A recent study of reactive aggregates incorporated in cement mortar bars and soaked in airfield pavement deicers strongly suggests that there is a correlation between the deicers and acceleration of an alkali-silica reaction (ASR) or a reaction similar to ASR (Reference IPRF Project 03-9, Potential for Acceleration of ASR in the Presence of Pavement Deicing Chemicals). The absence of reactivity in mortar bars made with a known innocuous aggregate and soaked in pavement deicers has been confirmed.
The chemical reaction that does occur in concrete in the presence of reactive aggregates and deicers, primarily Potassium Acetate, needs to be understood. (Note: Potassium Acetate is singled out because it is the most common deicer used on airfield pavement).
Several questions have been raised as previous research has progressed.
- Do the laboratory studies accomplished using standard Accelerated Mortar Bar Test methods for ASR expansion, and modifications of the standard test to include deicer chemicals as the soak solution, correlate to field observations?
- In the presence of a deicer, a sharp increase in the concrete pore solution pH has been observed. Why?
- The product seen in mortar bars that have been soaked in deicer is a gel, similar to that seen from ASR, of high viscosity that disperses rapidly. What are the properties of the gel?
- Is it a combination of materials that results in the observed distress or is it strictly a problem associated with aggregates?
A forensic study of some of the airfield pavement that exhibits the distress condition believed to be associated with the use of pavement deicers must be accomplished. It is expected that the findings of that study will help explain under what conditions the observed distress initiates and why there is accelerated damage to the pavement. A definition of “reactivity,” as related to the potential for some airfield pavement concrete to have potential for a deleterious response in the presence of airfield deicer, must be established. The mechanism(s) that result in pavement deterioration must be defined. A screening technique, for concrete materials, must be developed that can be used to identify those materials, or combinations of materials, for the potential for deleterious reactivity in the presence of a deicer. The screening technique must be short in duration and applicable for both existing and new concrete pavement.
The research program should be accomplished as a step solution.
- Understand and define the nature of the mechanism(s) that result in deleterious distress of some concrete pavement as a result of deicer application. The study will incorporate a forensic analysis of concrete samples collected from both distressed pavement and pavement that does not show distress.
1.1 A history of those pavements identified for forensics analysis will be developed. The history will include the length of time that deicers have been used, the concentrations and chemical make-up of materials applied, and an estimate of the application rates. The physical and chemical properties of constituent materials of the concrete will be defined using actual materials where possible. Where possible, samples shall be extracted from pavements that show distress and from pavements of the same construction that do not show distress. In the case of pavements constructed before the advent of deicer use, identify the age of the pavement at the time deicer was first applied.
1.2 A history will be developed for those pavement(s) that do not show distress as a result of the use of deicer. The forensics shall provide an accounting for those pavements studied at those airports that use multiple or combinations of deicer. The history will include the length of time that deicers have been used, the concentrations and types of materials, and an estimate of the application rates. The physical and chemical properties of constituent materials of the concrete will be defined using actual materials where possible. In the case of pavements that were constructed before the advent of deicer, identify the age of the pavement at the time deicer was first applied.
1.3 Concrete cores will be extracted from the pavements included in items 1.1 and 1.2 and carried to a laboratory for examination. As a result of the forensic study, understand and define the relevant physical properties of concrete pavement that have been treated with pavement deicer and one from the same construction that does not display distress. The investigator will perform the necessary examinations to define the mechanism(s) that result in distress and interpret the impact of deicers on the relevant properties of the concrete that were examined.
1.4 The critical concrete properties defined by the forensics as being contributory to the distress development, as a result of deicer use, will be prioritized based upon the relevant potential of the influence on deleterious distress development.
When the forensic studies are complete, and the distress mechanism(s) have been identified, develop an ALPHA screening protocol that can be used to identify relevant concrete properties of materials from both existing and new concrete pavement. Establish threshold limits for the relevant properties that can define limits beyond which potential for distress development is unacceptable. The thresholds selected will define when distress potential is high and when potential for deleterious distress is insignificant. See Figure 1.
