| SPR Active Projects |
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| SPR 682 |
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Replacing Thermal Sprayed Zinc Anodes
| Project Coordinator: |
Steve Soltesz |
| Research Agency: |
Montana State University |
| Principal Investigator: |
Xianming Shi, PdD, PE |
| Start Date for ODOT: |
July 2008 |
| Completion Date for ODOT: |
June 2010 |
OBJECTIVES:
The objectives of the research are the following:
1) To determine the most cost-effective method to remove existing zinc anodes;
2) To develop a protocol to prepare the concrete surface for the new anode.
1.1 Benefits
The research will allow ODOT to specify the most cost-effective approach to replace failing and end-of-life cathodic protection anodes. The outcome will ensure that the ODOT CP systems installed on historic coastal structures continue to protect those structures and extend their service lives.
This research will also provide owners of reinforced concrete structures (including highway agencies), engineers, architects, contractors, and other stakeholders with improved understanding pertinent to concrete surface preparation, anode performance monitoring, anode life prediction, and anode removal, which will lead to best practices of selecting, installing, maintaining, and replacing CP systems. These CP systems are expected to provide a powerful tool to greatly extend the service lives of existing reinforced concrete structures (especially those exposed to marine environments and deicing applications) in a measurable and predictable manner, and enable cost-effective corrosion mitigation strategies to provide safe and reliable structures for the traveling public and the freight.
This research will lead to best practices of preserving reinforced concrete (bridge decks, bridge substructures, buildings, car parks, etc.) and thus potentially realize considerable payoff in cost savings and benefits to the user and the environment. The cost of maintenance and rehabilitation required to reserve the structural integrity and overall safety of ODOT highway structures is phenomenal. Repeated rehabilitation and repair also incur a significant environmental toll, as well as the delays caused by closing roads or bridges. In contrast, appropriate selection, installation, maintenance and replacement of CP systems would generate substantial cost savings for the Department by minimizing the premature rehabilitation or failure of highway bridges and reducing the construction costs.
OVERVIEW:
Corrosion of reinforced concrete structures is a major and increasing problem worldwide. The remediation of concrete bridges undertaken as a direct result of chloride-induced rebar corrosion was estimated to cost the U.S. highway departments $5 billion per year[1]. ODOT has historic reinforced concrete bridges at the coast that employ impressed current cathodic protection (CP) to greatly reduce the corrosion of the embedded steel reinforcement. The CP systems rely on passing an electric current into the concrete through zinc metal anodes that have been sprayed onto the surface of the concrete. Some of these zinc anodes are nearing the end of their design lives, while others are beginning to separate from the concrete prematurely possibly due to erratic current controllers or initial contractor inexperience during installation. Anode sections that have debonded no longer protect the underlying steel reinforcement. When the natural rate of corrosion resumes, the unprotected sections are on the path to concrete spalling and steel section loss - the conditions that required ODOT to undertake expensive repairs and protection schemes. Currently, there is no procedure established by ODOT to remove old anodes, prepare the concrete surface, and install new anodes.
[1] FHWA, FOCUS Federal Highway Administration, Washington DC, 1999, Sept.: 6.
PROPOSED ACTIVITIES:
The main “product” expected from this research will be the final report that documents the background, methodology, and research findings of this project and includes procedures and recommendations for old anode removal and surface preparation before new anode application that can be incorporated into field specifications for CP systems. Interim deliverables will also be prepared and delivered to the ODOT TAC to report progress on the project tasks and to seek ODOT input on the overall project direction. The Principal Investigator (PI) will keep the ODOT bridge preservation engineers apprised of project progress and issues that may require direction through interim deliverables and through teleconferences arranged with the TAC as necessary. To minimize cost and delay, all deliverables will be sent electronically for review and comments.
The audience or “market” for this product will be ODOT bridge engineers, maintenance engineers, contractors, and other stakeholders. ODOT decision makers using the bridge management system can also benefit from the improved knowledge gained from this research on CP best practices.
At this stage, there are two major impediments identified for the successful deployment of the CP technology. First, the performance and durability of anodes in the field are affected by many other factors beyond the scope of this research, such as the site-specific contaminants and climatic conditions, structure-specific concrete conditions (depth of cover, resistivity, microstructure, levels of carbonation and chloride contamination, etc.), contractor practices, and CP system malfunctioning. Second, there are expected institutional issues to be addressed and resistance to change in practices and specifications. To minimize the difference between research findings obtained from the laboratory testing and what actually occurs in the real coastal environments, this research will consist of both laboratory investigation and field investigation.
