@article{narode_hao_pourghaz_ducoste_barlaz_2024, title={Measurement and Temperature Prediction from Ash Disposed in Landfills Using a Quasi-Adiabatic Flow Reactor}, volume={5}, ISSN={["2690-0645"]}, url={https://doi.org/10.1021/acsestengg.4c00023}, DOI={10.1021/acsestengg.4c00023}, journal={ACS ES&T ENGINEERING}, author={Narode, Asmita and Hao, Zisu and Pourghaz, Moe and Ducoste, Joel J. and Barlaz, Morton A.}, year={2024}, month={May} }
 @article{choi_dalton_peszlen_pourghaz_2024, title={The impacts of CaCO3 deposition in natural wood on its viscoelastic properties}, volume={275}, ISSN={["1879-1069"]}, url={https://doi.org/10.1016/j.compositesb.2024.111324}, DOI={10.1016/j.compositesb.2024.111324}, abstractNote={In this study, we discuss the methods used for depositing calcium carbonate (CaCO3) and the resulting 2D and 3D particle distributions of CaCO3 in two types of wood, which were quantified using scanning electron microscopy (SEM) and X-ray computed tomography (CT). We also present the results of dynamic mechanical analysis (DMA), which was used to measure the impact of CaCO3 deposition on the viscoelastic properties of the wood. X-ray CT scanning showed that CaCO3 deposits inside the wood scaffold with increased amounts as the deposition cycles were iterated. However, DMA results did not indicate significant improvement in storage moduli (E′) of CaCO3 deposited wood. SEM images revealed that the particles did not fill all the voids to provide stress transfer between the wood scaffold and the particles, indicating a lack of composite action between the wood and CaCO3 components. To address this issue, we hypothesized that heat-pressing would lead to a mechanical bond between the particles and the matrix. After heat-pressing, DMA results showed a dramatic increase in E′ not only in CaCO3 deposited wood samples but also in control wood samples. In other words, the densification of the structure led to significant increases in E′, primarily due to densification, while the impact of the presence of CaCO3 particles was minimal. This is mainly because the volume fraction of the deposited CaCO3 particles is small as compared to the total volume of the composite.}, journal={COMPOSITES PART B-ENGINEERING}, author={Choi, Hyunjun and Dalton, Laura E. and Peszlen, Ilona and Pourghaz, Moe}, year={2024}, month={Apr} }
 @article{calderon_pourghaz_kowalsky_2023, title={Critical Bending Strain and Mechanical Properties of Corroded Reinforcing Bars}, volume={120}, ISSN={["1944-737X"]}, DOI={10.14359/51738461}, abstractNote={First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address}, number={2}, journal={ACI MATERIALS JOURNAL}, author={Calderon, Victor and Pourghaz, Moe and Kowalsky, Mervyn}, year={2023}, month={Mar}, pages={77–86} }
 @article{dalton_rasanen_voss_seppanen_pourghaz_2023, title={Investigating the use of electrical capacitance tomography to image rapid transient moisture flow through cracks in concrete}, volume={140}, ISSN={["1873-393X"]}, DOI={10.1016/j.cemconcomp.2023.105070}, abstractNote={In this paper, we investigate the feasibility of electrical capacitance tomography (ECT) to image rapid three-dimensional (3D) moisture transport in damaged portland cement mortar and concrete. ECT is a tomography method that uses inter-electrode capacitance measurements to reconstruct the internal 3D distribution of the electrical permittivity which carries contrast with respect to moisture content. In the experimental study, ECT measurements were performed with a reservoir placed directly on the crack in each specimen to promote rapid moisture transport to test the high temporal resolution capabilities. An electrode array connected to an electrical tomography device was used to conduct moisture transport measurements in cracked specimens at a temporal resolution as high as 0.7 s. The results of this study illustrate that ECT can be used to detect rapid moisture transport through various crack patterns and capture the flow path of water around coarse aggregates with potential use for field monitoring.}, journal={CEMENT & CONCRETE COMPOSITES}, author={Dalton, Laura E. and Rasanen, Mikko and Voss, Antti and Seppanen, Aku and Pourghaz, Moe}, year={2023}, month={Jul} }
 @article{faeli_hosseini_gabr_pour-ghaz_2022, title={A new monitoring approach for sustainability assessment of subsurface utilities gasket materials against gasoline and chlorinated solvents: Field evaluation and model development}, volume={323}, ISSN={0301-4797}, url={http://dx.doi.org/10.1016/j.jenvman.2022.116217}, DOI={10.1016/j.jenvman.2022.116217}, abstractNote={Once installed, underground concrete pipes with rubber gaskets might be exposed to contaminated soil and groundwater. A pipe material monitoring capsule (PMMC) has been developed to evaluate volatile organic compounds (VOCs) breaking through three types of pipe gaskets; Neoprene, Buna-N, and Viton. The PMMCs were deployed in three contaminated sites: two with gasoline and one with chlorinated solvent (CS). A 3-D field-domain numerical model has been developed for each site to calibrate equivalent hydraulic parameters of each gasket material (ke, D) against benzene and PCE diffusion. The calibrated parameters were then used to compute the concentrations as well as rate of breakthrough of the two study contaminants. A protocol was developed for installing/retrieval of PMMCs to monitor PCE and benzene mass breaking through the gasket material with time. Employing PMMC, benzene concentrations breaking through the Neoprene and Buna-N after 4 months were approximately 70% and 60% respectively of the monitoring wells concentration. The corresponding value for PCE breakthrough after 4 months was 60% for both the Neoprene and Buna-N. Both gasket materials of Neoprene and Buna-N yielded similar performances, including higher rate of contaminant breakthrough compared to Viton. A nonlinear relationship of mass breaking through the gaskets of benzene and PCE with time was discerned from the modeling and field data.}, journal={Journal of Environmental Management}, publisher={Elsevier BV}, author={Faeli, Zahra and Hosseini, Payam and Gabr, Mohammed A. and Pour-Ghaz, Mohammad}, year={2022}, month={Dec}, pages={116217} }
 @article{hosseini_mcelroy_knappe_gabr_pour-ghaz_2022, title={Diffusion of benzene and tetrachloroethylene through saturated cement paste}, volume={329}, ISSN={0950-0618}, url={http://dx.doi.org/10.1016/j.conbuildmat.2022.127196}, DOI={10.1016/j.conbuildmat.2022.127196}, abstractNote={Diffusion of highly volatile organic compounds (VOCs) through buried concrete infrastructure components, such as pipes and culverts, can occur if these components come in contact with contaminated groundwater or soil. Among various VOCs, benzene and tetrachloroethylene (PCE), are the most common contaminants. This paper aims at measuring the effective diffusion coefficients of benzene and PCE in cement paste. The free diffusion coefficients of VOCs in simulated pore solution were also measured and used in empirical models. Results show that VOCs diffusion coefficients decreased with decreasing w/c because of reduced porosity and increased tortuosity of the pore network as well as increased ionic strength of the pore solution. The increased ionic strength of the pore solution reduced the solubility limit of VOCs in the pore solution and decreased the free diffusion coefficient of VOCs in the pore solution. Also, among all models, phenomenological model provided the most accurate estimates.}, journal={Construction and Building Materials}, publisher={Elsevier BV}, author={Hosseini, Payam and McElroy, Amie and Knappe, Detlef R.U. and Gabr, Mohammed and Pour-Ghaz, Mohammad}, year={2022}, month={Apr}, pages={127196} }
 @article{dalton_lamanna_jones_pour-ghaz_2022, title={Does ITZ Influence Moisture Transport in Concrete?}, ISSN={["1573-1634"]}, DOI={10.1007/s11242-022-01826-z}, journal={TRANSPORT IN POROUS MEDIA}, author={Dalton, Laura E. and LaManna, Jacob M. and Jones, Scott and Pour-Ghaz, Mohammad}, year={2022}, month={Jul} }
 @article{rashetnia_kusam_yadav_pour-ghaz_tayebali_2022, title={Quantifying moisture damage in asphalt concrete using axisymmetric flexural vibration technique}, volume={23}, ISSN={["1477-268X"]}, DOI={10.1080/10298436.2020.1757671}, abstractNote={ABSTRACT The Tensile Strength Ratio (TSR) test is commonly used to quantify the moisture susceptibility of asphalt mixtures. This test method is based on the indirect tensile strength, which is not a fundamental property and hence cannot be used in the asphalt mixture design process. Therefore, alternative test methods that use a fundamental property to quantify moisture sensitivity of asphalt mixtures are needed. This study investigates if the linear impact resonance shift and frequency spectrum bandwidth changes measured using Axisymmetric Flexural Vibration (AFV) technique can be used to quantify moisture damage. This test enables calculation of the dynamic elastic modulus of the disk, based on measured resonance frequency as well as quantification of vibration energy dissipation in the specimens based on the change in bandwidth of frequency spectrum. AFV test is used to quantify moisture damage susceptibility of asphalt mixture specimens with different moisture conditioning levels and different mixture designs. The results of the AFV test are compared with the TSR test. Also, the sensitivity of the AFV test to quantify the effect of thixotropic aging due to storage and temperature are discussed. The results show that the AFV technique can successfully quantify moisture damage and the effect of aging and temperature change.}, number={3}, journal={INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING}, author={Rashetnia, Reza and Kusam, Abhilash and Yadav, Shivpal and Pour-Ghaz, Mohammad and Tayebali, Akhtarhusein}, year={2022}, month={Feb}, pages={523–535} }
