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This study evaluates the performance of alkali-activated slag-fly ash blended concrete made with recycled concrete aggregates (RCA) and reinforced with steel fibers. Two blends of concrete with ground granulated blast furnace slag-to-fly ash ratios of 3:1 and 1:1 were used. Natural aggregates were substituted with RCA, while macro steel fibers with 35 mm of length and aspect ratio of 65 were incorporated in RCA-based mixtures at various volume fractions. Fine aggregates were in the form of desert dune sand. Mechanical and durability characteristics were investigated. Experimental results revealed that RCA replacement decreased the compressive strength of plain concrete mixtures with more pronounced reductions being perceived at higher replacement percentages. Mixtures made with 30%, 70%, and 100% RCA could be produced with limited loss in the design compressive strength upon incorporating 1%, 2%, and 2% steel fibers, by volume, respectively. In turn, splitting tensile strength was comparable to the NA-based control while adding at least 1% steel fiber, by volume. Moreover, higher water absorption and capillary sorptivity and lower ultrasonic pulse velocity, bulk resistivity, and abrasion resistance were reported during RCA replacement. Meanwhile, incorporation of steel fibers densified the concrete and enhanced its resistance to abrasive forces, water permeation, and water transport. Analytical regression models were developed to correlate hardened concrete properties to the 28-day cylinder compressive strength.
Hilal El-Hassan; Abdalla Hussein; Jamal Medljy; Tamer El-Maaddawy. Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand. Buildings 2021, 11, 327 .
AMA StyleHilal El-Hassan, Abdalla Hussein, Jamal Medljy, Tamer El-Maaddawy. Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand. Buildings. 2021; 11 (8):327.
Chicago/Turabian StyleHilal El-Hassan; Abdalla Hussein; Jamal Medljy; Tamer El-Maaddawy. 2021. "Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand." Buildings 11, no. 8: 327.
Reutilizing industrial by-products and recycled concrete aggregates (RCA) to replace cement and natural aggregates (NA) in concrete is becoming increasingly important for sustainable development. Yet, experimental evidence is needed prior to the widespread use of this sustainable concrete by the construction industry. This study examines the performance of alkali-activated slag concrete made with RCA and reinforced with steel fibers. Natural coarse aggregates were replaced with RCA. Steel fibers were added to mixes incorporating RCA at different volume fractions. Desert dune sand was used as fine aggregate. The mechanical and durability properties of plain and steel fiber-reinforced concrete made with RCA were experimentally examined. The results showed that the compressive strength did not decrease in plain concrete mixes with 30 and 70% RCA replacement. However, full replacement of NA with RCA resulted in a 20% reduction in the compressive strength of the plain mix. In fact, 100% RCA mixes could only be produced with compressive strength comparable to that of an NA-based control mix in conjunction with 2% steel fiber, by volume. In turn, at least 1% steel fiber, by volume, was required to maintain comparable splitting tensile strength. Furthermore, RCA replacement led to higher water absorption and sorptivity and lower bulk resistivity, ultrasonic pulse velocity, and abrasion resistance. Steel fiber incorporation in RCA-based mixes densified the concrete and improved its resistance to abrasion, water permeation, and transport, thereby enhancing its mechanical properties to exceed that of the NA-based counterpart. The hardened properties were correlated to 28-day cylinder compressive strength through analytical regression models.
Hilal El-Hassan; Jamal Medljy; Tamer El-Maaddawy. Properties of Steel Fiber-Reinforced Alkali-Activated Slag Concrete Made with Recycled Concrete Aggregates and Dune Sand. Sustainability 2021, 13, 8017 .
AMA StyleHilal El-Hassan, Jamal Medljy, Tamer El-Maaddawy. Properties of Steel Fiber-Reinforced Alkali-Activated Slag Concrete Made with Recycled Concrete Aggregates and Dune Sand. Sustainability. 2021; 13 (14):8017.
Chicago/Turabian StyleHilal El-Hassan; Jamal Medljy; Tamer El-Maaddawy. 2021. "Properties of Steel Fiber-Reinforced Alkali-Activated Slag Concrete Made with Recycled Concrete Aggregates and Dune Sand." Sustainability 13, no. 14: 8017.