The institutions and individuals who might take leadership in applying the research product will be the ODOT bridge preservation engineers that hopefully will benefit from its implementation.
The activities suggested for successful deployment include:
- Throughout the project duration, the research team will work closely with ODOT end users to identify user requirements for the CP technologies, to integrate previous ODOT research knowledge and field experience into this research, and to identify areas for improvement, in order to ensure the successful implementation of research results after the completion of this project in June 2010.
- At the conclusion of the project, the PI will present the research results to ODOT in a workshop forum, including a full explanation of the applied usefulness of the research. The research findings will also be transferred to all ODOT stakeholders through the circulation of the final report.
- This research includes deployment at the concept stage and at the laboratory prototype stage, which could lead to additional research phases as necessary, such as controlled field demonstration and field pilot projects before full corporate deployment.
REPLACING THERMAL SPRAYED ZINC ANODES WORK PLAN
Quarterly Reports:
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| SPR 683 |
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Calibration of LRFD Resistance Factor for the Wave Equation Analysis Program
| Project Coordinator: |
Steve Soltesz |
| Research Agency: |
Portland State University |
| Principal Investigator: |
Trevor Smith |
| Start Date for ODOT: |
July 2008 |
| Completion Date for ODOT: |
June 2010 |
OBJECTIVES:
The objective of the research is to recalibrate the LRFD resistance factor for restrike for use with the GRLWEAP program.
A comparison conducted under the preliminary study showed that the number of piles could double on some bridge projects when strictly following the new AASHTO LRFD code requirements (as compared to earlier designs using ASD procedures). It is believed that this research will result in a much less conservative resistance factor for the GRLWEAP method than what is currently provided in AASHTO but still maintain the level of safety required by the LRFD code. As Oregon continues replacing many of its highway bridges, employing more accurate, less conservative resistance factors will reduce bridge construction costs significantly. These benefits could be extended to other states, counties and governmental agencies that use the wave equation method to determine pile bearing capacity.
OVERVIEW:
Many Oregon bridges are supported by groups of steel and concrete piles driven deep into the underlying soils. The load bearing capacity of a pile depends on a complex interaction involving pile dimensions, pile structural capacity, the surrounding soil properties, time to loading and the depth of the pile.
The Wave Equation Analysis of Pile Driving program (WEAP) is a common computer algorithm used to estimate pile load bearing capacity while the pile is being driven. The most popular commercial program is released by GRL Inc. of Cleveland, Ohio, and is called GRLWEAP. ODOT has used the GRLWEAP program very successfully for pile driving operations over the last fifteen years in conjunction with the Allowable Stress Design (ASD) method. Starting in 2007, the FHWA required states to use a new design method on structures called Load and Resistance Factor Design (LRFD). The LRFD design method, as described in the AASHTO LRFD Bridge Design Specifications, has a default resistance factor of 0.40 that is applied to the ultimate (nominal) load bearing capacity generated by the GRLWEAP program. It is known that by using the AASHTO LRFD default resistance factor with GRLWEAP results in significantly more conservative pile designs than those prior to LRFD. In essence, the new design code forces ODOT to build foundations beyond the high level of safety achieved with the previous design (ASD) method. This will result in much more expensive foundation costs for bridge construction.
The new AASHTO LRFD code allows recalibration of resistance factors to account for standard of practice, site specific soil and pile conditions, and local judgment of transportation jurisdictions. A recalibration of the WEAP resistance factor using site specific soil parameters and Beginning of Restrike (BOR) pile driving data should result in a less conservative resistance factor for use in design. The TRB Circular “Calibration to Determine Load and Resistance Factors for Geotechnical and Structural Design” documents the procedure for conducting the recalibration that assures the level of safety intended by LRFD. A preliminary study funded by ODOT and OTREC determined that most of the data needed to perform the recalibration are already available.
PROPOSED ACTIVITIES:
ODOT foundation engineers and FHWA personnel responsible for authorizing new LRFD factors will be on the technical advisory committee to provide technical oversight of the research. Therefore, the recalibrated LRFD resistance factor for GRLWEAP that results from the research should be quickly available for use in new bridge designs in Oregon. The results of this research study will be submitted to AASHTO for adoption into the national code.
