Laboratory measurement of ultrasound velocity during accelerated aging tests: Implication for the determination of limestone durability

Abstract: The non-invasive ultrasound propagation technique was applied in laboratory tests with the purpose to evaluate the susceptibility to decay of stone materials. The ‘Scicli’ limestone was chosen as test material, since it is commonly employed as a building material of baroque churches and historical monuments in South Eastern Sicily. Eight samples were subjected to several hydric and accelerated aging tests (salt crystallization) and during these latter the longitudinal waves velocities were measured. The susceptibility of the rocks to decay was showed by the response to absorption/desorption and salt crystallization tests; in particular high values of mass loss were recorded (up to 41%) and the decay already started during the 4th cycle. During salt crystallization a general decrease of P-waves velocity was observed in response to the occurring of macro- and micro-fractures even if almost all the samples showed broadly irregular patterns. The data obtained by means of hydric and petro-physical tests were subsequently assembled and processed for multiple regression analysis. The goodness of the results and the statistical relevance of the chosen variables was testified by the R 2 values (0.99) and by the p <0.05 values respectively. Variables CA (capillary coefficient) and AB (absorption coefficient) resulted as the most important predictors of mass loss followed by variables linked to the ultrasound propagation indicating that this latter is a suitable non-invasive technique especially when is coupled to a preliminary petrographic and physical characterization of the rock. [Copyright &y& Elsevier]