- When the ALPHA protocol is considered reliable, apply the protocol to a group of materials, defined by the research team, that are proportioned as a concrete for new airport pavement. Use the correlations developed from the existing pavement forensic analysis, and the relevant critical properties of concrete, and judge the effectiveness of the threshold limits that are established. If there is confidence in predicting the critical property threshold limits, the protocol is to be published as a BETA version.
The final product will be an Innovative Pavement Research Foundation (IPRF) report that provides a summary of the results of the forensic investigations. The report will define the mechanisms that result in distress development when concrete is exposed to deicer chemicals. The report will include a recommended screening protocol of materials and for determining potential for the development of distress mechanisms. At the conclusion of the research there should be a document(s) that the engineer, airport owner or constructor can read and gain an understanding of the problem and how to measure the potential for distress development as a result of using pavement deicer on airfield concrete.
The screening protocol developed as a result of gaining an understanding of the distress mechanism evolution should:
Be a procedure that, ideally, requires less than 30 days to perform,
Have defined threshold limits for the relevant properties, prescriptive or performance related, of a concrete mix that predicts potential for distress manifestation, and
Can be used to assess the potential for deleterious distress for existing concrete when exposed to airfield pavement deicer.
The final report will be provided to the IPRF in the form of two originals, in a camera-ready format, including any artwork, graphics or photos. An electronic version of the final report in a format compatible with off-the-shelf desktop computer publication software will also be provided. The investigator will not be responsible for the reproduction and printing of the final document(s), but will assist with minor editing requirements generated by the printing and reproduction process.
The investigator is expected to develop sub-tasks that when completed will result in completion of the project within the time and budget available. It is not necessary that the proposal reflect the exact budget or the planned time. However, any deviation from the designated resources must be justified and clearly explained in the proposal. The following are the minimum tasks that are considered necessary to complete the project.
Task 1 – Literature Review and Information Gathering.
A. Review existing literature. Provide a summary of any previous research or reported problems with deicing chemicals used in the airport environment. Review existing protocols that might be used and/or modified to accomplish the screening protocol that is to be developed as a part of this research.
B. Using the list of airports provided by the IPRF, develop a list of the deicing chemicals used on airfield pavements by those airports. The IPRF will provide the list of airports only after a contract to perform the work has been negotiated. The list will not be provided to those individuals or organizations responding to the RFP.
Task 2 – Document a Research Plan and Schedule. Develop a plan for doing the research. Define the techniques to be used for sampling existing concrete pavement and the format of the forensics analysis. The anticipated techniques and tests to be employed in the forensics will be straightforward. The forensics evaluation must include petrographic techniques to investigate and document the nature of distress manifestation observed in concrete samples.
Task 3 –Discuss a Concept for a Screening Protocol. Discuss a protocol, that may or may not include several different tests or techniques, that could be developed under this research. The intent of the protocol is to screen materials obtained from samples of existing pavement, or from a proposed concrete mix proportion, and use the data from the screening protocol to predict the potential for distress manifestation as a result of exposure of concrete to airfield pavement deicer. The protocol would ultimately be implemented in Task 6.
A 20% on-board review will be accomplished. The investigator will not proceed to Task 4 without the written approval of the IPRF. An on-board review must be scheduled at least 30 days prior to the actual meeting. The PI will submit the products produced from Task 1, 2 and 3 for technical panel review at least 30 days prior to the meeting. The location of the meeting will be coordinated with the IPRF. The investigator is responsible for documenting the comments of IPRF Technical Panel members and the disposition of their comments.
Task 4 –Perform Initial Visits to Airports. Visit the two (2) airports, designated by the IPRF, that report the presence of pavement distress because of the use of airfield pavement deicer. Develop a pavement history and obtain samples from those pavements that exhibit evidence of surface deterioration. If they exist, look at pavement that is of the same construction as the distressed pavement and have not been subject to the deicer application. For the latter, obtain a pavement history and concrete samples. If one exists, obtain samples and the history of pavement at the same airport from a different construction that does not exhibit evidence of surface distress. Visit one (1) airport, designated by the IPRF, that has concrete pavement where deicer is used but in which the distress manifestation does not exist or has not developed. Obtain the pavement history and sample the pavement from the latter for forensics analysis.
