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Calcium-silicate-hydrate (C–S–H) represents a key microstructural phase that governs the mechanical properties of concrete at a large scale. Defects in the C–S–H phase are also responsible for the poor ductility and low tensile strength of concrete. Manipulating the microstructure of C–S–H can lead to new cementitious materials with improved structural performance. This paper presents an experimental investigation aiming to characterize a new synthetic polymer-modified synthetic calcium-silicate-hydrate (C–S–H)/styrene-butadiene rubber (SBR) binder. The new C–S–H/SBR binder is produced by calcining calcium carbonate and mixing this with fumed silica (SiO2), deionized water and SBR. Mechanical, physical, chemical and microstructural characterization was conducted to measure the properties of new hardened C–S–H binder. Results from the experimental investigation demonstrate the ability to engineer a new C–S–H binder with low elastic modulus and improved toughness and bond strength by controlling the SBR content and method of C–S–H synthesis. The new binder suggests the possible development of a new family of low-modulus silica-polymer binders that might fit many engineering applications such as cementing oil and gas wells.
J. Starr; E.M. Soliman; E.N. Matteo; T. Dewers; J.C. Stormont; M.M. Reda Taha. Mechanical characterization of low modulus polymer-modified calcium-silicate-hydrate (C–S–H) binder. Cement and Concrete Composites 2021, 124, 104219 .
AMA StyleJ. Starr, E.M. Soliman, E.N. Matteo, T. Dewers, J.C. Stormont, M.M. Reda Taha. Mechanical characterization of low modulus polymer-modified calcium-silicate-hydrate (C–S–H) binder. Cement and Concrete Composites. 2021; 124 ():104219.
Chicago/Turabian StyleJ. Starr; E.M. Soliman; E.N. Matteo; T. Dewers; J.C. Stormont; M.M. Reda Taha. 2021. "Mechanical characterization of low modulus polymer-modified calcium-silicate-hydrate (C–S–H) binder." Cement and Concrete Composites 124, no. : 104219.
Emerging technologies (ETs) are increasingly becoming more accessible, and as they make their way into the field will be an integral part of the engineering community’s work that impacts future civil infrastructure. In the meantime, infrastructure resilience has become a recurring theme in government and industry discussions. ETs are expected to contribute to improving infrastructure resilience capacities, namely, absorptive, adaptive, and restorative. Through an extensive literature review, an in-depth conspectus of the state of the art of ETs in civil engineering is provided, leading to a vision for how these technologies impact infrastructure resilience. Three distinct disruptive technologies that can impact infrastructure resilience are demonstrated—specifically, smart materials, advanced construction technology, and advanced sensing technology. Such ETs will remarkably affect the well-known four characteristic elements of infrastructure resilience: redundancy, robustness, rapidity, and resourcefulness. These innovative technologies will warrant infrastructure to withstand or efficiently recover from multihazard disruptive events, leading to improved resilience. A roadmap to field implementation is presented considering the financial cycles necessary for ETs to make an impact on infrastructure resilience.
Mahmoud Reda Taha; Bilal M. Ayyub; Kenichi Soga; Sherif Daghash; Daniel Heras Murcia; Fernando Moreu; Eslam Soliman. Emerging Technologies for Resilient Infrastructure: Conspectus and Roadmap. ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A: Civil Engineering 2021, 7, 03121002 .
AMA StyleMahmoud Reda Taha, Bilal M. Ayyub, Kenichi Soga, Sherif Daghash, Daniel Heras Murcia, Fernando Moreu, Eslam Soliman. Emerging Technologies for Resilient Infrastructure: Conspectus and Roadmap. ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A: Civil Engineering. 2021; 7 (2):03121002.
Chicago/Turabian StyleMahmoud Reda Taha; Bilal M. Ayyub; Kenichi Soga; Sherif Daghash; Daniel Heras Murcia; Fernando Moreu; Eslam Soliman. 2021. "Emerging Technologies for Resilient Infrastructure: Conspectus and Roadmap." ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A: Civil Engineering 7, no. 2: 03121002.
Dave Butry; Craig A. Davis; Sanjeev R. Malushte; Ricardo A. Medina; Mahmoud Reda Taha; John W. Van de Lindt; Cory R. Brett; Sherif Daghash; Caroline Field; Juan Fung; Paolo Gardoni; Sue McNeil; Fernando Moreu; Ali Mostatavi; Yalda Saadat; Neetesh Sharma; Kenichi Soga; Eslam Soliman; Elaina J. Sutley; Armin Tabandeh; Douglas Thomas; Eric Vugrin; Richard N. Wright. Hazard-Resilient Infrastructure. Hazard-Resilient Infrastructure 2021, 1 .