This study aims to examine the potential use of a geopolymeric matrix as a sustainable alternative to commercial mortars in carbon fabric-reinforced matrix composites. Single-lap shear tests were conducted to examine the bond behavior at the fabric-matrix interface. Test parameters included the type of matrix (geopolymeric and cementitious matrices) and the bonded length (50 to 300 mm). The geopolymeric matrix was a blend of fly ash/ground granulated blast furnace slag activated by an alkaline solution of sodium silicate and sodium hydroxide. The bond behavior of the geopolymeric-matrix specimens was characterized and compared to that of similar specimens with a cementitious matrix. The specimens failed due to fabric slippage/debonding at the fabric-matrix interface or fabric rupture. The effective bond lengths of the geopolymeric- and cementitious-matrix specimens were 150 and 170 mm, respectively. The geopolymeric-matrix specimens exhibited higher fabric strains, higher ultimate loads, and a steeper strain profile along the bonded length than those of their cementitious-matrix counterparts. New bond-slip models that characterize the bond behavior at the fabric-matrix interface for geopolymeric- and cementitious-matrix specimens were developed. Both models exhibited equal maximum shear stress of 1.2 MPa. The geopolymeric-matrix model had, however, higher fracture energy and higher slip at maximum shear stress than those of the cementitious matrix model.
Feras Abu Obaida; Tamer El-Maaddawy; Hilal El-Hassan. Bond Behavior of Carbon Fabric-Reinforced Matrix Composites: Geopolymeric Matrix versus Cementitious Mortar. Buildings 2021, 11, 207 .
AMA StyleFeras Abu Obaida, Tamer El-Maaddawy, Hilal El-Hassan. Bond Behavior of Carbon Fabric-Reinforced Matrix Composites: Geopolymeric Matrix versus Cementitious Mortar. Buildings. 2021; 11 (5):207.
Chicago/Turabian StyleFeras Abu Obaida; Tamer El-Maaddawy; Hilal El-Hassan. 2021. "Bond Behavior of Carbon Fabric-Reinforced Matrix Composites: Geopolymeric Matrix versus Cementitious Mortar." Buildings 11, no. 5: 207.
Curriculum-based exit exams play a crucial role in program assessment and measuring student achievement of program learning outcomes (PLOs). This study aims to examine the validity of using an internal exit exam as a direct assessment tool to evaluate student learning and attainment of PLOs. The validation entails evaluating and correlating students’ performance in the exit exam to that in corresponding coursework and their perception regarding attainment of the PLOs. Results highlighted inferior student performance in the exit exam compared to corresponding coursework, with a moderate degree of correlation at the program level. The survey response analysis indicated that students tended to overestimate their attainment level of PLOs and their preparation for the exit exam was not sufficient. Findings of this study would assist in the continuous improvement of prospective engineering programs and provide a framework for a proper analysis capable of examining the validity of curriculum-based assessment tools.
Hilal El-Hassan; Mohamed Hamouda; Tamer El-Maaddawy; Munjed Maraqa. Curriculum-based exit exam for assessment of student learning. European Journal of Engineering Education 2021, 1 -25.
AMA StyleHilal El-Hassan, Mohamed Hamouda, Tamer El-Maaddawy, Munjed Maraqa. Curriculum-based exit exam for assessment of student learning. European Journal of Engineering Education. 2021; ():1-25.
Chicago/Turabian StyleHilal El-Hassan; Mohamed Hamouda; Tamer El-Maaddawy; Munjed Maraqa. 2021. "Curriculum-based exit exam for assessment of student learning." European Journal of Engineering Education , no. : 1-25.
