College of Science and Engineering
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Browsing College of Science and Engineering by Department "Engineering Technology"
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Item Analytical Model of Two-Directional Cracking Shear-Friction Membrane for Finite Element Analysis of Reinforced Concrete(Multidisciplinary Digital Publishing Institute, 2021-03-17) Mitchell, Jeffrey; Cho, Bum-Yean; Kim, Yoo JaeThere are a multitude of existing material models for the finite element analysis of cracked reinforced concrete that provide reduced shear stiffness but do not limit shear strength. In addition, typical models are not based on the actual physical behavior of shear transfer across cracks by shear friction recognized in the ACI 318 Building Code. A shear-friction model was recently proposed that was able to capture the recognized cracked concrete behavior by limiting shear strength as a yielding function in the reinforcement across the crack. However, the proposed model was formulated only for the specific case of one-directional cracking parallel to the applied shear force. This study proposed and generalized an orthogonal-cracking shear-friction model for finite element use. This was necessary for handling the analysis of complex structures and nonproportional loading cases present in real design and testing situations. This generalized model was formulated as a total strain-based model using the approximation that crack strains are equal to total strains, using the proportional load vector, constant vertical load, and modified Newton–Raphson method to improve the model’s overall accuracy.Item Asynchronous Peer-to-Peer Learning: Putting Student Projects to Work in Future Classes(American Society for Engineering Education, 2018-03) Talley, Kimberly G.; Smith, ShaunnaFor instructors interested in flipping their courses or using in-class video introductions to new topics, the development of custom video lecture content can be a daunting task. Having students create videos as a term project creates the potential opportunity to engage students in peer-to peer learning via videos while also generating course content that could help flip a course over time. In addition to aiding the instructor in course content generation, the project helps the student creators learn the video content, as indicated by the literature. This paper explores the effectiveness of resulting asynchronous peer-to-peer video content at facilitating student learning amongst the students enrolled in a Construction Estimating course from four semesters of implementation. Pre- and post- video presentation quiz scores were analyzed to verify an overall statistically significant increase in student quiz performance for the majority of the video projects whether used in class to introduce a new topic during the semester or during the end-of-semester presentation day for new projects. Thus, this study shows the promise of student-produced videos as course content, especially for those instructors seeking to flip or partially flip their course. Additionally, the paper presents some lessons learned from the implementation of a video project to produce course content.Item Characterization and Early Age Physical Properties of Ambient Cured Geopolymer Mortar Based on Class C Fly Ash(Springer, 2015-03) Kotwal, Ashley Russell; Kim, Yoo Jae; Hu, Jiong; Sriraman, VedaramanThe critical element for sustainable growth in the construction industry is the development of alternative cements. A new technological process called geopolymerization provides an innovative solution, and the presence of aluminum and silicon oxides in fly ash has encouraged its use as a source material. Many previous investigations have involved curing the binder in a heated environment. To reduce energy consumption during the synthesis of geopolymers, the present study investigated the properties of ambient cured geopolymer mortar at early ages. An experimental program was executed to establish a relationship between the activator composition and the properties of geopolymer mortar in fresh and hardened states. Concentrations of sodium hydroxide and sodium silicate were ascertained that are advantageous for constructability and mechanical behavior. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques were also used to characterize the material. Test results indicate that there is potential for the concrete industry to use fly ash based geopolymer as an alternative to portland cement.Item Comprehensive Assessment of a Project Based Learning Application in a Project Management Course(Gate Association for Teaching and Education (GATE), 2021-07) Torres, Anthony; Sriraman, Vedaraman; Martinez Ortiz, AraceliThe focus of this study is to implement multiple assessment methods in order to comprehensively assess the impact of a Project Based Learning (PrBL) application in construction project management course. The assessment methods include various direct (objective) and indirect (subjective) evaluations methods. These methods included a pre and post questionnaire of student opinions, homework grades, in-class “clicker” quiz grades, overall project grades, embedded test question grades, a video lecture project, and short answer case study questions on exams from the Fall 2017 to Fall 2019 semesters. The data for this study was taken from the past six offerings of the same course, which was compared to a similar course in the same department. The analysis demonstrated that the students preferred both the use of an actual real-world project and the PrBL delivery method. The particular assessment methods that provided the most beneficial assessment were the embedded test questions and the case study section of the exam. The overall grade assessment method demonstrated an average of four percentage point increase in grades from previous offerings of the course and a similar course that does not include the PrBL pedagogy.Item Connector-Free World-to-Chip Interconnection for Microfluidic Devices(Multidisciplinary Digital Publishing Institute, 2019-02) Song, In-Hyouk; Park, TaehyunIn the development of functional lab-on-a-chip (LOC), there is a need to produce a reliable and high pressure connection between capillary tubes and microfluidic devices for carrying fluids. The current technologies still have limitations in achieving ideal interconnection since they are bulky, expensive or complicated. In this paper, a novel connector-free technique using an interference fit mechanism is introduced for world-to-chip interconnection. The proposed technique has considerable potential for replacing current interconnection tools for microfluidic devices due to the advantages including no chemical contamination, easy plugging, enough strength to sustain pressure, high density integration, simple and rapid integration.Item Constructing an Automation Table for an Image-Based Arabidopsis Resistance Assay(Elsevier, 2020-05) Makhija, Goldi; Pujara, Dinesh S.; Song, In-Hyouk; You, Byoung Hee; Kang, Hong-GuNo abstract prepared.Item Cost Effectiveness of Crack Treatment Methods: A Field Study(Elsevier, 2019-12) Mazumder, Mithil; Kim, Hyun Hwan; Lee, Soon-Jae; Lee, Moon-SupIn the United States, more than 94% highways are paved with asphalt materials and placing crack sealant materials has been a common pavement maintenance for decades. Crack sealing treatment includes the use of a router to create a reservoir on the intended cracks whereas crack filling is given without doing any modification to the crack wall. Although the initial cost of crack sealing is higher, it is expected to have a longer service period compared to crack filling. There is little research on comparison of short and long term cost effectiveness between these two treatments using the real field cost data analysis. In this study four test sites in Texas were treated with crack filling and sealing using the same sealant material and finishing technique. Cost effectiveness of both treatments was measured in terms of initial, annual average and life cycle cost based on the cost inputs during construction. In general, the results of this study indicated that (1) on an average approximately 45% initial cost increase was estimated with the two routing configurations of crack sealing; (2) material and labor cost is found to have the most significant effect on the higher initial cost of crack sealing compared to other associated costs; (3) annual average and life cycle costs have shown that crack sealing is more cost effective pavement maintenance compared to crack filling over a long period of time; (4) agency cost is observed to be reduced by approximately 24% with crack sealing treatment based on the 35 year analysis period.Item Cost-Effectiveness of Conventional Compaction (CC) and Intelligent Compaction (IC) Methods of Asphalt Pavement Overlay(Multidisciplinary Digital Publishing Institute, 2021-10-26) Mazumder, Mithil; Yun, Jihyeon; Lee, Soon-Jae; Jeong, Kyu-DongThe use of intelligent compaction (IC) in asphalt overlay includes the use of double-drum IC rollers, a roller measurement system, global position system (GPS) radio/receiver/base station, infrared temperature sensors, and an onboard computer reporting system. GPS based mapping and optional feedback control help to overcome the drawbacks associated with conventional compaction such as identifying soft spots, achieving consistent roller patterns, and monitoring asphalt surface temperature and levels of compaction with adequate quality control or quality assurance (QC/QA). Cost-effectiveness of both compaction types was measured in terms of initial and roadway lifecycle cost based on the cost inputs received from South Korea and other published literatures. Roadway lifecycle cost was reported based on the improvement in in-place density, smoothness, and fatigue life. The results of this study showed that: (1) with IC an approximate 4.1% initial cost reduction can