Task 5 –Perform the Forensics. Accomplish the forensics using the testing and protocols approved at the 20% review. As a result of the forensics, develop a hypothesis as to the nature of the distress development mechanism(s). Attempt to explain why the mechanism(s) did not develop in the pavements that were exposed to deicer but did not develop the distress. Based upon the hypothesis, prioritize the relevant properties that are present in the distressed pavement and suggest property thresholds that could be used to screen concrete materials for those undesired thresholds of properties for concrete exposed to deicer.
Task 6 –Adjust the Research Plan and Re-visit the Concept Protocol. Using the hypothesis developed in Task 5, adjust the research plan for the purpose of confirming the hypothesis formed. Further develop or modify the CONCEPT DRAFT protocol from Task 3.
As a part of the proposal, the Principal Investigator (PI) will submit the results of Task 5 and 6 as a report of the initial findings. The summary of initial findings is defined as the 40% review level of the research. The report will include the summary of observations of the forensics study and the lessons learned. The report should include the recommendations for the correction of the research plan, and/or modifications of test protocols, as deemed appropriate.
A 40% on-board review will be accomplished. The review will be a meeting between the PI and the IPRF Technical Panel. The initial findings report will be provided to the technical panel at least 30 days prior to the meeting. The investigator is expected to present to the technical panel discussion items that will result in policy decisions for critical elements that impact the future of the research. Additional research may be needed to respond to questions that are developed as a result of the on-board review. The Technical Panel will determine, based upon the results presented if the primary research will go forward. The work on Task 7 will not begin without approval from the IPRF. The location of the meeting will be coordinated with the IPRF. The PI is responsible for documenting the comments of IPRF technical panel members and the disposition of each comment.
Task 7 – Visit and Sample Concrete at Five Other Airports. The research team will visit and obtain concrete samples and pavement history from at least five (5) other airports. The airports will be designated by the IPRF. Return samples of concrete to the laboratory and perform the forensics using the protocols and tools developed in Tasks 5 and 6.
Task 8 – Refine the Concept Protocol and Perform Evaluations of Concrete Extracted from Pavements. Perform the ConceptProtocol on samples of concrete previously used for the forensics evaluation. If the protocol is considered reliable, the Concept Screening Protocol is to be defined as the ALPHA version.
A 60% on-board review will be accomplished. The review will be a meeting between the PI and the IPRF Technical Panel. The findings of the investigation through Task 8 will be provided to the technical panel at least 30 days prior to the meeting. The investigator is expected to present to the technical panel discussion items that will result in policy decisions for critical elements that impact the future of the research. Additional research may be needed to respond to questions that are developed as a result of the on-board review. The Technical Panel will determine, based upon the results presented if the primary research will go forward. The work on Task 9 will not start without approval of the IPRF. The location of the meeting will be coordinated with the IPRF. The investigator is responsible for documenting the comments of IPRF technical panel members and the disposition of each comment.
Task 9 – Visit and Obtain Concrete Samples from Two Other Airports. The research team will visit at least two (2) more airports and obtain pavement history and concrete samples. Samples will be returned to the laboratory and the ALPHA protocol performed. Perform the forensics and validate the screening potential for the ALPHA protocol. Define limits for the relevant properties used in the screening for the potential for development of deleterious distress of concrete in the presence of deicers. If the ALPHA protocol is considered reliable, perform screening of concrete materials selected and proportioned by the PI and asses the probability that the protocol will screen for the relevant properties. If the predictions are considered to be reliable designate the ALPHA protocol BETA.
Task 10 – Prepare Draft Final Report. Make corrections to the 60% report. Include in the report the results of Task 9, all artwork, graphical presentations, format, etc. The document shall be in a form that for all intent is complete with the exception of final comments made by the Technical Panel. The submittal of the advanced final report is designated as the 90% review point of the research project.
