@article{smyl_rashetnia_seppanen_pour-ghaz_2017, title={Can Electrical Resistance Tomography be used for imaging unsaturated moisture flow in cement-based materials with discrete cracks?}, volume={91}, ISSN={["1873-3948"]}, DOI={10.1016/j.cemconres.2016.10.009}, abstractNote={Previously, it has been shown that Electrical Resistance Tomography (ERT) can be used for monitoring moisture flow in undamaged cement-based materials. In this work, we investigate whether ERT could be used for imaging three-dimensional (3D) unsaturated moisture flow in cement-based materials that contain discrete cracks. Novel computational methods based on the so-called absolute imaging framework are developed and used in ERT image reconstructions, aiming at a better tolerance of the reconstructed images with respect to the complexity of the conductivity distribution in cracked material. ERT is first tested using specimens with physically simulated cracks of known geometries, and corroborated with numerical simulations of unsaturated moisture flow. Next, specimens with loading-induced cracks are imaged; here, ERT reconstructions are evaluated qualitatively based on visual observations and known properties of unsaturated moisture flow. Results indicate that ERT is a viable method of visualizing 3D unsaturated moisture flow in cement-based materials with discrete cracks.}, journal={CEMENT AND CONCRETE RESEARCH}, author={Smyl, Danny and Rashetnia, Reza and Seppanen, Aku and Pour-Ghaz, Mohammad}, year={2017}, month={Jan}, pages={61–72} }
 @article{smyl_ghasemzadeh_pour-ghaz_2017, title={Can the dual-permeability model be used to simulate unsaturated moisture flow in damaged mortar and concrete?}, volume={9}, ISSN={0975-0770 0975-5616}, url={http://dx.doi.org/10.1007/s12572-017-0180-y}, DOI={10.1007/s12572-017-0180-y}, number={2}, journal={International Journal of Advances in Engineering Sciences and Applied Mathematics}, publisher={Springer Science and Business Media LLC}, author={Smyl, Danny and Ghasemzadeh, Farnam and Pour-Ghaz, Mohammad}, year={2017}, month={Mar}, pages={54–66} }
 @article{rashetnia_hallaji_smyl_seppanen_pour-ghaz_2017, title={Detection and localization of changes in two-dimensional temperature distributions by electrical resistance tomography}, volume={26}, ISSN={["1361-665X"]}, DOI={10.1088/1361-665x/aa8f75}, abstractNote={This paper studies the feasibility of applying electrical resistance tomography (ERT) to detect changes in two-dimensional (2D) temperature distributions with potential applications in sensor development. The proposed sensor consists of a thin layer of porous metal film manufactured by spraying colloidal copper paint to a solid surface. A change of the temperature distribution on the surface changes the 2D distributed electrical conductivity of the metal film. The change of the electrical conductivity is localized and quantified with ERT, and further, to convert the estimated conductivity change of the sensor to temperature change, an experimentally developed model is used. The proposed temperature sensor is evaluated experimentally by applying it to a polymeric substrate, and exposing it to known temperature changes using heat sources of different shapes. The results demonstrate that the proposed sensor is capable of detecting and localizing temperature changes, and provides at least qualitative information on the magnitude of the temperature change.}, number={11}, journal={SMART MATERIALS AND STRUCTURES}, author={Rashetnia, Reza and Hallaji, Milad and Smyl, Danny and Seppanen, Aku and Pour-Ghaz, Mohammad}, year={2017}, month={Nov} }
 @article{ghasemzadeh_rashetnia_smyl_pour-ghaz_2016, title={A comparison of methods to evaluate mass transport in damaged mortar}, volume={70}, ISSN={["1873-393X"]}, DOI={10.1016/j.cemconcomp.2016.03.007}, abstractNote={The service life of reinforced concrete (RC) structures is directly influenced by the transport properties of concrete. These transport properties are adversely affected by the presence of cracks. Therefore, for accurate service life estimation of RC structures the effect of cracks on mass transport needs to be understood and quantified. To quantify the effect of cracks, different measurement methods have been developed. In this paper, we compare different mass transport measurement methods for quantifying the effect of damage, and investigate which method is more sensitive and provides the most information on the effect of damage. In this work, damage was induced by freeze-thaw in mortar specimens. Mass transport properties were measured using electrical resistivity, rapid chloride permeability, sorptivity, drying, air permeability, water permeability, and desorption isotherm. The results indicate that the measured effect of damage depends on the mechanisms of transport used in the measurement technique, and therefore, different measurement techniques do not necessarily provide the same measure of the effect of damage. The water and air permeability are comparatively more sensitive to the presence of damage.}, journal={CEMENT & CONCRETE COMPOSITES}, author={Ghasemzadeh, Farnam and Rashetnia, Reza and Smyl, Danny and Pour-Ghaz, Mohammad}, year={2016}, month={Jul}, pages={119–129} }