AMA StyleDave Butry, Craig A. Davis, Sanjeev R. Malushte, Ricardo A. Medina, Mahmoud Reda Taha, John W. Van de Lindt, Cory R. Brett, Sherif Daghash, Caroline Field, Juan Fung, Paolo Gardoni, Sue McNeil, Fernando Moreu, Ali Mostatavi, Yalda Saadat, Neetesh Sharma, Kenichi Soga, Eslam Soliman, Elaina J. Sutley, Armin Tabandeh, Douglas Thomas, Eric Vugrin, Richard N. Wright. Hazard-Resilient Infrastructure. Hazard-Resilient Infrastructure. 2021; ():1.
Chicago/Turabian StyleDave Butry; Craig A. Davis; Sanjeev R. Malushte; Ricardo A. Medina; Mahmoud Reda Taha; John W. Van de Lindt; Cory R. Brett; Sherif Daghash; Caroline Field; Juan Fung; Paolo Gardoni; Sue McNeil; Fernando Moreu; Ali Mostatavi; Yalda Saadat; Neetesh Sharma; Kenichi Soga; Eslam Soliman; Elaina J. Sutley; Armin Tabandeh; Douglas Thomas; Eric Vugrin; Richard N. Wright. 2021. "Hazard-Resilient Infrastructure." Hazard-Resilient Infrastructure , no. : 1.
The stiffness of wellbore cement fracture surfaces was measured after exposing to the advective flow of nitrogen, silicone oil, and medium sweet dead crude oil for different exposure periods. The test specimens were extracted from fractured cement cylinders, where the cement fracture surfaces were exposed to the different fluids up to 15 weeks. A nanoindenter with a Berkovich indenter tip was used to measure load-indentation depth data, which was used to extract the elastic modulus (E) and nano-hardness (H) of the cement fracture surfaces. A reduction in the elastic modulus compared with an unexposed specimen were observed in all the specimens. Both elastic modulus and nano-hardness for the specimens exposed to silicone oil were lower than specimens exposed to nitrogen gas and varied with the period of exposure. The elastic modulus and nano-hardness of the specimens exposed to crude oil were the lowest with a significant decrement with the exposure period. The frequency distribution of the nanoindentation measurements shows that the volume-fraction ratio of the two types of cement hydrated nanocomposites for both the unexposed and test specimens is about 70:30%. Phase transformation beneath the indenter is observed for all of the specimens, with more obvious plastic deformation in specimens exposed to crude oil. Analytical measurements (SEM, EDS, FT-IR, and XRD) on exposed cement fracture surfaces reveal different levels of physical and chemical alteration that are consistent with the reduction in stiffness measured by nanoindentation. The study suggests that cement stiffness will decrease due to crude oil exposure, and the fracture will be sensitive to stress and pore pressure with time.
Ishtiaque Anwar; Mahya Hatambeigi; Kirsten Chojnicki; Mahmoud Reda Taha; John C. Stormont. Alteration in micro-mechanical characteristics of wellbore cement fracture surfaces due to fluid exposure. Journal of Petroleum Science and Engineering 2021, 205, 108935 .
AMA StyleIshtiaque Anwar, Mahya Hatambeigi, Kirsten Chojnicki, Mahmoud Reda Taha, John C. Stormont. Alteration in micro-mechanical characteristics of wellbore cement fracture surfaces due to fluid exposure. Journal of Petroleum Science and Engineering. 2021; 205 ():108935.
Chicago/Turabian StyleIshtiaque Anwar; Mahya Hatambeigi; Kirsten Chojnicki; Mahmoud Reda Taha; John C. Stormont. 2021. "Alteration in micro-mechanical characteristics of wellbore cement fracture surfaces due to fluid exposure." Journal of Petroleum Science and Engineering 205, no. : 108935.