CALIBRATION OF LRFD RESISTANCE FACTOR FOR THE WAVE EQUATION ANALYSIS PROGRAM WORK PLAN
Quarterly Reports:
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| SPR 684 |
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Calibrating the Future HSM Predictive Methods for Oregon
| Project Coordinator: |
Mark Joerger |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Karen Dixon |
| Start Date for ODOT: |
October 2008 |
| Completion Date for ODOT: |
August 2010 |
OBJECTIVES:
The goal of this research effort is to prepare Oregon for the changing national safety assessment procedures for corridor or site-specific projects. Without this research, Oregon will be ill equipped to use the HSM predictive methods and their proactive analysis strategy. With this research, Oregon will continue to establish itself as a national leader in transportation safety. The funding of this research project in FY09 will enable project completion that will correspond with release of the manual and Oregon will be able to immediately achieve safety benefits from the HSM. The objective of this research will be to:
- Explore the recommended calibration procedures identified in the HSM and quantify the results of application to Oregon.
- Explore the appropriate level of calibration for Oregon-specific applications
- Produce calibration constants that can be readily used following the release of the HSM.
OVERVIEW:
AASHTO, FHWA, and TRB have combined efforts to develop a document similar to the Highway Capacity Manual known as the Highway Safety Manual (HSM). This publication will be published by AASHTO and is expected to be used as a supporting document in the design and assessment of highway facilities in the United States. The manual is targeted for release in 2010; however, there may be a NCHRP Synthesis released in 2009 so that agencies can see the recommended procedures and know how to prepare for these changes in safety assessment. The first edition of the HSM will include a section known as "Predictive Methods" that will provide science-based analytical procedures for estimating the safety of a road and how modifying certain road characteristics will influence the safety of a facility. The models and adjustment factors were developed from various data sets and it is emphasized in this document the importence of calibrating safety performance functions to specific local conditions. Without calibration of the predictive procedures for local conditions, the HSM methods can provide misleading recommendations that could result in inappropriate investment of safety funds. The calibration effort is generally viewed by most practioners as time consuming and complicated. Moreover, the calibration exercise is efficiently accomplished using a statewide approach and for all models simultaneously. Both Karen Dixon and Chris Monsere serve as members of the TRB Task Force for the Development of the Highway Safety Manual. In fact, Karen Dixon chairs the research sub-committee for this TRB effort. As a result, Oregon researchers already have full access to the procedures that will be included in the HSM and can initiate calibration of these procedures for the State of Oregon so that Oregon transportation agencies will be prepared to use the document to its fullest potential upon release.
PROPOSED ACTIVITIES:
Successful completion of this proposed research effort will include the following tasks:
- Literature Review: The literature review for this task will be limited to a brief review of the HSM procedures, and an evaluation of calibration issues appropriate for determining adequate sample size and variable representation.
- Data Collection and Formatting: The HSM includes predictive methods for rural, two-lane roads; rural, multilane highways; and urban and suburban arterial highways. Each of these predictive methods is based on unique assumptions or crash trends. This proposed research effort will use local conditions (crash data, road geometry information, traffic volume data, etc.) to calibrate the HSM predictive procedures for Oregon facilities. To do this, the research team will need to identify characteristics of the source models included in the HSM and verify that, at a minimum, the representative Oregon samples encapsulate the conditions included in the companion predictive models. This crash data will then be formatted using multiple years of data, varying Oregon regions, and, where possible, varying highway ownership. Upon completion of task 1 and 2, the research team will prepare an interim report. The research team has many synergistic activities that will aid in the efficient gathering and assembly of these data.
- Model calibration: The calibration effort will be divided into three specific model categories consistent with the three HSM predictive method road conditions indicated in task 2. The research team will use crash data calibration to determine how the HSM predictive models should be adjusted for use in Oregon. The team will explore potential calibration techniques and the benefits of local-scale calibration. In addition, accident modification factors included with the HSM predictive models will be compared and contrasted to current Oregon (crash reduction) factors in an effort to minimize confusion regarding the use of these safety adjustment values and assure consistent and accurate future use of the HSM manual in Oregon. An interim report will be prepared.
