Category: poster-mobility

EXPERIMENTAL TEST MATRIX OVERVIEW OF COATING PERFORMANCE ON ALKALI-SILICA REACTION AFFECTED CONCRETE

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PI: Kimberly Kurtis

Co-PI(s): Lauren Stewart

Institution(s): Georgia Institute of Technology

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Abstract

Alkali-Silica Reaction (ASR), is one of the many reactions that happen in concrete that lower its durability through cracking and expansion. Coatings have been explored in existing literature to expand the service life of concrete affected by this deleterious reaction through attempts to stop or slow expansion. Silanes, Siloxanes, Epoxies, and Linseed Oils are some of the many products experimented as coatings to achieve this goal, but it is clear that Silanes are the most effective. Within Silane coatings are several subsets of products varying in concentration and solvent basing. Performance of these subsets varies and demands further investigation. Prior to adding coatings to ASR-affected concrete, cracks are filled to limit unwanted ingress of chemicals into the concrete. It is already known that flexible caulking is a superior filler versus epoxy for filling cracks, but the order in application of filling cracks and applying coatings has not been explored. The test matrix proposed in this poster investigates a method to find the ideal scenario to these two issues.

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DEVELOPMENT OF TRAINING MODULES TO INCREASE USAGE AND UNDERSTANDING OF AGENCY-WIDE SOFTWARE PROGRAMS

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PI: Stephan A. Durham

Co-PI(s): Mi Geum Chorzepa, Sonny Kim, and Baabak Ashuri

Institution(s): The University of Georgia

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Abstract

Much of Georgia Department of Transportation?s (GDOT) current training practices are provided by the Human Resources Training and Development Office of GDOT through its Employee Learning Management System (ELMS). However, there is currently no on-demand training for a large portion of GDOT?s software needs including ProjectWise, Bluebeam, and CATS. RP 17-13 Development of Implementation Plan for GDOT E-Construction Program investigated 22 software types used across 15 offices and determined the need for GDOT specific training materials for the 3 software types listed above.

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RECOMMENDATIONS FOR NDT OF CONCRETE COMPONENTS FOR PERFORMANCE-BASED SPECIFICATIONS

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PI: Laurence Jacobs

Co-PI(s): Kim Kurtis, Ryan Sherman, Jin-Yeon Kim and Jianmin Qu

Institution(s): Georgia Institute of Technology

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Abstract

This poster demonstrates the feasibility of using a non-collinear wave mixing technique to image internal microscale damage throughout the interior volume of a relatively large (28 cm thick) concrete component. Unlike metals, concrete is rather heterogeneous with inherent microstructural features ranging in length from nanometers to millimeters or even centimeters. Many damage features that may significantly reduce the concrete material’s integrity are also within this range of length scales. This multiphase, heterogeneous, and multiscale nature of concrete makes the development of linear ultrasound based NDE and monitoring techniques for concrete technically challenging. Successful imaging using ultrasound requires that the ultrasonic wavelength be on the order of a few millimeters, yet the inherent length scale of this heterogeneous material with its fine and coarse aggregates is on this same millimeter length scale and larger. By exploiting the underlying mechanics of nonlinear wave mixing, this research shows it is possible to mix two incident waves with frequencies low enough to propagate without being scattered by the inherently heterogenous, concrete microstructure, while still being sensitive to damage features with length scales well below these incident wavelengths. Scanning and imaging is accomplished by manually adjusting the locations of the two incident waves, while knowledge of the wave speeds in concrete plus synchronization identifies the location of the mixing zone – the specific volume of concrete being imaged. The viability of the proposed technique is demonstrated by examining a concrete prism specimen with known, embedded internal microscale damage.