Strength of rocks in the confined tension region, where the minimum principal stress is tensile, has only infrequently been measured and is not well understood. Quasi-static confined Brazilian tests under a range of confining stresses (2.76 to 27.58 MPa) where used to determine the strength of sandstone in the confined tension region. The test results indicate that the strength in the confined tension region was a strong function of the intermediate principal stress: increasing the intermediate principal stress significantly increased the strength of the sandstone. The strength data were well fit by the Mogi–Coulomb criterion, which accounts for the intermediate principal stress. Unconfined Brazilian strength data were not well fit to the Mogi–Coulomb criterion derived from the confined Brazilian test data, consistent with a transition from tensile to shear processes dominating failure with increasing confining pressure. Observations of post-failure fracture surfaces reveal more indication of shear processes with increasing confining pressure. Numerical simulations from combined finite-discrete element method are compared to the experimental results and reflect similar conditions for failure compared to the experimental tests in the confined tension region.
Tyler Hagengruber; Mahmoud Reda Taha; Esteban Rougier; Earl Knight; John Stormont. Failure in Confined Brazilian Tests on Sandstone. Applied Sciences 2021, 11, 2285 .
AMA StyleTyler Hagengruber, Mahmoud Reda Taha, Esteban Rougier, Earl Knight, John Stormont. Failure in Confined Brazilian Tests on Sandstone. Applied Sciences. 2021; 11 (5):2285.
Chicago/Turabian StyleTyler Hagengruber; Mahmoud Reda Taha; Esteban Rougier; Earl Knight; John Stormont. 2021. "Failure in Confined Brazilian Tests on Sandstone." Applied Sciences 11, no. 5: 2285.
Cement is widely used in wellbores to stabilize the steel casing used in wellbore operations for oil and gas production, enhanced geothermal systems and carbon sequestration, and to limit fluid movement between sub-surface strata. Flaws such as microcracks in wellbore cement can lead to leakage along the wellbore compromising wellbore integrity. There is an increasing need for methods to monitor cement crack propagation in wellbore environments. In this study, we develop and report the first cementitious sensors capable of exhibiting high frequency acoustic bandgaps (ABGs) using carbon nanotubes. Computational simulations of a sensor unit cell are used to design cement-MWCNTs sensors that show a wide bandgap. When the cement-MWCNTs sensors is embedded in cement specimens, bandgaps were measured experimentally under 300 kHz and under 600 kHz, consistent with the computationally predicted bandgaps in the range of 290 – 360 kHz, 410 – 460 kHz and 515 – 585 kHz. These bandgap features were absent in homogeneous cement specimens. X-ray tomographic reconstructions showed microscopic debonding at cement-MWCNTs sensor interface. Frequency response analysis of a three-dimensional computational model indicated a shift of frequency of minimum transmission due to the interface debonding, but no perturbation of bandgap response was observed. The cement-MWCNTs sensors developed in this study show the potential of a packed carbon nanotube inclusion material in cementitious matrix to create ABGs in a cement matrix.
Shreya Vemuganti; John C Stormont; Laura J. Pyrak-Nolte; Thomas Dewers; Mahmoud Reda Taha. Cement sensors with acoustic bandgaps using carbon nanotubes. Smart Materials and Structures 2021, 30, 035011 .
AMA StyleShreya Vemuganti, John C Stormont, Laura J. Pyrak-Nolte, Thomas Dewers, Mahmoud Reda Taha. Cement sensors with acoustic bandgaps using carbon nanotubes. Smart Materials and Structures. 2021; 30 (3):035011.
Chicago/Turabian StyleShreya Vemuganti; John C Stormont; Laura J. Pyrak-Nolte; Thomas Dewers; Mahmoud Reda Taha. 2021. "Cement sensors with acoustic bandgaps using carbon nanotubes." Smart Materials and Structures 30, no. 3: 035011.
Glass fiber-reinforced polymer (GFRP) reinforcing bars have relatively low shear strength, which limits their possible use in civil infrastructure applications with high shear demand, such as concrete reinforcing dowels. We suggest that the horizontal shear strength of GFRP bars can be significantly improved by nanomodification of the vinyl ester resin prior to pultrusion. The optimal content of functionalized multiwalled carbon nanotubes (MWCNTs) well dispersed into the vinyl ester resin was determined using viscosity measurements and scanning electron micrographs. Longitudinal tension and short beam shear tests were conducted to determine the horizontal shear strength of the nanomodified GFRP reinforcing bars. While the tensile strength of the GFRP reinforcing bars was improved by 20%, the horizontal shear strength of the bars was improved by 111% compared with the shear strength of neat GFRP bars pultruded using the same settings. Of special interest is the absence of the typical broom failure observed in GFRP when MWCNTs were used. Differential scanning calorimetry measurements and fiber volume fraction confirmed the quality of the new pultruded GFRP bars. Fourier-transform infrared (FTIR) measurements demonstrated the formation of carboxyl stretching in nanomodified GFRP bars, indicating the formation of a new chemical bond. The new pultrusion process using nanomodified vinyl ester enables expanding the use of GFRP reinforcing bars in civil infrastructure applications.
