Specific surface area and salt weathering of limestones: a laboratory study

Specific surface area (SSA) results are used to discuss results of salt weathering tests on two grainstones and a travertine. SSA was found to be especially useful in the understanding of the travertine's heterogeneous behaviour (with higher SSA in the more clay-rich zones) and the conclusions can be considered transferable to travertines in general. The transferability of conclusions applies insofar as in these continental limestones the terrigenous clay-rich zones, whose composition was verified by their infrared spectra, would promote mesoporous portions that favour the migration of solutions and that are, hence, more susceptible to salt weathering. SSA did not distinguish the grainstone types (Semi-rijo and Moca Creme), which show different weight loss in the salt weathering tests (higher in Moca Creme), a result explained by the predominant macroporous (as defined by IUPAC) character of these rocks. These results suggest that petrographic studies can be employed in the definition of groups of rocks for which SSA could be used as estimator of mass loss under salt weathering conditions. Other aspects of the stone cycle are also considered for the travertine, related to the presence of a certain amount of pores of nanometre scale in this rock and the possible higher specific values of presumably more clay-rich residues from its cutting.