Low Pressure Deep Grouting

LPDG, Low Pressure Deep Grouting, is a process developed by Mainmark that is a similar form of permeation grouting. Mainmark have refined the technique allowing for grouting at very low pressures with the purpose of filling the voids in the fill without fracturing the soil structure. The plasticity and strength of the grout is refined so that is compatible with the cohesive soil. 

deep grouting team

Bespoke grouting solutions for complex and sensitive ground conditions

LPDG uses cement/bentonite grouts pumped at very low predetermined pressures to predetermined, predicted volumes and at various pre-defined depths. The result is the precise filling, binding and sealing of the target soils, improving the soils properties to carry and distribute loadings.

  • Adaptable and versatile, suitable for broad range of soil conditions, concurrent treatment to numerous locations, differing depths to adaptable performance criteria
  • Cost savings via pressures and movements recorded to demonstrate how the ground is reacting to the grouting
  • Bespoke, engineered outcomes to allow for engineer / client input in the establishment and refinement of performance criteria before and during the grouting
  • Low impact approach to a complex geotechnical issues

The potential causes of building or structure subsidence or settlement are myriad. One is ongoing settlement of compacted cohesive soil fill. Here the settlement can be to be due to the softening of the soil, by water ingress into small voids between the elements of partially compacted cohesive fill material. Permeation grouting can be used to reduce such settlement by filling the voids and preventing such water penetration, but permeation grouting in cohesive soils can easily fracture the structure of the soil. Such fracturing can lead to an increase in water penetration, softening of the soil and increased settlement. Simultaneously, permeation grouting can result in unwanted uplift of a slab or footing above.

low pressure deep groutingInjectors are first sunk to the required depth and grouting commences. The grouting continues until either a maximum defined pressure is encountered or a maximum defined volume is delivered to the ground. The injector is then lifted to the next depth increment and a similar grouting regime is undertaken. This is repeated at each of the pre-defined depths. Measurements are recorded of depth, maximum pressure and maximum volume at each injector location to demonstrate the extent of void filling.

The process is fast and efficient, in most cases the occupants can remain in the building while the technique is applied. The supreme benefit of applying this technique is the ability to tailor the operation in response to how the ground is reacting to the grouting. This allows for the application of a considered, adaptable approach in the treatment of sensitive and complex geotechnical conditions.