Impact of monotonic and cyclic suction variations on the thermal properties of a stabilized compacted silty soil

Abstract The soil stabilisation is employed to construct geostructures as embankments, river levees, road subbases or to backfill excavations, improving the mechanical behaviour and reducing the consumption of extracted primary aggregates. This study is focused on the use of lime/cement treated soils to backfill trenches where high power line cables are buried. Indeed, under these circumstances not only the mechanical properties but also the thermal characteristics of the treated soil are of primary importance. The effect of changes in suction (soil water content) on the thermo-mechanical properties was investigated on lime-treated and lime-hydraulic binder treated silty soils in the laboratory. The relationship between the Soil Water Retention Curve (SWRC) determined by suction control and measurement techniques, and the thermal properties along the drying path from the Optimum Proctor point (initial state) was analysed. Moreover, to investigate the successive heating/cooling periods induced by the cable, several drying/wetting cycles were applied to analyse their effect on the thermal properties and mechanical behaviour of compacted treated soils. The obtained data showed that increasing the suction from initial state to 3.5 MPa induces a decrease in the thermal conductivity (λ), this diminution becomes more important below 3.5 MPa of suction. An inverse trend was however observed in the change of the thermal capacity (C) with increasing section. The drying/wetting cycles appeared to have a significant impact on the mechanical performances and smaller effect on the thermal properties of the studied compacted treated silty soil.