Toogle Left

BATir banner

 

logo LGM logo LGM LIME logo LGM  IMPR

Lime treatment of silty soils

Contact Bertrand François
Keywords Lime treatment, pozzolanic reaction, soil stabilization, temperature effect
Collaboration
Prof F. Collin (ULg)

Prof. J.M. Fleureau (Ecole Centrale, Paris)

Prof. A. Gomes Correia (University of Minho, Portugal)

Prof. P.H. Duvignaud (ULB)

G. Herrier (Lhoist R&D)

R. De Bel (CRR)

Description
Lime treatment of fine soils is a common practice in Europe, mainly for the (re-)use of improper, too wet or too soft soils as embankments, capping layers, etc... Usually, only a provisional improvement of soil properties is expected to facilitate the earthworks. Indeed, lime addition initiates different immediate reactions: drying up, cation exchange and flocculation of clay particles what leads to a substantial increase in bearing capacity. But slow and continuous reactions also occur between lime and the silicate and aluminate constituents of the clay: the pouzzolanic reactions. The latter are the most important and create long time effects, inducing cementation of soil particles, mineralogical and microstructural changes in the treated soil. Although these effects are now well agreed, their influence on the evolution of the geomechanical properties of the treated soil has, till now, received little attention, and is so, less or not taken into account in stability calculations of earthworks projects.

In this study, the long-term effect of a lime treatment on the geotechnical properties of soils has been investigated. Four different silty soils were considered and the effect of water content, temperature and lime content was also investigated. The main parameters governing the testing program are the curing time (up to 448 days), the curing temperature (20 to 50°C) and the lime content (1.5, 3, 4.5 %)

The obtained results show a significant increase of the uniaxial compression strength after about 100 days of curing time. This effect can be attributed to the pouzzoloanic reactions that provide a additional cohesion to the soil when the product of the pouzzolanic reactions reinforce the contacts between particles. This effect is enhanced and accelerated under elevated temperatures (Figure 1).

 

figure 4

Figure 1: Influence of curing time and temperature on the compression strength of a silty soil treated with 3% of quicklime.

Support
  • COGESTAC project supported by the European Social Fund (FSE) and the General Directorate for Technology, Research and Energy (DGTRE) of the Ministry of Walloon Region in Belgium FRFC project: "Analysis of coupled problems in soils by a combined experimental and computational multi-scale approach"
   
Selected publications DE BEL R., GOMES CORREIA A., VERBRUGGE J.C. (2009) - Contribution of loamy soil treatment to rise embankment performance, Geotechnical Special Publication n° 189, American Society of Civil Engineers (ASCE), pp 186-191

DE BEL R., BOLLENS Q., GOMES CORREIA A., DUVIGNAUD P.H., VERBRUGGE J.C (2007) - Time and temperature dependency of the geomechanical properties of silty soils treated with lime, Proceedings International Conference on Adavance Characterization of Pavment and Soil Materials, Athènes, Taylor & Francis / Balkema, Vol 1, pp 513-521.

DE BEL R., VERBRUGGE J.C., GOMES CORREIA A. (2010) - Comportamento geomecanico de solos estabilizados com cal. principais contribuições do projecto cogestac -geomechanical behaviour of stabilized soils with lime; the main contributions of cogestac, 12TH Congresso Nacional De Geotecnica, Guimaraes (Portugal).