Porous construction materials such as masonry constituents are notoriously affected by weathering, pollutants attack and damp transport with manifest consequences on the masonry visible appearance and its mechanical reliability. Water transport mechanisms inside such materials as well as the chemical reactions and phase changes occurring in salt at varying combinations of temperature and humidity content have been previously studied. Nevertheless the investigation of damp and salts degradation processes since their appearance in real structural elements and the monitoring over time of their evolution is a problem never completely investigated. Nor it is clear so far which techniques would be available and appropriate for the investigation of whole masonry structural elements providing insight into the damp distribution and dissolved salt content across the wall height and thickness. As the conditions for water transport and salt crystallization in porous materials vary with meteoric and seasonal dependency, necessary inspection techniques should be at hand for continuous monitoring or at least for recurrent testing of the region of interest. In this contribution, experimental evidence is provided on the efficacy of monitoring and testing for the above-mentioned purposes by means of: - a wireless potential difference measurement node in combination with electrodes based on silver/silver-chloride for the selective detection of dissolved chloride salts, - a GPR radar system equipped with high-frequency antenna (2 GHz) for survey of moisture profiles and areas with salt content. The object of study was a full-scale 2-head brick masonry wall placed outdoors in natural weather conditions during a number of summer seasons. In addition, the specimen (1.3×0.25×1.3 m3) underwent capillary suction from its base with diluted NaCl solution. The focus of the paper lies in presenting vertical profiles of moisture and salt at increasing depths across the wall section, obtained by the two techniques, and by relating the outcome to the past weather conditions.
Investigation of damp and salt distribution in outdoors full-scale masonry wall via wireless monitoring and radar testing / Gabrielli, Elena; Colla, Camilla. - STAMPA. - 624:(2015), pp. IDN 141.155-IDN 141.162. (Intervento presentato al convegno 4th International Conference on Mechanics of Masonry Structures Strengthened with Composite Materials, MuRiCO 2014 tenutosi a Ravenna, Italy nel 9 - 11 September 2014) [10.4028/www.scientific.net/KEM.624.155].
Investigation of damp and salt distribution in outdoors full-scale masonry wall via wireless monitoring and radar testing
GABRIELLI, ELENA;COLLA, CAMILLA
2015
Abstract
Porous construction materials such as masonry constituents are notoriously affected by weathering, pollutants attack and damp transport with manifest consequences on the masonry visible appearance and its mechanical reliability. Water transport mechanisms inside such materials as well as the chemical reactions and phase changes occurring in salt at varying combinations of temperature and humidity content have been previously studied. Nevertheless the investigation of damp and salts degradation processes since their appearance in real structural elements and the monitoring over time of their evolution is a problem never completely investigated. Nor it is clear so far which techniques would be available and appropriate for the investigation of whole masonry structural elements providing insight into the damp distribution and dissolved salt content across the wall height and thickness. As the conditions for water transport and salt crystallization in porous materials vary with meteoric and seasonal dependency, necessary inspection techniques should be at hand for continuous monitoring or at least for recurrent testing of the region of interest. In this contribution, experimental evidence is provided on the efficacy of monitoring and testing for the above-mentioned purposes by means of: - a wireless potential difference measurement node in combination with electrodes based on silver/silver-chloride for the selective detection of dissolved chloride salts, - a GPR radar system equipped with high-frequency antenna (2 GHz) for survey of moisture profiles and areas with salt content. The object of study was a full-scale 2-head brick masonry wall placed outdoors in natural weather conditions during a number of summer seasons. In addition, the specimen (1.3×0.25×1.3 m3) underwent capillary suction from its base with diluted NaCl solution. The focus of the paper lies in presenting vertical profiles of moisture and salt at increasing depths across the wall section, obtained by the two techniques, and by relating the outcome to the past weather conditions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