Shreya Vemuganti; Rahulreddy Chennareddy; Amr Riad; Mahmoud M. Reda Taha. Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester. Materials 2020, 13, 5710 .
AMA StyleShreya Vemuganti, Rahulreddy Chennareddy, Amr Riad, Mahmoud M. Reda Taha. Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester. Materials. 2020; 13 (24):5710.
Chicago/Turabian StyleShreya Vemuganti; Rahulreddy Chennareddy; Amr Riad; Mahmoud M. Reda Taha. 2020. "Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester." Materials 13, no. 24: 5710.
Measurement of bridge displacements is important for ensuring the safe operation of railway bridges. Traditionally, contact sensors such as Linear Variable Displacement Transducers (LVDT) and accelerometers have been used to measure the displacement of the railway bridges. However, these sensors need significant effort in installation and maintenance. Therefore, railroad management agencies are interested in new means to measure bridge displacements. This research focuses on mounting Laser Doppler Vibrometer (LDV) on an Unmanned Aerial System (UAS) to enable contact-free transverse dynamic displacement of railroad bridges. Researchers conducted three field tests by flying the Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV) 1.5 m away from the ground and measured the displacement of a moving target at various distances. The accuracy of the UAS-LDV measurements was compared to the Linear Variable Differential Transducer (LVDT) measurements. The results of the three field tests showed that the proposed system could measure non-contact, reference-free dynamic displacement with an average peak and root mean square (RMS) error for the three experiments of 10% and 8% compared to LVDT, respectively. Such errors are acceptable for field measurements in railroads, as the interest prior to bridge monitoring implementation of a new approach is to demonstrate similar success for different flights, as reported in the three results. This study also identified barriers for industrial adoption of this technology and proposed operational development practices for both technical and cost-effective implementation.
Piyush Garg; Roya Nasimi; Ali Ozdagli; Su Zhang; David Dennis Lee Mascarenas; Mahmoud Reda Taha; Fernando Moreu. Measuring Transverse Displacements Using Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV): Development and Field Validation. Sensors 2020, 20, 6051 .
AMA StylePiyush Garg, Roya Nasimi, Ali Ozdagli, Su Zhang, David Dennis Lee Mascarenas, Mahmoud Reda Taha, Fernando Moreu. Measuring Transverse Displacements Using Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV): Development and Field Validation. Sensors. 2020; 20 (21):6051.
Chicago/Turabian StylePiyush Garg; Roya Nasimi; Ali Ozdagli; Su Zhang; David Dennis Lee Mascarenas; Mahmoud Reda Taha; Fernando Moreu. 2020. "Measuring Transverse Displacements Using Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV): Development and Field Validation." Sensors 20, no. 21: 6051.
Additive manufacturing relies on the deposition of layers of material upon existing ones. The nature of this method disadvantages materials such as concrete due to the rheological changes of the material over time, the lack of standardization of the printing process, and the nature of the deposition process. This paper examines the significance of infill printing patterns on the anisotropic properties of 3D printed concrete. The rheological properties, the compressive strength, and the interlayer and interfilamentous bond strength of the 3D printed concrete were characterized. We show that there is a directional dependency on all the infill patterns. The specimens show lower compressive strength, and modulus of elasticity in the Z (extrusion) direction compared with the X and Y directions but insignificant difference of the strength and modulus between the X and Y directions. However, no directional dependency was found for the strain at failure. On the other hand, no significant difference in the mechanical properties of 3D printed concrete was observed or can be attributed to the infill printing patterns. The results also show that the 3D printed concrete shows higher compressive strength, for two out of the three testing directions (X and Y) than conventionally cast concrete. This is due to the compactness associated with the printing process that is strongly dependent on the printing parameters.
Daniel Heras Murcia; Moneeb Genedy; M.M. Reda Taha. Examining the significance of infill printing pattern on the anisotropy of 3D printed concrete. Construction and Building Materials 2020, 262, 120559 .
AMA StyleDaniel Heras Murcia, Moneeb Genedy, M.M. Reda Taha. Examining the significance of infill printing pattern on the anisotropy of 3D printed concrete. Construction and Building Materials. 2020; 262 ():120559.
