This work analyses the characterization of the hygric behaviour of a stone heritage material by solving the inverse problem using experimental data obtained from a water absorption by capillarity test (EN 15801). This common test is undemanding and requires relatively simple equipment as compared to other hygric characterization tests. For the solution of the direct problem of transient flow in partially saturated porous media, a computational module was developed in COMSOL Multiphysics that includes the conceptual model from the standard EN 15026. The selected material was the heritage stone of the Cuenca Cathedral, differentiating between two characteristic lithotypes: one with greater porosity and another that is more resistant, with more reduced porosity.Based on the experimental results, the intrinsic permeability and the parameters of the moisture storage function are estimated for the two lithotypes. Similarly, contrast tests were conducted to quantify the estimation error. A stochastic analysis was performed to assess if the estimated hygric parameters satisfactorily characterize the behaviour of the studied stone.
Electroosmotic permeability is a soil parameter that is fundamental for designing and implementing environmental remediation, dewatering, or soil stabilization processes. It presents a narrow range of variation compared to hydraulic permeability, so that on many occasions no experimental tests are carried out to determine it. Traditionally, the Helmholtz-Smoluchowski equation has been used to estimate electroosmotic permeability, despite having several drawbacks that make it difficult to apply, as it was deduced for large capillaries (unusual in clays) and its dependence on the potential zeta of the soil, difficult to measure and dependent on a variety of factors that are difficult to control. The present work describes a semi-empirical formulation that allows the estimation of the electroosmotic permeability as a function of the specific surface area and the total void ratio and is based on the Donnan equilibrium and the ion hydration models. The parameters for modelling are calibrated and validated with experimental data, obtaining better results than those given by the Helmholtz-Smoluchowski model. In addition, the expected trends in the behavior of clays that can be found in the literature are obtained in a quantitative and consistent manner for different types of clays with variable water content and pore water salinity.
KEYWORDSÁnge 3 / 36 Ji m in 10 -5 (mol s -1 m -2 ) ue,i m in 10 -10 (m 2 V -1 s -1 ) ci m in 10 -5 (mol kgw -1 ) Ji m in 10 -9 (mol s -1 m -2 ) Exper * . Model K-C Exper Model K-C
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