Sustainable Handling of Soft Soils During the Design of Major Infrastructure Projects

This paper investigates whether cement stabilization of weak soft soils is a sustainable foundation solution, compared to traditional Danish methods used when weak soft soils are deemed unfit. Traditionally, a mass exchange, piled foundation, or pre-consolidation of the soil would be used. The paper is focused on a fictitious highway construction near Aalborg in Denmark, with a 6-m soft soil deposit below it. The effects of cement stabilization are investigated by casting specimens consisting of in-situ soft soil mixed with different cement amounts. Specimens with Aalborg Portland’s Basis cement and CO2-reduced FutureCem cement were subjected to oedometer and triaxial tests to determine stiffness and strength. To determine the CO2 emission from each foundation solution, Life Cycle Assessments (LCAs) are performed. Based on the experiments performed, it is concluded that 37.5 kg/m3 FutureCem gained a sufficient stiffness increase, why this cement was used in the LCA. The LCAs showed that cement stabilization could lower the CO2 emission by 85% compared to a mass exchange, 77% for piled foundation, and 58% for pre-consolidation. Thus, cement stabilization can be a sustainable alternative to conventional soft soil remediations, and it is important to consider multiple solutions for a project to reduce CO2 emissions.