- Recommendations: Following the model calibration and accident modification factor evaluation, the research team will determine specific calibration factors that should be used so that the HSM procedures can be directly applied to Oregon highways. Included in this effort will be a companion document for dissemination that will identify how to apply the HSM procedures to Oregon roads. This document will include example problems demonstrating the use of these procedures to increase technology transfer.
- Reports. The research team will prepare draft and final reports compiling the results of the interim reports as well as final recommendations.
Quarterly Reports:
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| SPR 685 |
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Safety Evaluation of Curve Warning Advisory Speed Signs
| Project Coordinator: |
June Ross |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Karen Dixon, Ph.D., P.E. |
| Start Date for ODOT: |
October 2008 |
| Completion Date for ODOT: |
September 2009 |
OBJECTIVES:
The goal of this proposed research is to ensure that advisory speeds are adequately posted in the state of Oregon in a manner that helps improve safety and with particular emphasis on higher speed rural horizontal curve locations. To accomplish this goal, the research proposed in this study will address several key objectives. These are summarized as follows:
· Using the randomly selected curve locations including upstream and downstream corridor segments, the research team can contrast the historic safety record at these curve locations to the advisory speeds posted as well as the required advisory speed thresholds for Oregon and national standards.
· Evaluate potential advisory speed posting assessment procedures that can be performed prior to or instead of the current ball-bank field evaluation. These alternative procedures may ultimately provide more consistent and cost effective advisory speed posting techniques.
3.1 Benefits
If this research is not performed, ODOT will have potentially unsafe conditions at improperly signed horizontal curve locations. Proposed changes to the MUTCD recommend a modified threshold for advisory speeds that varies significantly from the current Oregon threshold. Decision makers in Oregon must determine if they want to adopt new MUTCD thresholds or retain Oregon thresholds. In the event current Oregon thresholds are retained, the recent advisory speed study demonstrated that many of the current advisory speed signs do not meet Oregon criteria. The decision to invest in replacing these signs must also be considered. This research will aid Oregon decision makers by determining specific safety implications of current posted advisory speeds and the implications of either modifying the posting threshold or enforcing the current threshold. This proposed research will also help identify priorities for sign upgrades by determining the safety implications of the various compliance levels.
Additionally, since current advisory speed warning sign posting procedures require expensive site visits and field testing to determine the appropriate speed to post, the research team will determine if a more cost effective “office” technique for identifying advisory sign requirements may be feasible through the use of aerial photos or design plans.
OVERVIEW:
The use and placement of advisory speed signs at horizontal curve locations in the state of Oregon is determined by guidance in the Oregon Department of Transportation (ODOT) Traffic Manual and the ODOT Sign Policy and Guidelines. These regional guidelines are supplemented by the Manual of Uniform Traffic Control Devices (MUTCD). The 2003 MUTCD, however, included a change in recommended guidance for establishing advisory speeds on Exit, Ramp, and Curve Speed Signs. Traditionally, advisory speeds have been established by driving a vehicle equipped with a ball-bank indicator around a curve at a specified speed and noting the ball-bank indicator reading. The MUTCD notes that a 10-degree ball-bank indicator reading was formerly used in determining advisory speeds, based on research from the 1930’s. The 2003 Edition of the MUTCD (FHWA 2003) changed the 10-degree reading to a 16-degree ball-bank indicator reading, based on perceived performance of modern vehicles and speeds at which most drivers’ judgment recognizes “incipient instability” along a ramp or curve. Subsequent to the publication of the 2003 Edition of the MUTCD, the Advisory Speed Task Force of the National Committee on Uniform Traffic Control Devices Regulatory and Warning Signs Technical Committee identified inconsistencies in the MUTCD text regarding the advisory speed issue and began re-evaluating this modified advisory speed posting guidance. The Committee has recommended that the criteria for advisory speed engineering studies can be based on ball-bank criteria, accelerometer readings, or calculations using side friction factors. Included in the proposed procedures is a modification to the required ball-bank indicator reading (using a 16-, 14-, and 12-degree threshold based on curve speed).
PROPOSED ACTIVITIES:
The research team will make presentations to the appropriate officials as deemed necessary by the technical advisory committee in order to disseminate this information to ODOT and other appropriate Oregon transportation agencies. In addition, the research team will summarize the project results in an article suitable for publication in an archival journal or presentation at a national conference.