Chicago/Turabian StyleDaniel Heras Murcia; Moneeb Genedy; M.M. Reda Taha. 2020. "Examining the significance of infill printing pattern on the anisotropy of 3D printed concrete." Construction and Building Materials 262, no. : 120559.
The use of fiber-reinforced polymer (FRP) composite materials are continuously growing in civil infrastructure due to their high strength, low weight, and manufacturing flexibility. However, FRP is characterized by sudden failure and lacks ductility. When used in construction, gradual failure of FRP components is desired to avoid catastrophic structural collapse. Due to its mechanical orthotropy, the behavior of FRP relies significantly on fiber orientation and stacking sequence. In this paper, a novel multi-angled glass fiber reinforced polymer (GFRP) composite laminate showing pseudo ductile behavior is produced using 3D-printing. This is accomplished by varying fiber orientation angles, stacking sequence, and thickness of lamina. Single-angled GFRP composite specimens were 3D-printed with different fiber orientation angles of 0°, 12°, 24°, 30°, 45°, and 90° using continuous and fused filament techniques. The tension test results of the single-angled specimens were then used to aid the design of multi-angled laminate for potential progressive failure behavior. A 3D finite element (FE) model was developed to predict the response of the experimental results and to provide insight into the failure mechanism of the multi-angled laminate. The experimental observations and the FE simulations show the possibility of producing pseudo ductile FRP-by-design composite using 3D-printing technology, which leads the way to fabricate next-generation composites for civil infrastructure.
Shreya Vemuganti; Eslam Soliman; Mahmoud Reda Taha. 3D-Printed Pseudo Ductile Fiber-Reinforced Polymer (FRP) Composite Using Discrete Fiber Orientations. Fibers 2020, 8, 53 .
AMA StyleShreya Vemuganti, Eslam Soliman, Mahmoud Reda Taha. 3D-Printed Pseudo Ductile Fiber-Reinforced Polymer (FRP) Composite Using Discrete Fiber Orientations. Fibers. 2020; 8 (9):53.
Chicago/Turabian StyleShreya Vemuganti; Eslam Soliman; Mahmoud Reda Taha. 2020. "3D-Printed Pseudo Ductile Fiber-Reinforced Polymer (FRP) Composite Using Discrete Fiber Orientations." Fibers 8, no. 9: 53.
M. R. Sakr; M. T. Bassuoni; Mahmoud M. Reda Taha. Effect of Coatings on Concrete Resistance to Physical Salt Attack. ACI Materials Journal 2019, 116, 1 .
AMA StyleM. R. Sakr, M. T. Bassuoni, Mahmoud M. Reda Taha. Effect of Coatings on Concrete Resistance to Physical Salt Attack. ACI Materials Journal. 2019; 116 (6):1.
Chicago/Turabian StyleM. R. Sakr; M. T. Bassuoni; Mahmoud M. Reda Taha. 2019. "Effect of Coatings on Concrete Resistance to Physical Salt Attack." ACI Materials Journal 116, no. 6: 1.
Degradation due to exposure to ultraviolet (UV) radiation is an important durability challenge with glass fiber reinforced polymer (GFRP) composite. Design and construction guidelines of GFRP suggest using UV protection paint to prevent GFRP degradation. In this study we examine the possible use of multi-walled carbon nanotubes (MWCNTs) dispersed in epoxy matrix to produce UV-resistant GFRP composite. We suggest that MWCNTs can result in a significant improvement to UV degradation resistance in the GFRP. Direct tension tests of GFRP coupons incorporating 0.25 wt%, 0.50 wt%, and 1.0 wt% of MWCNTs show inherent stability and good resistance to UV degradation. Microstructural analysis shows the ability of MWCNTs to resist polymer backbone disassociation caused by UV radiation thus preventing UV degradation in GFRP. Scanning electron microscopy (SEM) images show MWCNTs can resist microcracking caused by UV radiation and thus improve UV degradation resistance of GFRP.
Rahulreddy Chennareddy; Hesham Tuwair; Usama F. Kandil; Mohamed ElGawady; M.M. Reda Taha. UV-resistant GFRP composite using carbon nanotubes. Construction and Building Materials 2019, 220, 679 -689.
AMA StyleRahulreddy Chennareddy, Hesham Tuwair, Usama F. Kandil, Mohamed ElGawady, M.M. Reda Taha. UV-resistant GFRP composite using carbon nanotubes. Construction and Building Materials. 2019; 220 ():679-689.
