Proceedings of the Deep Mixing 2015 Conference, (DFI)
Influence of Curing Conditions on the Stiffness and Strength of Cement-Stabilized Soils
Alain Le Kouby, University Paris-Est, France; Antoine Guimond-Barrett, SNCF, France
Nowadays, improving the strength and deformation properties of very soft soils by deep soil mixing is a commonly used stabilization method. There is an increasing interest in the use of this technique not only for soil stabilization but also to construct foundation/structural (load bearing) elements and excavation retaining walls. The compressive strength and elastic modulus of the soil mix material are essential parameters in the design of these structures. However, there is very limited information available on the impact of exposure to air drying (in the case of retaining wall) on the strength and stiffness of cement stabilized soils. The aim of this study is to investigate the effects of different curing conditions (immersion in water, cycles of wetting and drying, continuous air drying) on the mechanical properties of soils treated with cement in the laboratory. Unconfined compression tests were performed on specimens of silt and sand treated with blastfurnace slag cement. Strength increases more rapidly than stiffness between 7 and 30 days. The strength of stabilized soils submitted to cyclic wetting and drying before the cement hydration process is complete continues to increase. As long as the periods of drying do not induce microcracks, the stiffness of the treated soil specimens also increases with time. However, the stiffness is lower than for the specimens cured in water indicating a disruptive effect of the imposed wetting-drying cycles on stiffness. Continuous exposure to air drying inhibits strength development due to insufficient water for hydration. Significant stiffness decreases were observed on specimens of stabilized silt and are attributed to microcracking.
|article #2088; publication #1013 (DM-2015)|