It is expected that updated advisory speed posting procedures, including new methods for consistently evaluating speed posting evaluation methods, will result from this research. Ultimately, the research results may be included in modified state-wide advisory speed posting procedures.
SAFETY EVALUATION OF CURVE WARNING ADVISORY SPEED SIGNS WORK PLAN
Quarterly Reports:
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| SPR 686 |
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Health Risk Exposure to Naturally Occurring Hazardous Minerals During Construction Activity
| Project Coordinator: |
Matthew Mabey |
| Research Agency: |
DOGAMI |
| Principal Investigator: |
Clark Niewendorp |
| Start Date for ODOT: |
February 2009 |
| Completion Date for ODOT: |
July 2010 |
OBJECTIVES:
Objective 1: Identification and knowledge—Develop list of NOHMs that may plausibly occur in Oregon , and tailor and query existing mineral and geologic databases to determine where such occurrences may intersect ODOT operations; setting priorities based on hazard assessment.
Objective 2: Detection—Develop tools such as digital maps that inform ODOT personnel of the potential location of NOHM using results of Objective 1 as a screening tool and build awareness of environmental and health impact.
Objective 3: Control and management—Develop and implement best management practices for identified NOHM determined in Objective 1and located in Objective 2.
OVERVIEW:
Hazardous or problematic environmental conditions such as slope stability and drainage have been accommodated in roadway construction, in one way or another, for centuries. More recently human caused contamination with pollutants has also become the subject of concern as well. Environmental awareness has now reached the point where we are recognizing that naturally occurring materials can represent hazards equivalent to the human caused pollutants that are now routinely avoided or mitigated.
This work is intended to become the foundation for policies and procedures that will proactively identify and address naturally occurring hazardous materials in manners analogous to how similar hazardous environmental conditions are routinely dealt with at present.
PROPOSED ACTIVITIES:
Implementation of the research findings will occur at various ODOT levels (development, engineering, environmental) for NOHM associated with rock source pits and rock moved from cuts to fills. Using the NOHMGIS application, conduct surveys, inventories and map distribution, and monitor and perform hazard analysis at various spatial scales for ODOT’s geologic investigations and environmental assessment of projects and flag potential pollution liability. Based on hazard assessment information, implementation of cost-effective best management practices (solutions) to avoid or minimize unnecessary exposure to ODOT employees, its contractors, and traveling public.
HEALTH RISK EXPOSURE TO NATURALLY OCCURRING HAZARDOUS MINERALS DURING CONSTRUCTION ACTIVITY WORK PLAN
Quarterly Reports:
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| SPR 710 |
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Analysis and Design of Pipe Ramming Installations
| Project Coordinator: |
Matthew Mabey |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Armin Stuedlein |
| Start Date for ODOT: |
December 2009 |
| Completion Date for ODOT: |
August 2012 |
OBJECTIVES:
The main objectives of this study are to increase the understanding of the mechanics of pipe ramming and to develop an engineering framework for the design and evaluation of pipe ramming projects. One or more instrumented pipes, installed using pipe ramming techniques, will be monitored under field conditions to assess the mechanics of pipe installation including hammer performance, wave travel along the pipe in soil and upon breakout (i.e., exiting the embankment), and the development of internal and external shaft resistance. If the results of the field study indicate that the wave travel within the pipe is not significantly affected by stress gradients across the pipe section, the suitability of existing wave equation techniques will be evaluated (e.g., GRL WEAP, finite element). Otherwise, if the results indicate that the stress waves propagate in 2-D, a new finite element- or finite difference-based analytical tool will be developed to assess installation behavior. This research will develop a comprehensive framework for the methodological evaluation of pertinent pipe ramming variables to assist designers in optimizing safe and successful pipe ramming installations. It is emphasized that adaptation of existing techniques will be preferred over the development of new tools to maximize integration with the state of practice.
OVERVIEW:
While there has been adequate research into some aspects of pipe ramming, such as settlement, much of the process is based on doing what worked on previous projects. There is currently no method available to assess the suitability of proposed materials, equipment and installation techniques. Therefore, there is a need to develop a reliable framework for analyzing the structural and geotechnical engineering aspects of pipe ramming projects, including: (1) a methodology to evaluate a proposed site for suitability of pipe ramming, (2) assess combinations of proposed pipe materials (e.g., grade of steel), diameter, wall thickness, and length of pipe for a proposed project, and (3) design and specify the pipe ramming operation accordingly (e.g., hammer size, blow rate, lubrication, spoils removal).
