground. This can create new cracking in the structure - unless articulation joints are sawn completely through the walls.

Uretek resin injection technology does not exhibit this problem. This has been shown by empirical evidence, (university research and 20 years of specific field application). Uretek is different, addressing the nature of the foundation soils and any cracks and voids therein, improving bearing capacity, raising and restoring and maintaining a uniformity of bearing strata.

N.B.:  In relation to underpinning, Australian Standard AS 2870 warns, "Underpinning should generally be avoided where the problem is related to reactive clay," and "Deep underpinning should only be considered as a last resort."

In poor ground conditions where there is settlement, the added weight of concrete/masonry  underpinning (2400 kg/cu.m.) can exacerbate the situation, not correct it. With The Uretek Method and the exceptional specific rigidity (stiffness to weight) of Uretek material, this is avoided.

"Mud jacking"
"Mud jacking" is the name given in some places to the injection by hydraulic pressure of cement slurry (grout) under pavements, to re-support them and correct their levels. Sometimes it is called "slab-jacking" or referred to as "pressure grouting" (originally, actual mud was injected).

This process has long been recognised to have major draw backs, particularly in highway situations, in that after some time the brittle cement grout can powder and break up under the dynamic stress of heavy traffic, allowing the degeneration cycle to recommence.

Uretek, on the other hand, employs rigid elastic technology. Again with its exceptional specific rigidity (stiffness to weight), Uretek material withstands dynamic pavement loading, giving it a much longer effective life. This more than offsets the sometimes greater initial outlay in its application.

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Source: Uretek