 @article{dalton_crandall_pour-ghaz_2022, title={Supercritical, liquid, and gas CO2 reactive transport and carbonate formation in portland cement mortar}, volume={116}, ISSN={["1878-0148"]}, DOI={10.1016/j.ijggc.2022.103632}, abstractNote={In this study, we investigate carbonate formation and reactive transport rate in variably saturated portland cement mortars when high concentrations of gas, liquid, or supercritical CO2 flow through their pore network. X-ray computed tomography completed during CO2 flow is used to quantify the microstructural evolution as the mortar carbonates. After in situ tests, higher resolution scans, thermogravimetric analysis, and desorption isotherm analysis are performed to further quantify microstructural changes. We found that at dry conditions supercritical CO2 moves more rapidly through the pore space and precipitates more carbonates than liquid or gas CO2. However, at 50% degree of saturation (DOS) the CO2 state did not affect the rate of transport in that each specimen exposed to a different CO2 state carbonated within the first hour of CO2 exposure. When the pore space is at 50 or 100% DOS, supercritical CO2 did not react with hydration products more rapidly nor did it result in more carbonate formation during exposure compared to gas or liquid CO2. The amount of Ca(OH)2 that contributes to CaCO3 formation is correlated to the DOS. For the mortar composition analyzed, Ca(OH)2 contributes to approximately 40% of the carbonates formed in the 50% DOS specimens and 15% in the 100% DOS specimens. In other words, as the amount of moisture in the pore space increases, phases other than Ca(OH)2 contribute to more than 50% of the total CaCO3 formed.}, journal={INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL}, author={Dalton, Laura E. and Crandall, Dustin and Pour-Ghaz, M.}, year={2022}, month={May} }
 @article{alhomair_faeli_hosseini_gabr_pour-ghaz_parker_2021, title={Assessment of Mitigation Measures against Benzene Breakthrough into Subsurface Concrete Pipe}, volume={12}, ISSN={["1949-1204"]}, DOI={10.1061/(ASCE)PS.1949-1204.0000512}, abstractNote={AbstractWork in this paper investigates the efficacy of mitigation measures to minimize the contaminant ingress into subsurface concrete pipes. The 3D study model of the concrete pipe and the soil ...}, number={1}, journal={JOURNAL OF PIPELINE SYSTEMS ENGINEERING AND PRACTICE}, author={Alhomair, Sultan and Faeli, Zahra and Hosseini, Payam and Gabr, Mohammed and Pour-Ghaz, Mohammad and Parker, Cyrus}, year={2021}, month={Feb} }
 @article{rashetnia_pour-ghaz_2021, title={Deep learning surrogate interacting Markov chain Monte Carlo based full wave inversion scheme for properties of materials quantification}, volume={497}, ISSN={["1095-8568"]}, DOI={10.1016/j.jsv.2021.115934}, abstractNote={Full Wave Inversion (FWI) imaging scheme has many applications in engineering, geoscience and medical sciences. In this paper, a surrogate deep learning FWI approach is presented to quantify properties of materials using stress waves. Such inverse problems, in general, are ill-posed and nonconvex, especially in cases where the solutions exhibit shocks, heterogeneity and discontinuities. The proposed approach is proven efficient to obtain global minima responses in these cases. This approach is trained based on random sampled sets of material properties and sampled trials around local minima, therefore, it requires a forward simulation can handle high heterogeneity, discontinuities and large gradients. High resolution Kurganov–Tadmor (KT) central finite volume method is used as forward wave propagation operator. Using the proposed framework, material properties of 2D media are quantified for several different situations. The results demonstrate the feasibility of the proposed method for estimating mechanical properties of materials with high accuracy using deep learning approaches.}, journal={JOURNAL OF SOUND AND VIBRATION}, author={Rashetnia, Reza and Pour-Ghaz, Mohammad}, year={2021}, month={Apr} }
 @article{jativa_hosseini_gabr_pour-ghaz_2021, title={Effects of MgSO4 on Calcium-Silicate-Hydrate}, volume={10}, ISSN={2379-1357}, url={http://dx.doi.org/10.1520/ACEM20210013}, DOI={10.1520/ACEM20210013}, abstractNote={Abstract}, number={1}, journal={Advances in Civil Engineering Materials}, publisher={ASTM International}, author={Jativa, Francisco W. and Hosseini, Payam and Gabr, Mohammed and Pour-Ghaz, M.}, year={2021}, month={Dec}, pages={20210013} }
 @article{faeli_alhomair_hosseini_gabr_pour-ghaz_2021, title={Factors Affecting Multiphase Benzene Breakthrough into Drainage Concrete Pipe in the Unsaturated Subsurface Profile}, volume={12}, ISSN={["1949-1204"]}, DOI={10.1061/(ASCE)PS.1949-1204.0000554}, abstractNote={AbstractAnalyses presented herein explore transport aspects related to benzene breakthrough into gasketed subsurface concrete pipe embedded in an unsaturated soil profile. A series of three-dimensi...}, number={3}, journal={JOURNAL OF PIPELINE SYSTEMS ENGINEERING AND PRACTICE}, author={Faeli, Zahra and Alhomair, Sultan and Hosseini, Payam and Gabr, Mohammed and Pour-Ghaz, Mohammad}, year={2021}, month={Aug} }
 @article{kuusela_pour-ghaz_pini_voss_seppanen_2021, title={Imaging of reactive transport in fractured cement-based materials with X-ray CT}, volume={124}, ISSN={["1873-393X"]}, DOI={10.1016/j.cemconcomp.2021.104211}, abstractNote={The need to improve the understanding of the properties of cement-based materials calls for the development of tools for visualizing and quantifying chemical reactions and flows of fluids within them. In this paper, we report the results of an experimental study where a sample of fractured cement-paste was subjected to injection of fluids (krypton, CO2 and water) and imaged simultaneously by X-ray computed tomography (CT). Initial porosity of the sample was estimated using a subtraction method based on CT scans taken initially and during krypton injection. The CT reconstructions were segmented to visualize crack patterns and fluid flow in three-dimensions and to quantify the evolution of porosity during the experiment. The results show that CT captures the formation of a carbonate phase in the sample during CO2 injection, and the flow of water in the fractured media. We quantify the reduction of porosity resulting from the carbonation reaction. We observe that the newly formed carbonated layer impedes water flow and, locally, can lead to crack healing. The results demonstrate the ability of CT to image reactive transport in cement-based materials, and support the feasibility of this imaging tool for their characterization.}, journal={CEMENT & CONCRETE COMPOSITES}, author={Kuusela, P. and Pour-Ghaz, M. and Pini, R. and Voss, A. and Seppanen, A.}, year={2021}, month={Nov} }
 @article{narode_pour-ghaz_ducoste_barlaz_2021, title={Measurement of heat release during hydration and carbonation of ash disposed in landfills using an isothermal calorimeter}, volume={124}, ISSN={0956-053X}, url={http://dx.doi.org/10.1016/j.wasman.2021.02.030}, DOI={10.1016/j.wasman.2021.02.030}, abstractNote={Temperatures as high as 100 °C have been reported at a few municipal solid waste (MSW) landfills in the U.S. A recently published model describing landfill heat accumulation identified reactions that contribute significant heat to landfills including the hydration and carbonation of Ca-containing wastes such as ash from MSW and coal combustion. The objective of this study was to develop a method to measure heat release from Ca-containing ash by isothermal calorimetry. The method was confirmed by comparing measured heat release from hydration and carbonation of pure CaO and Ca(OH)2 to the theoretical heat. Theoretical heat release was determined by characterizing test materials before and after experiments using thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Heat recovery efficiencies with both water and synthetic leachate ranged from 79 to 90% for CaO hydration and between 65 and 74% for Ca(OH)2 carbonation, with no effect attributable to leachate. Additionally, simultaneous hydration and carbonation of CaO/Ca(OH)2 mixtures resulted in efficiencies of 65 to 74%. The developed method was applied to eight samples that were excavated from a landfill and known to contain coal ash, and the ratio of measured to theoretical heat was 0.5 to 4. Thus, calculation of theoretical heat release from XRD data was not a good predictor of the experimentally measured heat release. The developed method can be used by landfill operators to evaluate the heat potential of a waste, thereby facilitating decisions on the quantity of a waste that can be buried in consideration of landfill temperatures.}, journal={Waste Management}, publisher={Elsevier BV}, author={Narode, Asmita and Pour-Ghaz, M. and Ducoste, Joel J. and Barlaz, Morton A.}, year={2021}, month={Apr}, pages={348–355} }
 @article{jauhiainen_pour-ghaz_valkonen_seppanen_2021, title={Nonplanar sensing skins for structural health monitoring based on electrical resistance tomography}, volume={36}, ISSN={["1467-8667"]}, DOI={10.1111/mice.12689}, abstractNote={Abstract}, number={12}, journal={COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING}, author={Jauhiainen, Jyrki and Pour-Ghaz, Mohammad and Valkonen, Tuomo and Seppanen, Aku}, year={2021}, month={Dec}, pages={1488–1507} }
 @article{park_castellano_barlaz_pour-ghaz_2020, title={Abrasion Resistance of Concrete Exposed to Organic Acids}, volume={32}, ISSN={["1943-5533"]}, DOI={10.1061/(ASCE)MT.1943-5533.0003251}, abstractNote={AbstractThe objective of this study is to investigate how exposure of concrete to organic acids affects its resistance to mechanical abrasion and to identify the most important factors contributing...}, number={8}, journal={JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, author={Park, Sungwoo and Castellano, Lisa and Barlaz, Morton A. and Pour-Ghaz, Mohammad}, year={2020}, month={Aug} }