be achieved compared to conventional compaction; (2) QC/QA cost is found to have the most significant effect on the higher initial cost of conventional compaction compared to other associated costs whereas intelligent roller cost is the vital cost category for IC; (3) improvement of in-place air voids and density due to the IC has shown that at 97% field density (or at 3% air void content) the State Highway Agency can save approximately 44% over a 20-year service period; and (4) agency cost is observed to be reduced by approximately 62% with the IC method based on the 25-year analysis period due to the increase in fatigue life.Item Deep Regression Prediction of Rheological Properties of SIS-Modified Asphalt Binders(Multidisciplinary Digital Publishing Institute, 2020-12-16) Ji, Bongjun; Lee, Soon-Jae; Mazumder, Mithil; Lee, Moon-Sup; Kim, Hyun HwanThe engineering properties of asphalt binders depend on the types and amounts of additives. However, measuring engineering properties is time-consuming, requires technical expertise, specialized equipment, and effort. This study develops a deep regression model for predicting the engineering property of asphalt binders based on analysis of atomic force microscopy (AFM) image analysis to test the feasibility of replacing traditional measuring estimate techniques. The base asphalt binder PG 64-22 and styrene–isoprene–styrene (SIS) modifier were blended with four different polymer additive contents (0%, 5%, 10%, and 15%) and then tested with a dynamic shear rheometer (DSR) to evaluate the rheological data, which indicate the rutting properties of the asphalt binders. Different deep regression models are trained for predicting engineering property using AFM images of SIS binders. The mean absolute percentage error is decisive for the selection of the best deep regression architecture. This study’s results indicate the deep regression architecture is found to be effective in predicting the G*/sin δ value after the training and validation process. The deep regression model can be an alternative way to measure the asphalt binder’s engineering property quickly. This study would encourage applying a deep regression model for predicting the engineering properties of the asphalt binder.Item Developing Sustainable Ultra High Strength Concrete Mixtures Using Spent Foundry Sand(David Publishing Company, 2019-01) Torres, Anthony; Aguayo, Federico; Allena, SrinivasThis study presents the development of ultra high strength concrete (UHSC) that has been made more sustainable by using both local materials from central Texas and spent foundry sand (FS) from the metal casting industry, which has also been obtained locally. This study first describes various trial mixtures tested as well as the specimen preparation techniques investigated that led to the final UHSC-FS mixtures. The developed mixtures were proportioned with local constituents to increase the sustainable impact of the material by reducing emissions due to shipping as well as making UHSC more affordable to a wider variety of applications. The final mixture design constituents were: river sand, locally available type I/II cement, silica fume, and spent FS, which was obtained from a local steel casting company. Multiple variables were investigated, such as the aggregate type and size, concrete age (7, 14, and 28-days), the curing regimen, and the water-to-cement ratio (w/cm) to optimize a UHSC mixture that used local materials and FS. This systematic development revealed that heat curing the specimens in a water bath at 50ºC (122ºF) after demolding and then dry curing at 200ºC (392ºF) two days before testing with a w/cm of 0.20 at 28-days produced the highest compressive strengths. Once an optimum UHSC mixture was identified a partial replacement of the fine aggregate with FS was completed at 10%, 20%, and 30%. The results showed an increase of compressive strength performance at 10% replacement, followed by no change at 20%, and finally a slight decrease at 30%. Developing this innovative material with local materials and FS ultimately produces a novel sustainable construction material, reduces the costs, and produces mechanical performance similar to prepackaged, commercially, available construction building materials.Item Development of Non-Proprietary Ultra-High Performance Concrete Mixtures(Multidisciplinary Digital Publishing Institute, 2022-11-03) Hasan, Tawsif Mohammad; Gilbert, Levi; Allena, Srinivas; Owusu-Danquah, Josiah; Torres, AnthonyThe development of non-proprietary Ultra-High Performance Concrete (UHPC) is one way to reduce the initial cost of construction. However, workability is a major issue for which such mixtures are not practical in field conditions. Ultra-high performance cannot be achieved in field conditions if the concrete is not placed, finished, and compacted properly during placement. In this research, six UHPC mixtures were developed (three with steel fibers and three without fibers) using materials