Chicago/Turabian StyleRahulreddy Chennareddy; Hesham Tuwair; Usama F. Kandil; Mohamed ElGawady; M.M. Reda Taha. 2019. "UV-resistant GFRP composite using carbon nanotubes." Construction and Building Materials 220, no. : 679-689.
Prefabricated concrete bridge deck panels are utilized in Accelerated Bridge Construction (ABC) to simplify bridge deck construction. Concrete with good bond and shear strength as well as excellent flowability is required to fill bridge deck closure joints. This paper discusses the use of polymer concrete (PC) for bridge deck closure joints in ABC. PC produced using poly methyl methacrylate and standard aggregate was tested. Test results of PC are compared to Ultra-High Performance Concrete (UHPC). Development length, lap splice length and shear strength of unreinforced PC were tested. It is shown that PC has a development length of 3.6 to 4.1 times the reinforcing bar diameter that is close to one-half the development length of 6 to 8 times the bar diameter required with UHPC. PC also showed a shorter splice length compared with that reported for UHPC. Finally, unreinforced PC showed shear strength that is twice that of UHPC. It is evident that using PC in bridge deck closure joints in ABC can improve constructability and provide cost-savings and eliminate reinforcing bar congestion.
Islam Mantawy; Rahulreddy Chennareddy; Moneeb Genedy; Mahmoud Reda Taha. Polymer Concrete for Bridge Deck Closure Joints in Accelerated Bridge Construction. Infrastructures 2019, 4, 31 .
AMA StyleIslam Mantawy, Rahulreddy Chennareddy, Moneeb Genedy, Mahmoud Reda Taha. Polymer Concrete for Bridge Deck Closure Joints in Accelerated Bridge Construction. Infrastructures. 2019; 4 (2):31.
Chicago/Turabian StyleIslam Mantawy; Rahulreddy Chennareddy; Moneeb Genedy; Mahmoud Reda Taha. 2019. "Polymer Concrete for Bridge Deck Closure Joints in Accelerated Bridge Construction." Infrastructures 4, no. 2: 31.
Numerous regulations have been imposed worldwide by governments and environmental organizations in order to reduce the negative environmental impact resulting from large numbers of solid waste landfills. Recycling of industrial by-products is a step toward sustainable waste management. By utilizing ceramic waste powder (CWP) as a partial cement replacement, the construction industry can play a significant role in energy conservation and limit future generations of CO2. This paper examines the feasibility of producing self-compacting concrete (SCC) mixtures yielding acceptable fresh and hardened concrete characteristics with the inclusion of high-volume CWP as partial replacement of cement. The fresh properties of the new SCC are evaluated through various tests (i.e., slump flow, J-ring, column segregation, V-funnel, and L-box). The investigations show a slight reduction in the slump flow but with an enhancement of the other fresh properties. In addition, the use of CWP slightly reduces compressive strength. It is shown that it is possible to produce SCC with acceptable properties incorporating high-volume CWP.
Sama Tarek Aly; Amr Salah El-Dieb; Mahmoud Reda Taha. Effect of High-Volume Ceramic Waste Powder as Partial Cement Replacement on Fresh and Compressive Strength of Self-Compacting Concrete. Journal of Materials in Civil Engineering 2019, 31, 04018374 .
AMA StyleSama Tarek Aly, Amr Salah El-Dieb, Mahmoud Reda Taha. Effect of High-Volume Ceramic Waste Powder as Partial Cement Replacement on Fresh and Compressive Strength of Self-Compacting Concrete. Journal of Materials in Civil Engineering. 2019; 31 (2):04018374.
Chicago/Turabian StyleSama Tarek Aly; Amr Salah El-Dieb; Mahmoud Reda Taha. 2019. "Effect of High-Volume Ceramic Waste Powder as Partial Cement Replacement on Fresh and Compressive Strength of Self-Compacting Concrete." Journal of Materials in Civil Engineering 31, no. 2: 04018374.
Mark Scherbarth; Mahmoud M. Reda Taha. Stowage Testing and Modeling of Viscoelastic Composite Tape Springs. AIAA Scitech 2019 Forum 2019, 1 .
AMA StyleMark Scherbarth, Mahmoud M. Reda Taha. Stowage Testing and Modeling of Viscoelastic Composite Tape Springs. AIAA Scitech 2019 Forum. 2019; ():1.