 @article{hosseini_alhomair_faeli_pour-ghaz_gabr_knappe_parker_2020, title={Degradation Model for the Tensile Strength of PVC and Rubber Gasket Materials Exposed to Benzene and PCE-Saturated Aqueous Solutions}, volume={2674}, ISSN={["2169-4052"]}, DOI={10.1177/0361198120906126}, abstractNote={ In this paper, a tensile strength degradation model is developed for polyvinyl chloride (PVC) pipe and three rubber gasket materials commonly used in stormwater drains and wet utilities; the degradation model considers exposure to a single contaminant at its saturation level. The contaminant considered included benzene and tetrachloroethylene (PCE) because of their prevalence. The materials considered are unplasticized Polyvinyl chloride (u-PVC) utilized as the pipe material, and three types of rubber gaskets: Polychloroprene (Neoprene-CR), Acrylonitrile (nitrile) butadiene rubber (Buna-N), and fluoroelastomer rubber (FKM—Grade A VitonTM). First, the degradation rates of these materials are experimentally quantified using accelerated testing; then using the experimental results and Williams–Landel–Ferry (WLF) method a degradation model is developed. Finally, a simplified method is introduced to relate the tensile strength degradation of PVC to the penetration rate of the contaminants. }, number={2}, journal={TRANSPORTATION RESEARCH RECORD}, author={Hosseini, Payam and Alhomair, Sultan and Faeli, Zahra and Pour-Ghaz, Mohammad and Gabr, Mohammed and Knappe, Detlef and Parker, Cyrus}, year={2020}, month={Feb}, pages={274–283} }
 @article{voss_pour-ghaz_vauhkonen_seppanen_2020, title={Retrieval of the saturated hydraulic conductivity of cement-based materials using electrical capacitance tomography}, volume={112}, ISSN={["1873-393X"]}, DOI={10.1016/j.cemconcomp.2020.103639}, abstractNote={Moisture transport properties have an important part in the durability of cement-based materials, because water plays a major role in the majority of degradation mechanisms and can carry other agents that are detrimental. One of the key transport properties is the permeability, or saturated hydraulic conductivity (SHC), which is a function of porosity, pore size distribution, and pore connectivity. Therefore, information on the SHC is very useful in predicting the durability; however measuring SHC is often difficult due to required experimental setup and the low SHC of cement-based materials. In this paper, we propose an electrical capacitance tomography (ECT) -based approach to estimate the SHC of cement-based materials. The proposed technique is applied to capillary absorption experiments, where specimens are imaged with ECT during water absorption, and the time-series of ECT reconstructions are used for tracing the water front propagation. The water front data, in turn, is used for estimating the SHC of the material. Here, we make a simplifying approximation for the moisture ingress and use (a 1D) sharp front model for estimating the SHC from the ECT-based data. The proposed SHC estimation scheme is tested both numerically and experimentally. The results of the numerical studies support the feasibility of the SHC retrieval both in ideal cases of 1D moisture flow and also in more realistic cases where the flows are not 1D. In the experimental part, the ECT-based estimates for the SHCs of mortars are in good agreement with the values determined using the falling-head method measured independently.}, journal={CEMENT & CONCRETE COMPOSITES}, author={Voss, Antti and Pour-Ghaz, Mohammad and Vauhkonen, Marko and Seppanen, Aku}, year={2020}, month={Sep} }
 @article{dalton_jarvis_pour-ghaz_2020, title={The Effect of Gas Solubility on the Secondary Sorption in a Portland Cement Mortar Observed by X-ray CT}, volume={133}, ISSN={["1573-1634"]}, DOI={10.1007/s11242-020-01429-6}, number={3}, journal={TRANSPORT IN POROUS MEDIA}, author={Dalton, Laura E. and Jarvis, Karl and Pour-Ghaz, Mohammad}, year={2020}, month={Jul}, pages={397–411} }
 @article{park_pour-ghaz_2019, title={Another Look at the Abrasion Resistance of Concrete}, volume={8}, ISSN={["2165-3984"]}, DOI={10.1520/ACEM20180159}, abstractNote={Abstract}, number={1}, journal={ADVANCES IN CIVIL ENGINEERING MATERIALS}, author={Park, Sungwoo and Pour-Ghaz, Mohammad}, year={2019}, pages={423–434} }
 @article{khalafalla_pour-ghaz_elsafty_rizkalla_2019, title={Durability of CFRP strands used for prestressing of concrete structural members}, volume={228}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2019.116756}, abstractNote={This paper presents a comprehensive research conducted to study the synergistic effect of environmental conditions and sustained loading on the mechanical properties of Carbon Fiber Reinforced Polymer (CFRP) prestressing strands. The environmental conditions included exposure of CFRP strands to alkaline solution and sustained loading at an elevated temperature of 55 °C for 3000 and 7000 h. The sustained loading was equivalent to 65 percent of the guaranteed tensile strength of the strands. Mechanical testing performed on the strands included tensile, shear and bond strength as well as evaluation of the elastic modulus of the CFRP strands as affected by the environmental conditions and sustained loading. Durability of the constituent materials of the CFRP strands was also studied.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Khalafalla, Omar and Pour-Ghaz, Mohammad and ElSafty, Adel and Rizkalla, Sami}, year={2019}, month={Dec} }
 @article{mohammadian_rashetnia_lucier_seracino_pour-ghaz_2019, title={Numerical simulation and experimental corroboration of galvanic corrosion of mild steel in synthetic concrete pore solution}, volume={103}, ISSN={["1873-393X"]}, DOI={10.1016/j.cemconcomp.2019.04.027}, abstractNote={Corrosion of reinforcing steel in concrete is one of the most prevalent deterioration mechanisms affecting reinforced concrete structures. While there have been significant advances in modeling the initiation stage of corrosion, corrosion kinetic models for predicting the rate of corrosion after depassivation of steel are scarce, and models with experimental corroboration under controlled experimental conditions are virtually nonexistent. Furthermore, the sensitivity of corrosion kinetic models to the uncertainty of their input parameters is not understood. The objective of the present work is to model active corrosion of steel in synthetic solution, experimentally corroborate the modeling approach under controlled conditions, and study the effect of uncertainty of the input parameters on the model predictions. To this end, a two-dimensional finite element method is used to solve the coupled system of Poisson-Nernst-Planck (PNP) equations subjected to electroneutrality constraint. To corroborate the modeling approach, the results of computations are compared against one-dimensional and two-dimensional galvanic corrosion of stainless/carbon steel in dilute and non-dilute NaCl electrolytes as well as two synthetic concrete pore solutions. The modeling parameters, including electrode polarization behaviors and electrolyte properties, are obtained experimentally. Monte Carlo simulations are used to understand the effect of uncertainty of polarization parameters on the predicted corrosion rate.}, journal={CEMENT & CONCRETE COMPOSITES}, author={Mohammadian, Armita and Rashetnia, Reza and Lucier, Gregory and Seracino, Rudolf and Pour-Ghaz, Mohammad}, year={2019}, month={Oct}, pages={263–278} }
 @article{voss_hosseini_pour-ghaz_vauhkonen_seppanen_2019, title={Three-dimensional electrical capacitance tomography - A tool for characterizing moisture transport properties of cement-based materials}, volume={181}, ISSN={["1873-4197"]}, DOI={10.1016/j.matdes.2019.107967}, abstractNote={Water often plays a major role in the degradation processes of cement-based materials and structures, and thus the durability of these structures strongly depends on their ability to impede transport of water. This paper reports the results of imaging three-dimensional (3D) unsaturated moisture flow in mortar specimens using electrical capacitance tomography (ECT) imaging, which is based on non-intrusive and contact-free capacitance surface measurements. In a series of experiments, three mortar specimens with differing moisture transport properties were imaged with ECT during a 3D ingress of water. For comparison, we also modeled the flow of moisture numerically, by Finite Element Method (FEM) approximation of the 3D equation of unsaturated moisture flow in porous media, commonly referred to as Richard's equation. The ECT reconstructions are in good agreement with the flow model for all specimens which supports the ability of ECT to image 3D water transport in cement-based materials.}, journal={MATERIALS & DESIGN}, author={Voss, Antti and Hosseini, Payam and Pour-Ghaz, Mohammad and Vauhkonen, Marko and Seppanen, Aku}, year={2019}, month={Nov} }
 @article{smyl_pour-ghaz_seppanen_2018, title={Detection and reconstruction of complex structural cracking patterns with electrical imaging}, volume={99}, ISSN={["1879-1174"]}, DOI={10.1016/j.ndteint.2018.06.004}, abstractNote={The ability to detect cracks in structural elements is an integral component in the assessment of structural heath and integrity. Recently, Electrical Resistance Tomography (ERT) -based sensing skins have been shown to reliably image progressive surface damage on structural members. However, so far the approach has only been tested in cases of relatively simple crack patterns. Because the spatial resolution of ERT is generally low, it is an open question whether the ERT-based sensing skins are able to image complex structural cracking patterns. In this paper, we test the accuracy of ERT for reconstructing cracking patterns experimentally and computationally. In the computational study, we use a set of numerical simulations that model progressive cracking in a rectangular beam geometry. We also investigate the effect of image reconstruction methods on the crack pattern estimates: In addition to the contemporary image reconstruction method used in the recent sensing skin studies, we test the feasibility of a novel approach where model-based structural prior information on the cracking probability is accounted for in the image reconstruction. The results of this study indicate that ERT-based sensing skins are able to detect and reconstruct complex structural cracking patterns, especially when structural prior information is utilized in the image reconstruction.}, journal={NDT & E INTERNATIONAL}, author={Smyl, Danny and Pour-Ghaz, Mohammad and Seppanen, Aku}, year={2018}, month={Oct}, pages={123–133} }