The efficiency of the use of near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) strips confined with CFRP wraps to strengthen reinforced concrete (RC) columns will be experimentally and analytically investigated in this paper. A total of 15 specimens of RC columns strengthened with different numbers of NSM-CFRP strips (0, 4, and 8) and confined with different numbers of CFRP wraps (0, 2, and 4), will be prepared and tested under concentric and eccentric loading with different eccentricity ratios of 0, 0.25, 0.50, and 0.75, respectively. The axial load capacity, lateral deflection (Δ), axial deflection, and longitudinal and transverse strains will be measured. The effects of NSM-CFRP strips, the number of CFRP layers, and the eccentricity ratio on the capacity of the specimen will be investigated. The strengthened specimens showed a significant increase in load-carrying capacity and ductility over the control specimens. The increase in the load-carrying capacity of the confined specimens strengthened with strips in axial and uniaxial bending reached 49% and 95%, respectively, over the control specimen. It was concluded that strengthening RC columns with NSM-CFRP strips wrapped with CFRP composite sheets enhanced both the capacity and ductility consistently, for all applied eccentricity ratios. In addition, an analytical model will be developed to predict the strength of NSM-CFRP-strengthened RC columns and will be validated using the obtained experimental results.
Raed Abokwiek; Jamal A. Abdalla; Rami A. Hawileh; Tamer El Maaddawy. RC Columns Strengthened with NSM-CFRP Strips and CFRP Wraps under Axial and Uniaxial Bending: Experimental Investigation and Capacity Models. Journal of Composites for Construction 2021, 25, 04021009 .
AMA StyleRaed Abokwiek, Jamal A. Abdalla, Rami A. Hawileh, Tamer El Maaddawy. RC Columns Strengthened with NSM-CFRP Strips and CFRP Wraps under Axial and Uniaxial Bending: Experimental Investigation and Capacity Models. Journal of Composites for Construction. 2021; 25 (2):04021009.
Chicago/Turabian StyleRaed Abokwiek; Jamal A. Abdalla; Rami A. Hawileh; Tamer El Maaddawy. 2021. "RC Columns Strengthened with NSM-CFRP Strips and CFRP Wraps under Axial and Uniaxial Bending: Experimental Investigation and Capacity Models." Journal of Composites for Construction 25, no. 2: 04021009.
Mohammed Alzard; Hilal El-Hassan; Tamer El-Maaddawy. Life Cycle Inventory for the Production of Recycled Concrete Aggregates in the United Arab Emirates. International Journal of Civil Infrastructure 2021, 4, 78 -84.
AMA StyleMohammed Alzard, Hilal El-Hassan, Tamer El-Maaddawy. Life Cycle Inventory for the Production of Recycled Concrete Aggregates in the United Arab Emirates. International Journal of Civil Infrastructure. 2021; 4 ():78-84.
Chicago/Turabian StyleMohammed Alzard; Hilal El-Hassan; Tamer El-Maaddawy. 2021. "Life Cycle Inventory for the Production of Recycled Concrete Aggregates in the United Arab Emirates." International Journal of Civil Infrastructure 4, no. : 78-84.
Shahrukh Shoaib; Hilal El-Hassan; Bilal El-Ariss; Tamer El-Maaddawy. Workability and Early-Age Strength of Recycled Aggregate Concrete Incorporating Basalt Fibers. International Journal of Civil Infrastructure 2021, 4, 68 -77.
AMA StyleShahrukh Shoaib, Hilal El-Hassan, Bilal El-Ariss, Tamer El-Maaddawy. Workability and Early-Age Strength of Recycled Aggregate Concrete Incorporating Basalt Fibers. International Journal of Civil Infrastructure. 2021; 4 ():68-77.
Chicago/Turabian StyleShahrukh Shoaib; Hilal El-Hassan; Bilal El-Ariss; Tamer El-Maaddawy. 2021. "Workability and Early-Age Strength of Recycled Aggregate Concrete Incorporating Basalt Fibers." International Journal of Civil Infrastructure 4, no. : 68-77.
While continuous reinforced concrete deep beams with fixed and hinged support conditions are every so often found in structures, little research has focused on their performance. This, in part, can be attributed to the demanding nature of ensuring fixed supports in experimentally testing such members. Nonetheless, conducting numerical analysis in comparison with experimental study has been a typical technique for producing a reliable numerical model as an alternative to destructive tests. This paper is aimed at numerically investigating the impact of different support conditions in the performance of two-span continuous reinforced concrete deep beams. A numerical model of three experimentally tested beams with two exterior rollers and interior hinge support conditions was generated. Good comparison, with an acceptable variation between numerical and experimental results, was achieved by tuning a few parameters in the numerical model, including element type, mesh size, and material constitutive relations. The refined numerical model was used as an alternative to destructive tests to conduct a parametric study to further investigate the impact of different sets of support conditions in the performance of two-span continuous reinforced concrete deep beams. This study highlights the potentially serious consequences of the support conditions in the performance of such deep beams.
