Glendale, OH, United States
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Sun X.,Michigan Technological University | Dai Q.,Michigan Technological University | Ng K.,IET Inc.
Construction and Building Materials | Year: 2014

This study applied the Transmission X-ray Microscope (TXM) characterization techniques and permeability-solver computational program to investigate the transport properties of a microscale cement paste specimen. The TXM techniques allow fast-image acquisition of pore microstructure at a resolution of 30 nm. The microscale cement paste specimen with 0.45 water/cement ratio was specially prepared with a capillary tube. The pore microstructure of the microscale paste specimen was characterized by using the Advanced Photon Source at the Argonne National Lab. The image processing technique was conducted to identify the pore distribution in the captured images. The digital samples with different porosities were generated to compute the transport properties. The burning algorithm was employed to estimate the pore connectivity. The finite difference method with artificial compressibility relaxation algorithm was applied to simulate water transport in capillary pores with Stokes equation. The pore permeability was computed with the calculated average flow velocity using Darcy's Law. The computed permeability results of digital samples were also compared with the predicted values from the Katz-Thompson equation to demonstrate the computational accuracy. © 2014 Elsevier Ltd. All rights reserved.


Dai Q.,Michigan Technological University | Ng K.,Michigan Technological University | Ng K.,IET Inc.
Construction and Building Materials | Year: 2014

This paper presents two-dimensional (2D) cohesive zone modeling (CZM) techniques to simulate microscale crack propagation with cementitious digital samples under various loading conditions. The 2D multiphase bilinear cohesive zone models were employed to investigate the fracture behavior within heterogeneous cementitious material samples. The microstructure of concrete and cement paste samples were characterized with scanned surface (SS) and scanning electron microscope (SEM) imaging techniques, respectively. The digital concrete sample was generated from gray-scale SS images in millimeter. The single-edge notched beam (SEB) simulation on crack propagation within aggregate-cement microstructure was favorably compared with the tested sample. The digital cement samples with pores and unhydrated cement particles were generated from SEM images in micron scale. The compact tension (CT) test was simulated to predict crack propagation through pores. The study finally simulated the internal frost damage caused by ice crystallization with the SEM digital sample. The pore pressure calculated from thermodynamic analysis was input for model simulation. The CZM predicted the crack initiation and propagation within cement microstructure. The favorably predicted crack paths in concrete and cement paste samples indicate the developed CZM techniques have the ability to capture crack initiation and propagation in concrete or cement microstructure system with multiphase and associated interfaces. © 2014 Elsevier Ltd. All rights reserved.


Ng K.,IET Inc. | Sun Y.,Case Western Reserve University | Dai Q.,Michigan Technological University | Yu X.,Case Western Reserve University
Construction and Building Materials | Year: 2014

This study investigates the internal-frost damage due to the development of ice crystallization pressure in the capillary pores of concrete. The SEM imaging analysis, microdamage modeling and ultrasonic wave scattering techniques were developed and integrated to study the internal-frost damage in cementitious material samples. The pore structures have significant impacts on the freeze-thaw durability of cement/concrete specimens. The scanning electron microscope (SEM) techniques were applied to characterize the microstructure of concrete as well as the patterns of freeze-thaw damage within the pore structure. The digital sample was generated by processing the SEM images. In the microscale pore system, the development of crystallization pressures at subcooling temperatures were calculated using the interface energy balance with the principles of thermodynamics. The largest crystallization pressure on the pore wall was used for the fracture simulation with the developed Extended Finite Element Model (XFEM). The comparison study between model simulation and test results indicates that the internal-frost damage model can reasonably predict the crack nucleation and propagation within multiphase cement microstructure. In addition, the ultrasonic wave scattering technique was developed for rapid measurement of the pore size distribution and volume fraction of the air in cementitious concrete, which provided important inputs to simplify the computational model for materials damages simulations. The inverse analysis results show the promising measurements of size distribution of pores in concrete samples. Future study can link the micromechanics analysis and the ultrasonic wave scattering techniques to provide a full-blown study on the internal-frost damage evolution mechanisms. © 2013 Elsevier Ltd. All rights reserved.


Trademark
I.E.T. Inc. | Date: 2014-02-12

Electro-chemical activation equipment for the production of anolyte and catholyte solutions.


Trademark
I.E.T. Inc. | Date: 2014-02-12

Electro-chemical activation equipment for the production of anolyte and catholyte solutions.


Trademark
IET Inc. | Date: 2016-08-19

Sanitizing preparations for commercial and household use; Sanitizing preparations for use in institutional and industrial areas; Cleansing solutions for medical use. Electronic equipment, namely, electrolysis cell for use in the manufacture of various ionic solutions; Electrolysers. Water purification units.


Trademark
IET Inc. | Date: 2016-08-19

Sanitizing preparations for commercial and household use; Sanitizing preparations for use in institutional and industrial areas; Cleansing solutions for medical use. Electronic equipment, namely, electrolysis cell for use in the manufacture of various ionic solutions; Electrolysers. Water purification units.


Trademark
I.E.T. Inc. | Date: 2013-04-18

Anolyte solutions.


Trademark
I.E.T. Inc. | Date: 2013-04-18

Anolyte solutions.


Trademark
I.E.T. Inc. | Date: 2013-08-20

Biocides, germicides, bactericides, virucides, fungicides, insecticides, pesticides and herbicides.

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