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Thermohydromechanical behaviour of soils and soil structure interfaces 257

Figure 5.44 Clay concrete interface (medium roughness) response subjected to cyclic shearing at
20 C and 50 C under constant normal stiffness conditions. (A) volumetric behaviour and (B) failure

envelope. Redrawn after Di Donna, A., Ferrari, A., Laloui, L., 2015. Experimental investigations of the
soil concrete interface: physical mechanisms, cyclic mobilisation and behaviour at different tempera-
tures. Can. Geotech. J. 53 (4), 659 672.
the clay concrete interface. As for the monotonic clay concrete interface tests with
rough concrete, it appears that the higher the temperature, the lower the volume con-
traction during shearing cycles and thus the slower the cyclic degradation. Yet, the
interface angle of shear strength reduces slightly at higher temperature but the adhe-

sion between the two materials increases. The adhesion at 50 C (12 kPa) is three times

higher than the one at 20 C (4 kPa), even if in this case it is lower with respect to the
rough concrete case. This evidence confirms that it comes from the contact area
between the soil and the concrete asperities, which is lower in the case of smoother
surface.

5.9 Thermally induced effects on soil concrete interface properties

Based on current experimental evidence (Xiao et al., 2014; Di Donna et al., 2015;
Yavari et al., 2016; Yazdani et al., 2019), the behaviour of interfaces with coarse-
grained soils does not appear to be affected by temperature variations, while that of
interfaces with fine-grained soils shows a variation of strength with temperature. In
particular, an increase in the strength with temperature is observed for concrete inter-
faces with fine-grained soils initially under NC conditions, then heated and eventually
sheared (monotonically or cyclically). Based on the previous result, the direct effect of
temperature on the soil structure interface is absent in the case of concrete interfaces