Chicago/Turabian StyleMark Scherbarth; Mahmoud M. Reda Taha. 2019. "Stowage Testing and Modeling of Viscoelastic Composite Tape Springs." AIAA Scitech 2019 Forum , no. : 1.
Wellbores are comprised by a steel casing surrounded by a cement sheath. The microannulus is the typically very small annular or degraded space that may develop between cement and casing that has been identified as a common leakage pathway in wellbore systems. Although data regarding the actual size and character of wellbore microannuli are limited, the hydraulic aperture of the microannulus can be estimated from pressure build up or flow measurements at the wellhead. Such information can be misleading, however, as it represents microannuli as uniform annular gaps along the wellbore. This study aims to provide a quantitative measure of the variability of the microannuli. We generated wellbore-based samples with microannuli between the steel casing and cement, and calculated their hydraulic aperture and permeability by flowing gas through the microannuli. We then injected dyed epoxy into the microannuli, cut the specimens into five circumferential sections per sample, and used microphotographs to measure microannulus aperture size and contact between the steel and the cement to generate microannulus profiles for each section. These measurements are unique as they provide a quantitative measure of the variability of the microannulus with a resolution as low as 3 μm. Aperture sizes were fitted to different statistical distributions, most frequently lognormal and gamma. Capillary entry pressure (CEP) for gas displacing brine in the microannulus was estimated from measured aperture size. CEP estimated from actual aperture size was generally much greater than that estimated from the hydraulic aperture of the entire specimen, resulting in a wide range of values. Measured aperture sizes were used to evaluate possible microannulus repair by estimating the penetration of cementitious materials. The data showed that the repair using cementitious materials is unlikely to be effective for microannuli with a hydraulic aperture <50 μm.
Serafin Garcia Fernandez; Edward N. Matteo; Mahmoud Reda Taha; John C. Stormont. Characterization of wellbore microannuli. Journal of Natural Gas Science and Engineering 2018, 62, 13 -25.
AMA StyleSerafin Garcia Fernandez, Edward N. Matteo, Mahmoud Reda Taha, John C. Stormont. Characterization of wellbore microannuli. Journal of Natural Gas Science and Engineering. 2018; 62 ():13-25.
Chicago/Turabian StyleSerafin Garcia Fernandez; Edward N. Matteo; Mahmoud Reda Taha; John C. Stormont. 2018. "Characterization of wellbore microannuli." Journal of Natural Gas Science and Engineering 62, no. : 13-25.
Polymer concrete (PC) is a type of concrete where a polymer is used to replace cement as the binder. PC is an impermeable and chemical resistant concrete with appreciable mechanical properties. However, for most structural engineers, PC advantages do not outweigh its higher cost when compared with normal cement concrete. We report on the production of very ductile PC (measured by tensile strain at failure) with appreciable tensile strength utilizing a hybrid mixture of pristine and carboxyl (COOH) functionalized multi-walled carbon nanotubes (MWCNTs) at 2.0 wt% of epoxy resin. Experimental investigations reveal that COOH functionalization maximizes PC ductility reaching unprecedented 5.5% failure strains and increasing toughness by 184%. Fourier transformation infrared spectroscopy and dynamic modulus analysis indicate an increase in crosslinking density of the epoxy matrix up to 84% due to the carbonyl band formation induced by the COOH functionalization of MWCNTs. The significant improvement in ductility and energy absorption provides a promising platform for creating very ductile PC with attractive properties.
Alaeddin Douba; Mehmet Emiroglu; Usama F. Kandil; Mahmoud M. Reda Taha. Very ductile polymer concrete using carbon nanotubes. Construction and Building Materials 2018, 196, 468 -477.
AMA StyleAlaeddin Douba, Mehmet Emiroglu, Usama F. Kandil, Mahmoud M. Reda Taha. Very ductile polymer concrete using carbon nanotubes. Construction and Building Materials. 2018; 196 ():468-477.
Chicago/Turabian StyleAlaeddin Douba; Mehmet Emiroglu; Usama F. Kandil; Mahmoud M. Reda Taha. 2018. "Very ductile polymer concrete using carbon nanotubes." Construction and Building Materials 196, no. : 468-477.
