Effets de sollicitations hydriques cycliques sur le gonflement d’un sol argileux traité à la chaux

Abstract

Impact of cyclic wetting and drying on the swelling properties of a lime-treated expansive clay AbstractLime addition is a very wide spread technique to improve the engineering behaviour of soils and it is known to reduce the swelling potential of expansive soils. However, in the long term, the permanence of that lime effect is questionable. Some authors have shown that a lime-treated expansive soil can recover its initial swelling/shrinkage ability after some successive wetting/ drying cycles. This question is of interest since lime might be used to prevent swelling of expansive soils in earthworks. An experimental study was undertaken to assess the effects of successive wetting/drying cycles on the swelling behaviour of lime-treated expansive soils. This study was conducted both on three-years-old field-samples coming from an experimental backfill and samples reconstituted in the laboratory. Osmotic suction-controlled oedometers were used to determine their swelling/shrinkage behaviour when submitted to wetting/ drying cycles. The results obtained on the reconstituted samples showed that the lime treatment can reduce dramatically the swelling capacity of an expansive soil. However, the limetreated samples taken from the experimental backfill exhibited important swelling and shrinkage deformations when submitted to successive wetting and drying. The obtained results clearly indicated that the lime treatment efficiency decreased with time.

In Situ Alteration of the Hydro-Mechanical Behaviour of a Compacted Stabilised Expansive Soil

“…The in situ conditions experienced by soil-treated structures are a combination of natural hydric, thermal and/or chemical variations, depending on the type of structure and its location. Despite the need to assess the service life of treated earth structures, little is known about the in situ performance of such stabilised materials several years after construction, and very few studies are available, especially in the case of stabilised expansive soils [30,34,35]. Existing studies faced various issues due to the lack of knowledge about the initial conditions of the stabilised soil at the time of construction, making an analysis of the performance evolution over time difficult.…”

Impact quantitatif de sollicitations hydriques sur la microstructure d’un sol gonflant traité à la chaux

“…Certaines études in situ de sols stabilisés à la chaux ont montré qualitativement que l'exposition aux conditions climatiques peut avoir un impact négatif sur le comportement des sols stabilisés à long terme (Gutschick, 1978;Kelley, 1988). Cela a également été mis en évidence par des études en laboratoire qui ont montré que la succession d'humidification / séchage (Alavez-Ramirez et al, 2012;Chittoori et al, 2018;Consoli et al, 2017;Cuisinier et Deneele, 2010;Dempsey and Thompson, 1968;Guney et al, 2007;Khattab et al, 2007) ou des cycles répétés de gel/dégel (Bin-Shafique et al, 2010;Dempsey and Thompson, 1973) pouvaient entraîner une diminution significative des caractéristiques hydromécaniques du sol traité. D'autres processus comme le lessivage (Le Runigo et al, 2011;McCallister and Petry, 1991;Moghal et al, 2015), le contact permanent avec l'eau (Kenai et al, 2006;Mehenni et al, 2015) peuvent également potentiellement induire une évolution des performances dans le temps.…”