Soil injection technology

Unstable or weak building soil remains one of the key problems for planners and engineers in the construction industry. It can cause considerable structural damage, such as cracking, deformation or settlement, which exceeds the permissible limits of load-bearing capacity and serviceability. Typical triggers include shear failure, uneven compaction, erosion due to water movement, washouts and suffusion – i.e. the mobilisation and removal of fine soil particles by flowing water in the subsoil. In this case, stabilising and reinforcing the building ground is therefore an essential measure, especially when renovating existing structures and constructing new buildings on unstable ground. Modern injection methods are used specifically to improve the load-bearing capacity of the soil and protect structures in the long term.

Soil stabilisation methods aim to improve the load-bearing capacity and deformation resistance of a subsoil in order to make it permanently resistant to mechanical loads. At the same time, susceptibility to the effects of water and frost can be reduced. However, the main focus is on preventing potential settlement of structures, which is often caused by shear failure and soil compaction, but can also be caused by water washout and associated soil erosion and suffusion (displacement and removal of fine soil particles in the soil) due to washout and water action.

These processes can lead to cavities or depressions in soft soil layers or loose rock and ultimately to settlement or deformation of the structures above. Soil stabilisation and raising the structure can remedy this. Special injection solutions are used for soil stabilisation to protect foundations, floor slabs, roadways, runways, excavation pits and underwater structures against erosion, excessive settlement and failure of load-bearing capacity.

Conventionally, such damage is repaired by cement injections. However, this method is often associated with high costs, long curing times, a large amount of space required for implementation and significant collateral damage. Special injection resins based on polyurethane and organo-mineral resins have established themselves as a modern, minimally invasive alternative. They are characterised by very good penetration, optimum expansion force, high strength and fast curing.

There are two main technical processes for grouting soils: displacement injection and penetration grouting. In displacement injection, the resin is injected into the subsoil with high expansion force. This displaces the surrounding soil material, resulting in targeted compaction. This results in improved soil mechanical properties such as increased shear strength, a higher modulus of elasticity and improved cohesion and friction angle. This method is particularly suitable for raising foundations or floor slabs, but also for renovating traffic areas or runways.

Soil stabilisation is a frequently necessary step in everyday construction work – both in existing buildings and in new construction. In existing structures, settlement can occur as a result of construction defects, flooding, landslides, burst pipes or natural erosion processes. In such cases, targeted soil stabilisation and, if necessary, raising the structure is essential to ensure its continued use. In new construction, the focus is on stabilising excavation pits against water ingress and settlement, improving the load-bearing capacity of the subsoil or creating load-bearing access areas for heavy construction equipment.

The special resins of the MC-Montan Injekt product family provide a proven and efficient solution to the challenges of unstable subsoil. They enable precise, versatile and economical geotechnical injections – quickly, reliably and in compliance with European standards – and help to compensate for difficult ground conditions, increase load-bearing capacity and even enable the controlled lifting of structures.