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ABSOILS

Project's pilots

With the application of proper design and innovative treatment methods, surplus soft clays and sediments can be turned into construction materials. The prevailing soil improvement method used in the ABSOILS project was mass stabilisation.

Mass stabilisation is the process of utilising chemical admixtures and stabilising agents to alter the engineering properties of a soil mass so that cost-effective development results are achieved. The goals of the mass stabilisation programme are typically to improve the geotechnical engineering performance of a given subgrade, or to achieve environmental performance objectives. The application of mass stabilisation techniques alters the technical engineering and environmental properties of soft soil in such a way that it is possible to construct directly on top of the stabilised soil or to utilise it as filling or construction material. Owing to the development of versatile binders, various kinds of soft soils can be stabilised in a cost-effective way.

All mass stabilisation projects utilise a binder, or chemical stabilising agent which reacts with the soil mass to change its properties. As a result of the ground investigation and laboratory testing programmes, the quantity and quality of the binder are optimised to achieve target properties with minimal investment. The use of various industrial by-products as binders in mixtures with commercial binders enables cost-effective application of the mass stabilisation method.

The material tests were run for all the pilots before the construction stage and the follow-up studies were carried out afterwards. The LCA and LCC evaluations were performed on the basis of the results. These studies have supplied information on the structures and utilisation possibilities of surplus soft soils. Moreover, the new binder mixtures and techniques have been developed and tested. The aim of the ABSOILS project has been to increase the eco-efficient utilisation of surplus soft soils by demonstrating the benefits of applying the stabilisation technique.

PILOT APPLICATIONS

• Flood barriers

  • Dog Park in Espoo (2012/2013)
    

  • Pirttiranta in Vantaa (2012)
    

• Noise barriers

  • Jätkäsaari 3 in Helsinki (2014)

• Supporting banks

  • Arcada 2 in Helsinki (2011)
    

  • Dog Park in Espoo (2012/2013)
    

  • Honkasuo in Helsinki (2014, 2015)

• Landscape construction

  • Jätkäsaari I and II in Helsinki (2011/2012/2013)
    

  • Dog Park in Espoo (2012/2013)

Pilots 2014 / 2015

Jätkäsaari III

In the Jätkäsaari III pilot, stabilisation method was used to treat dredged sediments in the basins. Stabilisation works were carried out in spring 2014. Two different methods were used: mass stabilisation and windrow turner stabilisation. Various binders and binders' mixtures were applied. these include also such secondary materials as fly ash, FGD and oil shale ash from Estonia. The stabilised material was used for the construction of the trail noise barriers at the Jätkäsaari site in January 2015. (Read more and see photo gallery)

Honkasuo

The Honkasuo pilot site is located in Helsinki. It is a new residential area is under construction. This pilot application allows for applying the stabilisation method for soft clays and peat, which was not earlier tested in the framework of the Absoils project. Stabilisation laboratory tests were carried out in 2014. The preparatory works at the site started in spring 2014 and surplus soft soils from other construction sites in Helsinki were transported there for temporary storage to be further used in the stabilisation process. (Read more)

Pilots 2013

Perkkaa Dog Park, Espoo

The stabilisation works were carried out in January/February2013.The designed area was divided into different sections where individual binder recipes were used. A stabilisation map was created by the designer for the needs of the contractor carrying out the work. The stabilisation work-plan created by the contractor on the basis of the stabilisation map shows the location of the areas and blocks to be stabilised. (Read more and see photo gallery)

Pilots 2012

Perkkaa Dog Park, Espoo

The preliminary works including planning, permitting, clearings, etc., were carried out in 2012. The stabilisation works took place at the beginning of 2013.

The area of the park is ≈4 500 m2 and it lies in the flood prone zone. The soil of the area was described as soft clay which used to be seabed. The thickness of the clay is ≈11 ... 14 m and the area has been classified as a very difficult constructing target due to its low load bearing capacity. The purpose of the pilot was to raise the area to prevent flooding. In order to prevent mass exchange, landfilling of the soft soils and replacing them with other materials, it was planned to utilise both the poor quality spoils encountered in the target and the surplus clays obtained from an adjacent construction site – the construction of a street foundation with a mass replacement method.

The redundant clays from the neighbouring street were transported to the pilot site where the materials were stockpiled in the area surrounded with an embankment to prevent the escape of the fluid clay material out from the stabilisation area. The transportation and construction of the embankment tool place between January and March 2012. The transportation distance in this case was only 200…500 meters. The transportation distance to the landfill would have been about 25 km had it not been possible to use the redundant masses in the construction process of the Perkkaa Dog Park. Surplus soft clay is a very troublesome and expensive material to dispose at landfill.

Please take a look at the pilot’s photo gallery

Pirttiranta Flood Prevention Wall, Vantaa

Pirttiranta was chosen to be a supportive pilot for the needs of the Absoils project in 2012. Pirttiranta is a housing area in Vantaa in the vicinity of the Vantaa river. The area has been prone to flooding an there was a need to construct dikes to prevent floods in the future. It was decided to construct the dikes with the abandoned soils (clays) generated in Vantaa. The construction of the dikes took place in May-June 2012.

Jätkäsaari II

In August 2012, the works in Jätkäsaari started as a second stage of the Jätkäsaari I/2011 pilot application.  Dredged sediments were solidified by mass stabilisation technique in the basins placed in the Jätkäsaari area. The works were completed by the end of November 2012. After the stabilisation part of the masses were excavated and transported to the part of Helsinki called Vuosaari and used for infrastructure construction works. These included, among others, the landscaping of the Vuosaari landfill and Ida Aalberg Park. The stabilisation works in this site in 2011 and 2012 have allowed for the utilisation of about 110000m3 of dredged sediments for the construction purposes. If not the project piloting, they would have to be deposited to landfill. Stabilisation in this site was carried out mostly with cement. However, fly ash (from the Helsinki Energy Power station) was also used for the stabilisation of a small scale trial field carried out with a special permission for trial fields.

Pilots 2011

Arcada 2, Kyläsaari, Helsinki 

Arcada 2 is located in Helsinki in the Kyläsaari area at the northern end of the street Kyläsaarenkatu. The project includes the construction of the street Kyläsaarenkuja (190 m) to a pile plate, removal of the contaminated soils, removal of the heavy aggregate material, filling with abandoned soils and construction of new driveway connection to the road Hermanninrantatie. (Read more)

Jätkäsaari, Sediment basins, Helsinki

In the first stage of the pilot application, the dredged sediments of Jätkäsaari are mass stabilised and utilised in the fillings of the adjacent park. The amount of the utilised dredged sediments is about 20 000 m3. The dredged sediments are mostly clay. The implementation of the first stage of this pilot application took place in the spring 2011.

In the second stage, the dredged sediments are planned to be utilised by stabilising with fly ashes and sulphur removal product. However, the original environmental permit does not allow for the use of ashes in the stabilisation process. Therefore, there was a need to apply for a new permit and the start of works depends on the length of the permitting process.

Please take a look at the Jätkasaari I photo gallery