RESEARCH PROBLEM STATEMENT:
The numerous variables encountered in the process of determining flexural strength of concrete, using ASTM C-78, are well documented as sources of error. The people that routinely use C-78 can cite numerous examples of disputes that involved intangible sources of error such as field sampling and curing, laboratory curing, machine calibration, etc. Variables that cannot be controlled include batch to batch variability, impacts of field curing, handling and transport of specimens, etc. The magnitude of the potential error for the latter is unknown.
There are also physical property variables that influence the measured flexural strength of concrete that can be controlled and they include aggregate type, aggregate gradation, cement content, concrete slump, entrained air content, etc. There are documented studies that report the influence of each.
The precision of the laboratory test procedure ASTM C-78 is documented. ASTM C-78 reports the single operator coefficient of variation to be 5.7%. The multi-laboratory coefficient of variation is 7%. These precision statements are for a single operator and two different laboratories on a single batch using samples prepared in the laboratory, respectively. There has been no documented attempt to measure the impact and determine a precision statement for field cured specimens; or, what is the impact of the initial steps in determining the flexural strength of batch concrete?
OBJECTIVES:
Provide a statement as to a statistically valid measure of the inter-laboratory precision of the flexural strength of concrete for field sampled beams for a single batch using ASTM C-78. All test plan writing, recruitment of research participants, quality control and data analysis will be accomplished by a central laboratory under direction of a single investigator.
- Develop an experimental plan for meeting the objective. The plan should be detailed and written with clarity so that anyone participating can implement the steps necessary to attain the objective. Using created data, test the plan and determine if an analysis can be accomplished.
- Identify 10 qualified laboratories to participate in the study. If 10 laboratories cannot be identified, determine how many laboratories could participate and the results of the study remain statistically valid. Provide options if a statistically valid number of laboratories cannot be recruited from within a reasonable distance of a central hub location. Different operators on different machines within the same laboratory should be explored when necessary. The central laboratory should not be excluded as a testing participant.
- Identify a central hub location where a single batch of concrete can be mixed, samples obtained, beams field cured, and beams transported to the place identified for laboratory or wet cure. The concrete should be a P-501 mix with a flexural strength consistent with Federal Aviation Administration (FAA) circulars and policy.
- Distribute beams to each laboratory for curing and testing for flexural strength. The distance of transport, method of transport and timing with respect to curing will be critical to the end result. Each option for curing and transporting must be considered.
- Accomplish data analysis. If data is statistically valid, repeat the single batch test with a different flexural strength.
PRODUCTS:
The final document will be an Innovative Pavement Research Foundation (IPRF) report that addresses the stated objectives and provides designers, contractors, and owners with a document that provides an assessment of the precision of testing to determine flexural strength of field cured concrete beams. The report should clearly document the variables, the results and limitations of the data.
The investigator will provide two original documents, in a camera-ready format including artwork, graphics, and/or photos. The final report will also be submitted in an electronic format compatible with off-the-shelf desktop computer publication software.
TASK ORGANIZATION:
The investigator will be responsible for developing a series of sub-tasks that when completed will result in completion of this study within the time and budget available. It is not necessary that the proposal reflect the exact budget or the performance period indicated in the RFP; however, any deviation from the available resources must be justified and clearly explained in the proposal.
The following are considered as the minimum tasks that are necessary to do the work to complete the study. The proposal may include an increase in the number of tasks but the number of reviews by the Technical Panel will be retained.
Task 1 - Literature Review: The intent of the literature review is to include and not duplicate research results that have already been done in the area of field curing of concrete beams and precision statements. The investigator is encouraged to take advantage of research already conducted outside the airport concrete pavement environment and include the findings when applicable.
Task 2 - Experiment Plan: The investigator will develop a plan for executing the project. The plan will identify the minimum tasks necessary to achieve the objectives and will include an outline of the final report. The plan will discuss key elements of the outline, summarize the literature review, and identify any pitfalls that might be expected. The plan will include precise statements for execution by the participating entities. Accomplish a “test” of the plan by doing data analysis of created results based upon a mythical implementation.
A review will be accomplished at the end of Task 2. The investigator will not proceed to Task 3 without the written approval from the IPRF. The review should be scheduled for a period of 10 working days beginning with the first working Monday following the date of submittal. Written comments will be provided to the Investigator. If topics of discussion arise, a conference call will be used to allow participants to mediate the discussion.