PROPOSED ACTIVITIES:
Meetings will be held with ODOT personnel to present research findings and progress reports. The frequency of these meetings will be determined by the ODOT TAC members, however, at a minimum, there will be one progress meeting with ODOT at 18 months following the start of the contract. The results of this research will be drafted in a formal report and be primarily aimed towards assessing proposed pipe ramming installations prior to the start of a project. Following completion of the experimental, analytical evaluation, and parametric study, a meeting with the TAC committee will be conducted for the purpose of discussing the proposed design guidelines. The TAC committee will be able to shape the guidelines to maximize the impact and implementation of the research. The draft guidelines and procedures for assessing pipe ramming installations generated as part of this study will be presented to the ODOT TAC members for review two months prior to close of the contract It is anticipated that the guidelines and design specifications presented in the final report will be referenced and/or implemented in the ODOT Hydraulics, Geotechnical, and Structural Design Manuals for use by State engineers and design consultants. Additionally, the findings of this study will be disseminated through state and national presentations, conference proceedings, and journal publications.
ANALYSIS AND DESIGN OF PIPE RAMMING INSTALLATIONS
Quarterly Reports:
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| SPR 711 |
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Internal Curing of Concrete Bridge Decks
| Project Coordinator: |
Steve Soltesz |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Jason Ideker |
| Start Date for ODOT: |
July 1, 2009 |
| Completion Date for ODOT: |
December 31, 2011 |
OBJECTIVES:
The goal of this research project is to determine if the incorporation of saturated lightweight aggregate into high-performance concrete bridge deck mixtures can significantly reduce external curing requirements (currently 14 days) while maintaining crack-free or crack-resistant concrete. While research has already shown the benefits of reducing cracking risk due to autogenous shrinkage through the incorporation of saturated fine LWA it is necessary to further this technology to quantify the potential reductions in external curing.
Specific research objectives are:
– Identify high-performance concrete mixture proportions incorporating saturated fine LWA which will provide sufficient internal curing to reduce autogenous shrinkage and subsequent cracking risk
– Identify significantly shortened external curing regimes that will complement the use of internal saturated fine LWA to reduce early-age cracking risk in high performance concrete bridge decks
– Demonstrate effectiveness of selected strategies in small scale field trials/applications identified through collaborative efforts with ODOT
– Provide guidelines for contractors and finishers to take advantage of new materials/mixture proportions identified in this research program to provide internal curing in high performance concrete applications
– Expand existing literature and state-of-knowledge in this area and bring new expertise to the state of Oregon related to internal curing through use of lightweight saturated aggregate
OVERVIEW:
Current Oregon Department of Transportation (ODOT) Standard Specifications for curing of high-performance bridge deck concrete requires wet curing be initiated within 20 minutes of the final pass of the finishing machine and not greater than 20 feet from the back of the pavement machine. This wet cure is specified for a duration of 14 days with longer curing possible if cooler ambient temperatures (T < 45 °F) are encountered during the initial 14-day period. This long wet cure reduces evaporation that can lead to cracking, and it provides water to the bulk concrete to participate in the chemical reactions in the cement paste during curing. While this curing period reduces bridge deck cracking, the time requirement represents a significant burden on constructability and project scheduling. There is a need for accelerated/alternate curing techniques that will allow for increased construction efficiency while still producing crack-free or crack-resistant high-performance concrete bridge decks.
PROPOSED ACTIVITIES:
While interim reports and a final report will be issued as part of this research project, providing detailed summation of all work performed under this project to complement the ODOT research database it will also be essential to disseminate information in a variety of other ways. Actively involved in ACI, Dr. Ideker and his research team will make at least one presentation at a national meeting of ACI regarding the research findings of this project. It is also anticipated that the graduate student researcher will make a presentation early-on at a national ACI Convention, either in a Research in Progress Session or Open Paper Session. As a voting member of ASTM C01 and C09 (cement and concrete/aggregates subcommittees, respectively), knowledge gained under this project will allow Dr. Ideker to provide expertise to this key international standardization body. Dr. Ideker and his research team will also publish several technical journal articles related to the research findings in the top technical journals in the field of concrete materials research (Cement and Concrete Research, ACI Materials Journal, ASCE Journal of Materials in Civil Engineering, etc.).
