Multi-cycle statistical analysis of laboratory salt weathering tests

Soluble salts are an important pollutant and the main decay agent of stone in the built environment. While their erosive effects are well established, the evolution along time has been much less studied. This temporal aspect is nonetheless frequently very important in an applied perspective when it is necessary to assess whether a given observed decay situation is at equilibrium or will evolve in the sense of further erosion (hence requiring interventions to avoid that kind of evolution). Laboratory tests for assessing the effect of salt weathering are generally based on the final mass variation after a certain number of cycles simulating salt effects (as is indicated in the European Standard EN12370).

While there have been proposals of parameters that consider the results of the cycles (average and extreme values), here it is aimed to present analyses based on the values in different cycles. This will allow to use statistical multivariate tools and since these cycles follow a sequence, it will be possible to evaluate the presence of trends.

These tools will be discussed in the concrete context of three limestone types and it will be shown that this analysis lends a further quantitative and reproducible support and corroboration to the petrological models that have been proposed to explain the answer of these rock types to salt pollution.