Moustafa Mansour; Bilal El-Ariss; Tamer El-Maaddawy. Effect of Support Conditions on Performance of Continuous Reinforced Concrete Deep Beams. Buildings 2020, 10, 212 .
AMA StyleMoustafa Mansour, Bilal El-Ariss, Tamer El-Maaddawy. Effect of Support Conditions on Performance of Continuous Reinforced Concrete Deep Beams. Buildings. 2020; 10 (11):212.
Chicago/Turabian StyleMoustafa Mansour; Bilal El-Ariss; Tamer El-Maaddawy. 2020. "Effect of Support Conditions on Performance of Continuous Reinforced Concrete Deep Beams." Buildings 10, no. 11: 212.
Shahrukh Shoaib; Hilal El-Hassan; Bilal El-Aris; Tamer El Maaddawy. Early-Age Strength and Workability of Basalt Fiber ReinforcedConcrete Made with Recycled Aggregates – A Pilot Study. Proceedings of the 4th International Conference on Civil, Structural and Transportation Engineering (ICCSTE'19) 2020, 1 .
AMA StyleShahrukh Shoaib, Hilal El-Hassan, Bilal El-Aris, Tamer El Maaddawy. Early-Age Strength and Workability of Basalt Fiber ReinforcedConcrete Made with Recycled Aggregates – A Pilot Study. Proceedings of the 4th International Conference on Civil, Structural and Transportation Engineering (ICCSTE'19). 2020; ():1.
Chicago/Turabian StyleShahrukh Shoaib; Hilal El-Hassan; Bilal El-Aris; Tamer El Maaddawy. 2020. "Early-Age Strength and Workability of Basalt Fiber ReinforcedConcrete Made with Recycled Aggregates – A Pilot Study." Proceedings of the 4th International Conference on Civil, Structural and Transportation Engineering (ICCSTE'19) , no. : 1.
Three-dimensional (3D) finite element (FE) models were developed in this study to simulate the nonlinear structural behavior of double-sided concrete corbels internally-reinforced with glass-fiber reinforced polymer (GFRP) bars. The accuracy of the numerical models was demonstrated by comparing their results with published experimental data of twelve specimens tested previously by the authors. Two sets of models were first developed. In one set, a perfect bond assumption was adopted between the GFRP bars and the concrete. In the other set, a bond stress-slip law was adopted at the GFRP-concrete interface. Numerical results were in good agreement with those recorded experimentally, except for the specimens with a high concrete strength and high GFRP reinforcement ratio, which failed prematurely in a diagonal splitting mode of failure. In an effort to capture such a mode of failure numerically, additional four models were developed without considering the tension-softening curve in the concrete material constitutive law. Results of the models with the bond-slip law were insignificantly lower than those with perfect bond assumption at GFRP-concrete interface. Eliminating the tension-softening curve from the concrete material constitutive law used in modeling specimens with a high concrete strength and high GFRP reinforcement ratio yielded numerical results closer to those obtained from the tests.
Ayman Abu-Obaida; Tamer El-Maaddawy; Bilal El-Ariss. Numerical Simulation of Double-Sided Concrete Corbels Internally-Reinforced with GFRP bars. Composites Part C: Open Access 2020, 2, 100040 .
AMA StyleAyman Abu-Obaida, Tamer El-Maaddawy, Bilal El-Ariss. Numerical Simulation of Double-Sided Concrete Corbels Internally-Reinforced with GFRP bars. Composites Part C: Open Access. 2020; 2 ():100040.
Chicago/Turabian StyleAyman Abu-Obaida; Tamer El-Maaddawy; Bilal El-Ariss. 2020. "Numerical Simulation of Double-Sided Concrete Corbels Internally-Reinforced with GFRP bars." Composites Part C: Open Access 2, no. : 100040.