In addition to technical presentations and articles, the research team will work closely with ODOT to ensure involvement from a variety of agencies during field trials/investigations. Key personnel from ODOT, FHWA, and the Oregon Concrete and Aggregate Producers Association will observe the field trials during casting and finishing and at key stages of curing. Input from these personnel will be critical for developing guidelines that are realistic for concrete production and construction practices that can be incorporated into ODOT specifications. Dr. Ideker will work closely with ODOT to ensure that an updates to ODOT specifications, as a result of this research project are clearly defined, updated and disseminated to relevant parties. Dr. Ideker will be glad to help ODOT in the development of a training workshop or manual to better provide contractors with information to successfully incorporate strategies identified in this research project to reduce early-age cracking in high-performance concrete.
INTERNAL CURING OF CONCRETE BRIDGE DECKS WORK PLAN
Quarterly Reports:
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| SPR 712 |
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Near-Surface Mounted CFRPs for Shear Strengthening
| Project Coordinator: |
Steve Soltesz |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Chris Higgins |
| Start Date for ODOT: |
July 2009 |
| Completion Date for ODOT: |
December 2011 |
OBJECTIVES:
The objectives of the proposed research are:
· Develop analysis, design, detailing, and installation quality assurance recommendations for NSM-CFRP shear applications.
· Compare the cost of NSM versus external CFRP reinforcement installations.
1.1 Benefits
Research will reduce project costs and improve bridge strengthening project outcomes by enabling effective and durable design alternatives that may make use of NSM-CFRP materials to minimize installation labor and reduce the amount of inorganic chemical compounds used for repairs. Findings may also be extended to flexural strengthening. Finally, this project will further enhance ODOT’s leadership role in applications of CFRP materials for bridge strengthening.
OVERVIEW:
ODOT is actively engaged in bridge rehabilitation and strengthening throughout the state. One area of focus has been in shear strengthening of conventional reinforced concrete deck girder bridges (RCDG). A number of methods have been deployed including internal and external supplemental steel stirrups, post-tensioning, surface-bonded carbon fiber reinforced polymers (CFRP), and post-tensioning.
A new strengthening system called near-surface-mount CFRP has emerged that may permit shear and flexural strengthening of RCDG bridge members. This relatively new technology involves cutting a groove in the surface concrete, filling the groove with an epoxy adhesive, and positioning CFRP material (often a carbon fiber tape or precured laminates) in the groove. The installation requires substantially less labor and uses significantly less inorganic adhesive materials than alternative CFRP methods. Test results completed at Oregon State University (OSU) on a single large girder with NSM-CFRP show promise for use of this material, but additional data are needed. Further, recent research on environmental durability of surface bonded CFRP for shear strengthening (a common alternative technique using bonded polymers) showed that for some cases, exposure to 300 cycles of freeze-thaw combined with available moisture can result in significant strength deterioration of the strengthened member and thus there is some uncertainty in the long-term performance of these systems. NSM application of CFRP appears to have advantages over more common surface-bonded CFRPs because the adhesive is applied within the groove which improves bonding between the two materials and may be more resistant to environmental degradation, as moisture cannot get trapped behind the material and lead to progressive strength loss from freeze-thaw exposure. However, NSM-CFRP for strengthening is a new technique with little available test data and has undocumented long-term durability under environmental exposure and fatigue conditions.
Due to this lack of information, it is uncertain if NSM-CFRPs will provide the resistance needed for shear strengthening over time. Experimental results are needed to quantify the structural performance of members strengthened with NSM-CFRP for validation of design methods for shear strengthening, as well as to enhance economy, and refine detailing and constructability. Further, experience with NSM-CFRP may facilitate other applications such as flexural strengthening of bridge members with poor flexural cut-off details.
PROPOSED ACTIVITIES:
Meetings and workshops will be held with ODOT personnel to present research findings in-progress as well as summary findings. Background information and findings will be described in reports, papers, and peer-reviewed journals. Design examples will be provided for the methods developed. Results will be reported at local, regional, and national meetings and symposia.