Task 3 –Identify a “hub” location and 10 Participants: The study shall be implemented beginning with selection of a hub location that will mix the concrete. There should be at least one uniformity test of the mixing plant accomplished as a part of the “single batch” or prior. Identify 10 laboratories that will be at the hub location on the date of mixing. Individual labs will sample the concrete and prepare beam specimens.
A review will be accomplished at the end of Task 3. The investigator will not proceed to Task 4 without the written approval from the IPRF. The review should be scheduled for a period of 10 working days beginning with the first working Monday following the submittal of the hub location and the participant laboratories. The plant configuration, specifications and proposed materials to be used for the concrete mix will be included in the submittal. Testing participants and qualifications will be identified. Written comments will be provided to the Investigator. If topics of discussion arise, a conference call will be used to allow participants to mediate the discussion.
Task 4 – Implement the Study: When the plan, the hub location and the study participants are approved by the Technical Panel, the study shall be implemented.
Task 5 – Data Analysis and Draft Report Preparation: A draft report will be prepared and submitted to the IPRF. The draft report will include documentation and results of the Tasks as accomplished.
A review of the draft report will be held after the submission of the draft report. Comments of the technical panel will be provided.
Task 6 – Repeat Tasks 3 through 5. This Task is subject to resources available. Additional funding will be made available if study suggests that a statistically reasonable answer can be expected. Repeat of the experiment will be at flexural strengths higher and / or lower than the value selected for the current study.
Task 7 - Final Report: The investigator will submit the final report to the IPRF.
PRODUCTS SUMMARY:
1. Submit 5 copies of the literature review findings, experiment plan and instructions for experiment accomplishment.
2. Submit 5 copies of the identification of the “hub” location and study participants.
3. Submit 5 copies of the Draft Final Report.
4. Final deliverables include a Final Report (as two originals) complete with all artwork, graphics, tables, pictures, documentation, etc. ready for reproduction. The report will also be submitted on electronic media compatible with desktop publication software.
OTHER CONSIDERATIONS AND REQUIREMENTS:
The investigator is responsible for the preparation of quarterly reports that describe the progress of the research effort. Quarterly reports are due in the offices of the IPRF on the last day of the last month of the fiscal year quarter. The reports will be limited to two pages. 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 through the end of the quarter.
The investigator will, as a minimum, reference the following as baseline. Deviations from the reference Standards is permitted when the Investigator can define the impact.
- ASTM C-670-03, Preparing Precision and Bias Statements for Test Methods for Construction Materials.
- ASTM C 802-96 (2002), Conducting an Inter-laboratory Test Program to Determine the Precision of Test Methods for Construction Materials.
- ASTM E 177-06b, Use of the Terms Precision and Bias in ASTM Test Methods.
- ASTM C 78-08, Flexural Strength of Concrete (Using Simple Beam and Third Point Loading).
SPECIAL CONSIDERATIONS:
As part of the selection process, the IPRF technical panel will evaluate each proposal and each of the proposals will be rank ordered. The organization, group, or individual ranked as the first and second choice for the recommendation to award may be asked to participate in a telephone interview with the Technical Panel. The Principal Investigator and one other person representing the investigating team will be asked to participate in the interview. The interview, if it does occur, will occur within a 45-day window subsequent to the proposal submittal deadline. The IPRF will attempt to notify the people that submit proposals of the approximate date that interviews will be accomplished.
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 5 copies.
The documents required as an aide to the preparation of the proposal include:
FUNDS
AVAILABLE: Incurred Cost Not to Exceed $100,000 (Task 6 Not Included)
CONTRACT
TIME: Approximately 7 Months
PROJECT
DIRECTOR: Mr. Jim Lafrenz, P.E., (785) 742-6900, jlafrenz@pavement.com
ESTIMATED
NOTICE TO PROCEED DATE: February 27, 2009
PROPOSAL
DUE DATE: January 30, 2009 not later than 4:00 P.M. (Central Standard Time)
DELIVERY
INSTRUCTIONS:
Proposals will be delivered to:
Innovative Pavement Research Foundation
Cooperative Programs Office, Attn: Jim Lafrenz
201 Shawnee Street
Hiawatha, KS 66434
Fax: (785) 742-6908
