Soil stabilisation using lime cement columns was developed in Sweden during the 1970s, and the latest work is looking at widening the applications with other kinds of binders and other types of soils. The aim is to establish what materials give improvements particular to a defined application, so that for example it will be possible to specify on the basis of treatment required to produce a deformation acceptable to say a new bridge under construction, rather than just strength improvement.
The five year research co-operation, performed within the Swedish Deep Stabilisation Reserch Centre (SD), which has its secretariate based at SGI, involves input from the state roads and railways administrations, industry, universities and research institutes. Work is focusing on both dry mixing and mass stabilisation.
At SEK40M (3M), the project is the largest single piece of soil mechanics research undertaken in Sweden. The hope is the work will increase the application of deep stabilisation and expand its use especially in Europe, where there is thought to be considerable potential for the technique.
According to SGI's Goran Holm, who is heading the deep stabilisation project, the work is focused on gaining scientific data to allow treatment of a wider range of soils, such as peat, identifying new applications and finding more cost effective ways of operating.
Soil stabilisation is not simply about improving strength. Treatment can easily increase the strength of a 10KPa clay by 20 times ie, from a very soft clay to a very stiff material, says Holm, but that is not the real aim. 'We want to achieve interaction between the structure and the ground, it is not really trying to produce an alternative to a pile,' he says. For this reason Holm prefers to use the term lime-cement columns, not lime cement piles.