Web-based access to in-progress test data and images, analytical methods, and summary findings will be available on-line where appropriate.
NEAR-SURFACE MOUNTED CFRPs FOR SHEAR STRENGTHENING WORK PLAN
Quarterly Reports:
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| SPR 713 |
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Asphalt Binder Grade Selection for HMAC with RAP/RAS
| Project Coordinator: |
Norris Shippen |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Todd Scholz |
| Start Date for ODOT: |
November 10, 2009 |
| Completion Date for ODOT: |
March 31, 2011 |
OBJECTIVES:
The objectives of this research effort are to develop recommendations for:
1. A design process for selecting the grade of virgin asphalt binder for HMAC mixtures containing RAP or RAS, or combinations of RAP and RAS, such that the blended binder meets the design grade for the mixture;
2. A procedure for effectively and efficiently recovering asphalt binder from recycled asphalt shingles;
3. A procedure for batching virgin materials (binder and aggregate) with RAP or RAS, or combinations of RAP and RAS, for mix design purposes and ignition oven tests;
4. A procedure for determining ignition oven calibration factors for HMAC mixtures containing RAP and/or RAS;
5. QC/QA test procedures for mixtures incorporating RAP or RAS, or combinations of RAP and RAS, as well as independent assurance parameters associated with determining asphalt binder content based on incineration (ignition oven tests); and
The recommendations will be incorporated in a field pilot study that will evaluate the procedures when RAP and RAS are used in HMAC.
OVERVIEW:
Oregon currently allows up to 30% recycled asphalt pavement (RAP) by weight to be used in hot mixed asphalt concrete (HMAC). While not in current practice at ODOT, the use of blending charts for RAP proportions greater than 15% by weight is recommended to: a) establish the maximum RAP proportion so that the virgin binder properties are not adversely affected; or b) adjust the grade of the virgin binder so that the blended binder possesses the desired properties.
ODOT has also been approached about allowing the use of recycled asphalt shingles (RAS) in HMAC. The two principal sources of recycled asphalt shingles include manufacturer waste (which is in limited supply in Oregon), and post-consumer waste arising from removal of old shingles from roofs (which are commonly referred to as tear-off shingles, and are in abundant supply in Oregon). Irrespective of the source, RAS contains asphalt binder that is substantially stiffer than that used in HMAC in Oregon; hence, inclusion of RAS in HMAC could significantly impact the properties of the blended asphalt binder.
A preliminary investigation is currently underway at ODOT and Oregon State University to investigate how varying percentages of added RAP with a single percentage of added RAS impact the blended binder properties. Additional research is needed to extend the preliminary investigation to include a wider range of percentages of RAP and RAS, to develop a design process for selecting the virgin binder grade based on the varying proportions of RAP and RAS, and to investigate how inclusion of RAP and RAS affects the mix design process for HMAC that include these materials. In addition, significant difficulties with regard to recovering the asphalt binder from shingles were encountered in the preliminary investigation; hence, additional work is needed to identify or develop an effective and efficient procedure for doing so.
A key issue concerning the design, manufacture, and acceptance of HMAC mixtures (with or without RAP and/or RAS) is accurately determining the content of the asphalt binder in the mixture. ODOT currently uses calibrated ignition ovens (incinerators) for determining asphalt binder content of HMAC for mix design verification purposes as well as for both quality control (QC) and quality assurance (QA) purposes. However, over the past few years ODOT has been experiencing an increasing number of issues in validating the contractor’s test results for the asphalt binder content of mixtures containing RAP. Binder contents derived from QC/QA testing are used to determine pay quantities, payment for asphalt binder escalation, and price adjustments based on the ODOT statistical analysis processes. Accurate determination of the asphalt binder content (which requires an accurate determination of the calibration factor for a particular mixture and a particular ignition oven) is therefore essential for determining appropriate pay quantities and payment for asphalt binder in HMAC.
PROPOSED ACTIVITIES:
The recommended procedures will be utilized in the design and QC/QA processes for HMAC mixtures that incorporate RAP and/or RAS. They will also be used to determine more accurate pay quantities and price adjustments.
ASPHALT BINDER GRADE SELECTION FOR HMAC WITH RAP/RAS WORK PLAN
Quarterly Reports:
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