Low-carbon Deep Mixing and Compaction

The continuous growth of Finnish cities presses municipalities to reconsider city plans and use for construction areas covered by soft soils. Before construction in areas dominated by clays, mud and peats, the ground must be improved. DeMiCo project proposes two new innovative low-carbon footprint solutions for ground improvement, developing soil mixing and dynamic replacement ground improvement methods for Finnish soils.

Dry deep mixing (DDM), in which the soft soil is stabilized by mixing it with a binder typically lime-cement, is one of the most frequent ground improvement techniques in Finland. The production of lime and cement creates substantial amounts of C02 emissions. The DeMiCo project aims to drastically reduce those emissions by developing low-carbon or even carbon-neutral DDM. The project will demonstrate the effect of binder type and binder content on C02 sequestration capacities in small and large-scale experiments. The large-scale field tests pilot is done together with stakeholders and companies. Later, we will investigate the actual net carbon emissions from DDM with alternative binders in field measurements and testing.

Dynamic replacement improves ground by repeated drops of a heavy rammer from a height while filling the crater with other granular material, creating columns of stronger material. This potentially carbon-neutral method creates a lot of noise and vibration, problematic in an urban environment. Hence the project will investigate noise and vibration protection and the potential use of recycled materials for column creation by piloting the method together with companies.

The three year research involves Aalto University and VTT, as well as potential early adopters of research: municipalities of Helsinki, Espoo, and Vantaa, construction companies, binder producers and consultancy companies. The project consists of three work packages, one for deep mixing, one for dynamic replacement and one for dissemination.