which are readily available on the local marketplace with water-to-cementitious materials ratios ranging between 0.17 to 0.30. The workability was determined using standard ASTM flow table apparatus, and specimens were prepared to determine compressive strength, splitting tensile strength, and permeable porosity. Flow table test exhibited flow values greater than 250 mm. Such high workability of the mixtures was achieved by optimizing the silica fume content and water reducing admixture dosage. These mixtures exhibited compressive strengths greater than 120 MPa and splitting tensile strengths greater than 5.10 MPa in both ambient and elevated curing temperatures. Results indicated that UHPC can be produced with a water-to-cementitious materials ratio as high as 0.30. Steel fibers helped to increase splitting tensile strength due to fiber-matrix interactions. Very low permeable porosity (1.7–16.7%) was observed which indicates superior durability due to the significant reduction of ingress of deleterious ions.Item Effect of Production Process on Performance Properties of Warm Rubberized Binders(Elsevier, 2019-12) Kim, Hyun Hwan; Mazumder, Mithil; Lee, Soon-Jae; Lee, Moon-SupThe study presents an experimental evaluation of performance properties of two different production processes of warm rubberized binder. Two types of rubberized binder were produced through dry process and wet process and two of the available wax additives were added into the rubberized binders (i.e., LEADCAP and Sasobit). Rubberized binders with wax additives were artificially short-term and long-term aged using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were carried out on the binders through the rotational viscometer (RV), the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). In general, the results of this study indicated that (1) the viscosity properties have been found to be similar between dry and wet processes, (2) the rubberized binders manufactured by wet process were observed to have the higher rutting resistance than those by dry process, (3) the wet process resulted in better performance in the fatigue cracking test than the dry process, and (4) the blending method was found to have little influence of stiffness properties.Item Evaluation of Petroleum Resin in Rubberized Asphalt Binder(Multidisciplinary Digital Publishing Institute, 2021-08-19) Kim, Hyun Hwan; Mazumder, Mithil; Lee, Moon-Sup; Lee, Soon-JaeThe crumb rubber modified (CRM) binder was evaluated considering the general operating temperatures of high, intermediate, and low temperatures. CRM binders were produced with four different contents (0, 5, 10, and 15%) using the base asphalt binder (PG64-22). Then, they were artificially aged by a rolling thin-film oven (RTFO) and pressure aging vessel (PAV). Superpave binder tests using a rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR) was applied to characterize the performance of the original and aged binders. Multiple stress creep recovery (MSCR) tests were also performed for deeper rutting characterization. The results of this study are as follows: (1) the presence of PR increases the binder viscosity, (2) the integration of CRM greatly improved the rutting resistance of the binder, and it was found that PR also improved the rutting characteristics, and (3) it is observed that PR is detrimental to the cracking properties of CRM binders.Item Evaluation of the Efficiency of Limestone Powder in Concrete and the Effects on the Environment(Multidisciplinary Digital Publishing Institute, 2018-02) Kim, Yoo Jae; Van Leeuwen, Ryno; Cho, Bum-Yean; Sriraman, Vedaraman; Torres, AnthonyThe major environmental impact of concrete comes from the CO2 emissions, produced during the cement manufacturing process. The main goal of this research project is to evaluate the efficiency of limestone powder as a partial cement replacement, in order to reduce energy consumption and CO2 emissions. This study utilizes limestone powders, with different particle sizes, to replace a portion of Portland cement using various ratios. Due to the dilution effect when partially replacing cement, there is a reduction in the concrete’s physical properties. To assess the dilution effect, a modification to Féret’s equation is used to calculate an efficiency factor for the limestone powder when compared to cement. To measure the environmental impact, a life cycle assessment is conducted on concrete made with limestone powder combined with cement. This allows for an evaluation of the various cement/limestone powder ratios that will maximize the environmental benefit, with minimal reduction in concrete strength. Additional microstructural analysis using petrographic examination was completed to provide a visual understanding of the distribution of the limestone particles within the cement paste. The results indicate that the efficiency of limestone powder in partially replacing cement can be achieved by particle packing and particle distribution in