Test stabilization with low carbon binders – case Malminkenttä

Abstract

Malminkenttä is an old airfield covering an area of around 2.4 km2. Area is on soft subsoil which consists mainly of 5 to 20 m deep clay layers. The amount of required column stabilization is estimated to be about 10 million meters in total. The clay layer is a challenging task for deep mixing. The uppermost clay layer is sulphate clay where the pH value is even at level 4 at the oxidized layer. The water content of the clay layer is up to 160 %. The City of Helsinki has decided to discontinue the use of lime cement in column stabilisation due to its high carbon dioxide emissions. The city has decided to use low-carbon binders, only some of which the city has previous experience, in column stabilisation in the future. One aspect at the construction at Malminkenttä area is the creek Longinoja, which is located next to the construction area and is an important living area for threatened trout and thus any negative effect to water quality of the creek is not allowed. All this together means that laboratory testing, test stabilization and environmental monitoring are very appropriated.