Soil cement foundation procedure developed jointly by Kemroc and Schönberger Bau

Published 27/12, 2018 at 09:57

Based on Kemroc trenching technology, the innovative Schökem procedure for the construction of soil cement foundations has been jointly developed by Kemroc and Schönberger Bau.

This uses an excavator attachment which, after penetration into the soil, simultaneously injects and mixes a binder suspension with the soil to create a soil cement structure without the need for any excavation or filling work. 

German companies Kemroc GmbH and Schönberger Bau GmbH & Co. KG have developed a new excavator attachment for ground stabilisation. This attachment can treat soil in-situ, without the need for costly shoring or soil replacement. While mixing the soil, a binder material is simultaneously injected into the soil. After a few days of settling time, the treated soil turns into a stable load bearing, impermeable structure. After completion of the first field trials, the homogeneity, strength and impermeability of the soil cement slabs were tested by geotechnical testing company Dipl.-Ing. A. Pampel GmbH (GCE) from Leipzig. Test results confirmed the compressive strength at 3 to 4 MPa.

 

Load bearing foundations for civil engineering

The innovative so-called ‘Schökem’ procedure is based on a proven method of soil stabilisation by mixing soil and cement. It conforms to methods specified by planners and contractors, and to the DIN standard for deep soil mixing by the injection of a cement suspension for the stabilisation of soils (FMI) as used in civil engineering projects. In this process, the soil is mixed with an injected cement suspension using a mixing machine that can reach the required depths in the soil. This creates a homogenous, impermeable, frost proof and crack free soil cement slab. Typical applications where the load bearing capacity of the ground needs to be increased by soil stabilisation include road and railway construction, stabilisation of embankments, sealing contaminated areas or in flood defences. Regardless of the application, the process is economical as it eliminates transportation of excavated and fill material.

Working in close cooperation, the manufacturer Kemroc and the specialist civil engineering company Schönberger Bau have further developed the process. The new ‘Schökem’ process has made this technology available to operators of standard hydraulic excavators which provide an added degree of flexibility. The new KSI range (Kemroc Schönberger Injector) was developed by modifying the tried and tested Kemroc chain cutter attachment. The cement suspension material is transported to the injection nozzles by hydraulic hoses from the drive unit through channels in the support frame. In modern grout mixing plants (both partners recommend compact, self-contained plants from Gertec GmbH) it is possible to regulate the amount of cement used in the suspension material with a high degree of accuracy. By modifying the amount of cement used according to soil conditions, it is possible to stabilise soils to pre-defined characteristics.

With a set-up time of about two hours, it is possible to create load bearing soil cement slabs to the dimensions required. These can be used in road construction, flood defences, retaining walls for deep excavations in civil engineering and pipelines, as well as railway construction. The KSI range of attachments can be used on standard, relatively small sized hydraulic excavators. The construction of larger soil cement structures is also possible as the process offers a working range of 500m from the excavator in both directions.

 

Range of sizes and blade lengths

The new KSI soil stabilising attachment is available in two sizes with a variety of blade lengths. The KSI 5000 drive unit (130kW) can be equipped with blades for 3m, 4m or 5m mixing depth and, depending on the blade length, used on excavators in the 30t to 50t operating weight range. The larger KSI 10000 (220 kW) can be fitted with blades for mixing depths of 6m, 8m or 10m and can be used on excavators in the 45t to 70t weight range. Accessories for both models include mixer extensions (1m), the KRM 80 rotation unit and replacement mixer teeth.

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