 @article{smyl_ghasemzadeh_pour-ghaz_2016, title={Modeling water absorption in concrete and mortar with distributed damage}, volume={125}, DOI={10.1016/j.conbuildmat.2016.08.044}, abstractNote={The deterioration rate of concrete structures is directly influenced by the rate of moisture ingress. Modeling moisture ingress in concrete is therefore essential for quantitative estimation of the service life of concrete structures. While models for saturated moisture transport are commonly used, concrete, during its service life, is rarely saturated and some degree of damage is often present. In this work, we investigate whether classical isothermal unsaturated moisture transport can be used to simulate moisture ingress in damaged mortar and concrete and we compare the results of numerical simulations with experimental measurements of water sorption. The effect of hysteresis of moisture retention is also considered in the numerical simulations. The results indicate that the unsaturated moisture transport models well simulate early stages of moisture ingress at all damage levels, where capillary suction is the prominent mechanism. At later stages of moisture transport, where air diffusion and dissolution have a more significant contribution, simulations that consider moisture hysteresis compare most favorably with experimental results.}, journal={Construction & Building Materials}, author={Smyl, D. and Ghasemzadeh, F. and Pour-Ghaz, M.}, year={2016}, pages={438–449} }
 @article{smyl_hallaji_seppanen_pour-ghaz_2016, title={Quantitative electrical imaging of three-dimensional moisture flow in cement-based materials}, volume={103}, ISSN={["1879-2189"]}, DOI={10.1016/j.ijheatmasstransfer.2016.08.039}, abstractNote={The presence of moisture significantly affects the mechanical, hydraulic, chemical, electrical, and thermal properties of cement-based and other porous materials, and therefore, methods for detecting and quantifying the moisture ingress in these materials are needed. Recent research studies have shown that the ingress of moisture in porous materials can be qualitatively imaged with Electrical Impedance Tomography (EIT) – an imaging modality which uses electrical measurements from object’s surface to reconstruct the electrical conductivity distribution inside the object. The aim of this study is to investigate whether EIT could image the three-dimensional volumetric moisture content within cement-based materials quantitatively. For this aim, we apply the so-called absolute imaging scheme to the EIT image reconstruction, and use an experimentally developed model for converting the electrical conductivity distribution to volumetric moisture content. The results of the experimental studies support the feasibility of EIT for quantitative imaging of three-dimensional moisture flows in cement-based materials.}, journal={INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER}, author={Smyl, Danny and Hallaji, Milad and Seppanen, Aku and Pour-Ghaz, Mohammad}, year={2016}, month={Dec}, pages={1348–1358} }
 @article{smyl_hallaji_seppanen_pour-ghaz_2016, title={Three-Dimensional Electrical Impedance Tomography to Monitor Unsaturated Moisture Ingress in Cement-Based Materials}, volume={115}, ISSN={["1573-1634"]}, DOI={10.1007/s11242-016-0756-1}, abstractNote={The development of tools to monitor unsaturated moisture flow in cement-based material is of great importance, as most degradation processes in cement-based materials take place in the presence of moisture. In this paper, the feasibility of electrical impedance tomography (EIT) to monitor three-dimensional (3D) moisture flow in mortar containing fine aggregates is investigated. In the experiments, EIT measurements are taken during moisture ingress in mortar, using electrodes attached on the outer surface of specimens. For EIT, the so-called difference imaging scheme is adopted to reconstruct the change of the 3D electrical conductivity distribution within a specimen caused by the ingress of water into mortar. To study the ability of EIT to detect differences in the rate of ingress, the experiment is performed using plain water and with water containing a viscosity-modifying agent yielding a slower flow rate. To corroborate EIT, X-ray computed tomography (CT) and simulations of unsaturated moisture flow are carried out. While X-ray CT shows contrast with respect to background only in highly saturated regions, EIT shows the conductivity change also in the regions of low degree of saturation. The results of EIT compare well with simulations of unsaturated moisture flow. Moreover, the EIT reconstructions show a clear difference between the cases of water without and with the viscosity-modifying agent and demonstrate the ability of EIT to distinguish between different flow rates.}, number={1}, journal={TRANSPORT IN POROUS MEDIA}, author={Smyl, Danny and Hallaji, Milad and Seppanen, Aku and Pour-Ghaz, Mohammad}, year={2016}, month={Oct}, pages={101–124} }