replaces concrete piles
Ground stabilization is needed for foundations of buildings, and to prevent erosion leading to landslides, compromised flood protection or sinkholes. Concrete piles are usually driven into the soil for this purpose, but concrete is known for its hefty climate impact.
MeduSoil has an alternative solution for soil stabilization that reproduces and stimulates an organic mechanism which already occurs in nature. A liquid mix containing water, urea and lime is injected into the soil and the micro-organisms present there react by forming calcium carbonate; bio-cement.
From their pilot projects, MeduSoil knows how much water, urea and lime are equivalent to a volume of concrete that would stabilize the same amount of soil. To know if MeduSoil offers a climate-friendly alternative to concrete is to answer this question:
Is the climate impact of the MeduSoil mix and process, less than that of the equivalent amount of concrete?
Step 1 of the MeduSoil Cif is straightforward. The impact of MeduSoil scales with the amount of soil stabilized, so the functional unit of ‘one medium-sized construction project (of 2000m3)’ is well chosen. MeduSoil aims to deliver 12 of these projects annually.
The important differences of MeduSoil are in the extraction and of materials and the production. Extraction entails replacing concrete with the medusoil mix. In production (= stabilizing the soil) the difference in energy use for pumping versus pile driving is negligible, but there is a significant difference in the amount of transport.
In step 2 the concrete used today, and the ingredients of the MeduSoil mix, are selected from the database. Urea is a key ingredient and the database does not include it. There is data for Nitrogen fertilizer and would be a good equivalent, but there is an important difference between the use of urea as a fertilizer and the use of urea in the MeduSoil process.
The chemistry of fertilizer in the field contributes the majority of its climate impact, and MeduSoil needed the impact data for urea without its use as fertilizer. This data was found in a publication of fertilizers Europe which includes the table below. The impact of 0,91 kg CO2eq per kg of urea (at plant gate) was used in the MeduSoil Cif as custom data.
The quantities are added in step 3. This step is not illustrated here but the quantities can be found in the result.
The result: MeduSoil has significant positive climate impact
“The CIF tool and its rich database enabled us to provide a clear picture of our climate impact in a quantified and robust manner”
– Dimitrios Terzis, PhD, Research Scientist at the Laboratory for Soil Mechanics and co-founder of MeduSoil