The flexural performance of steel fiber-reinforced concrete made with recycled concrete aggregates (RCA) and desert dune sand was investigated. Natural aggregates were replaced by 30, 70, and 100% RCA. Steel fibers were incorporated into mixes in 1, 2, and 3% volume fractions. To evaluate the flexural behavior of plain and steel fiber-reinforced RCA concrete mixes, three- and four-point bending tests were conducted. Experimental results showed that RCA replacement had a predominant impact on compression behavior compared to steel fiber addition, while the latter was more influential on flexural performance. Higher pre-peak slope, flexural strength, deflection, toughness, and equivalent flexural ratio were noted when steel fibers were added to RCA-based concrete tested under four-point bending. Similar improvement in flexural performance was reported from load-crack mouth opening displacement curves of three-point bending tests. Accordingly, analytical regression models were developed to correlate the different properties obtained from these two flexural bending test results.
Nancy Kachouh; Hilal El-Hassan; Tamer El-Maaddawy. Influence of steel fibers on the flexural performance of concrete incorporating recycled concrete aggregates and dune sand. Journal of Sustainable Cement-Based Materials 2020, 10, 165 -192.
AMA StyleNancy Kachouh, Hilal El-Hassan, Tamer El-Maaddawy. Influence of steel fibers on the flexural performance of concrete incorporating recycled concrete aggregates and dune sand. Journal of Sustainable Cement-Based Materials. 2020; 10 (3):165-192.
Chicago/Turabian StyleNancy Kachouh; Hilal El-Hassan; Tamer El-Maaddawy. 2020. "Influence of steel fibers on the flexural performance of concrete incorporating recycled concrete aggregates and dune sand." Journal of Sustainable Cement-Based Materials 10, no. 3: 165-192.
The durability performance of basalt fiber-reinforced polymer (BFRP) reinforcing bars conditioned for 3, 6, and 9 months at temperatures of 20, 40, and 60 °C was investigated. BFRP specimens were exposed to two environments: moist concrete and an alkaline solution simulating the concrete pore solution. Correlations among tensile strength, moisture uptake, matrix digestion, and microstructure characteristics were furnished. The degree of deterioration was more sensitive to the conditioning temperature than the conditioning duration. The tensile strength retentions of the specimens conditioned in the alkaline solution at a temperature not exceeding 40 °C were comparable to those conditioned in the moist concrete environment irrespective of the conditioning duration. Conditioning in the alkaline solution at 60 °C for a duration ≥6 months had a more detrimental effect on the microstructure and strength of the BFRP than encasing in moist concrete. After 9 months of exposure at 60 °C, the specimens conditioned in the alkaline solution lost 29% of the initial tensile strength while those encased in moist concrete lost only 15%. The intensified tensile strength reduction caused by the former conditioning scheme was due to disintegration of the matrix and degraded fiber-matrix interfacial bond caused by a higher moisture uptake and development of more hydroxyl groups during conditioning. The accelerated aging test results were utilized to develop a master curve for service life prediction of BFRP bars.
Mohamed Al Rifai; Hilal El-Hassan; Tamer El-Maaddawy; Farid Abed. Durability of basalt FRP reinforcing bars in alkaline solution and moist concrete environments. Construction and Building Materials 2020, 243, 118258 .
AMA StyleMohamed Al Rifai, Hilal El-Hassan, Tamer El-Maaddawy, Farid Abed. Durability of basalt FRP reinforcing bars in alkaline solution and moist concrete environments. Construction and Building Materials. 2020; 243 ():118258.
Chicago/Turabian StyleMohamed Al Rifai; Hilal El-Hassan; Tamer El-Maaddawy; Farid Abed. 2020. "Durability of basalt FRP reinforcing bars in alkaline solution and moist concrete environments." Construction and Building Materials 243, no. : 118258.
Nancy Kachouh; Hilal El-Hassan; Tamer El Maaddawy. Effect of steel fibers on the performance of concrete made with recycled concrete aggregates and dune sand. Construction and Building Materials 2019, 213, 348 -359.
AMA StyleNancy Kachouh, Hilal El-Hassan, Tamer El Maaddawy. Effect of steel fibers on the performance of concrete made with recycled concrete aggregates and dune sand. Construction and Building Materials. 2019; 213 ():348-359.