A 90% on-board review will be accomplished. The advanced final report will be submitted to the IPRF Technical Panel for review. The Technical Panel will have 30-days to perform a desk top review and comment on the report. The report will include a summary of the results of testing and recommendations for the research plan that should be followed for mitigation of problems that are discovered as a result of the research. The investigator is responsible for documenting the comments of IPRF Technical Panel members and the disposition of comments made on the report.
Task 11 – Final Report. Make corrections to the 90% document and submit the final documents to the IPRF. Assist the IPRF with publication related editing.
- A brief summary of the literature search, a research plan with time schedule and a discussion of a CONCEPT Protocol for that might have potential use for screening concrete materials to predict the potential for deleterious distress manifestation of airfield concrete subjected to deicing chemicals. Submit 9 copies. This is defined as the 20% level of completion.
- The 40% and 60% on-board review will be accomplished approximately 30-days after submittal of interim reports. The interim report(s) (9 copies) will include a summary of all research completed to date.
- Advanced final report submittal (9 copies) for 90% review.
- A final report (an IPRF Report) that includes recommendations based on the research with all artwork, graphics, tables, pictures, documentation, etc. ready for reproduction and distribution. The report will be submitted as two original documents and one on electronic media.
1. Research Team Members and Qualifications.
1.1 The Principal Investigator (PI) will have a working knowledge of concrete mixture proportioning for use in airport pavements and has demonstrated experience in the differentiation of construction related and material distress. The PI will define as a part of the proposal the technique that will be employed to define when the research results describe a reasonable answer after reasonable resources have been expended.
1.2 The research team will include a petrographer qualified with relevant experience. The petrographer, as a part of the proposal, will describe the approach to the forensic analysis and the employment of advanced technology that might be employed during the progress of work. The persons actually doing the petrography will be described by experience level and peer group review for qualifications.
1.3 The research team will include having access to an individual who understands cement and pavement deicer chemistry and has specific expertise in the chemical and engineering properties of concrete.
2. During the research team visits to airfields, the research team is responsible for coordinating their own arrangements for access to the pavements that are the subject of this study.
3. The research team will investigate any FHWA and other programs that are initiated during the period of this research and have similar goals and/or objectives.
4. The research team will use Potassium Acetate as the “airfield pavement deicer” because it is the most commonly used at airports.
5. The PI will be responsible for the preparation of quarterly reports that describe the progress of the research effort. Reports are due in the offices of the IPRF on the last day of the fiscal year quarter. The reports will be limited to two pages in a format specified by the IPRF. The first page will be a word document describing the progress of the work. The second page will provide a summary of the estimated costs versus the costs incurred to the report date.
After the technical panel completes the evaluation of proposals, each of the proposals will be rank ordered. The organization, group, or individual that is ranked as the first and second choice for the recommendation to award may be asked to participate in a telephone interview. The Principal Investigator, and one other person, representing the entity ranked first and second choice by the technical panel may be asked to participate in the interview to discuss the project details, goals, and objectives. The interview will occur within a 45-day window subsequent to the proposal submittal deadline.
IPRF PROCEDURAL GUIDANCE:
Persons preparing proposals are urged to review the following documents to be sure that there is a full understanding of IPRF procedures and requirements. Proposals must be prepared in the format specified in the instruction documents. The proposal will be submitted as one (1) original and 9 copies.
documents required to aide in the preparation of the proposal
Program Formulation and Management (October 2005)
for Preparing and Submitting Proposals - IPRF Project 01-G-002-05-7
Instructions for Preparing a Numbered Paragraph Subordination
Type Technical Document
Aviation Administration Order 9550.7A, Research Grants Program,
April 19, 2001.
PDF files require Acrobat Reader to view.
AVAILABLE: Not to Exceed $480,000
TIME: Not to exceed 27 Months
DIRECTOR: Mr. Jim Lafrenz, P.E., (785) 742-6900, (firstname.lastname@example.org)
NOTICE TO PROCEED DATE: December 20, 2006
DUE DATE: October 27, 2006 not later than 4:00 P.M. (Central Time)
will be delivered to:
Pavement Research Foundation
Cooperative Programs Office, Attn. Jim Lafrenz
201 Shawnee Street
Hiawatha, KS 66434
FAX: (785) 742-6908