the concrete and the benefits of emission reductions exceed the loss in compressive strength when higher levels of limestone powder is used to replace cement.Item Geosynthetic Reinforced Steep Slopes: Current Technology in the United States(Multidisciplinary Digital Publishing Institute, 2019-05) Kim, Yoo Jae; Kotwal, Ashley Russell; Cho, Bum-Yean; Wilde, James W.; You, Byung HeeGeosynthetics is a crucial mechanism in which the earth structures can be mechanically stabilized through strength enforcing tensile reinforcement. Moreover, geosynthetic reinforcement stabilizes steep slopes through incorporating the polymeric materials, becoming one of the most cost-effective methods in not only accommodating budgetary restrictions but also alleviating space constraints. In order to explicate on the applicability and widen the understanding of geosynthetic reinforcement technology, a synthesis study was conducted on geosynthetic reinforced steep slope. This study is very important because in not only highlighting the advantages and limitations of using geosynthetic reinforcement but also in investigating the current construction and design methods with a view to determining which best practices can be employed. Furthermore, this study also identified and assessed the optimal condition of the soil, performance measures, construction specifications, design criteria, and geometry of the slope. To further concretize the understanding of these parameters or factors, two case studies were reviewed and a summary of the best practices, existing methods, and recommendations were drawn in order to inform the employment of geosynthetics in reinforcing steep slopes.Item Integrating an Introduction to Engineering Experience into a University Seminar Course(American Society for Engineering Education, 2016-06) Talley, Kimberly Grau; Martinez Ortiz, Araceli; Novoa, Clara; Sriraman, VedaramanRetention statistics show that the most drastic decline in retention rates for engineering and engineering technology majors at Texas State University occur after the first and second years. To address this issue, the LBJ Institute of STEM Education and Research at Texas State is employing a multi-faceted approach to implement proven strategies for increasing student retention as a part of an NSF IUSE (Improving Undergraduate STEM Education) grant, Texas State STEM Rising Stars. One of these strategies is to introduce a new first-year introduction to engineering/engineering technology course that was designed to support student retention. A new course could not simply be added to the existing curriculum of the university’s engineering and engineering technology degrees, however, as state law capped the hours required for an undergraduate degree. Instead, the researchers customized an introduction to the university freshman seminar course for engineering and engineering technology majors. This course design adapted elements from successful first-year introductory classes in Engineering and Engineering Technology at other universities. Besides fostering a learning community between Engineering and Engineering Technology students, the objectives of the new course include: (1) introduction of design and problem solving through project-based learning and (2) familiarization with the careers paths and practices of Engineering and Engineering Technology through tours and talks by industry representatives and faculty and (3) providing a common experience that introduces university resources to support the development of the students and prepares them for academic success. The pilot section of Introduction to Engineering in University Seminar was offered in Fall 2015. As these seminar courses are offered in the fall semesters, the researchers will be able to analyze changes in engineering design self-efficacy over the semester and conduct focus groups with students to refine the course content prior to an expanded second round of experimental sections that will be put in place for Fall 2016. This paper presents this work in progress, including preliminary results and lessons learned from this integration of Introduction to Engineering with University Seminar.Item Investigation of Rheological Properties of Blended Cement Pastes Using Rotational Viscometer and Dynamic Shear Rheometer(Hindawi Publishing Corporation, 2018-02) Kim, Yoo Jae; Cho, Bum-Yean; Lee, Soon-Jae; Hu, Jiong; Wilde, James W.To successfully process concrete, it is necessary to predict and control its flow behavior. However, the workability of concrete is not completely measured or specified by current standard tests. Furthermore, it is only with a clear picture of cement hydration and setting that full prediction and control of concrete performance can be generalized. In order to investigate the rheological properties of blended cement pastes, a rotational viscometer (RV) was used to determine the flow characteristics of ordinary and blended pastes to provide assurance that it can be pumped and