The UK's Largest Fleet of Soil Mixing Equipment

GDL owns and operates the largest fleet of specialist soil mixing equipment in the UK. Our systems have been refined and adapted over the last decade to suit the broad range of soil conditions that we have across the UK.

Turbojet Column Soil Mixing

The largest deep mixing operation ever undertaken worldwide to date was done as part of the rehabilitation and upgrading of the New Orleans levee system to withstand the 100-year hurricane storm surge. The works where implemented by Italian geotechnical contractor Trevi using their patented Turbojet process.

What is Turbojet Column Soil Mixing?

Turbojet is the combination of mechanical mixing and jet grouting.  Itis an important development of the Soil Mixing Technology which allows the construction of consolidated structures in a fast and cost-effective way, with high-quality standards.

How does Turbojet Column Soil Mixing work?

The method of Turbojet Column Soil Mixing is based on the use of a mechanical tool, equipped with blades and jetting nozzles, to construct a column of consolidated soil.

During the drilling phase, the cement-based grout is ejected at very high pressure through the nozzles to break up the soil, which is then mixed by the blades. This technology allows for the execution of columns to have far superior geotechnical and engineering qualities than low pressure soil mixing systems such as single and double rotary auger systems.

GDL is the only UK contractor, and one of only a few in Europe, to own and operate the Turbojet Deep Soil Mixing system. Our investment in the system is based on our years of experience of working with both single and double auger soil mixing systems, which introduce grout at low pressure, which we found  to deliver a greatly inferior performance in respect to their ability to execute the works needed to the required standard.

What is Cutter Soil Mixing?

The Cutter system consists of a cutter head with two cutter wheels. Cement slurry is injected in the middle of the cutter head between the wheels. As a result, a homogenous mixed mass is created and the cutter head can easily sink into the soil under its own weight.

The version of the cutter soil mixer system that GDL uses is the Turbo Cutter system, which in contrast to other systems,  introduces the grout at very high pressure which is very beneficial when mixing the high plasticity clays and soft organic soils typically found across the UK.

The cutter soil mixer is particularly efficient in executing wall panel arrangements of soil mixing when compared against scanted soil mixed columns. It is also useful when there is the need to create a mass block of improved soil at depths which cannot be achieved using mass soil mixing equipment.

Mass Soil Stabilisation

Our mass soil stabilisation plant has been developed in – house with the support of several major equipment manufacturers such as Soilmec UK, the Wirtgen Group, Erkat, Caterpillar and Komatsu.

Notably our machinery has much higher performance capabilities with respect to torque and rotation speed when compared with similar equipment from other manufacturers.

Our fleet of mass stabilisation rigs includes variants based on excavators which range from 35 – 50 tons. We have several mixing arms with depth capabilities ranging from 4.5 – 6.5 metres in depth.

The introduction of the grout at high pressure is unique to our process.


GDL has invested considerable effort and resources into developing the precision monitoring and positioning systems which are an integral part of our soil mixing systems.

Our GPS machine control systems have been integrated to control position and depth. This is linked with various sensors and other instrumentation which records the various aspects of the process such as grout flow, grout pressure and rotational speed, When this information is brought together using our software it provides a real time graphical representation of the work that has been completed.

Recording each of the aspects of our process, not only ensures we can validate the works in accordance with the relevant technical standards, it provides our operators and management team with real-time information to assist with the successful implementation of the works.

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