 @article{voss_hanninen_pour-ghaz_vauhkonen_seppanen_2018, title={Imaging of two-dimensional unsaturated moisture flows in uncracked and cracked cement-based materials using electrical capacitance tomography}, volume={51}, DOI={10.1617/s11527-018-1195-y}, number={3}, journal={Materials and Structures}, author={Voss, A. and Hanninen, N. and Pour-Ghaz, M. and Vauhkonen, M. and Seppanen, A.}, year={2018} }
 @article{rashetnia_ghasemzadeh_hallaji_pour-ghaz_2018, title={Quantifying prestressing force loss due to corrosion from dynamic structural response}, volume={433}, ISSN={["1095-8568"]}, DOI={10.1016/j.jsv.2018.07.012}, abstractNote={In prestressed concrete structures, corrosion of prestressing strands is a major durability concern. In advanced stages, corrosion may result in the rupture of strands. At early stages, corrosion of strands results in microcracking, deterioration of bond between strands and concrete, and therefore, in the loss of prestressing force. These effects, in turn, result in the change of dynamic response of prestressed elements. In this paper, we investigate whether the prestressing force of prestressed beams can be estimated indirectly using dynamic vibration test. For this purpose, six prestressed concrete beams were manufactured. Two beams were kept as control, two beams were corroded along the entire length of the strand, and two beams were corroded along one-third of the strand length. The induced accelerated corrosion was monitored by corrosion current measurements and passive acoustic emission. Two system identification approaches were developed where both utilize the free vibration response of an Euler-Bernoulli beam to estimate prestressing force of strands. Due to the ill-possedness of the identification problems and the presence of random and systematic errors in the experiment, Tikhonov regularization method was used. Finally, results were compared with analytical solution of vibration of a simply supported beam with external compressive force. It was concluded that using dynamic vibration of prestressed concrete beams and using indirect estimation approaches, it is possible to quantify the loss of prestressing force due to corrosion.}, journal={JOURNAL OF SOUND AND VIBRATION}, author={Rashetnia, Reza and Ghasemzadeh, Farnam and Hallaji, Milad and Pour-Ghaz, Mohammad}, year={2018}, month={Oct}, pages={129–137} }
 @article{park_pour-ghaz_2018, title={What is the role of water in the geopolymerization of metakaolin?}, volume={182}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2018.06.073}, abstractNote={Despite the significant advances in understanding the structure of geopolymers in the last decades, the role of water in the geopolymerization of aluminosilicates and within the structure of geopolymers remains elusive. The present paper investigates the role of water in the geopolymerization of metakaolin, a low calcium aluminosilicate. We differentiate between different states of water in these materials and discuss the nature and the origin of non-evaporable (chemically bound) water, and evaporable water. We propose a conceptual model for the microstructure of metakaolin based geopolymers that accounts for different states of water within their structure and discuss the implications of their composition on pore size distribution.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Park, Sungwoo and Pour-Ghaz, Mohammad}, year={2018}, month={Sep}, pages={360–370} }
 @article{seppanen_hallaji_pour-ghaz_2017, title={A functionally layered sensing skin for the detection of corrosive elements and cracking}, volume={16}, ISSN={["1741-3168"]}, DOI={10.1177/1475921716670574}, abstractNote={In this paper, we propose an electrical impedance tomography (EIT)-based multifunctional surface sensing system, or sensing skin, for structural health monitoring. More specifically, the EIT-based sensing skin is developed for detecting and localizing the ingress of chlorides and cracking: two phenomena which are of concern in many structures, including reinforced concrete structures. The multifunctional sensing skin is made of two layers: one layer is sensitive to both chlorides and cracking, and the other layer is sensitive to cracking only. In the experiments, the sensing skin is tested on a polymeric and concrete substrate. The results demonstrate the feasibility of using the multifunctional multi-layer sensing skin for detecting and localizing corrosive elements and cracking, and for distinguishing between them.}, number={2}, journal={STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL}, author={Seppanen, Aku and Hallaji, Milad and Pour-Ghaz, Mohammad}, year={2017}, month={Mar}, pages={215–224} }
 @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{pour-ghaz_wilson_spragg_nadukuru_kim_o’connor_byrne_sigurdardottir_yao_michalowski_et al._2017, title={Performance and damage evolution of plain and fibre-reinforced segmental concrete pipelines subjected to transverse permanent ground displacement}, volume={14}, ISSN={1573-2479 1744-8980}, url={http://dx.doi.org/10.1080/15732479.2017.1349809}, DOI={10.1080/15732479.2017.1349809}, abstractNote={Abstract This paper presents the results of three full-scale experiments performed on segmental concrete pipelines subjected to permanent ground displacement. The first pipeline was made of reinforced concrete pipes and the second pipeline was made of steel fibre-reinforced concrete pipes. The third pipeline was made of a combination of fibre-reinforced and reinforced concrete pipes. An array of sensing techniques was used to assess the damage evolution in pipelines and their overall performance. Three stages of damage were observed. In the first stage, damage was concentrated in the joints near the fault line. In the second stage, the damage occurred in all joints along the pipeline. While in the first two stages damage was mainly concentrated at the bell and spigot joints of the pipe segments, the third stage of damage was characterised by severe damage and rupture of the body of pipe segments located in the immediate vicinity of the fault line. The modes of failure for the plain and fibre-reinforced concrete pipelines were similar in the first and second stages of damage. However, in the pipeline constructed using both plain and fibre-reinforced concrete pipe segments, the damage was concentrated in the standard reinforced concrete pipe segments.}, number={2}, journal={Structure and Infrastructure Engineering}, publisher={Informa UK Limited}, author={Pour-Ghaz, Mohammad and Wilson, Jacob and Spragg, Robert and Nadukuru, Srinivasa (Sid) S. and Kim, Junhee and O’Connor, Sean M. and Byrne, Edward M. and Sigurdardottir, Dorotea H. and Yao, Yao and Michalowski, Radoslaw L. and et al.}, year={2017}, month={Jul}, pages={232–246} }
 @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{pour-ghaz_miller_alla_rizkalla_2016, title={Do mechanical and environmental loading have a synergistic effect on the degradation of pultruded glass fiber reinforced polymers?}, volume={106}, ISSN={["1879-1069"]}, DOI={10.1016/j.compositesb.2016.09.007}, abstractNote={This paper investigates the effect of simultaneous mechanical and environmental loading on the degradation rate of pultruded Glass Fiber Reinforced Polymer (GFRP) composites. The experimental program included testing a large number of GFRP coupons, with vinylester or polyester matrices, conditioned for 1000 or 2000 h under a wide range of sustained stresses and exposed to freshwater or saltwater at an elevated temperature of 60 °C. Mechanical tests, including tensile strength and elastic modulus measurements were performed on the GFRP composites. In addition, glass transition measurements, moisture uptake measurements, scanning electron microscopy, and acoustic emission testing were performed to better understand the synergistic effect of mechanical loading and environmental conditions.}, journal={COMPOSITES PART B-ENGINEERING}, author={Pour-Ghaz, Mohammad and Miller, Bryant L. H. and Alla, Omar Khalaf and Rizkalla, Sami}, year={2016}, month={Dec}, pages={344–355} }
 @article{voss_pour-ghaz_vauhkonen_seppanen_2016, title={Electrical capacitance tomography to monitor unsaturated moisture ingress in cement-based materials}, volume={89}, ISSN={["1873-3948"]}, DOI={10.1016/j.cemconres.2016.07.011}, abstractNote={This paper reports the investigation of the feasibility of electrical capacitance tomography (ECT) for monitoring unsaturated moisture flow in cement-based materials. ECT is an imaging modality in which the electrical permittivity distribution within an object is reconstructed based on measured capacitances between electrodes attached on the object's surface. In a series of experiments, mortar specimens with different water-cement mass ratios (w/c) (0.25, 0.45 & 0.60) were monitored with ECT during the moisture ingress. The results demonstrate that ECT is able to image the moisture ingress within the specimens, and further, to distinguish between different moisture flow rates in mortars with different porosities resulting from differing w/c ratios. These findings suggest that ECT could provide a tool for monitoring, visualizing and quantifying the rate of moisture ingress in cement-based materials non-destructively.}, journal={CEMENT AND CONCRETE RESEARCH}, author={Voss, Antti and Pour-Ghaz, Mohammad and Vauhkonen, Marko and Seppanen, Aku}, year={2016}, month={Nov}, pages={158–167} }
