Sampaanala bay is a former receiving water course for paper and pulp industry mill effluents located in the west coast of Finland near the city of Rauma. The total area of the bay is 10 hectares, water depth nowadays varies between 0-3 meters. The top layer of the sediment consists mostly of fibre sludge, 0-fibre, from the pulp and paper industry, below that a clay stratum reaching ocasionally in 17 meters. In the early 2000s the bay was decided to fill and turn into storage area for the use of nearby industry. The filling of the bay with traditional methods would have required massive, approximately 2 million ton, mass replacement. Therefore, mass stabilization was selected as an alternative method for mass exchange. The filling of bay was started with laboratory testing in 2011 with basin A which is already filled, stabilized and constructed and now basin B is to be filled.
The ambition in the Sampaanala bay was: 1) increase the utilization rate of surplus soils locally 2) reduce the landfilling need of local industrial by-products, 3) increase the storage area for the need of local industry and 4) receive economical savings by reducing material transportation, landfilling and binder material costs. Surplus soils from the nearby region were used in basin A and dredged slightly contaminated sediments from the nearby fairway deepening are used in B basin fillings to increase the bottom to the water level. A wide variety of industrial by-products are used for different purpose in construction: lime mud, green liquor dregs, bottom ash, coating paste and stockpiled fly ash were mixed with sediment to improve the stabilization and minimize the binder material need.
The binder costs could be reduced by replacing cement with biomass fly ash from nearby power plant. This enables the complete utilization of the ash in earth construction at least for a decade ahead and provides significant economical savings and reduced CO2 emissions compared to cement. A comprehensive research of utilization other industrial by-products in binder mixture e.g gypsum waste, oil shale ash etc. have been done. The studies have resulted that by-product based, and mechanically activated binder have potential to reduce remarkable amount of the cement in mass stabilization and produce further savings in binder costs.
A novel by-product based binder is piloted in the mass stabilization of the side areas in basin B in November 2017. The pilot construction is continued during 2018 with more difficult masses in the center of the basin. The novel binder is also planned to be tested in base course structure applications such as base course stabilization after the whole basin B is filled. As a part of EU LIFE IP CIRCWASTE project, the Sampaanala bay case is excellent example of transition from linear production process towards circular model and higher material utilization rate. The technical, environmental and economical effects of the material utilization applications will be monitored, evaluated and compared to traditional applications during the project. Furthermore, the best practices are presented and reported for the further replications.
Lessons learnt from practical projects , Interaction and chemical compatibility with other materials and structures , Processing possibilities and logistics
