URETEK HYBRIDINJECTION®
URETEK is recognised worldwide as a technically advanced specialist in the repair of subsided concrete floors and steel foundations.
Unstable or subsided foundations of houses and buildings are one of the factors contributing to damage to façades and compromising the long-term stability of the structural framework. In soil layers with insufficient bearing capacity and very low cone resistance, such as clay and peat, a ground compaction technique using expanding resins may not provide a satisfactory solution, as insufficient stress can be built up in the yielding soil. URETEK has also developed a specific, low-disruption method for these soil layers to stabilise subsided concrete structures and steel foundations.
Principle of operation
Using the patented URETEK Hybrid Injection® method, a geotextile element is installed directly beneath the subsided foundation, extending down to the soil layer with sufficient bearing capacity. This element consists of an injection lance wrapped in a geotextile sleeve. The two-component URETEK expansion resin is then injected into the element. The expansion resin expands within the element, increasing its volume (up to 30 times). The element expands from 40 mm to 360 mm. This creates a very solid element that supports the structure on the stable layer with sufficient bearing capacity. The foundation is thereby stabilised. The injection process is monitored very carefully using precision laser measuring equipment.
Technical data:
- Injection depth (currently) max. 8 metres below ground level;
- Diameter of the expanded element: 360 mm;
- Load-bearing capacity: max. 15 tonnes (150 kN) per element;
- The expansion resin is FCWK, formaldehyde- and radon-free;
- Installation capacity: on average 6 elements per working day.
Injection
At intervals of 1.75–2.00 metres, injection holes with a diameter of 80 mm are drilled through the foundation base on the outside of the property, running flush against the façade. A metal casing is inserted into the boreholes down to the layer with sufficient bearing capacity. The Hybrid Injection® element is placed inside the metal casing. The casing is then withdrawn, leaving the element in place. A specially developed injection gun is subsequently connected to the lance of the installed element.
Expansion
A powerful, two-component expansion resin is now injected into the element via the injection lance under low pressure. Immediately after injection, the two components react, causing rapid and powerful expansion within the element to up to 30 times its original volume. The expansion resin causes the element to expand from 40 mm to 360 mm. During injection, the injection lance is withdrawn from the element and the resin is filled evenly right down to the base of the foundation. This process is precisely controlled by a computer, allowing the formation of the element within the ground to be monitored.
Underfilling and Lifting
As soon as the Hybrid Injection® element has been filled up to the underside of the foundation, a minimal upward movement of the foundation occurs. This means that the foundation has been stabilised. The injection process is monitored by precision laser measuring equipment. Each element can bear a load of up to 15 tonnes (150 kN) and transfers the forces from a foundation to the stable, sufficiently load-bearing layer in the subsoil. This method can also be used for the preventative treatment of foundations.
Benefits of URETEK HYBRIDINJECTION®
- Minimal disruption
- No pile driving
- Repair in just one or a few days
- Fast and cost-effective
- No major foundation repairs