 @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{rashetnia_ghasemzadeh_pour-ghaz_2016, title={The Consequences of Material Nonlinearity on the Axisymmetric Flexural Vibration Measurements for Estimating the Dynamic Elastic Modulus of Damaged Cement Based Materials}, volume={14}, ISSN={["1347-3913"]}, DOI={10.3151/jact.14.287}, abstractNote={Elastic modulus measurements are often required to evaluate the structural performance or to estimate the damage in cement-based materials. The axisymmetric flexural vibration (AFV) of a thick circular disk is a test method that can be used to estimate the dynamic elastic modulus of cement-based materials. Cement-based materials are inherently nonlinear materials and their nonlinearity increases with damage. The main objectives of this paper are to investigate the consequences of material nonlinearity on the AFV measurements, and to understand the implications of the change of material nonlinearity with damage on these measurements. In this work, experimental measurements are performed on mortar specimens damaged by freeze-thaw. Acoustic emission is used as a benchmark method to monitor and quantify the damage.}, number={6}, journal={JOURNAL OF ADVANCED CONCRETE TECHNOLOGY}, author={Rashetnia, Reza and Ghasemzadeh, Farnam and Pour-Ghaz, Mohammad}, year={2016}, month={Jun}, pages={287–298} }
 @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} }
 @article{li_pour-ghaz_trtik_wyrzykowski_muench_lura_vontobel_lehmann_weiss_2016, title={Using neutron radiography to assess water absorption in air entrained mortar}, volume={110}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2016.02.001}, abstractNote={Concrete highway and airport pavements are designed to be long lasting; however, some concrete pavements have shown premature deterioration at the cracks and joints. It has been hypothesized that one cause of this deterioration is associated with fluid ingress, especially in cases where those fluids contain deicing salts. This paper examines fluid ingress in mortar using a cross-sectional geometry that is similar to a typical concrete pavement joint. Time-dependent and spatial aspects of fluid ingress are examined using neutron radiography (NR), which was performed using the thermal neutron radiography station at the neutron spallation source at the Paul Scherrer Institut (PSI). Specifically, this paper examines the role of the initial relative humidity (or degree of saturation) and air content on the fluid ingress. The work indicates that the initial fluid ingress reaches a specific degree of saturation relatively rapidly, where the large capillary and gel pores appear to be filled in (commonly referred to as the nick point in sorption tests) and the entrapped and entrained air pores fill in more slowly over time.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Li, Wenting and Pour-Ghaz, Mohammad and Trtik, Pavel and Wyrzykowski, Mateusz and Muench, Beat and Lura, Pietro and Vontobel, Peter and Lehmann, Eberhard and Weiss, W. Jason}, year={2016}, month={May}, pages={98–105} }
 @article{ghasemzadeh_pour-ghaz_2015, title={Effect of Damage on Moisture Transport in Concrete}, volume={27}, ISSN={["1943-5533"]}, DOI={10.1061/(asce)mt.1943-5533.0001211}, abstractNote={AbstractThis paper presents the results of an experimental and analytical study on the effect of distributed cracks (damage) on moisture transport in concrete. Specifically, the writers investigate the following: (1) how damage affects the saturated and unsaturated transport and electrical resistivity, (2) whether one-dimensional (1D) analysis based on the sharp front (SF) theory can explain the relation between the saturated and unsaturated transport in damaged concrete, and (3) which transport mechanism is more sensitive to damage. Conceptual models are developed based on damage mechanics and fluid transport to explain the experimental data. Material constants are also provided for numerical modeling of unsaturated transport in damaged concrete. The results show that damage differently affects each of the transport mechanisms, and saturated hydraulic conductivity is more sensitive to damage as compared to sorptivity and electrical resistivity. The simplified 1D analysis, based on the sharp front theory,...}, number={9}, journal={JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, author={Ghasemzadeh, Farnam and Pour-Ghaz, Mohammad}, year={2015}, month={Sep} }
 @inproceedings{hallaji_seppaznen_pour-ghaz_2015, title={Electrical impedance tomography-based sensing skin for structural health monitoring}, DOI={10.12783/shm2015/381}, abstractNote={In this paper, we develop a multi-layer multi-functional electrical impedance tomography-based sensing skin. This sensing skin is made of two layers. The electrical conductivity of one layer changes due to cracking and the presence of chloride ions, while the electrical conductivity of the other layer changes only due to cracking. We monitor the local change in conductivity of each layer with Electrical Impedance Tomography (EIT). This sensing skin enables detection and differentiation of both cracking and the presence of chloride ions. We apply this sensing skin to concrete substrate. The results indicate that the developed technology can be potentially used for health monitoring of critical infrastructure systems where cracking and leakage of certain ions might be of concern. doi: 10.12783/SHM2015/381}, booktitle={Structural health monitoring 2015: system reliability for verification and implementation, vols. 1 and 2}, author={Hallaji, M. and Seppaznen, A. and Pour-Ghaz, M.}, year={2015}, pages={3081–3088} }
 @article{hallaji_seppanen_pour-ghaz_2015, title={Electrical resistance tomography to monitor unsaturated moisture flow in cementitious materials}, volume={69}, ISSN={["1873-3948"]}, DOI={10.1016/j.cemconres.2014.11.007}, abstractNote={Traditionally the electrically-based assessment of the moisture flow in cement-based materials relies on two- or four-point measurements. In this paper, imaging of moisture distribution with electrical resistance tomography (ERT) is considered. Especially, the aim is to study whether ERT could give information on unsaturated moisture flows in cases where the flow is non-uniform. In the experiment, the specimens are monitored with ERT during the water ingress. The ERT reconstructions are compared with neutron radiographs, which provide high resolution information on the 2D distribution of the moisture. The results indicate that ERT is able to detect the moisture movement and to show approximately the shape and position of the water front even if the flow is nonuniform.}, journal={CEMENT AND CONCRETE RESEARCH}, author={Hallaji, Milad and Seppanen, Aku and Pour-Ghaz, Mohammad}, year={2015}, month={Mar}, pages={10–18} }
 @inproceedings{rashetnia_pour-ghaz_2015, title={Estimating the mechanical properties of layered media using ultrasonics: Numerical study with high resolution wave propagation}, DOI={10.12783/shm2015/318}, abstractNote={Estimating the mechanical properties of layered media using ultrasonics is challenging due to the ill-posed, nonconvex, and nonlinear nature of the problem. To address this challenge, we use Kurganov Tadmor (KT) central scheme for the forward model of wave propagation since it provides a robust model for layered media with sharp boundaries. KT also minimizes numerical challenges such as dispersion error propagation. In this study, we consider a one-dimensional stress wave propagation problem. To solve the inverse problem of estimating the mechanical properties, we utilize non-heuristic random search algorithm with surrogate model. The random search algorithm performs a global search within the feasible search area, and the surrogate model applies an artificial Neural Network and a genetic algorithm to produce optimal estimations. This method also decreases the computational cost. The results show that this method can be successfully used to estimate the mechanical properties of the layered one-dimensional media. doi: 10.12783/SHM2015/318}, booktitle={Structural health monitoring 2015: system reliability for verification and implementation, vols. 1 and 2}, author={Rashetnia, R. and Pour-Ghaz, M.}, year={2015}, pages={2559–2566} }
 @article{hallaji_pour-ghaz_2014, title={A new sensing skin for qualitative damage detection in concrete elements: Rapid difference imaging with electrical resistance tomography}, volume={68}, ISSN={["1879-1174"]}, DOI={10.1016/j.ndteint.2014.07.006}, abstractNote={In this paper we investigate whether a thin layer of electrically conductive materials that is painted to the surface of concrete elements can be used as sensing skin to detect and locate cracking and damage in the concrete substrate. Cracking of the concrete results in the rupture of the sensing skin, thus locally increasing its electrical resistivity. We monitor the local change in the electrical resistivity of the sensing skin using electrical resistance tomography. In this work, we utilize difference imaging scheme. Experiments on polymeric substrates as well as on concrete substrates are performed. The results indicate that the developed sensing skin can be successfully used to detect and locate cracking and damage on concrete and potentially other nonconductive substrates.}, journal={NDT & E INTERNATIONAL}, author={Hallaji, Milad and Pour-Ghaz, Mohammad}, year={2014}, month={Dec}, pages={13–21} }
