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The values of hydric dilatation are lower than 0.09 mm/m, with excepetion of the Valverde (VAV) samples which reach 0.22–0.26 mm/m.

Usually limestones show low hydric dilatation values, because these rocks have low clay content (Siegesmund and Dürrast, 2014). The dilatation of the VAV sample could be explained by some possible clay content within the dark material observed in microstylolites. Further investigations must be performed to clarify this hypothesis.

The bowing tests show the absence of permanent changes in almost all of the selected limestone. In fact, only the Valverde (VAV) sample is affected by this experiment. In the first 24 wet cycles the bending increases continuosly and reaches the value of 7 mm/m. Followed by dry conditions, the sample shows some recovery down to 6 mm/m within the first cycles. This value remains stable during the next 41 dry cycles. When the wet cycles start again a new increase of the bowing is evident with a maximum expansion around 9 mm/m.

149High values of bowing are frequently observed in marbles (e. g. Siegesmund et al. 2008) but unknown in limestones. Furthermore, as the mineralogy of all selected limestones is similar the bowing of the VAV sample turns strange. The only different factor are the microstylolites, which therefore seem to be the reason for the bowing potential. Since no bending occurs when dry cycles are performed, the water is an important factor. The interaction of heat and water seems to open and offset the microstylitic cracks, avoiding the recontraction and resulting in an irreversible deformation.

The thermal expansion measurements for the VAV sample show some residual strain about 0.25 mm/m after 4 wet cycles, while the performed dry cycles do not exhibit permanent deformation. Additionally, the sample has been measured in two directions, Z and XY, perpendicular and parallel to the microstylolites considering any effect caused by directional dependence. As depicted in Fig. 4, the expansion of both directions is comparable. Consequently no directional dependence of the expansion can be observed.

Residual strain is only observed under wet conditions as well as the bowing behavior is only evident under wet conditions. Despite the values of residual strain are lower than the range of values found in marbles exhibiting bowing (Mennigen et al. 2018), they confirm the bowing behavior of this sample. The areas with parallel microstylolites affecting the groundmass are aleatory distributed in the limestone and each one possibly contributes the total bending of the sample.

These preliminary results show the influence of the water in the bowing behavior under thermal cycles. However the nature of the microstylolites needs to be completely analysed, especially if clays are present. Therefore, more studies are necessary to understand completely the anomalous bowing behavior of the Valverde limestone.