handled. Additionally, a dynamic shear rheometer (DSR) was used to characterize both the viscous and elastic components of pastes. Ordinary Portland cement paste and blended pastes (slag, fly ash, and silica fume) were investigated in this study. The stress and strain of the blended specimens were measured by the DSR, which characterizes both viscous and elastic behaviors by measuring the complex shear modulus (the ratio of total shear stress to total shear strain) and phase angle (an indicator of the relative amounts of recoverable and nonrecoverable deformation) of materials. Cement pastes generally exhibit different rheological behaviors with respect to age, mineral admixture type, and cement replacement level.Item Laboratory Characterization of Asphalt Binders Modified with Styrene Butadiene Rubber (SBR)(Multidisciplinary Digital Publishing Institute, 2021-12-12) Hemmati, Navid; Yun, Jihyeon; Mazumder, Mithil; Lee, Moon-Sup; Lee, Soon-JaeThe study describes the laboratory assessment (physical and rheological properties) of the binders (PG 64-22 and PG 76-22) modified with Styrene Butadiene Rubber (SBR), and a comprehensive comparison between these two modified binder types. PG 64-22 and PG 76-22 were used as base binders. Both of the base binders were blended with SBR at four different percentages of content (0%, 4%, 6%, and 8% by the weight of the binder). The base and modified binders were artificially short-term and long-term aged using a rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were conducted on the SBR modified binder using rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR). In depth rutting performance was investigated using Multiple Stress Creep Recovery (MSCR). The results of this study indicated that (1) the addition of SBR into both binders increased the viscosity and polymer modified asphalt (PMA) binders observed to have more significant effect on its viscosity property; (2) the higher the SBR content, the better the rutting resistance of the binder and it is observed that the effect is prominent on the control binder; (3) MSCR test results showed that the SBR modified binders improved the binder percentage recovery and found to have a more significant effect on the PG 76-22 binder compared to PG 64-22; and (4) both the control PG 64-22 and PMA PG 76-22 binders resulted in similar trends on the cracking properties and were found to have insignificant effects due to the addition of an SBR modifier.Item Laboratory Evaluation of Sustainable PMA Binder Containing Styrene-Isoprene-Styrene (SIS) and Thermoplastic Polyurethane(Multidisciplinary Digital Publishing Institute, 2020-12-02) Kim, Hyun Hwan; Mazumder, Mithil; Lee, Soon-Jae; Lee, Moon-SupIn this study, thermoplastic polyurethane (TPU) and styrene-isoprene-styrene (SIS) were utilized to enhance asphalt binder properties. Superpave asphalt binder tests and multiple stress creep recovery (MSCR) were conducted to evaluate the physical and rheological performance (viscosity, rutting, and cracking properties) of the asphalt binders before and after short-term aging and after the long-term aging process. The results showed that (i) TPU has a positive effect on workability, including the mixing and compaction processes, which was evident from the reduced binder viscosity; (ii) asphalt binders with TPU and SIS showed better rutting resistance compared to the SIS binders without TPU; (iii) the cracking resistance of asphalt binders was found to be improved significantly with the addition of TPU; and (iv) TPU has the potential to be considered as a sustainable polymer modifier for producing bearable asphalt binders by improving rutting and crack resistance without increasing the melting temperature of the asphalt bindersItem Micro-Accelerometer Based on Vertically Movable Gate Field Effect Transistor(Springer Open, 2015-01) Kang, Heung Seok; Lee, Kang-Hee; Yang, Dong-Youk; You, Byoung Hee; Song, In-HyoukA vertically movable gate field effect transistor (VMGFET) is proposed and demonstrated for a micro-accelerometer application. The VMGFET using air gap as an insulator layer allows the gate to move on the substrate vertically by external forces. Finite element analysis is used to simulate mechanical behaviors of the designed structure. For the simulation, the ground acceleration spectrum of the 1952 Kern County Earthquake is employed to investigate the structural integrity of the sensor in vibration. Based on the simulation, a prototype VMGFET accelerometer is fabricated from silicon on insulator wafer. According to current-voltage characteristics of the prototype VMGFET, the threshold voltage is measured to be 2.32 V, which determines the effective charge density and the mutual transconductance of 1.545x10 -8 C cm-2 and 6.59 mA V -1, respectively. The device sensitivity is 9.36-9.42 mV g-1 in the low frequency, and the first natural frequency is found to be 1230 Hz. The profile smoothness of the sensed signal is in 3 dB range up to 1 kHz.