 @article{hallaji_seppanen_pour-ghaz_2014, title={Electrical impedance tomography-based sensing skin for quantitative imaging of damage in concrete}, volume={23}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/23/8/085001}, abstractNote={This paper outlines the development of a large-area sensing skin for damage detection in concrete structures. The developed sensing skin consists of a thin layer of electrically conductive copper paint that is applied to the surface of the concrete. Cracking of the concrete substrate results in the rupture of the sensing skin, decreasing its electrical conductivity locally. The decrease in conductivity is detected with electrical impedance tomography (EIT) imaging. In previous works, electrically based sensing skins have provided only qualitative information on the damage on the substrate surface. In this paper, we study whether quantitative imaging of the damage is possible. We utilize application-specific models and computational methods in the image reconstruction, including a total variation (TV) prior model for the damage and an approximate correction of the modeling errors caused by the inhomogeneity of the painted sensing skin. The developed damage detection method is tested experimentally by applying the sensing skin to polymeric substrates and a reinforced concrete beam under four-point bending. In all test cases, the EIT-based sensing skin provides quantitative information on cracks and/or other damages on the substrate surface: featuring a very low conductivity in the damage locations, and a reliable indication of the lengths and shapes of the cracks. The results strongly support the applicability of the painted EIT-based sensing skin for damage detection in reinforced concrete elements and other substrates.}, number={8}, journal={SMART MATERIALS AND STRUCTURES}, author={Hallaji, Milad and Seppanen, Aku and Pour-Ghaz, Mohammad}, year={2014}, month={Aug} }
 @article{villani_spragg_pour-ghaz_weiss_2014, title={The Influence of Pore Solutions Properties on Drying in Cementitious Materials}, volume={97}, ISSN={["1551-2916"]}, DOI={10.1111/jace.12604}, abstractNote={The drying of cementitious materials can be influenced by the properties of the fluid in the pores. While there are numerous studies on drying, very few explicitly focus on the properties of the pore fluid. This work investigates the influence of deicing salts on the properties of the pore fluid. The change that deicing salts cause in surface tension and viscosity is described in this study as a function of concentration and temperature. As a relatively limited number of measurements have been reported in literature, it can be difficult to describe the properties over a wide range of concentrations or temperatures. To overcome this limitation, this work provides measurements over concentration and temperature ranges. Semiempirical relationships were successfully fitted to the data confirming the possibility to predict viscosity and surface tension changes with temperature and salt concentration. The implications of the fluid properties on the drying behavior are also discussed as they relate to the diffusion coefficient. The models applied effectively predict the initiation of drying. Further improvements are however necessary to describe the diffusion coefficient as function of the degree of saturation in the presence of deicing salts which appear to be needed to account for the chemical interaction between the matrix and the fluid.}, number={2}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Villani, Chiara and Spragg, Robert and Pour-Ghaz, Mohammad and Weiss, W. Jason}, year={2014}, month={Feb}, pages={386–393} }
 @article{pour-ghaz_barrett_ley_materer_apblett_weiss_2014, title={Wireless Crack Detection in Concrete Elements Using Conductive Surface Sensors and Radio Frequency Identification Technology}, volume={26}, ISSN={["1943-5533"]}, DOI={10.1061/(asce)mt.1943-5533.0000891}, abstractNote={This paper describes the results of an experimental study that uses radio frequency identification (RFID) technology to detect cracking in concrete elements. A RFID-based sensor is used to monitor the change in electrical resistance that occurs in conductive materials applied to the surface of the concrete. When the concrete substrate is strained, the conductive material at the surface is stretched, and its electrical resistance increases. If the concrete substrate is strained to the point where it cracks, the conductive material at the surface also cracks, causing its electrical resistance to increase by orders of magnitude. This paper describes how this increase in electrical resistance attributable to cracking can be detected wirelessly by RFID technology. To experimentally illustrate the application of this technology, an RFID-based sensor and conductive surface materials are used to detect cracking in the restrained ring test. The experimental results indicate that this technology can be easily implemented and successfully used for wireless crack detection in concrete and reinforced concrete members. The technology that is described in this paper is not limited to the laboratory environment and can be easily extended to field applications.}, number={5}, journal={JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, author={Pour-Ghaz, Mohammad and Barrett, Timothy and Ley, Tyler and Materer, Nicholas and Apblett, Allen and Weiss, Jason}, year={2014}, month={May}, pages={923–929} }
 @article{pour-ghaz_2013, title={Sustainable Infrastructure Materials: Challenges and Opportunities}, volume={10}, ISSN={["1546-542X"]}, DOI={10.1111/ijac.12083}, abstractNote={The recent quest for developing new low carbon footprint construction materials to lower the environmental emissions and implications of infrastructure has imposed many challenges and has created many opportunities for research and development in academia and industrial sectors. The present paper, discusses and summaries these challenges and opportunities and provides a synopsis of the ideas presented in the Infrastructure sessions of the Fourth International Congress on Ceramics (ICC4). This paper also discusses recent advances in the development of sustainable infrastructure materials.}, number={4}, journal={INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY}, author={Pour-Ghaz, Mohammad}, year={2013}, month={Jul}, pages={584–592} }
 @article{kim_nadukuru_pour-ghaz_lynch_michalowski_bradshaw_green_weiss_2012, title={Assessment of the Behavior of Buried Concrete Pipelines Subjected to Ground Rupture: Experimental Study}, volume={3}, ISSN={1949-1190 1949-1204}, url={http://dx.doi.org/10.1061/(asce)ps.1949-1204.0000088}, DOI={10.1061/(asce)ps.1949-1204.0000088}, abstractNote={Rapid assessment of damage to buried pipelines from earthquake-induced ground deformation is a crucial component to recovery efforts. This paper reports on the first year of a four-year study aimed at developing rapid, reliable, and cost-effective sensing systems for health monitoring and damage detection for buried concrete pipelines subjected to ground deformation. A custom-designed sensing strategy was implemented in a ground rupture experiment with a scaled-down concrete pipeline. The behavior of the pipeline, including the failure modes and damage inflicted to the pipe segments, was monitored during the test. Two modes of failure were identified in the test: (1) compression associated with telescoping-type deformation and (2) bending at the pipeline joints closest to the fault plane. Consequently, future research toward advancing sensing technology for concrete pipelines will likely focus on the behavior of the joints.}, number={1}, journal={Journal of Pipeline Systems Engineering and Practice}, publisher={American Society of Civil Engineers (ASCE)}, author={Kim, J. and Nadukuru, S. S. and Pour-Ghaz, M. and Lynch, J. P. and Michalowski, R. L. and Bradshaw, A. S. and Green, R. A. and Weiss, W. J.}, year={2012}, month={Feb}, pages={8–16} }
 @article{pour-ghaz_castro_kladivko_weiss_2012, title={Characterizing Lightweight Aggregate Desorption at High Relative Humidities Using a Pressure Plate Apparatus}, volume={24}, ISSN={0899-1561 1943-5533}, url={http://dx.doi.org/10.1061/(asce)mt.1943-5533.0000422}, DOI={10.1061/(asce)mt.1943-5533.0000422}, abstractNote={AbstractThis paper describes the results of an experimental study that was performed to obtain desorption isotherms for a wide range of fine lightweight aggregates that are used commercially in North America. The desorption isotherms were determined for the entire gradation of the fine lightweight aggregates (as received). To obtain the desorption isotherms a pressure plate apparatus (porous plate) was used. The pressure plate enables the desorption isotherm to be measured at high relative humidities (beginning at 100%). In addition to providing experimental results obtained with the pressure plate method, desorption results obtained by gravimetric desorption and dynamic vapor desorption methods are also provided. The gravimetric desorption and dynamic vapor desorption methods are generally used at lower relative humidities (98% and 0% relative humidity). The results indicate that water leaves the fine lightweight aggregates at relative humidities as high as 99.9%. This suggests that internal curing water...}, number={8}, journal={Journal of Materials in Civil Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Pour-Ghaz, Mohammad and Castro, Javier and Kladivko, Eileen J. and Weiss, Jason}, year={2012}, month={Aug}, pages={961–969} }