Chicago/Turabian StyleNancy Kachouh; Hilal El-Hassan; Tamer El Maaddawy. 2019. "Effect of steel fibers on the performance of concrete made with recycled concrete aggregates and dune sand." Construction and Building Materials 213, no. : 348-359.
Fiber reinforced polymer (FRP) composites have been suggested as corrosion-resistant alternatives to traditional steel reinforcement in concrete structures. Within this family of composites, glass fiber reinforced polymers (GFRPs) have been gaining momentum as the primary selection of FRP for construction applications. Despite being advantageous, its wide adoption by the industry has been hindered due to the degradation of its performance in severe environmental conditions. As such, significant studies have been carried out to assess the mechanical properties of GFRP bars subject to different conditioning schemes. However, the inconsistencies and wide variations of results called for more in-depth microstructure evaluation. Accordingly, this paper presents a critical review of existing research on the microstructure of GFRP reinforcing bars exposed to various conditioning regimes. The review analysis revealed that sustained load limits set by codes and standards were satisfactory for nonaggressive environment conditions but should be updated to include different conditioning regimes. It was also found that conditioning in alkaline solutions was more severe than concrete and mortars, where test specimens experienced irreversible chemical degradation, more hydroxyl group formation, and more intense degradation to the microstructure. The progression of hydrolysis was reported correlatively through an increase in hydroxyl groups and a decrease in the glass transition temperature. While moisture uptake was the primary instigator of hydrolysis, restricting it to 1.6% could limit the reduction in tensile strength to 15%. Further, the paper identifies research gaps in the existing knowledge and highlights directions for future research.
Hilal El-Hassan; Tamer El Maaddawy. Microstructure Characteristics of GFRP Reinforcing Bars in Harsh Environment. Advances in Materials Science and Engineering 2019, 2019, 1 -19.
AMA StyleHilal El-Hassan, Tamer El Maaddawy. Microstructure Characteristics of GFRP Reinforcing Bars in Harsh Environment. Advances in Materials Science and Engineering. 2019; 2019 ():1-19.
Chicago/Turabian StyleHilal El-Hassan; Tamer El Maaddawy. 2019. "Microstructure Characteristics of GFRP Reinforcing Bars in Harsh Environment." Advances in Materials Science and Engineering 2019, no. : 1-19.
The outcomes-based learning (OBL) approach focuses on academic outputs rather than educational input for quality assurance (QA) and quality enhancement (QE). The practicality and feasibility of adopting OBL in engineering education are questionable. Little is known about how students in different academic levels perceive OBL in engineering education. This paper aims to fill this gap through a study designed to obtain and evaluate perceptions of students of the effectiveness of adopting OBL in civil engineering education. Data was collected from 79 students enrolled in four different undergraduate and graduate civil engineering courses. Students' perceptions were collected through a questionnaire distributed on students at the end of the offering semester. Findings demonstrated the feasibility and effectiveness of adopting OBL in civil engineering courses to support student learning and improve their understanding of course topics. Students of the senior- and graduate-level courses held more positive attitude towards the value-added learning offered by OBL-based courses rather than students of the junior-level courses.
Tamer El Maaddawy; Hilal El-Hassan; Hamad Al Jassmi; Lina Kamareddine. Applying Outcomes-Based Learning in Civil Engineering Education. 2019 IEEE Global Engineering Education Conference (EDUCON) 2019, 986 -989.
AMA StyleTamer El Maaddawy, Hilal El-Hassan, Hamad Al Jassmi, Lina Kamareddine. Applying Outcomes-Based Learning in Civil Engineering Education. 2019 IEEE Global Engineering Education Conference (EDUCON). 2019; ():986-989.
Chicago/Turabian StyleTamer El Maaddawy; Hilal El-Hassan; Hamad Al Jassmi; Lina Kamareddine. 2019. "Applying Outcomes-Based Learning in Civil Engineering Education." 2019 IEEE Global Engineering Education Conference (EDUCON) , no. : 986-989.
