ABSTRACT
Lime and lime/cement columns, where quicklime and/or dry cement are mixed in situ with soft soil as shown in Figure 8.1, are common in Sweden and Finland, to stabilize soft clay and silt as well as organic soils. The method has gradually been improved and new applications have been found. Lime and lime/cement columns have mainly been used to increase the stability and to reduce the settlements of road and railroad embankments and to increase the stability of trenches for sewer lines, water mains and heating ducts. New efficient machines have been developed for the installation of the columns. The diameter and the length have gradually increased and the time required for the installation of the columns has been reduced significantly as well as the costs. New methods have been introduced to check in situ the shear strength, the bearing capacity and the stiffness of the columns. Lime/cement columns have also been used to stabilize organic soils,
where unslaked lime alone has not been effective. Lime columns have the advantage that the permeability and the ductility are normally high. In addition the ground temperature is increased by the heat generated during the slaking. The increase of the shear strength, caused by the reduction of the water content, is usually significant. Since a large number of factors affect the behaviour of lime and lime/
cement columns, it is necessary to determine for each site the effect of different stabilizers (e.g. lime, cement, gypsum, industrial waste and different ashes) on compressibility, shear strength and permeability of the stabilized soil. Extensive field and laboratory tests are usually required. The stabilized soil has a high angle of internal friction even at undrained
conditions since the stabilized soil is only partially saturated. The bearing capacity and the shear resistance of the columns are to a large extent governed by the axial load and by the confining pressure.