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GUIDELINES FOR INCORPORATION OF CEMENT STABILIZED RECLAIMED BASE (CSRB) IN PAVEMENT DESIGN

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PI: Jayhyun Kwon

Co-PI(s): Youngguk Seo

Institution(s): Kennesaw State University

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Abstract

GDOT is in the process of implementing an updated Mechanistic-Empirical Pavement Design Guide (MEPDG). To support this implementation, a research study was conducted to calibrate the national performance models for local conditions. However, reliable calibration coefficients could not be derived for semi-rigid pavements due to the lack of sufficient performance data. GDOT will therefore continue to utilize the current pavement design procedure (AASHTO 72/93) until appropriate MEPDG local calibration coefficients have been identified. This research project was undertaken to improve the reliability of the current GDOT pavement design procedure for CSRB and to provide recommendations regarding the steps required to verify and calibrate CSRB for use in MEPDG. A preliminary laboratory study of typical CSRB mix and field cores was conducted to characterize the CSRB materials and evaluate the accuracy of the relationship between elastic modulus and unconfined compressive strength, after which performance data was collected for samples from 4 different sites in Georgia. The FWD deflection data and UCS values of the field cores were then used to calculate the structural layer coefficient of the CSRB layer and a sensitivity analysis was performed to identify the input variables with the greatest influence on the performance predicted by the PMED. Two different pavement types were used to model the FDR pavement: flexible pavement and semi-rigid pavement. Finally, a data collection plan was developed to guide the collection of the data needed for local calibrations of the MEPDG for roads in Georgia.

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REAL-TIME NETWORK ASSESSMENT AND UPDATING USING VEHICLE-LOCATING DATA

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PI: Iris Tien

Co-PI(s): Zachary Roberts

Institution(s): Georgia Institute of Technology

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Abstract

Road infrastructure makes up a crucial component of Georgia’s asset network. Throughout the state, connections link different areas to each other, providing access to employment, social, and health services, thereby stimulating economic development. Halting these services are the presence of road blockages, including vehicular accidents, debris, flooding, which limit/prohibit travel along reported routes. Real-time traffic information needs to be collected and processed to ensure timely maintenance and hazard minimization. As most past studies have focused on stationary sources for real-time network analysis1 (e.g., loop detectors and traffic cameras), this study will utilize the wider-reaching and lower operational costing mobile sources of GDOT employee vehicles. Our network analysis will draw from three sources of data provided by GDOT (seen below in Figures 1-3, respectively): Georgia Network Database, WebEOC Executive Report, and the Verizon Network Fleet Database. The Georgia Network Database consists of a series of interconnected polylines representing the midpoint of Georgia roads. The WebEOC Executive Report is a large .csv file with the state route location, incident description, and the number of lanes passable. With processing, the data is converted into a usable ArcGIS Shapefile (.shp). The GDOT Verizon Network Fleet Geodatabase is a converted .csv of GDOT vehicle tracking information, including Vehicle ID, location, time, and ignition status of the vehicle (On/Off). Vehicles will be tracked with the same IDs in increments of 2 minutes to create vehicle route segments for further analysis.

Project Video

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USE OF GROUND PENETRATING RADAR TECHNOLOGY TO ASSESS AND MONITOR PAVEMENT STRUCTURAL CONDITIONS FOR IMPROVED PAVEMENT MAINTENANCE AND REHABILITATION STRATEGIES