 @article{li_pour-ghaz_castro_weiss_2012, title={Water Absorption and Critical Degree of Saturation Relating to Freeze-Thaw Damage in Concrete Pavement Joints}, volume={24}, ISSN={["1943-5533"]}, DOI={10.1061/(asce)mt.1943-5533.0000383}, abstractNote={Fluid ingress is a primary factor that influences freeze-thaw damage in concrete. This paper discusses the influence of fluid ingress on freeze-thaw damage development. Specifically, this paper examines the influence of entrained air content on the rate of water absorption, the degree of saturation, and the relationship between the saturation level and freeze-thaw damage. The results indicate that whereas air content delays the time it takes for concrete to reach a critical degree of saturation it will not prevent the freeze-thaw damage from occurring. The results of the experiments show that when the degree of saturation exceeds 86–88%, freeze-thaw damage is inevitable with or without entrained air even with very few freeze-thaw cycles.}, number={3}, journal={JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, author={Li, Wenting and Pour-Ghaz, Mohammad and Castro, Javier and Weiss, Jason}, year={2012}, month={Mar}, pages={299–307} }
 @inproceedings{bradshaw_green_lynch_michalowski_kim_o'connor_pour-ghaz_nadukuru_weiss_2011, place={Seattle, Washington}, title={A Simple Soil-Structure Interaction Model for Indirect Damage Assessment of Segmented Concrete Pipelines during PGD}, ISBN={9780784411872}, url={http://dx.doi.org/10.1061/41187(420)71}, DOI={10.1061/41187(420)71}, abstractNote={This paper describes a simple soil-structure interaction model of a buried segmented concrete pipeline that can be used for indirect health monitoring during Permanent Ground Deformation (PGD). Buried pipelines are difficult to inspect visually, and thus accurate health monitoring systems can improve the efficiency and effectiveness of repair efforts immediately following an earthquake. A Winkler pipeline model is developed for indirect health monitoring that incorporates the two primary modes of failure observed in pipeline experiments, namely telescoping and rotation at the joints. Very approximate estimates of the model parameters are made, and the model results are compared to experimental results. In general the model captures both the magnitude and patterns of joint deformation. However, the model yields axial forces that are two orders of magnitude higher than the measured values. This suggests that the first order approximation of the joint as an elastic beam is inaccurate. Structural}, booktitle={Pipelines 2011}, publisher={American Society of Civil Engineers}, author={Bradshaw, A. S. and Green, R. A. and Lynch, J. P. and Michalowski, R. L. and Kim, J. and O'Connor, S. and Pour-Ghaz, M. and Nadukuru, S. and Weiss, W. J.}, year={2011}, month={Jul} }
 @article{dean_pour-ghaz_weiss_2011, title={Application of Frequency Selective Circuits for Crack Detection in Concrete Elements}, volume={8}, ISSN={1546-962X}, url={http://dx.doi.org/10.1520/jai103826}, DOI={10.1520/jai103826}, abstractNote={Abstract}, number={10}, journal={Journal of ASTM International}, publisher={ASTM International}, author={Dean, S. W. and Pour-Ghaz, Mohammad and Weiss, Jason}, year={2011}, pages={103826} }
 @inproceedings{green_lynch_michalowski_bradshaw_kim_o'connor_pour-ghaz_naukuru_weiss_2011, place={Dallas, TX}, title={Damage Detection and Health Monitoring of Buried Segmental Concrete Pipes}, ISBN={9780784411650}, url={http://dx.doi.org/10.1061/41165(397)178}, DOI={10.1061/41165(397)178}, abstractNote={Presented herein is a summary of the results from the first two years of a four-year study on damage detection and health monitoring of buried, segmental concrete pipes, such as those used in urban water distribution networks. The rapid assessment of damage to such networks from earthquake-induced permanent ground deformations is an essential component to recovery efforts. To identify the failure modes that occur in the pipelines subjected to permanent ground deformation and to assess the performance of sensor technologies for detecting these modes and for potential use in situ , large-scale tests were performed at the NEES Lifeline Experimental and Testing Facility at Cornell University. The predominant failure modes identified in the tests performed to date include compression at all joints and combined compression and bending at the pipe joints closest to the fault. Accurate measurements of the pipeline displacements and strains were recorded up to the compressive and flexural failure of the pipeline joints.}, booktitle={Geo-Frontiers 2011}, publisher={American Society of Civil Engineers}, author={Green, R. A. and Lynch, J. P. and Michalowski, R. L. and Bradshaw, A. S. and Kim, J. and O'Connor, S. and Pour-Ghaz, M. and Naukuru, S. S. and Weiss, W. J.}, year={2011}, month={Mar}, pages={1743–1752} }
 @article{pour-ghaz_weiss_2011, title={Detecting the time and location of cracks using electrically conductive surfaces}, volume={33}, ISSN={0958-9465}, url={http://dx.doi.org/10.1016/j.cemconcomp.2010.09.015}, DOI={10.1016/j.cemconcomp.2010.09.015}, abstractNote={This paper describes the use of electrical impedance spectroscopy to detect the time, location, and approximate number of cracks on the surface of concrete. This method uses an electrically conductive thin film that is applied to the surface of the cementitious materials. The electrical resistance of this film is monitored as the substrate cracks. A sudden increase in the electrical resistance of the film corresponds with the time of cracking. The location of the cracks can be obtained when the conductive film is applied to two parallel surfaces of the cementitious material using the ratio of the capacitances (or resistances) before and after cracking. For monitoring damage evolution consisting of multiple cracks an equivalent circuit model is proposed. Using this model an increase in the electrical resistance that occurs due to the growth of a single crack can be differentiated from the increase in the electrical resistance that occurs due to the formation of more than one crack.}, number={1}, journal={Cement and Concrete Composites}, publisher={Elsevier BV}, author={Pour-Ghaz, Mohammad and Weiss, Jason}, year={2011}, month={Jan}, pages={116–123} }
 @article{pour-ghaz_poursaee_spragg_weiss_2011, title={Experimental Methods to Detect and Quantify Damage in Restrained Concrete Ring Specimens}, volume={9}, ISSN={["1347-3913"]}, DOI={10.3151/jact.9.251}, abstractNote={This paper describes the use of three experimental methods to detect shrinkage cracking in restrained ring specimens. These methods include monitoring the strain at the inner surface of the restraining steel ring, using passive acoustic emission, and measuring the electrical resistance of conductive materials that are applied to the surface of the mortar. The methods for detecting cracking are compared and their advantages and limitations are discussed. Both plain and steel fiber reinforced (2% steel fiber by volume) mortar were evaluated in this study. The time of through cracking detected by the three methods corresponds to the time of visible cracking. In the mixtures containing fibers the time of through cracking is delayed significantly when compared to the plain systems. The delay in the age of through cracking can be explained by the role of fibers in arresting the cracks as they develop and their role in transferring stress across the crack width that keeps the cracks from opening. The passive acoustic emission data indicates substantial damage development before a through crack forms. The time of through cracking can be detected using conductive surfaces with a sudden increase in resistance of these conductive elements. Cracking can be detected using conductive coatings when the crack is 0.02 mm or larger. Specimens with different degrees of restraint show through cracking at approximately the same stress level; however, the age at which cracking occurs decreases as the degree of restraint increases. This can be attributed to the increased micro-cracking (i.e., damage and precritical crack growth) as confirmed with acoustic emission data.}, number={3}, journal={JOURNAL OF ADVANCED CONCRETE TECHNOLOGY}, author={Pour-Ghaz, Mohammad and Poursaee, Amir and Spragg, Robert and Weiss, Jason}, year={2011}, month={Oct}, pages={251–260} }
 @article{raoufi_pour-ghaz_poursaee_weiss_2011, title={Restrained Shrinkage Cracking in Concrete Elements: Role of Substrate Bond on Crack Development}, volume={23}, ISSN={0899-1561 1943-5533}, url={http://dx.doi.org/10.1061/(asce)mt.1943-5533.0000247}, DOI={10.1061/(asce)mt.1943-5533.0000247}, abstractNote={Several specimen geometries have been used to assess restrained shrinkage-cracking behavior of concrete materials. This paper used a series of restrained slab tests to illustrate the importance of specimen geometry on the restrained shrinkage cracking behavior. While restraint was provided along the base of the slab, a portion of the slab was left unbonded to the base in the center of the specimen. The length of this unbonded portion was varied to demonstrate its impact on the age of cracking and crack width that occurred. The age of cracking was measured using visual analysis, image analysis, conductive surface coating, and acoustic emission. Whereas image analysis and conductive paint detect cracks only after they appear on the surface, acoustic emission also provides information on damage development before the cracks were visible. Cracking occurred in a less stable fashion in slabs with a larger unbonded region. The larger unbonded length in a slab caused wider cracks to appear at an earlier age than in a slab with a smaller unbonded region.}, number={6}, journal={Journal of Materials in Civil Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Raoufi, Kambiz and Pour-Ghaz, Mohammad and Poursaee, Amir and Weiss, Jason}, year={2011}, month={Jun}, pages={895–902} }