This paper reports on student's quantitative and qualitative feedback on a flipped-classrooms pedagogy used to deliver an undergraduate Civil Engineering course. The flipped-classrooms pedagogy was used in teaching some of the course modules. Students were asked to reflect on the perceived difference of the new method compared to the traditional method, used for teaching the rest of the course modules. The online survey results showed that the vast majority of students Agreed or Strongly Agreed that the flipped classrooms approach improved their learning experience and level of interaction. While students were initially doubtful about the new format, they adapted quickly and found it to be satisfactory and effective. A worthwhile suggestion raised by plenty of students to the instructor is to spare 15-20 minutes of the beginning of the face-to-face session for questions and answers and to recap the material covered at the primarily online session before starting class problem solving activities. Results of this study provide a statement of encouragement for Civil Engineering faculty to implement flipped-classrooms as a contemporary and effective teaching method.
Hamad Al Jassmi; Salini Ramesh; Tamer El Maaddawy; Omniah Alqahtani; Waleed Ahmed. A Pilot Study on Civil Engineering Students Acceptance to a Flipped Classrooms Pedagogy. 2019 Advances in Science and Engineering Technology International Conferences (ASET) 2019, 1 -4.
AMA StyleHamad Al Jassmi, Salini Ramesh, Tamer El Maaddawy, Omniah Alqahtani, Waleed Ahmed. A Pilot Study on Civil Engineering Students Acceptance to a Flipped Classrooms Pedagogy. 2019 Advances in Science and Engineering Technology International Conferences (ASET). 2019; ():1-4.
Chicago/Turabian StyleHamad Al Jassmi; Salini Ramesh; Tamer El Maaddawy; Omniah Alqahtani; Waleed Ahmed. 2019. "A Pilot Study on Civil Engineering Students Acceptance to a Flipped Classrooms Pedagogy." 2019 Advances in Science and Engineering Technology International Conferences (ASET) , no. : 1-4.
Nancy Kachouh; Hilal El-Hassan; Tamer El Maaddawy. The use of steel fibers to enhance the performance of concrete made with recycled aggregate. 2019, 1 .
AMA StyleNancy Kachouh, Hilal El-Hassan, Tamer El Maaddawy. The use of steel fibers to enhance the performance of concrete made with recycled aggregate. . 2019; ():1.
Chicago/Turabian StyleNancy Kachouh; Hilal El-Hassan; Tamer El Maaddawy. 2019. "The use of steel fibers to enhance the performance of concrete made with recycled aggregate." , no. : 1.
This paper aims to investigate the behavior of short-span concrete members with a shear span–to–effective depth ratio (a/d) less than 2, internally reinforced with glass fiber–reinforced polymer (GFRP) bars. The study comprised testing of 12 specimens. Test parameters included the a/d ratio, GFRP reinforcement ratio, and concrete grade. The study was supplemented by an analytical investigation to predict the strength of the tested specimens. The experimental study highlighted that increasing the longitudinal GFRP reinforcement ratio together with the concrete strength in the absence of web reinforcement might be detrimental to the strength of GFRP-reinforced short-span concrete members due to a shift in the mode of failure from crushing of a diagonal strut to diagonal splitting. Experimental results indicate also that increasing the a/d does not necessarily reduce the strength of short-span GFRP-reinforced concrete specimens with a low concrete strength due to a greater angle of inclination of the critical shear crack developed during testing relative to that considered in the analysis. The strut-and-tie modeling (STM) provided conservative predictions for the nominal strength of the tested specimens except for those failed by diagonal splitting where it overestimated the strength by a maximum of 12%. The accuracy and validity of two published analytical approaches were examined. These approaches tended to provide less conservative, yet reasonable, nominal strength predictions but overestimated the strength of the specimens with the diagonal splitting mode of failure.
Ayman Abu-Obaida; Bilal El-Ariss; Tamer El-Maaddawy. Behavior of Short-Span Concrete Members Internally Reinforced with Glass Fiber–Reinforced Polymer Bars. Journal of Composites for Construction 2018, 22, 04018038 .
AMA StyleAyman Abu-Obaida, Bilal El-Ariss, Tamer El-Maaddawy. Behavior of Short-Span Concrete Members Internally Reinforced with Glass Fiber–Reinforced Polymer Bars. Journal of Composites for Construction. 2018; 22 (5):04018038.
