Category: 2019

POSTER 19-17: CHARACTERIZING ALKALI-SILICA REACTION MITIGATION OF RECLAIMED ASH USING MICRO-X-RAY FLUORESCENCE

CHARACTERIZING ALKALI-SILICA REACTION MITIGATION OF RECLAIMED ASH USING MICRO-X-RAY FLUORESCENCE

PI: Kimberly Kurtis

Co-PI(s): 

Institution(s): Georgia Institute of Technology

Abstract

Over the past 80 years, concrete mixtures have become reliant on the use of fly ash to improve performance. The closure of coal power plants in the US has raised concerns about the supply of traditional fly ash. Fortunately, there are billions of tons of fly ash stored in solid waste disposal sites that can be easily accessed. However, current classification procedures are not suited to handle this variety of available ash and new specifications are needed on the usage of reclaimed fly ash to produce concrete mixtures with long-lasting performance. This study addresses this knowledge gap through experiments on samples made incorporating reclaimed fly ashes. Mortar bar samples were subjected to an aggressive and accelerated test to assess the alkali-silica reaction (ASR) mitigation potential of the reclaimed ashes. At the end of the test duration, Micro-X-Ray Fluorescence (MicroXRF) analysis was conducted to better understand transport of alkali into the microstructure and how it may lead to deleterious expansion due to ASR. The results showed that the length expansions of the reclaimed ash mortar bars were significantly lower compared to the reference OPC and inert filler samples. From the MicroXRF analysis, there was a range of magnitudes for surface concentrations and diffusivity coefficients in the reclaimed ash samples. This showed that it is not enough to look at diffusivity coefficient in isolation as surface concentration is also important factor in the resulting expansion. Overall, the results of this study suggest the potential of using reclaimed fly ashes for alkali silica reaction mitigation in concrete.

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POSTER 19-27: STRATEGIES AND RESOURCES FOR STRENGTHENING THE IMPLEMENTATION OF THE CONSTRUCTION QUALITY ACCEPTANCE FIRM (CQAF) MODEL IN THE INNOVATIVE PROJECT DELIVERY ENVIRONMENT

STRATEGIES AND RESOURCES FOR STRENGTHENING THE IMPLEMENTATION OF THE CONSTRUCTION QUALITY ACCEPTANCE FIRM (CQAF) MODEL IN THE INNOVATIVE PROJECT DELIVERY ENVIRONMENT

PI: Jung Hyun Lee

Co-PI(s): Baabak Ashuri, Lier Liu, Evan Mistur, and Gordon Kingsley

Institution(s): Georgia Institute of Technology

Abstract

Considering the social and economic values of high-quality transportation infrastructure in the U.S., major projects delivered using innovative project delivery require a new model to ensure effective quality management. Several State Departments of Transportation (DOTs) have adopted a new quality management system requiring the use of the developers’ construction quality acceptance firm (CQAF), also known as an independent quality firm (IQF). A better understanding is needed to develop innovative methods of conducting quality assurance (QA) in the construction engineering and inspection (CEI) industry. Therefore, this research aims to provide guidance on strengthening the QA process in the innovative project delivery environment. To identify the current state of understanding in the CQAF model compared to traditional quality management, this study conducted a combination of content analysis, survey, and follow-up interviews. The content analysis identified the major differences in the approach taken by different state DOTs and compiled the primary similarities and differences in QA between design-build (DB) and public-private partnership (P3) projects. A survey of the CEI industry provided valuable lessons for future improvement in quality management services in federal-aid design-build projects. We further consolidated our interpretation of QA topics and investigated strategies for QA at GDOT through in-depth interviews with 15 survey participants. Our findings offer a better understanding of the roles and responsibilities of the CQAF model and contribute to adopting the new quality assurance program and enhancing the CQAF model for current and future projects in the DB and P3 environments.