 @article{pour-ghaz_kim_nadukuru_o’connor_michalowski_bradshaw_green_lynch_poursaee_weiss_2011, title={Using electrical, magnetic and acoustic sensors to detect damage in segmental concrete pipes subjected to permanent ground displacement}, volume={33}, ISSN={0958-9465}, url={http://dx.doi.org/10.1016/j.cemconcomp.2011.04.004}, DOI={10.1016/j.cemconcomp.2011.04.004}, abstractNote={This paper describes results of an experimental study that used sensing methods for monitoring damage along segmental concrete pipelines resulting from permanent ground displacement across a simulated earthquake fault. The literature contains examples of such damage occurring during actual earthquakes, significantly impacting the functionality of the pipelines. Detecting the location of the damage and the extent of the damage in pipelines can significantly accelerate post-earthquake repair efforts. In this paper, electrical sensing methods, magnetic sensing, and acoustic emission are used to monitor structural damage in a segmental concrete pipeline during a large-scale test. In this test, the segmental concrete pipeline was subjected to a concentrated transverse permanent ground displacements (PGDs). The majority of the damage to the pipe segments was localized at the joints, especially the bell sections while the damage to the spigots was minimal. The damage extended away from the joints in the pipe segments in the immediate vicinity of the fault line. Telescoping (i.e., crushing of the bell-and-spigot) was a primary mode of failure that was observed. The results of this study indicate that electrical sensing methods (including the use of conductive grout), magnetic sensing, and acoustic emission, employed alone or in combination, can detect and quantify the damage in segmental concrete pipelines.}, number={7}, journal={Cement and Concrete Composites}, publisher={Elsevier BV}, author={Pour-Ghaz, Mohammad and Kim, Junhee and Nadukuru, Srinivasa S. and O’Connor, Sean M. and Michalowski, Radoslaw L. and Bradshaw, Aaron S. and Green, Russell A. and Lynch, Jerome P. and Poursaee, Amir and Weiss, W. Jason}, year={2011}, month={Aug}, pages={749–762} }
 @article{spragg_castro_li_pour-ghaz_huang_weiss_2011, title={Wetting and drying of concrete using aqueous solutions containing deicing salts}, volume={33}, ISSN={0958-9465}, url={http://dx.doi.org/10.1016/j.cemconcomp.2011.02.009}, DOI={10.1016/j.cemconcomp.2011.02.009}, abstractNote={A series of wetting and drying tests were performed on concrete using different aqueous solutions containing deicing salts. The rate of fluid absorption was generally lower for aqueous solutions containing deicing salts than it was for water. In addition, less fluid was absorbed for samples exposed to aqueous solutions containing deicing salts than for samples exposed to water. The change in the rate of aqueous fluid absorption was proportional to the square root of the ratio of surface tension and viscosity of the absorbed fluid. Concrete that has been exposed to solutions containing deicing salts showed less mass loss during drying. Measures of equilibrium relative humidity over the salt solutions are used to interpret drying behavior. Experimental data indicates that concretes that had previously been exposed to deicing solutions can also exhibit reduced rate of absorption, even if water is the fluid being absorbed.}, number={5}, journal={Cement and Concrete Composites}, publisher={Elsevier BV}, author={Spragg, Robert P. and Castro, Javier and Li, Wenting and Pour-Ghaz, Mohammad and Huang, Pao-Tsung and Weiss, Jason}, year={2011}, month={May}, pages={535–542} }
 @article{pour-ghaz_isgor_ghods_2009, title={Quantitative Interpretation of Half-Cell Potential Measurements in Concrete Structures}, volume={21}, ISSN={0899-1561 1943-5533}, url={http://dx.doi.org/10.1061/(asce)0899-1561(2009)21:9(467)}, DOI={10.1061/(asce)0899-1561(2009)21:9(467)}, abstractNote={The interpretation of half-cell potential measurements in reinforced concrete structures can be a major challenge for civil engineers. The main reason for this is that half-cell potential mapping provides information to predict the probability of corrosion in concrete, but it does not give clear insight on the rate and the nature of corrosion. Although for general uniform corrosion, half-cell data can provide valuable information about the probability of corrosion. In the case of localized corrosion, the predictions of half-cell measurements can be misleading. The main objective of the present work is to provide practicing engineers a tool that they can use to better interpret the results of half-cell potential measurements. This tool quantitatively relates the potential readings on the surface of the concrete to the rate of probable localized reinforcement corrosion through concrete resistivity, cover thickness, and temperature, allowing the engineers to gain supplementary information from half-cell tests. Experimental comparisons presented in this paper demonstrate the potential benefits of the proposed approach when typical half-cell measurements may not be able to predict the localized corrosion mechanism.}, number={9}, journal={Journal of Materials in Civil Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Pour-Ghaz, Mohammad and Isgor, O. Burkan and Ghods, Pouria}, year={2009}, month={Sep}, pages={467–475} }
 @article{pour-ghaz_isgor_ghods_2009, title={The effect of temperature on the corrosion of steel in concrete. Part 1: Simulated polarization resistance tests and model development}, volume={51}, ISSN={0010-938X}, url={http://dx.doi.org/10.1016/j.corsci.2008.10.034}, DOI={10.1016/j.corsci.2008.10.034}, abstractNote={The effect of temperature on the corrosion rate of steel corrosion in concrete is investigated through simulated polarization resistance experiments. The simulated experiments are based on the numerical solution of the Laplace’s equation with predefined boundary conditions of the problem and have been designed to establish independent correlations among corrosion rate, temperature, kinetic parameters, concrete resistivity and limiting current density for a wide range of possible anode/cathode (A/C) distributions on the reinforcement. The results, which successfully capture the resistance and diffusion control mechanisms of corrosion as well as the effect of temperature on the kinetic parameters and concrete/pore solution properties, have been used to develop a closed-form regression model for the prediction of the corrosion rate of steel in concrete.}, number={2}, journal={Corrosion Science}, publisher={Elsevier BV}, author={Pour-Ghaz, M. and Isgor, O. Burkan and Ghods, P.}, year={2009}, month={Feb}, pages={415–425} }
 @article{pour-ghaz_burkan isgor_ghods_2009, title={The effect of temperature on the corrosion of steel in concrete. Part 2: Model verification and parametric study}, volume={51}, ISSN={0010-938X}, url={http://dx.doi.org/10.1016/j.corsci.2008.10.036}, DOI={10.1016/j.corsci.2008.10.036}, abstractNote={A comprehensive model for predicting the corrosion rate of steel in concrete has been developed using the concept of simulated polarization resistance experiments. This model is developed by carrying out a nonlinear regression analysis on data obtained from numerical experiments that are based on the solution of Laplace’s equation in a domain determined by the polarized length of the rebar. This part of the paper provides a comprehensive verification of the developed model and illustrates the application of the model to investigate the coupled effects of parameters affecting corrosion of steel in concrete. The results of the verification study show that the model predictions are in good agreement with the experimental data.}, number={2}, journal={Corrosion Science}, publisher={Elsevier BV}, author={Pour-Ghaz, M. and Burkan Isgor, O. and Ghods, P.}, year={2009}, month={Feb}, pages={426–433} }
 @article{ghods_isgor_pour-ghaz_2007, title={A practical method for calculating the corrosion rate of uniformly depassivated reinforcing bars in concrete}, volume={58}, ISSN={0947-5117 1521-4176}, url={http://dx.doi.org/10.1002/maco.200604010}, DOI={10.1002/maco.200604010}, abstractNote={Abstract}, number={4}, journal={Materials and Corrosion}, publisher={Wiley}, author={Ghods, P. and Isgor, O.B. and Pour-Ghaz, M.}, year={2007}, month={Apr}, pages={265–272} }
 @article{ghods_isgor_pour-ghaz_2007, title={Experimental verification and application of a practical corrosion model for uniformly depassivated steel in concrete}, volume={41}, ISSN={1359-5997 1871-6873}, url={http://dx.doi.org/10.1617/s11527-007-9320-3}, DOI={10.1617/s11527-007-9320-3}, number={7}, journal={Materials and Structures}, publisher={Springer Science and Business Media LLC}, author={Ghods, Pouria and Isgor, O. Burkan and Pour-Ghaz, Mohammad}, year={2007}, month={Oct}, pages={1211–1223} }
 @inproceedings{pour-ghaz_isgor_ghods_2007, title={Virtual Experiments to Investigate Steel Corrosion in Concrete}, ISBN={9780784409374}, url={http://dx.doi.org/10.1061/40937(261)64}, DOI={10.1061/40937(261)64}, abstractNote={Virtual experiments are one of the integral parts of the advanced civil engineering practice since they eliminate time-consuming and expensive laboratory studies, and they are useful for educational and training purposes. In the present work, a number of virtual experiments for investigating the corrosion of reinforcement in concrete are designed, and the effect of different parameters on the corrosion process is examined. The design of the experiments is based on non-linear solution of Laplace's equation with polarized surface boundary conditions by the finite element method, for which an under-relaxation technique is implemented. Using the results of the virtual experiments, a closed-form solution for the considered domain is obtained. By using this solution, the effect of a number of factors that affect the corrosion process can be investigated; an example of this investigation is presented. These experiments can also be effectively used for service life design and structural health and integration monitoring purposes; these two approaches are discussed in detail.}, booktitle={Computing in Civil Engineering (2007)}, publisher={American Society of Civil Engineers}, author={Pour-Ghaz, M. and Isgor, O. Burkan and Ghods, P.}, year={2007}, month={Jul} }