Toogle Left

BATir banner

 

logo LGM logo LGM LIME unsat-lime Multi-physical testing of the lime treatment of sand-bentonite mixture
Contact

Bertrand François

Thierry J. Massart

Jean-Claude Verbrugge

Amid Hashemi Afrapoli

Collaboration Prof F. Collin (ULg)

G. Herrier (Lhoist R&D)

R. De Bel (CRR)

S. Salager (Laboratoire 3S-R, Grenoble)

Description

This research focuses on the influence of the lime-treatment on sand-bentonite mixtures. In reality, the variety of natural soils and the disruptive elements do not allow comparing these soils to each other and giving any quantitative conclusions in terms of mechanical improvement. The goal of this study is to build a progressive comprehension of this phenomenon by avoiding any disruptive elements and controlling the most part of the parameters. Consequently, it is considered to study a synthetic soil by controlling its particle size and composition. As a first step, relatively conventional experimental tests in soil mechanics are performed: uniaxial compression tests and indirect traction tests. As shown in Figure 1, sand takes an important part into soil stabilization meaning that a soil containing a lot of clay does not necessary give the best mechanical characteristics.


amid 1

Figure 1 : Lime treatment of soil with higher clay quantity does not necessarily give the best mechanical results showing that sand surprisingly takes an important part in soil stabilization

 

In addition to those conventional mechanical tests, more specific experiments are carried out in order to characterized the physico-chemical reactions of the lime with soil at the particle scale: X-Ray Computed Tomography images (Figure 2), Leroux tests (to determine the amount of aluminate and sulfate created during the reaction), X-Ray diffraction, ...


amid 2

Figure 2 : X-Ray CT pictures of sand-bentonite mixtures show the mixture distribution with sand particles, clay aggregates, free water and air voids.


In parallel to this PhD thesis, a second thesis addresses the numerical modeling of those processes through a two-scale approach and a homogenization procedure. It allows us to better understand the effect of the lime reaction at the scale of the particles on the global improvement of the mechanical behaviour. As a final objective, this work aims at providing experimental evidence that can be integrated in a double scale mechanical model.
   


Support

  • This project has been funded by the "Fonds National de la Recherche Scientifique" through a FRFC grant (Projet 2.4.626.10.F Etude de comportements multi-physiques couplés dans les sols par une approche expérimentale et numérique multi-échelles).
   
Selected publications Hashemi M.A., Kadiri H., Massart Th., Verbrugge J.C., François B., Influence of the clay content of a lime-treated soil on its compression strength, ISSMGE, TC211 IS-GI, 2012.

Hashemi M.A., Massart Th., Verbrugge J.C., François B., Lime treatment of sand improved by bentonite addition, European Young Geotechnical Engineer's Conference (22th EYGEC), 2012.