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POSTER 19-06: LRFD PROCEDURE FOR PILES WITH PILOT HOLE IN ROCK

LRFD PROCEDURE FOR PILES WITH PILOT HOLE IN ROCK

PI: Soonkie Nam

Co-PI(s): Xiaoming Yang

Institution(s): Georgia Southern University

Abstract

In Georgia, when a hard/dense layer exists in the pile length or the vibration/noise during the driving causes secondary issues, a pilot hole is often adopted as a pile-driving assistance method to aid driving displacement piles through, especially if a competent hard rock layer exists in a reasonable depth. The use of a pilot hole reduces construction time and uncertainties related to driving through the problematic layers. However, the pilot hole is considered different from a pre-drilled hole in terms of construction method and design assumption. This process also complicates the prediction of long-term pile capacity with a predrilled hole. An objective of this study was to identify and document the current guidelines available and adopted by different states, and investigate the relationship between the load capacity of piles installed in rock and their design parameters with respect to the pilot hole, rock conditions, and installation method. Another objective was to identify a reliable design procedure that incorporates proper LRFD resistance factors, and a field verification method for quality assurance of rock. It is found that pile driving analyzer (PDA) can be applied to the piles with a pilot hole on rock and verify the structural capacity of the pile if not the geotechnical capacity due to the higher bearing capacity on rock. It also can check the internal stress to avoid the damage during striking. Thus, the study recommends the use of PDA tests and the AASHTO resistance factor for driven piles with dynamic testing, while collecting the strength properties of the rock mass. The driving refusal criterion can be used when the rock condition is evident. However, it is still recommended that the correlations between the refusal guidelines and rock properties are verified with PDA.

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POSTER 19-10: FLASH TRACKING IMPLEMENTATION GUIDELINES COMPLEMENTING EXISTING DESIGN-BUILD MANUAL

FLASH TRACKING IMPLEMENTATION GUIDELINES COMPLEMENTING EXISTING DESIGN-BUILD MANUAL

PI: Pardis Pishdad-Bozorgi

Co-PI(s): Jesus M. de la Garza

Institution(s): Georgia Institute of Technology

Abstract

The overarching objective of this research is to develop Flash Tracking implementation guidelines that would complement the existing Design-Build Manual. These standardized implementation guidelines are captured in an appendix to the DesignBuild Manual. The research methodology comprised three phases. In the first phase, the research team studied and analyzed the effectiveness of flash track best practices implementation on three GDOT projects—namely, improvements to the I-16/I-95 interchange, the I-85 Widening, and SR 400 EL. In the second phase, the team reviewed and analyzed the GDOT DesignBuild Manual to identify its strengths, weaknesses, opportunities, and threats (i.e., a SWOT analysis) in terms of its treatment of flash track best practices. This involved cross-referencing the D-B manual against the 83 flash track best practices, to determine the presence or absence of each flash track best practice in the manual. In the third phase, an appendix to the D-B manual was developed to serve as an official source on implementing flash track best practices on D-B projects. Furthermore, modified RFQ and RFP templates were developed to incorporate flash track practices on projects and specific recommendations were made for the RFQ and RFP for the Houlihan Bridge P.I. No. 0013741/0013742 – SR 25 at Savannah & Middle River Bridges.

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POSTER 19-21: USE OF GROUND PENETRATING RADAR TECHNOLOGY TO ASSESS AND MONITOR PAVEMENT STRUCTURAL CONDITIONS FOR IMPROVED PAVEMENT MAINTENANCE AND REHABILITATION STRATEGIES

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

PI: S. Sonny Kim

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

Institution(s): University of Georgia

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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POSTER 19-07: INVESTIGATION AND GUIDELINES FOR DRILLED SHAFT EXCAVATION INSPECTIONS

INVESTIGATION AND GUIDELINES FOR DRILLED SHAFT EXCAVATION INSPECTIONS

PI: Adam Kaplan

Co-PI(s): Jayhyun Kwon

Institution(s): Kennesaw State University

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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Poster 19-04: PHASE II – INVESTIGATION AND GUIDELINES FOR BEST PRACTICES OF MASS CONCRETE CONSTRUCTION MANAGEMENT

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

PI: Yong Cho

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

Institution(s): Georgia Institute of Technology

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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DAVID JARED RETIREMENT FAREWELL RECEPTION

David Jared, Assistant Office Head, Office of Performance-based Management and Research (OPMR), will be retiring from GDOT with 25 years of service, effective October 1, 2019. David manages GDOT’s research and development program, one of the largest among state DOT’s in the U.S. He plans to work for the Transportation Research Board (TRB) in Washington D.C., a part of the National Academy of Sciences.

A farewell reception will be held at the OMAT Auditorium in Forest Park on September 20, from 10:30 a.m. – noon. Please contact Supriya Kamatkar of OPMR for details (404.347.0552).  

Finally, David wishes to thank all who have supported GDOT’s research program over the years. This broad support has been vital to the success and stature of the program within the AASHTO community.

To RSVP or give a farewell message click here.