Chicago/Turabian StyleAyman Abu-Obaida; Bilal El-Ariss; Tamer El-Maaddawy. 2018. "Behavior of Short-Span Concrete Members Internally Reinforced with Glass Fiber–Reinforced Polymer Bars." Journal of Composites for Construction 22, no. 5: 04018038.
Performance of fibre reinforced cementitious matrix (FRCM) strengthened non-ductile reinforced concrete frames with hollow concrete masonry infill (RCFMI) subjected to cyclic in-plane loading was experimentally assessed herein. A set of nine two-third scaled one bay-single story RCFMI prototypes were constructed that represented one bay of a low to medium height RCFMI building. Of these specimens, one frame was tested as-built without infill, one frame was tested as-built with infill, and the remainder were retrofitted using different FRCM schemes. The as-built tested frames served as control specimens and represented the baseline collapse risk associated to RCFMI buildings. Three different types of fibre grids (i.e. basalt, carbon, and glass) and three different FRCM configurations were used for retrofitting (i.e. full surface, diagonal bands with varying width). FRCM strengthened test frames exhibited a controlled failure mode characterised by distributed cracking in the FRCM matrix, without any signs of fibre slippage/rupture or deboning noted during the testing. Separation at the un-strengthened infill-frame contact region in FRCM strengthened frames was noted at a lateral drift of 0.4–0.6% and an applied lateral force of 1.2–2.0 times the strength of as-built tested frame. In general, test frames strengthened using diagonal bands with width equal to 1/6 infill diagonal length performed very similar to other configuration and therefore was deemed the most effective configuration. Carbon fabric had the highest strength compared to other fabrics used, but resulted in the lowest strength increment for the RCFMI, whereas Basalt-FRCM strengthened RCFMI exhibited the largest in-plane strength.
N. Ismail; Tamer El Maaddawy; N. Khattak. Quasi-static in-plane testing of FRCM strengthened non-ductile reinforced concrete frames with masonry infills. Construction and Building Materials 2018, 186, 1286 -1298.
AMA StyleN. Ismail, Tamer El Maaddawy, N. Khattak. Quasi-static in-plane testing of FRCM strengthened non-ductile reinforced concrete frames with masonry infills. Construction and Building Materials. 2018; 186 ():1286-1298.
Chicago/Turabian StyleN. Ismail; Tamer El Maaddawy; N. Khattak. 2018. "Quasi-static in-plane testing of FRCM strengthened non-ductile reinforced concrete frames with masonry infills." Construction and Building Materials 186, no. : 1286-1298.
The curing of concrete requires high water demand. In this study reinforcement corrosion protection of self-curing concrete (SC) mixtures incorporating two water-soluble polymers; polyethylene glycol (PEG) and polyacrylamide (PAM) have been evaluated. Durability indices; electrical resistivity, chloride ion penetrability and water permeability, were evaluated and compared to that of control concrete mixture with no self-curing agents under different curing regimes. Reinforcement corrosion monitoring was conducted by exposing reinforced concrete prisms at the age of 28 days to wet-dry cycles for a total period of 96 weeks. In the wetting cycle, the prisms were partially immersed in 5% sodium chloride solution at ambient temperature. The corrosion activity was evaluated by measuring the corrosion potential and corrosion current density. Self-curing concrete mixtures showed better reinforcement protection and durability indices than those of air-cured control mixture. Short water curing period of 3 days significantly improved the reinforcement protection and durability indices of the self-curing concrete mixtures to a level comparable to that of the control mixture that was moist-cured for 28 days. Self-curing concrete represents a step towards a new construction material due to its lower demand for curing water and hence can reserve the limited water resources in many parts of the world.
A.S. El-Dieb; Tamer El Maaddawy. Assessment of reinforcement corrosion protection of self-curing concrete. Journal of Building Engineering 2018, 20, 72 -80.
AMA StyleA.S. El-Dieb, Tamer El Maaddawy. Assessment of reinforcement corrosion protection of self-curing concrete. Journal of Building Engineering. 2018; 20 ():72-80.
Chicago/Turabian StyleA.S. El-Dieb; Tamer El Maaddawy. 2018. "Assessment of reinforcement corrosion protection of self-curing concrete." Journal of Building Engineering 20, no. : 72-80.