Salt weathering of sandstone during drying : effect of primary and secondary crystallisation

ACTInternational audienc

Multiphase model for hygrothermal analysis of porous media with salt crystallization and hydration

A new fully coupled multiphase model for hygrothermal analysis and prediction of salt diffusion and crystallization in porous building materials is presented. The relative humidity, the temperature, the concentration of the dissolved salt and the concentration of precipitated salts are assumed as independent variables. A suitable modelling of the crystallization/dissolution and hydration/dehydration processes allows considering salts with hydrous and anhydrous crystals. Some numerical applications on fired-clay bricks show the effectiveness of the proposed approach

ASSESSMENT OF SALT CRYSTALLIZATION THROUGH NUMERICAL MODELLING

Salt crystallization is one of the major factors of degradation of porous materials such as masonry. This paper presents a coupled multiphase model for hygrothermal analysis of masonry structures and the effective prediction of stress induced by salt crystallization. The independent variables chosen to describe all the process are: the pore humidity, the concentration of dissolved salt and the temperature. The governing equations of the model are: the moisture balance equation, expressed in function of the humidity, the conservation equation for the total stored energy, the balance equation for the dissolved salt and a kinetic expression for the salt crystallization law. The model is used to simulate the results of an extensive experimental campaign carried out on a masonry wall exposed to weather conditions for four months

Drying of salt contaminated building sandstones: from experiments to numerical modelling

COMInternational audienceEnvironmental conditions are one of the most important factors that lead to the deterioration of salt contaminated stones or masonry materials. In particular, when environmental conditions such as humidity, exposure to rain or rising damp vary, salts in contact with water (liquid or vapour) can dissolve and cause damage to the material by crystallization upon drying. In this paper this challenging coupled problem is modelled improving the multiphase model developed in [1, 2]. The model - fully coupled, highly non-linear and time dependent - is referred to a Representative Elementary Volume, and takes as primary variables the relative humidity, the temperature, the mass fraction of the dissolved salt and the concentration of precipitated salt. This tool is used to simulate experiments [3] in which sodium chloride contaminated sandstones, put in contact with liquid water and water vapour until complete saturation, are dried at different humidities. The good agreement with experimental evidences proves the effectiveness of the proposed model

Salt contaminated sandstone under environmental loading : recrystallization process and its consequences

ACTInternational audienc

Salt crystallization dynamics in sandstone quantified by 4D laboratory X-ray micro-CT

COMInternational audienc

Drying of salt contaminated building sandstones: from experiments to numerical modelling

COMInternational audienceEnvironmental conditions are one of the most important factors that lead to the deterioration of salt contaminated stones or masonry materials. In particular, when environmental conditions such as humidity, exposure to rain or rising damp vary, salts in contact with water (liquid or vapour) can dissolve and cause damage to the material by crystallization upon drying. In this paper this challenging coupled problem is modelled improving the multiphase model developed in [1, 2]. The model - fully coupled, highly non-linear and time dependent - is referred to a Representative Elementary Volume, and takes as primary variables the relative humidity, the temperature, the mass fraction of the dissolved salt and the concentration of precipitated salt. This tool is used to simulate experiments [3] in which sodium chloride contaminated sandstones, put in contact with liquid water and water vapour until complete saturation, are dried at different humidities. The good agreement with experimental evidences proves the effectiveness of the proposed model

Drying of salt contaminated building sandstones: from experiments to numerical modelling

COMInternational audienceEnvironmental conditions are one of the most important factors that lead to the deterioration of salt contaminated stones or masonry materials. In particular, when environmental conditions such as humidity, exposure to rain or rising damp vary, salts in contact with water (liquid or vapour) can dissolve and cause damage to the material by crystallization upon drying. In this paper this challenging coupled problem is modelled improving the multiphase model developed in [1, 2]. The model - fully coupled, highly non-linear and time dependent - is referred to a Representative Elementary Volume, and takes as primary variables the relative humidity, the temperature, the mass fraction of the dissolved salt and the concentration of precipitated salt. This tool is used to simulate experiments [3] in which sodium chloride contaminated sandstones, put in contact with liquid water and water vapour until complete saturation, are dried at different humidities. The good agreement with experimental evidences proves the effectiveness of the proposed model