Mechanical properties of URETEK expansion resin

All URETEK expansion resins increase the density of the expanded material, thereby also improving its mechanical properties. The density of our material depends heavily on the resistance it encounters during expansion. When used beneath floors and structures using the URETEK FloorLift® method, the density varies between 70 kg/m³ and 120 kg/m³. When injected into the ground using the URETEK DeepInjection® method, the density varies between 150 kg/m³ and 300 kg/m³. Unlike other injection materials – which typically have a density of between 800 and 1,500 kg/m³ – our expansion resin therefore exerts only a very limited load on the subsoil. This is an ideal property for use in floors with low load-bearing capacity.

The URETEK expansion resin exhibits elastic properties within certain limits: when a force is applied to the material, it deforms linearly in proportion to the force applied. As soon as the pressure is relieved, the material returns to its original shape. The internal cellular structure only undergoes permanent deformation under extreme loads, when the settlement (contraction) exceeds 10 per cent. The material then no longer returns to its original shape.

Test graphs

The test data shown in the graphs were determined in accordance with the American standard ASTM. The graphs show, in turn, the compressive strength and the shear strength. The horizontal axis indicates the density of the samples, whilst the vertical axis shows the strength values. The range within which the densities of the expanded URETEK material fall is shaded in yellow in all graphs. As the URETEK expansion resin is mainly used for ground stabilisation and for raising subsided structural elements, compressive strength is the most important property from a practical point of view. In the graph showing compressive strength, we can see that at a density of 96 kg/m³, the compressive strength reaches 3.2 kg/cm² = 32,000 kg/m² = 0.32 N/mm². Example: For residential floors, a live load of 150 to 200 kg/m² is to be expected, whilst for factory and warehouse floors, a live load of 5,000 kg/m² is extremely high.

Resistance to ageing

The certificate for the URETEK expansion resin was issued by the Materials Testing Department at the University of Hanover. A long-term assessment of a batch of high-density polyurethane E165 – Caradate 30 indicates a service life of at least 33 years. An ongoing study indicates an extended service life that far exceeds this period. Furthermore, both independent studies and studies by major raw material suppliers generally reach the same conclusion. The latter report long-term stability and durability, even in adverse environments.

Thermal stability

The University of Hanover has carried out a quantitative assessment of thermal stability in terms of dynamic weight loss using differential thermal analysis. It is expected that the service life of composite pipes containing E165 Caradate 50 rigid foam and tested in accordance with the research report will be 30 years at a permissible continuous operating temperature of 133 °C.