## 3 Results
### Drying Paths of all the Tested Specimens  
In total, 10 of the 16 samples analysed in the present study were subjected to drying paths during which suction measurements were conducted (with either the filter paper technique or the ICL high-capacity tensiometers or both). All the data collected are reported in Figure 9 in terms of matrix suction, s, against degree of saturation, S\({}_{\rm r}\) (Figure 9a), void ratio, e (Figure 9b), and volumetric water content, \(\vartheta_{\rm w}\) (Figure 9c).  
The initial degrees of saturation are consistently close to or lower than 90% (Figure 9a), supporting the idea, previously introduced, that the \"first\" air-entry value of the tested fissured clay (i.e., the \"inter-element AEV\") is likely to correspond to very low suction values. This would imply that all the tested specimens probably had empty or almost empty fissures at the start of drying. The initial stages of the drying paths are characterised by S\({}_{\rm r}\) values that are scattered, but generally higher than 75-80%, until s = 1000-2000 kPa is approached. For most of the specimens, major S\({}_{\rm r}\) reductions are observed after this \"second\" air-entry value, which was previously identified as the stage at which air enters the intra-element pores (i.e., the \"intra-element AEV\").  
Figure 8: High-capacity tensiometer measurements conducted on Specim 3 at the end of the last drying stage (the dotted segment is an extrapolation of the last measurement).  
Figure 9: Water retention data of all the specimens (tested with both the filter paper technique, FP, and high-capacity tensiometers, T) reported in terms of matrix suction against: (**a**) degree of saturation; (**b**) void ratio; (**c**) volumetric water content.  
The data in Figure 9b show that the intra-element AEV (i.e., s =1000-2000 kPa) corresponds to a volumetric collapse for most of the specimens subjected to drying paths that reached high suction values. The data in Figure 9b also confirm that the volumetric collapse corresponds to a void ratio variation, \(\Delta\)e, close to or bigger than 0.1. It is interesting to notice that the smallest void ratios (e \(\approx\) 0.45) correspond to the values measured on Specim 2, i.e., the specimen that did not show a volumetric collapse in drying (Figure 6b). It is also worth highlighting that for s < 1000 kPa, the specimens show a stiffness that is broadly comparable with the stiffness observed for s > 2000 kPa, when the material moves toward its shrinkage limit.  
All the data collected on the specimens subjected to drying paths are reported in Figure 9c in terms of s-\(\vartheta_{\mathrm{w}}\). As previously observed with reference to the data reported in Figure 6c, the volumetric water content variations reflect the variations of the data shown in Figure 9a,b. The highest \(\vartheta_{\mathrm{w}}\) measured, not corresponding to fully saturated conditions, are close to 42.5%, while the lowest values are close 10%. The latter, achieved after prolonged drying stages, correspond to sutions close to or slightly bigger than 30 MPa, which can be considered as the upper limit for matrix suction measurements performed with the filter paper technique, according to [33; 34].