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PI: S. Sonny Kim

Co-PI(s): Stephan A. Durham, Jidong J. Yang

Institution(s): University of Georgia

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Abstract

Subgrade density is one of the essential components for a structurally sound pavement system. In the field, subgrades soils are compacted to a desirable level to provide a robust platform for pavement layers. Insufficient field compaction is the most frequent construction-related issue resulting in lower subgrade density and potential structural failure. Electromagnetic (EM) density gauges have recently been introduced as an alternative to the nuclear density gauges. These nonnuclear devices use EM signals to measure in-situ density. Such EM density gauges eliminate the need for licenses, training, and specialized storage, as well as the risks associated with devices that use a radioactive source (Romero and Kuhnow, 2002). However, like the traditional methods, the nonnuclear density gauges do not provide continuous test results for the entire pavement area. Determining field subgrade condition in pavement requires a specified number of samples regardless of the density measurement method used. The sample-based assessment is only performed at limited spots and may not represent the entire surveyed road section. Further, a spot test may need traffic control during the test, which may cause traffic congestion. Therefore, a rapid and reliable test method that covers expansive surface areas becomes necessary to enhance the level of confidence in the evaluation. This study proposes a prediction model to estimate in-place subgrade dry density using ground penetrating radar (GPR) shown in Figure 1, which is fast, continuous, and reliable. Besides the subgrade density estimation, the GPR tests provide additional information about pavement structures, such as layers’ thicknesses and layers’ changes.

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INVESTIGATION AND GUIDELINES FOR DRILLED SHAFT EXCAVATION INSPECTIONS

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PI: Adam Kaplan

Co-PI(s): Jayhyun Kwon

Institution(s): Kennesaw State University

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Abstract

A proper drilled shaft (a.k.a. caisson) excavation inspection is crucial to the structural integrity of the shaft. Factors such as irregularities on the sidewalls, verticality of the shaft, and debris on the shaft bottom play an important role in the constructability and the structural performance of the shaft under service loads. In the case of a dry shaft construction, the field inspector may visually assess the walls and base of the drilled shaft by entering the excavation. An entry into a drilled shaft requires compliance with Occupational Safety & Health Agency (OSHA) requirements, which may include testing for toxic and flammable gases. Due to such safety concerns, field inspectors have been reluctant to carry out such inspections. In this study, a range of drilled shaft excavation inspection equipment with the capability to eliminate sending a human into the dry shaft excavation has been investigated. The objectives are: 1) Evaluating existing equipment and methods 2) Conducting field demonstrations 3) Making recommendations based on safety, cost, moblity, accuracy, speed and DoT experience

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PHASE II – INVESTIGATION AND GUIDELINES FOR BEST PRACTICES OF MASS CONCRETE CONSTRUCTION MANAGEMENT

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PI: Yong Cho

Co-PI(s): Kimberly Kurtis, and Russell Gentry

Institution(s): Georgia Institute of Technology

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Abstract

The durability of mass concrete structures may be compromised due to stresses and cracking induced by temperature rise due to hydration of the concrete, and subsequent cooling. Delayed ettringite formation and thermal cracking may occur when maximum temperatures and maximum temperature differentials, respectively, are greater than the allowable thresholds. Construction practices in mass concrete scenarios, therefore, seek to limit maximum and differential temperatures below acceptable limits. This work investigates a mass concrete abutment wall that was constructed as part of relocating and widening a state road in Douglasville, Georgia beneath a railway line. Thermal control measures for the construction of the wall included both precooling of the concrete at the ready-mix plant using liquid nitrogen and post-cooling the abutment wall using internal cooling pipes. Both of these technologies increased the cost and complexity of construction. This research focuses on developing means to better characterize the heat of hydration of the cements and SCMs and temperature rise of concretes proposed for the project, and on proposing means to construct the abutment wall with less stringent and less costly thermal control measures. Alternative modeling approaches using isothermal calorimetry and machine learning, as well as nomogram decision-making tools have been proposed. Further analysis has been completed to investigate alternative design and construction options to satisfy maximum and differential temperature limits imposed by Georgia DOT guidelines. The variables considered are types and finenesses of cementitious materials, mix designs, concrete placement temperatures, and time of removal of insulation and formwork. It has been found that the accuracy of the thermal modeling can be improved with up-to-date techniques. The research concludes that both maximum and differential thermal limits could have been satisfied and post-cooling eliminated with the use of alternative materials and performance-based limits. The investigation shows that with proper heat of hydration modeling and decision-making tools, the cost and complexity of mass concrete construction can be significantly reduced.

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