Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item RELATING RISKS TO PAY FACTORS FOR HIGHWAY PAVEMENTS THROUGH MONTE CARLO SIMULATION(2019) Zhao, Yunpeng; Goulias, Dimitrios G; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The majority of State Highway Agencies (SHAs) now employ statistical-based specifications for the acceptance of highway materials and pavement construction. The parameters of these statistical acceptance plans are specified based on engineering judgment and may result in a high level of risk to both agency and contractor. In order to appropriately apply such specifications to the pavement construction industry, the associated production quality (i.e., materials and construction variability) needs to be well understood by all parties involved and its potential impacts require to be assessed. To address this objective of this study was to: (i) quantify the risks to the agencies and contractors (i.e., Type I and Type II errors); (ii) examine how the key components in a statistical acceptance plan impact its performance; and, (iii) identify a methodology to balance the risks and pay factors. Risk and pay factor analysis were conducted for both single and multiple quality characteristics through Monte Carlo simulation, and the development of Operating Characteristic, OC, curves. Furthermore, case studies were presented to demonstrate the value of the analyses proposed in this study. The methodology and findings identified in the study can be applied elsewhere to evaluate the acceptance plans and the associated risks pertinent to pavement construction and the production of highway materials.Item Modulus Based Compaction Quality Assurance for Unbound Materials Using Lightweight Deflectometer(2019) Afsharikia, Zahra; Schwartz, Charles W; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Moving away from traditional density-based methods of compaction quality assurance (QA) towards modulus-based procedures using Light Weight Deflectometer (LWD) require developing practical framework to: (1) determine soil- specific LWD target modulus, and (2) evaluate LWD modulus in the field effectively. This dissertation draws upon work from two research studies, TPF-5(285) pooled fund study and pilot projects conducted by Maryland State Highway Administration to refine the two proposed QA specifications for road base, subgrade, and embankment construction. The practical method of establishing the target modulus based on LWD drops on compacted Proctor molds was proposed and evaluated. Three types of LWDs (Zorn ZFG3000, Olson LWD-01, Dynatest 3031) were utilized and their field to target modulus ratio was compared to the percent compaction as a criterion for goodness of compaction. Results confirmed the validity of procedures for the variety of geomaterials tested and suitability for practical implementation by field inspection personnel. Target modulus values, calibrated acceptance criteria, sampling method, and frequency is presented for future implementation in the state of Maryland and other state DOTs. The LWD manufacturers collaborated to facilitate the implementation by instrument design and improvement or software/application development.Item RESILIENCE OF NETWORKED INFRASTRUCTURE WITH EVOLVING COMPONENT CONDITIONS: A PAVEMENT NETWORK APPLICATION(2016) Asadabadi, Ali; Miller-Hooks, Elise; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis deals with quantifying the resilience of a network of pavements. Calculations were carried out by modeling network performance under a set of possible damage-meteorological scenarios with known probability of occurrence. Resilience evaluation was performed a priori while accounting for optimal preparedness decisions and additional response actions that can be taken under each of the scenarios. Unlike the common assumption that the pre-event condition of all system components is uniform, fixed, and pristine, component condition evolution was incorporated herein. For this purpose, the health of the individual system components immediately prior to hazard event impact, under all considered scenarios, was associated with a serviceability rating. This rating was projected to reflect both natural deterioration and any intermittent improvements due to maintenance. The scheme was demonstrated for a hypothetical case study involving Laguardia Airport. Results show that resilience can be impacted by the condition of the infrastructure elements, their natural deterioration processes, and prevailing maintenance plans. The findings imply that, in general, upper bound values are reported in ordinary resilience work, and that including evolving component conditions is of value.Item Rutting performance of asphalt pavements(2016) Farzaneh, Azadeh; Schwartz, Charles; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cold in-place recycling (CIR) and cold central plant recycling (CCPR) of asphalt concrete (AC) and/or full-depth reclamation (FDR) of AC and aggregate base are faster and less costly rehabilitation alternatives to conventional reconstruction for structurally distressed pavements. This study examines 26 different rehabilitation projects across the USA and Canada. Field cores from these projects were tested for dynamic modulus and repeated load permanent deformation. These structural characteristics are compared to reference values for hot mix asphalt (HMA). A rutting sensitivity analysis was performed on two rehabilitation scenarios with recycled and conventional HMA structural overlays in different climatic conditions using the Mechanistic Empirical Pavement Design (MEPDG). The cold-recycled scenarios exhibited performance similar to that of HMA overlays for most cases. The exceptions were the cases with thin HMA wearing courses and/or very poor cold-recycled material quality. The overall conclusion is that properly designed CIR/FDR/CCPR cold-recycled materials are a viable alternative to virgin HMA materials.Item OPTIMIZATION OF THE INFRARED ASPHALT REPAIR PROCESS(2015) Leininger, Christopher William; Schwartz, Charles W; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Infrared asphalt repair is an alternative technology that potentially allows for year round pavement patching that can be more durable, less expensive, and longer lasting than conventional techniques. Although infrared repair has been used for over 10 years by state and local agencies and commercial property owners in several areas of the country, some continuing resistance to this technique still remains. The principal reasons for this resistance are the largely unknown engineering properties of the patch material as compared to the native in situ pavement and the lack of standardized methods, specifications and quality assurance procedures. The following is a preliminary assessment of these engineering properties and current QA/QC procedures. A proposed specification for adoption is included in addition to recommendations for improving current practice.Item DESIGN AND MECHANICAL PROPERTIES OF FOAMED ASPHALT STABILIZED BASE MATERIAL(2012) Khosravifar, Sadaf; Schwartz, Charles W; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Foamed asphalt stabilized base (FASB) combines reclaimed asphalt pavement (RAP) and/or recycled concrete (RC) with a foamed asphalt binder. The pavement structural properties of FASB fall somewhere between conventional graded aggregate base (GAB) and hot mix asphalt (HMA). Therefore, the required thickness of the pavement section can be reduced, resulting in cost savings in addition to recycling benefits. Mix designs were developed for eight different combinations of RAP, RC, and GAB. Details of the mix design procedure and the effects of factors representative of design and field conditions are evaluated. Triaxial test specimens from the weakest and strongest mixtures were tested for dynamic modulus and repeated load permanent deformation resistance, which can be used as inputs to the new AASHTO mechanistic-empirical design procedure. The measured stiffness values were also used to determine an appropriate structural layer coefficient value for use in the AASHTO empirical pavement design method.Item Using Radio-Frequency Identification Technology To Measure Asphalt Cooling(2010) Pfeiffer, Grant Howard; Schwartz, Charles W; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Realistic prediction of asphalt temperatures as a function of time during paving is essential for optimizing compaction operations. Continued compaction after the asphalt lift has dropped below a critical threshold temperature may result in particle breakage and degradation of the material properties. To address this issue, this study evaluates the feasibility of using Surface Acoustic Wave (SAW) based Radio-Frequency Identification (RFID) technology to measure HMA temperatures via wireless sensors during paving. The survivability and temperature measurement capabilities of the SAW RFID sensors are demonstrated in the field. The measured asphalt cooling curves (temperature versus time) are compared with predictions from previously developed theoretical models for mat cooling. The prediction accuracy of these models is improved via a field calibration procedure using measured temperatures from the SAW RFID sensors. The predictions from the calibrated theoretical model are reasonable and agree well with the measured temperatures in the field.