Significant progress has taken place in the past few years in developing terahertz devices to make use of their superior capabilities in radio astronomy, security screening, chemical analysis, medical imaging, biological sensing, etc. With such advance in terahertz devices, electromagnetic interference shielding (EMI) in the terahertz frequency region is becoming significantly important. In this work, we examine the time-domain spectroscopy, THz-TDS, performance of carbon nanoparticles/epoxy nanocomposites. Two types of carbon nanoparticles (carbon nanofibers and multi-walled carbon nanotubes) with different carbon contents (0.5, 1.0, 2.0, 2.5 wt. %) were used to fabricate epoxy nanocomposites using both sonication and mechanical stirring processes and were experimentally investigated in terahertz (0.1-1.0 THz) frequency range. Shielding efficiency, together with the dielectric properties of both types of carbon-epoxy nanocomposites were studied and compared with that of neat epoxy as a reference. We demonstrate the potential use of carbon nanofibers and multi-walled carbon nanotubes for THz-EMI applications and show that the variation of carbon contents in epoxy matrix can greatly affect EMI shielding efficiency.
Eman Taha; Asmaa El-Deeb; Usama Kandil; Mahmoud Taha. EMI Shielding of Carbon Nanoparticles/Polymer Composites at Terahertz Frequency Region. Proceedings of 1st International Online Conference on Nanomaterials 2018, 1 .
AMA StyleEman Taha, Asmaa El-Deeb, Usama Kandil, Mahmoud Taha. EMI Shielding of Carbon Nanoparticles/Polymer Composites at Terahertz Frequency Region. Proceedings of 1st International Online Conference on Nanomaterials. 2018; ():1.
Chicago/Turabian StyleEman Taha; Asmaa El-Deeb; Usama Kandil; Mahmoud Taha. 2018. "EMI Shielding of Carbon Nanoparticles/Polymer Composites at Terahertz Frequency Region." Proceedings of 1st International Online Conference on Nanomaterials , no. : 1.
Christina Salas; Justin A. Brantley; James Clark; Mahmoud Reda Taha; Orrin Myers; Deana Mercer. Damage in a Distal Radius Fracture Model Treated With Locked Volar Plating After Simulated Postoperative Loading. The Journal of Hand Surgery 2018, 43, 679.e1 -679.e6.
AMA StyleChristina Salas, Justin A. Brantley, James Clark, Mahmoud Reda Taha, Orrin Myers, Deana Mercer. Damage in a Distal Radius Fracture Model Treated With Locked Volar Plating After Simulated Postoperative Loading. The Journal of Hand Surgery. 2018; 43 (7):679.e1-679.e6.
Chicago/Turabian StyleChristina Salas; Justin A. Brantley; James Clark; Mahmoud Reda Taha; Orrin Myers; Deana Mercer. 2018. "Damage in a Distal Radius Fracture Model Treated With Locked Volar Plating After Simulated Postoperative Loading." The Journal of Hand Surgery 43, no. 7: 679.e1-679.e6.
Strain energy deployable composite structures offer spacecraft designs reduced payload and compact volume. One of the greatest advantages presented by deployable composite structures arises from their ability to maintain high-strain configurations for extended periods of stowage. Because of the viscoelastic nature of the polymer matrix, the stowed composite structure undergoes stress relaxation that results in a decrease of the energy available for deployment. This paper focuses on a three-layered (±45 deg plain weave/0 deg unidirectional/±45 deg plain weave) carbon-fiber-reinforced polymer composite deployable structure, known as a tape spring. Stress relaxation testing was used to define the viscoelastic behavior of the epoxy matrix. Experimental long-term stowage and deployment testing was performed on the (±45/0/±45 deg) tape spring specimens. Finite element simulations considering viscoelastic, orthotropic stress relaxation were developed to predict the effects of stress relaxation on the deployment of a (±45/0/±45 deg) tape spring.
Elisa C. Borowski; Eslam M. Soliman; Arafat I. Khan; Mahmoud M. Reda Taha. Stowage and Deployment of a Viscoelastic Orthotropic Carbon-Fiber Composite Tape Spring. Journal of Spacecraft and Rockets 2018, 55, 829 -840.
AMA StyleElisa C. Borowski, Eslam M. Soliman, Arafat I. Khan, Mahmoud M. Reda Taha. Stowage and Deployment of a Viscoelastic Orthotropic Carbon-Fiber Composite Tape Spring. Journal of Spacecraft and Rockets. 2018; 55 (4):829-840.
Chicago/Turabian StyleElisa C. Borowski; Eslam M. Soliman; Arafat I. Khan; Mahmoud M. Reda Taha. 2018. "Stowage and Deployment of a Viscoelastic Orthotropic Carbon-Fiber Composite Tape Spring." Journal of Spacecraft and Rockets 55, no. 4: 829-840.