The building process at the new Vuosaari harbor in Helsinki in 2003-2008 has been serving as a successful field for utilization of alternative materials.
The TBT-contaminated sediment dredged from the sea bottom at the area of 75 hectares was transported into the lagoons as a five meter thick layer. The sediment layer, totally about 0,5 million cubic meters was mass stabilized with cement and the strengthened layer formed the sub base of 10 hectares of the harbor. The QC/QA was based on the control of permeability and shear strength and was agreed together by the project owner, the geotechnical designer and the contractor and approved by the authorities. The settlements under preloading were carefully observed, too. The target value of the strength and the permeability was achieved throughout. The stabilized layer was covered with the drainage and the surface layers with an asphalt layer on top. Now, after ten years, the results of the new sounding tests have proved the continuous strengthening of the stabilized mass.
Due to the former activities of the closed dock yard, soils contaminated with heavy metals and arsenic were utilized as filling material in the noise barrier at the area of Melumäki. The construction site of the barrier was situated on soft clay. The bearing capacity and the stability was increased by mass stabilisation and mass replacement. The environmental permit allowed for the disposal of maximum 140 000 m3 of contaminated soils which were capsulated in the noise barrier with insulation course at the bottom, side and top. The bottom and the sides of the noise barrier were insulated with compacted stabilized clay. It was not possible to make a sealing layer with the local clay because of its high water content and low shear strength. However, after the mass stabilization, local clay turned into an excellent material for construction of the sealing. Currently the noise barrier serves as an outdoor recreation area in the neighbourhood of the Vuosaari harbour and the Natura conservation area.
At the site of the container field the layer of crushed stone # 0/31 mm was stabilized with the binder at an area of 6 hectares. The binder was a mixture of cement, fly ash, FGD residue and plast furnace slag powder. Thanks to the new base layer structure the asphalt layer could be made as thin as 50 mm instead of the conventional 180 mm.
The noise abatement wall, 11.2 m in height and 1 km in length, was built on eastern cost of the harbor. The lower part of the enclosed structure of cavities was filled with crushed stone and the middle part was filled with bottom ash, totally about 20 000 m3. The top was filled with growth medium and used as planting basins. The advantage of bottom ash is its light weight compared to the crushed stone. So the bottom pressure is more useable for the bearing capacity of the wall founded on the rock fill.
In 2016, the demands of the new depot area forced the harbor to take the closed shipyard basin for container depot purposes. The basin, totally about 300 000 m3, the area of 2.2 ha and 13 m in height was filled by moraine, blasted rock, sand, gravel and bottom ash. Bottom ash was used 30 000 m3 in total.
