ABSOILS

Perkkaa Dog Park, Espoo

Stabilisation block is a basic unit which takes a certain amount of binder. The width and length of the block ranges normally from 4…5 m × 4…5 m. Immediately after stabilisation, a 0.5 meter high compaction embankment of crushed rock was constructed on top of the stabilised material. Before the construction of the embankment, a non-woven had been spread over the mass stabilised clay. Such embankment consolidates/compacts the stabilised material and finally remains as a part of the surface structure. Mass stabilisation in the Perkkaa Dog Park included the following work steps:

harrowing and homogenisation of the stabilised surface
plotting and marking the corner points of the stabilisation blocks
construction of a platform, e.g. timber grating
mass stabilisation work of surplus clay and subsoil
construction of the compaction embankment on top of the stabilised layer
quality assurance soundings and test pits after stabilisation and strengthening period
instrumentation of the mass stabilised layer

After consolidation of the mass stabilised soils, quality assurance was performed with the quality control soundings (column penetrometer and vane penetrometer for columns). The soundings provided information about the strength properties of the material. The quality control soundings after 28 days of hardening time were carried out at the end of February and the 90 days soundings will be carried out at the end of May, 2013. On the basis of the 28 d sounding results, it has been concluded that the hardening of the mass stabilised layer has been moderate or good with all the binder mixes.

In addition to soundings, the stabilised structure was examined by excavating of the test pits (all together 10 test pits). The field test methods applied with the test pits included photograph documentation and depth profiling, pocket vane shear apparatus, penetrometer testing (hand held), Niton XRF and sampling for the laboratory (water content and pH determination).

Also the lysimeters and settlement plates were installed in the Perkkaa Dog Park. The water samples for the laboratory analyses will be collected first in the autumn 2013 and afterwards, during several years.