BAUER Maschinen GmbH and RTG Rammtechnik GmbH introduce new soil mixing tool (SCM-DH)
Different soil mixing techniques have been in operation for many years. When mixing cement slurry into loose or soft, non-load-bearing subsoil, the load-bearing capacity of the subsoil increases and the settlement is reduced. For this purpose, the BAUER Group offers several types of equipment and processes which are also suitable for the construction of cut-off and load-bearing retaining walls (CSM, SMW, MIP, SCM Single Column Mixing). With the development of the new SCM-DH (Single Column Mixing-Double Head) soil mixing tool, BAUER Maschinen GmbH, together with its subsidiary RTG Rammtechnik GmbH, is responding to a growing number of enquiries from various customers with regard to mixing tools for soil mixing columns with ever increasing diameters.
The newly developed SCM-DH Single Column-Double Head mixing tool represents a significant improvement of the single column mixing tools that have proved themselves over many years and established themselves world-wide. The two counter-rotating mixing tool components are capable of achieving exceptionally intensive levels of mixing and homogenization of the soil with the slurry. The tool cannot only be employed in sandy, silty soils. Due to its intensive mixing capability, it is also suitable for the construction of soil mixing columns in cohesive soils.
Two interlinked sets of mixing paddles are driven in opposite direction by two coaxial casing tubes. The unit is driven either by a double-head rotary drive (i.e. DKS 100/200-02 or DKS 50/100) or a KDK rotary drive of the Bauer BG rotary drilling rigs in combination with a BTM torque multiplier. The outer set of mixing paddles is driven with high torque by the outer casing tube which is connected to the lower rotary drive. Its primary task is to loosen the soil. The inner counter-rotating mixing paddle is driven at a higher rotational speed by the inner casing tube, which is connected to the upper rotary drive, and facilitates exceptionally intensive levels of mixing between the loosened soil and the slurry. Based on their extremely sturdy design, mixing tools are currently available for column diameters of 1,800 mm and 2,400 mm.
Both the RG machines of RTG Rammtechnik and the rotary drilling rigs of the Bauer BG Series can be used for this technique. Due to the high level of hydraulic power output produced by the RG rigs, these machines are particularly suitable for this soil mixing process.
In August 2012, the new SCM-DH Single Column Mixing tool was tested successfully in a large-scale field trial. For this trial, the mixing tool was attached to an RG 25S fixed leader rig and driven by the latest double rotary drive DKS 100/200-02. The installed engine power of 570 kW proved particularly beneficial in maintaining a high rotational speed throughout the mixing process, despite an increase in soil resistance. The maximum mixing depth attainable with an RG 25S machine is approximately 23.5 m.